quan trac & phan tich moi truong

7/28/2019 Quan Trac & Phan Tich Moi Truong

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Li gii thiu

Quan trc v phn tch mi trng (QT&PTMT) l mt hot ng quan trng ca

cng tc qun l nh nc v bo v mi trng. Ti cc iu 37 v 38 ca Lut Bo vmi trng quy nh rng, B Khoa hc, Cng ngh v Mi trng (nay l B Tinguyn Mi trng) chu trch nhim trc Chnh ph v hot ng qun l nh ncv bo v mi trng v mt trong nhng ni dung cbn ca cng tc ny l: "Tchc, xy dng, qun l h thng quan trc, nh knh gi hin trng mi trng, d

bo din bin mi trng."

thc hin cc quy nh trn ca Lut Bo v mi trng, t nm 1994, BKHCN&MT ( nay l B Ti nguyn & Mi trng) tng bc xy dng Mng licc trm QT&PTMT quc gia. Mng li ny c xy dng trn csphi hp lin

b nhm tn dng c cc nng lc sn c v QT&PTMT ti mt s b, ngnh, aphng v nhanh chng a c Mng li vo hot ng phc v kp thi cc yucu cp bch v qun l mi trng. Ngoi Mng li QT&PTMT quc gia th vi nmtr li y, hng chc a phng trong nc cng bt u xy dng v bc u avo hot ng cc trm QT&PTMT a phng. Cng vi s pht trin ca hot ngQT&PTMT th nhu cu v b ti liu php quy hng dn vic bo m v kim sotcht lng ca hot ng ny ngy cng trnn bc xc.

Bn hng dn ny c son tho nh l mt trong cc n lc ca Cc Bo vmi trng, B TN&MT, trong vic m bo v kim sot cht lng ca hot ngQT&PTMT nhm a ra c cc s liu quan trc c tin cy v chnh xc cao.

Bn hng dn y s bao gm nhiu thnh phn mi trng khc nhau, bnhng dn u tin ny son tho cho quan trc mi trng nc lc a bao gm 2chng :

Chng 1 - Nhng vn chung, bao gm cc khi nim cbn v quan trcmi trng v hot ng m bo v kim sot cht lng trong quan trc mi trng

Chng 2 - Hng dn c th vm bo v kim sot cht lng trong quantrc mi trng nc lc a.

i tng p dng Bn hng dn ny l tt c hot ng QT&PTMT c tinhnh trong Mng li quc gia v cc trm QT&PTMT a phng. Bn hng dncng c thc s dng nh ti liu tham kho cho hot ng QT&PTMT ca ccB/ngnh khc.

Ti liu ny do Cc Bo v mi trng ch tr bin son vi s tham gia ca ccchuyn gia v quan trc v phn tch mi trng thuc cc n v sau:

1. Trung tm k thut mi trng th v Khu cng nghip, i hc Xy dngH Ni

2. Tng cc Tiu chun - o lng - Cht lng, B KHCN3. Vin Khoa hc v Cng ngh mi trng, i hc Bch khoa H Ni;


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Bn hng dn ny c coi nh c gng ban u nhng rt cn thit nhm nngcao cht lng v a dn vo n np hot ng QT&PTMT ti Vit Nam. B ti liuhng dn v QT&PTMT s cn c tip tc hon thin v b theo yu cu ca thct.

Do thi gian gp gp cng tc m bo v kim sot cht lng trong quan trcmi trng ti Vit Nam cn rt mi m nn Bn hng dn chc chn cn nhiu thiust. Cc Bo v Mi trng mong nhn c nhiu kin ng gp ca cc chuyn gia,cc nh khoa hc trong lnh vc QT&PTMT cng nh cc lnh vc lin quan tip tctrin khai v hon thin b ti liu quan trng ny.


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Chng 1

Nhng vn chung v bo m v kim sot cht lngtrong quan trc v phn tch mi trng

I.1. Mt s khi nim:

1. Quan trc mi trng (QTMT) l mt qu trnh o c thng xuyn mt hocnhiu ch tiu v tnh cht vt l, ho hc v sinh hc ca cc thnh phn mi trng,theo mt k hoch lp sn v thi gian, khng gian, phng php v quy trnh o lng, cung cp cc thng tin cbn c tin cy, chnh xc cao v c thnh gi cdin bin cht lng mi trng

2. Bo m cht lng (QA: Quality Assurance) trong quan trc mi trngl mth thng tch hp cc hot ng qun l v k thut trong mt t chc nhm bo mcho hot ng quan trc mi trng t c cc tiu chun cht lng quy nh.

3. Kim sot cht lng (QC: Quality Control) trong quan trc mi trng l victhc hin cc bin php nh gi, theo di v kp thi iu chnh t c chnh xc v tp trung ca cc php o theo yu cu ca cc tiu chun cht lngnhm bo m cho hot ng quan trc mi trng t cc tiu chun cht lng ny.

4. Khoch quan trc mi trngl mt chng trnh quan trc c lp ra nhm png mt s mc tiu nht nh, trong bao gm nhng yu cu v thng tin, cc thngs, cc a im, tn sut v thi gian quan trc, cc yu cu v trang thit b, phng

php phn tch, o, th; yu cu v nhn lc v kinh ph thc hin.

Cc hot ng QA/QC gn b vi nhau, b sung cho nhau v mt s ni dungging nhau, cng din ra trong khun kh h thng qun l cht lng ca t chc, vinh ngha h thng qun l cht lng l ccu t chc, trch nhim, cc th tc, qutrnh v ngun lc cn thit thc hin qun l cht lng.

II.2. m bo cht lng v kim sot cht lng trong quan trc v phn tchmi trng

1.2.1. QA/QC trong xc nh nhu cu thng tin

m bo cht lng ch c th thc hin tt khi cc yu cu v sn phm c xcnh r rng, c th. Cc yu cu v quan trc v nh gi l nhu cu c tnh cht thng

tin (nhu cu thng tin). Nhu cu thng tin l im khi u trong chu trnh quan trc vphn tch mi trng.

Nhu cu thng tin chung chung l khng c ngha. Nhng c nhng yu t lmphc tp vic xc nh cc nhu cu thng tin, c bit l trong hp tc quc t v quantrc v nh gi mi trng. V d: thiu cc thut ng, nh ngha cn thit; s g bdo chuyn ngnh ca cc chuyn gia; nhng tho thun phi t c...

Nhu cu thng tin phi phn nh chnh sch hin hnh v qun l mi trng vphi bao hm c nhng cn nhc, xem xt c tnh cht lu di. Csu tin xcnh nhu cu thng tin l cc lut v cc vn bn tho thun tm quc gia v quc t.

Ngoi ra, nhng yu cu phc v vic sot xt cc quy nh, vic xy dng mt chnh


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sch mi, quan im ca cc nh qun l hin hnh, cng l nhng cs xc nhnhu cu thng tin.

Hnh 1. Cc bc ch yu trong quan trc v phn tch mi trng

1.2.2. QA/QC trong xc nh chng trnh quan trc

T nhu cu thng tin, phi xc nh mc tiu v nhu cu quan trc c th, tc lphi xc nh mt chin lc cho vic quan trc.

Chin lc quan trc phi quyt nh r loi quan trc cn thit: vt l, sinh hc,ho hc, thu vn, cht thi hoc cnh bo sm ... Phi qui nh cc thng s cn quan

trc, chnh xc v tin cy cn thit v.v... Cn vic thit k mng li s xc nh nphi c quan trc nh th no. Chin lc quan trc cng phi bao gm c vic phntch s liu v bo co, v nhng cng vic ny c th c nh hng ti cc yu cu cavic thit k mng li quan trc. Chin lc quan trc phi c lm thnh ti liu vcn c nhng ngi hay cquan c thm quyn ra quyt nh ph duyt

Cc thnh phn ca mt bo co chin lc quan trc l:

1. Cc nhu cu thng tin bao gm trong chin lc quan trc v phn nhu cuthng tin s khng bao gm trong chin lc quan trc.

2. Khi nim v h thng quan trc v i tng quan trc (vt l, ho hc, sinh

hc, thu vn, cht thi...), cc thng s cn quan trc v cc iu kin ban u la

Qun l mi trng

Phn tch trong PTN

Nhu cu thng tin S dng thng tin

Chng trnh quan trc

Thit k mng li

Bo co

Phn tch s liu

Ly mu v quan trc tihin trn

X l s liu


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chn a im v tn sut ly mu i vi tng bin s (nh khong cch ln nht/ bnht tnh tng bin; tin cy...).

3. Khi nim v h thng nh gi, v d nh cc phng php tnh ton c sdng ( tnh ton mc e do hoc khuynh hng); cc tiu chun quc t ph hp

nht; vic s dng th, cng c thng k v cc cng c khc trnh by s liu.4. Cc kha cnh v mt t chc: t chc no s chu trch nhim v mt no ca

h thng quan trc; nhng thay i cn thit trong t chc, nhng kh khn cho victhc hin h thng quan trc v.v... s hp tc gia cc b phn, cquan thc hin.

5. K hoch thit k v thc hin mng li quan trc; nhng iu kin banu l g, k hoch ca nhng bc tip theo v k hoch ti chnh.

6. S phn tch v cc ri ro; nhng vn c th dn ti cc tht bi ca hthng quan trc v nu ln bin php khc phc.

1.2.3. QA/QC trong thit kmng liThit k mng li phi c mt nhm chuyn gia c kin thc a ngnh thchin. Thit k mng li cn xc nh thng s no phi quan trc, quan trc a imno v vi tn sut bao nhiu. Trong thit k mng li cng cn cp ti vic s dngcc phng php ly mu, cc phng php phn tch trong phng th nghim v cc

phng php x l s liu.

Cn c bit quan tm n vic ng dng thng k trong thit k mng li. Vics dng thng k hc c th lm gim n mc ti thiu cc a im thng qua mitng quan gia cc trm. Thng k hc cng l cs chn la gia hai phng n:nhiu a im vi tn sut thp hoc t a im vi tn sut cao.

Mt vn quan trng trong thit k mng li l xc nh tnh hiu qu cathng tin nhn c t mng li. Cn c s hiu bit chi tit v chi ph v hiu qu camng li thit k.

Thit k mng li phi c ti liu ho bng mt vn bn. Vn bn ny phichuyn ti nhng ngi ph trch v qun l chin lc quan trc quc gia. T vn bnny h s rt ra kt lun l mng li quan trc c nm trong chin lc v mc tiuquan trc chung hay khng.

Bo co thit kmng li gm cc phn sau:

1. Gii thch phn chin lc quan trc c cp n trong thit k mng liv phn ca thit k mng li khng c trong chin lc quan trc.

2. M t mng li quan trc: cc bin s cn o; cc a im ly mu v tnsut; vic s dng cc tiu chun, v d TCVN; ISO...

3. Cch thc trnh by v th hin cc kt qu.

4. Cc kha cnh v mt t chc. V d nh nhim v ca cc t chc tham giai vi tng bc khc nhau trong chng trnh quan trc: thu thp, x l v vnchuyn mu, phn tch trong phng th nghim; x l s liu; phn tch s liu; boco...

5. K hoch thc hin ca mng li quan trc.


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6. Cc kt qu phn tch chi ph- hiu qu; m t cc tranh lun ra quyt nh.

7. Phn tch cc ri ro. Ci g s xy ra nu c sai st v cc bin php no c ththc hin trnh hoc gim thiu cc thit hi.

1.2.4. QA/QC trong hotng ti hin trng

Hot ng ti hin trng bao gm ly mu v quan trc hin trng. Tu thucvo thnh phn mi trng m c cc phng php tin hnh khc nhau.

1.2.5. QA/QC trong hotngphng th nghim

QA/QC phng th nghim chnh l vic xy dng v p dng h thng qun lcht lng trong c san xen, kt hp cc hot ng QC, theo yu cu ca ISO/IECGuide 25 TCVN 5958: 1995, Yu cu chung v nng lc ca phng th nghim/hiuchun hin nay c chuyn thnh mt tiu chun quc t mang tn ISO/IEC 17025:1999, tng ng vi TCVN ISO/IEC 17025: 2001.

1.2.6. QA/QC trong xl sliuTrong mt chng trnh quan trc, s liu thu c s dng thng l rt ln.

thun li cho s dng, hu ht cc s liu ngy nay u c lu gi trong cc files liu ca my tnh. C hai loi s liu c lu gi. Mt loi c lu gi sntrong my tnh v mt loi l nhng s liu o c ca chng trnh quan trc hinhnh. Phi m bo cho cc loi s liu ny c phn bit r rng, khng nhm ln vinhau v an ton.

Khi s dng phn mm ca my tnh, cn phi c bit quan tm n vic kimtra, pht trin v duy tr h thng my tnh. Phn mm ca my tnh cng c th thc

hin cc chc nng kim sot khc nhau, nh cc php phn tch tng quan v vic sdng cc cp gii hn.

1.2.7. QA/QC trong phn tch sliu

Phn tch s liu l giai on chuyn s liu th thnh thng tin s dng c. nhng thng tin nhn c t s liu th c th so snh v truy nguyn ngun gc, phitrin khai cc bin bn phn tch s liu.

Phi c phng php t liu ho chun mc nhm bin cc s liu c thnh csd liu truy cp v x dng khi cn thit.

1.2.8. QA/QC trong lp bo co

Mc tiu cui cng ca mt chng trnh quan trc l chuyn thng tin thu thpc ti ngi s dng thng tin. C th thc hin cng vic ny bng nhiu cch khcnhau: truyn ton b cc php phn tch s liu hoc ch l nhng kt lun ngn gn

bng vn bn, li ni hoc bng s... Mt s k thut trnh by s liu c s dngrng ri l:

1/ Cc bng sliu o

Cch lit k s liu o vo trong cc bng to iu kin khng lm mt s liu.Tuy nhin, t cc s liu trong bng, ngi c s liu phi t to thnh cc thng tin

cn thit cho mnh.2/ Sliu o c xl thng k


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X l thng k s chuyn i s liu ri rc thnh cc gi tr h thng thay itheo thi gian v khng gian. Chng to ra thng tin c th s dng ngay cho ngi c.

3/ th

th gip cho ngi c nhanh chng rt ra c nhng nhn nh tng qut.Bng vic nu ra cc tiu chun hoc cc ti liu tham kho trn th, tnh hnh mitrng c phn nh ng thc trng ca n. Cc th c th l dng ng, dng cthoc biu phn trm (% )...

4/ Thng tin c trnh by c tnh chta l

Cch trnh by ny gip hiu bit tt hn tnh hnh cht lng ca mi trng quaphn b khng gian ca cc thng s lin quan.

5/ Thng tin tng hp

Vic tng hp li cc s liu l rt cn thit x l nhanh mt lng ln s liu.

S dng cc ph lc l phng php hay c dng p ng yu cu ny.


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Chng 2

Hng dn m bo cht lng/kim sot chtlng (QA/QC) trong quan trc v phn tch mi

trng nc lc aII.1. Tng quan v bo m v kim sot cht lng trong quan trc nc lca

II.1.1. Mc tiuCc hot ng quan trc v phn tch mi trng nc din ra ngoi hin trng

(ly mu, bo qun mu, o c mt s thng s khng bn) v phn tch trong phngth nghim. thu thp c thng tin cn phi tin hnh mt lot hot ng bao gmt khu lp k hoch, thit k chng trnh, thit k mng li, ly mu, phn tch trong

phng th nghim v x l s liu.Mc tiu ca chng trnh m bo cht lng/kim sot cht lng (QA/QC) trong

hot ng quan trc v phn tch mi trng nc (bao gm nc lc a v nc bin)l cung cp nhng s liu tin cy v c kim sot v hin trng mi trng nc

bao gm cc thng s ch yu nh: nhit , pH, DO, kim loi nng, cn l lng, c, COD, BOD5/TOC (vi nc bin), clorua, amoni, tng P, tng N, tng coliform,trm tch, ph du, vi sinh vt... tho mn yu cu thng tin cn thu thp, theo mc tiucht lng t ra, :

nh gi hin trng cht lng nc khu vc/a phng; nh gi din bin cht lng mi trng nc theo thi gian; Cnh bo sm cc hin tng nhim ngun nc; Theo cc yu cu khc ca cng tc qun l mi trng v pht trin kinh t.

II.1.2. QA/QC trong lp k hoch/thit k chng trnh

Khi lp k hoch quan trc phi bao hm cc ni dung chnh nh sau:

Xc nh ni dung nhim vt quan trc: a im/trm v, cc thng s cn oc, cc loi mu cn ly, thi gian thc hin.

Xc nh yu cu v nhn lc tham gia (s lng, lnh vc chuyn mn). Yu cu v trang thit b. Lp k hoch ly mu. Phng php ly mu v phn tch. Kinh ph cho chng trnh quan trc v QA/QC Cc vn m bo an ton con ngi, thit b cho cc hot ng quan trc nht

l quan trc trn sng, bao gm:

- Cc bin php, phng tin bo m an ton (ngi v thit b);


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- Phng n cu h;

- Lit k nhng vng nc xoy, bi ct ngm trong vng quan trc tu thuyn ntrnh;

- Nhng yu t thi tit bt thng c th xy ra trong thi gian quan trc.II.1.3. QA/QC trong thit k mng li

Thit k mng li l s la chn a im ly mu, la chn tn sut ly mu, thigian ly mu v loi mu cn phi ly. m bo cht lng/kim sot cht lng trongthit k mng li l lp k hoch ly mu p ng c yu cu mc tiu ca chngtrnh quan trc v phn tch mi trng.

- B tr cn b theo k hoch;

- Din ly mu, a im ly mu;

- Tn sut v thi gian;

- Cc dng ly mu; mu o ti hin trng, mu mang v PTN.

- m bo tnh kh thi v an ton;

La chn vng/im ly mu, la chn tn sut,thi gian ly mu v dng ly mucho tng loi nc c trnh by chi tit trong cc tiu chun TCVN 5994-1995(Hng dn ly nc h ao nhn to), TCVN 5996-1995 (Hng dn ly mu ncsng v sui), TCVN 5998-1995 (Hng dn ly mu nc thi), TCVN 6000-1995(Hng dn ly mu nc ngm), ISO 5667-13:1993 (Hng dn ly mu nc, ncthi v bn) cc trm quan trc nn nghin cu trc khi lp k hoch thit k mng

li bo m tnh khoa hc, phn nh c mc tiu cht lng, p ng nhu cu thngtin trong cng tc qun l mi trng.

II.2.m bo cht lng v kim sot cht lng ti hin trng

II.2.1. QA/QC trong hot ng ly mu

II.2.1.1. Mc tiu ca chng trnh kim sot cht lng ly mu

Mc tiu chng trnh kim sot cht lng ly mu l:

Cung cp c nhng phng php gim st v pht hin cc sai st do ly muv do c cc bin php loi tr cc d liu khng hp l hoc sai lc.

Chng minh c rng cc sai s ly mu c kim sot mt cch thch hp. Ch ra c cc thay i ca vic ly mu v t truy nguyn cc ngun gc

gy sai s.

Mc tiu ca vic ly mu l ly c mt th tch mu vn chuyn v x ltrong phng th nghim nhm phn tch chnh xc cc thng s cn thit ti v tr lymu.

Tu thuc vo mc ch ly mu l phn tch cc ch tiu (thng s) l hc, hohc hay vi sinh m la chn phng php ly mu thch hp.

Mu c ly phi i din cho khu vc quan trc v khng gian v thi gian v png c cc yu cu ca chng trnh quan trc v phn tch mi trng.


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II.2.1.2.m bo cht lng ly mu

Mt k hoch m bo cht lng ly mu cn phi c thit lp, bao gm:

Cc nhn vin ly mu u c o to v tp hun. Chun b cng tc thc a chu o: dng c, thit b, ho cht thuc th bo qunmu phi y v ph hp. m bo rng cc phng php ly mu u c ph bin ti tt c cc nhn

vin trong nhm quan trc.

m bo rng mi mt bc ly mu hin nay v qu trnh ly mu trc y utun theo mt vn bn.

m bo rng dng c ly mu v my mc o c hin trng phi c bo trv hiu chun nh k, s sch bo tr cn phi c lu gi.

Quy nh thng nht v nhn dng mu c ly bao gm dn nhn ln tt c ccmu c ly, trn ghi chp chnh xc ngy thng, a im, thi gian ly mu v tnngi ly mu, s m hiu ca mu bng mc khng thm nc.

Quy nh v ghi chp li tt c cc chi tit c lin quan n vic ly mu vo binbn/nht k ly mu, nhng iu kin v cc bin ng bt thng t k thut ly muthng thng n nhng yu cu c bit.

Quy nh viu kin, ni cc dng c trnh lm nhim bn mu, lm schdng c ly mu, kim tra sch v hiu qu ca dng c (bng cch phn tch mutrng v mu so snh thch hp).

Quy nh v tin hnh bo qun mu cho tng thng s cht lng nc, trmtch, ph du, vi sinh vt ... theo cc ch dn trong cc tiu chun tng ng.

Bo m chnh xc ca cc php o, phn tch ngoi hin trng khi cc iukin mi trng khng c m bo. Cc thng s hin trng (nhit , m, psut...) cn phi ghi chp khi ly mu chuyn i cc gi tro c viu kin tiuchun khi lp bo co, th d: s liu pH phi chuyn viu kin 250C.

Cn phi m t chi tit:

Qu trnh trao i chi tit cho nhng ngi cha c nhiu kinh nghim vn c kh nng hon thnh vic ly v x l mu;

Qu trnh chun b thuc th v bo qun; Hng dn s dng dng c ly mu, my o hin trng ... b xung cho cc ti

liu vn hnh ca nh sn xut;

Phng php chun b mu QC; Tiu ch kim sot cht lng ( ngha l gii hn chp nhn);Phng php ly mu v cc ti liu cn phi xem xt thng xuyn v khng c

qu 1 nm/mt ln. Phng php cn phi c ph duyt li theo nh kc bit cs thay i v thit b hoc con ngi.

Khi ti liu c lu gi trong cc file my tnh, nhng thay i v phng php lymu cn phi c phn nh bng cch thay i cc m s my tnh c lin quan.


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Nguyn nhn gy ra sai sdo ly mu:

Nhng nguyn nhn gy ra sai s do ly mu c th l:

Nhim bn:Nhim bn do cc thit b ly v cha mu gy ra; do dng c cha mu bn; do sly nhim gia cc mu; do cch bo qun, lu kho v b tr vn chuyn mu khng

thch hp.

Tnh khng n nh ca mu:- Bn cht ca mu

- Tng tc ca mu vi dng c khc

- nh hng ca nhit , nh sng

Ly mu khng chnh xc:- Quy trnh ly mu khng ph hp,

- Khng tun thng quy trnh ly mu.

Vn chuyn mu:- Do thi gian vn chuyn mu qu gii hn cho php,

- Do iu kin vn chuyn khng ph hp.II.2.2. Kim sot cht lng hin trng

Kim sot cht lng hin trng yu cu phi tin hnh ly cc loi mu trng,

mu p nhm kim tra mc tinh khit ca ho cht dng lm cht bo qun, kimtra mc nhim bn ca dng c ly, cha mu, giy lc hay cc thit b khc c linquan n cng vic thu, bo qun v vn chuyn mu. Mu lp cng c thu nhmkim tra mc ti lp ca vic ly mu. Thi gian v tn xut ly mu trng, mu pv mu lp c xc nh khi thit k chng trnh. Ni chung khong 10 ln thu mu,tin hnh thu 1 ln cc loi mu trng, mu p, mu lp. Cch thc v ngha thu ccloi mu nh sau:

a, Mu trng dng c cha mu

Ly mt dng c cha mu mt cch ngu nhin, sau np dng c bng nc ct

mang ra hin trng. Mu ny c bo qun, vn chuyn v phn tch cc thng strong phng th nghim tng t nh cc mu thng thng. Mu trng loi ny nhmkim sot s nhim bn do qu trnh ra, bo qun dng c.

b, Mu trng dng c ly mu

Dng nc ct trng hoc vo dng c ly mu. Sau np vo chai cha mu.Mu c bo qun, vn chuyn v phn tch cc thng s tng t nh mu cn ly.Mu loi ny nhm kim sot mc nhim trong qu trnh bo qun, s dng dngc ly mu.

c, Mu trng thit blc mu


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Nu mu nc cn lc ngoi hin trng xc nh cc hp phn ho tan th ccb lc mu sc ra, bo qun v vn chuyn ngoi hin trng. Tin hnh ly mutrng dng c lc mu bng cch: cho nc ct hai ln lc qua dng c lc mu. Phnlc c np vo dng c cha mu v c bo qun vn chuyn v phng th nghimtng t nh cc mu ly phn tch cc thng s mi trng.

d) Mu trng vn chuyn v mu trng hin trng

Mu trng vn chuyn: cho vo dng c cha mu mt lng nc ct tinh khithoc nc kh ion, y kn np, chuyn t phng th nghim ra ngoi hin trng vc vn chuyn cng vi mu tht. Mu trng vn chuyn dng xc nh s nhim

bn c th xy ra khi x l, vn chuyn v bo qun mu.

Mu trng hin trng: cho vo dng c cha mu mt lng nc ct tinhkhit/nc kh ion v chuyn t phng th nghim ra ngoi hin trng. Ti hin trngnp dng c cha mu c m ra v x l ging nh cc mu tht. Mu trng hin

trng dng xc nh s nhim bn gy ra t cc dng c ly mu, dng c x lmu (cc loi mng lc) hoc do cc iu kin khc ca mi trng trong qu trnh lymu (do bi bc ln chng hn).

C th m t cch thc chun b mu trng theo s nh sau:

Cc thng tin v mu trng hin trng, mu trng vn chuyn cn phi c th

hin trong bo co cng vi mu tht. Khi cc cht gy nhiu c nhn bit cnphi iu tra tng nguyn nhn v kp thi khc phc.

e) Mu p (mu chia i)

Mu p c thu bng cch chia mt mu thnh 2 hay nhiu mu ging nhau.Mu ny s dng nh gi cc sai s ngu nhin v h thng do c s thay i trongthi gian ly v vn chuyn mu v phng th nghim.

f) Mu lp theo thi gian

Ly hai hoc nhiu mu ti mt a im. Mu loi ny nh gi s bin ng

theo thi gian ca cc thng s mi trng trong khu vc.g) Mu lp theo khng gian

Nc ct tinh khit

Phn A(Gi li trong phng TN) Phn B (Chia lm hai

Mu trng hin trng(X l nh mu tht)

Mu trng vn chuyn(Khng x l)


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Ly hai hoc nhiu mu cng mt lc trn mt lt ct ngang c xc nh trctrong thu vc. Mu loi ny dng nh gi s bin ng theo khng gian ca ccthng s mi trng.

h) Mu chun i chng hin trng:

Mu chun i chng vn chuyn l mt lng nc tinh khit c cha cht phntch (cht chun) bit trc nng c chuyn t phng th nghim ra hin trngsau quay trv cng vi mu tht. Ti hin trng khng mnp y mu. Muchun i chng vn chuyn dng xc nh c s nhim bn v s mt mt cht phntch c th xy ra khi x l mu, vn chuyn v bo qun mu ng thi cng xcnh sai s phn tch.

Mu chun i chng hin trngl lng nc tinh khit c cha cht phn tch(cht chun) bit trc nng c mang t phng th nghim ra ngoi hin trng.Ti hin trng, np y c mra v tin hnh x l nh mu tht. Mc ch ca vic

to mu chun i chng hin trng l xc nh s nhim bn hoc s mt mt chtphn tch xy ra do dng c ly mu, dng c x l mu v nh hng ca iu kinmi trng trong sut qu trnh ly mu cho vn phng th nghim.

Cc kt qu phn tch mu chun i chng hin trng cn phi c a vo boco cng vi mu tht. Khi xy ra s sai lch vi gi tr thc khng c chnh sa sliu m cn phi tin hnh iu tra v khc phc kp thi.

i) Mu lp hin trng

L hai (hoc nhiu hn) mu c ly ti cng mt v tr, s dng cng mt thit b lymu v c cng mt cn b tin hnh, c x l, bo qun, vn chuyn v phn tch

cc thng s trong phng th nghim tng t nh mu tht. Mu QC loi ny c sdng kim sot chm ca vic ly mu ngoi hin trng.

k) Mu thm

Vic thm cht phn tch (cht chun) bit trc nng vo nc ct hay nckh ion cng thi im ly mu ngay ti hin trng xem xt s phn hu cc thngs k t khi ly mu.

Mu thm c s dng khi bt u mt k thut mi hoc thit b mi bo mrng phng php hoc thit b l thch hp cho cc mu ang c ly c tnh phc tpnh vy. Vic thm cht chun vo mu phi do nhng cn b phn tch c kinh nghimthc hin.

II.2.3. QA/QC trong vn chuyn mu

II.2.3.1.m bo cht lng

Vn chuyn mu: cn phi c quy trnh vn chuyn mu ph hp nhm bo tonmu v mt s lng v cht lng. Trong quy trnh cn nu r mt sim chnhnh sau:

- Mu khi vn chuyn phi c nhn (k hiu) trnh nhm ln.- Th tc sp xp mu nhm trnh v.


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- Yu cu trong qu trnh vn chuyn: thi gian vn chuyn v nhit ca mu, yucu ny da theo tiu chun (TCVN, ISO) i vi tng thng s quan trc v cch

bo qun mu (bng 2.1).

Bng 2.1. Yu cu khi vn chuyn mu

TT Tn mu Cc yu cu khi vnchuyn

Ghi ch

- Phng tin vn chuyn: c xc nh trn csyu cu ca thng s quan trc(Bng 2.2).

Bng 2.2. Phng tin vn chuyn v ngi chu trch nhim

TT Tn mu Phng tinvn chuyn

Ngi chutrch nhim

Thi gianvn chuyn

Ghi ch

Giao v nhn mu: c thc tin hnh hin trng (nhm hin trng bn giaocho ngi vn chuyn, v phng th nghim (nhm hin trng hay ngi vnchuyn bn giao cho phng th nghim)) theo quy trnh vi ni dung c th hin

trong bin bn bn giao:- H v tn ngi bn giao:- H v tn ngi nhn:- Thi gian bn giao:- S lng mu:- Tnh trng mu khi bn giao:- Ghi ch (nhng im bt thng cn quan tm):

Kim tra v loi b cc mu khng t yu cu nh v, bt nt,... v tin hnhkhi phc li cc mu b sai st nu c th.

Khi tip nhn mu, phi bn giao y v s lng, bo m cht lng, ghi chpr rng v tnh trng mu, nhng sai hng trong qu trnh vn chuyn

II.2.3.2. Kim sot cht lng

kim sot cht lng trong qu trnh vn chuyn mu, mu kim sot cht lngthng c s dng:

Mu trng vn chuyn: mt mu nh vt liu sch ca i tng nghin cu cvn chuyn cng vi mu tht trong cng mt mi trng, c bo qun, phn tch ccthng s trong phng th nghim nh mu tht. Mu QC loi ny c s dng kim

sot s nhim bn trong qu trnh vn chuyn mu.


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II.2.4. QA/QC trong o, phn tch ti hin trng

Mt s thng s khng bn nh nhit , pH, DO, cht rn llng, c cn cxc nh ti ch hoc ngay sau khi ly mu cng sm cng tt.

Khi o, phn tch ti ch cc thng s khng bn, cn phi ch :

La chn phng php phn tch ph hp khng hoc t bnh hng caiu kin bn ngoi hoc to cc iu kin mi trng thch hp (nh phng th nghimdi ng, b tr bung lm vic trn tu ...) bo m kt qu phn tch.

Nhng thay i bt thng khi ly mu Tnh trng hot ng ca thit b Ngn nga nhim bn mu:- o c hin trng: Khi o c cc thng s bng my mc ngoi hin trng (v

d pH, t

o

, mn,...) khng c nhng trc tip cc thit bo vo my ly nc mphi ly cc mu pho, sau khi o, mu phi i.

- Chai l cha mu phi c ra sch theo ng yu cu i vi tng thng s.Khng c tn dng cc loi chai l dng cha ho cht trong phng th nghim s dng cho vic cha mu.

- Dng c cha mu phi c bo qun trong mi trng sch s, trnh bi, khi vcc ngun gy nhim khc.

- Cc loi giy lc, b dng c lc phi c ng gi cn thn, bc bng cc chtliu thch hp.

m bo cc thit b hot ng quan trc ngoi hin trng lm vic chnh xc nnh, cn phi nh k hiu chun cc thit b ny theo cc quy nh ca nh sn xut.Tt c h shiu chun phi c lu gi.

Trong trng hp khng c iu kin hiu chun th phi c cc bin php nhnbit tnh trng lm vic ca thit b. Th d: so snh thng xuyn gia cc thit bging nhau hoc cng loi vi nhau theo mt ch tiu ph hp.

Trc mi t quan trc cn phi kim tra tnh trng hot ng ca thit b.

i vi nhng mu c phn tch ti hin trng (cht rn llng, c ...) cngphi tin hnh phn tch mu QC kim sot c cht lng s liu.

II.2.5. Thuc thho cht bo qun mu

Ton b thuc th v ho cht bo qun mu phi t tinh khit theo yu cu camc phn tch v c nhn dn r rng

Ho cht v thuc th bo qun c thc ong o trc v cho vo cc l nhhoc ampul v hn kn trnh phi pha ch ngoi hin trng.

II.2.6. Nc ct

Nc ct s dng ngoi hin trng cn phi ch :

Ph hp vi tiu chun,


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Khng s dng nc ct cha bit ngun gc, Khng dng nc ct qu hn.

II.2.7. Dng c cha mu

Dng c cha mu phi c phng phn tch lm sch trc v y np. Nu ciu kin phi bc giy trng paraphin mng chng bi. Dng c cha mu phi c kim tra nh k pht hin nhim bn bng cch

ly mu trng hoc thm cht chun nng thp.

Khng c ng mu trong dng c cha mu khng c np y. Trong nhng trng hp khi phn tch nhy cao phi s dng dng c cha

mu hon ton mi.

II.2.8. Kim sot cht lng v khc phc sai st

Cc k thut kim sot cht lng phi c p dng cho tng mu c ly, chomt lot mu v cc o c c thc hin ti hin trng.

Cn c s trao i thng tin gia ngi ly mu v ngi phn tch gii thchs liu v c bin php khc phc sai st.

S liu v kt qu QC phi c tp hp li thnh bo co. Lp biu kim sot lp kim sot cht lng s liu (ISO 5667-14). Nu kt

qu phn tch mu QC vt ra ngoi gii hn cho php cn tin hnh cc bin php khcphc.

II.3.m bo cht lng v kim sot cht lng trong phng th nghimII.3.1. Cc yu cu chung v nng lc phng th nghim phn tch mi trng

c th cung cp c nhng s liu tin cy, duy tr cc hot ng kim sot chtlng thng xuyn, mt phng th nghim phn tch mi trng (cnh hoc di ng)

phi p ng c cc yu cu v nng lc qun l v k thut theo chun mc caISO/IEC 17 025: 2002.

Cc yu t quyt nh mc chnh xc v tin cy ca php th do phng thnghim thc hin, bao gm:

Ccu t chc ph hp (ngi qun l v ngi thc hin). Yu t con ngi lm phn tch (cng tc tp hun, kim tra tay ngh), Trang thit b; qun l, bo dng, kim chun v hiu chun thit b, iu kin, vt cht, tin nghi v mi trng, Qun l mu th, Phng php phn tch v hiu lc ca phng php, Cht chun, mu chun,

Nh vy ngoi yu t qun l, con ngi, phng th nghim phi c csvt cht tin hnh cc php th c cht lng, tho mn mc tiu cht lng s liu.


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Phng th nghim phi tin hnh cc th tc kim sot cht lng, bao gm:

Thng xuyn s dng cht chun c chng nhn trong cc php th, Tham gia cc chng trnh so snh lin phng hoc th nghim thnh tho, T chc phn tch mu QC theo k hoch v duy tr thng xuyn .

II.3.2. Qun l muPhng th nghim phi t chc vn chuyn, tip nhn, bo qun, lu gi hoc thanh

l mu theo cc quy nh cn thit v thng nht nhm bo m tnh trn vn ca mutrc v sau khi phn tch theo:

Bo qun mu nc trong thi gian ngn: 40C Bo qun mu nc trong thi gian di: -200C Vi cc mu sinh vt, tissue: -200C

Vi mu trm tch: Tu vo i tng phn tch m s dng mu t hay kh.Nu s dng mu kh phi lm kh mu trong khng kh, nhit phng.

C th bo qun mu bng cch thm ho cht vi nhng lng thch hp. Nhngho cht c chn phi khng nh hng n vic kim tra tip theo hoc nh hngn kt qu.

Ghi chp li tt c cc bc bo qun trong bo co kt qu.II.3.3. La chn v cng nhn phng php phn tch

Phng th nghim phi s dng nhng tiu chun/phng php ph hp vi thit bsn c nhng phi p ng cc mc tiu cht lng v theo cc vn sau:

Thng s phn tch, Yu cu gii hn pht hin, chnh xc ca phng php ( chnh xc, chun xc), Yu cu v kh nng so snh s liu, S ph hp ca phng php vi cc iu kin phng th nghim.Phng th nghim phi tin hnh cc th tc chp nhn/ph duyt phng php

II.3.4. Kim sot cht lng

Kim sot cht lng bng mu QC

Mu QC phng th nghim dng nh gi hiu qu ca phng php trong phngth nghim v mu QC hin trng nh gi cht lng tng hp ca qu trnh thumu ngoi hin trng v phng php trong phng th nghim.

Cc kt qu mu trng hin trng c so snh vi cc kt qu mu trng phngth nghim phn bit s nhim bn ngoi hin trng v s nhim bn trong phngth nghim.

Mu thm hin trng c so snh vi mu thm phng th nghim phn bitcc vn bo qun v vn chuyn mu ngoi hin trng v cc vn bo qun mutrong phng th nghim.


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Mu lp ngoi hin trng c so snh vi mu lp trong phng th nghim phn bit chun xc ca vic thu mu ngoi hin trng vi chun xc ca phntch trong phng th nghim.

kim sot cht lng s liu, phng th nghim phi duy tr phn tch mu QC,

bao gm: Mu trng thit b (Blanks): s dng nc ct lm mu trng nhm nh gi

nhiu ca thit b v xc nh gii hn pht hin ca thit b. Gii hn pht hin ca thitb theo quy nh bng 3 ln nhiu ng nn.

Mu trng phng php (Method Blanks): s dng nc ct + cc cht chun bmu (ho cht to mi trng, ho cht che, thuc th hin mu ...) nhng khng ccht nh phn tch. Mu trng phng php nh gi gi hn pht hin ca phng

php, nh gi mc tinh khit ca ho cht s dng.

Mu lp (Replcates/Duplicates): Do tnh phc tp ca cc phng php phn tchmu nc nn ta khng th lm c tt c mu lp nh gi lch chun cng nh khng m bo ca php o. Nn nh cp trn chng ta ch lm mt s mulp/mu p cho mt nhm mu (1520 mu) nh gi tp trung ca php th.

Chun thm tra (Control Standards) Chun so snh (Refrence Standards) Mu chun i chng(CRMs): Vi mi trng nc, mu chun i chng thng

thng l cc mu ly ti hin trng hoc cc mu t to c thnh phn phc tp nhngoi mi trng, c a n nhiu phng th nghim c uy tn xc nh gi trtrung bnh v khong tin cy. Mu chun i chng c lm song song vi mu thc.

Cn c vo khong tin cy cho php ta nh gi kt qu phn tch mu thc. S liuphn tch mu chun i chng cn phi lu trong h sdi dng biu kim tra nh gi hiu qu cng nh sai s h thng ca phng php.

Mu ng hnh (Surrogate Compounds): mu ng hnh l cc mu c c imnh mu tht, cc cht phn tch trong cng c tnh cht vt l ho hc tng t vicc cht trong mu tht nhng li khng c trong t nhin, hoc s dng cc cht ngv phng x trong thnh phn nguyn t ca cc cht phn tch (14C, 37Cl...). Mu nghnh thng s dng khi phn tch cc hp cht hu cnh PAHs, thuc tr su.

Kt qu thc hin phn tch mu QC c i km vi s liu chng trnh quan trcv phn tch mi trng v trnh by nh bng sau:

Mu Kt qu

Mu trng thit b:Mu trng phng php:Chun thm tra:Mu No.1:Mu No.2:............Mu No.n :Mu lp No.2:

Mu lp No.m (m n)Mu trng phng php:


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CRM/Mu ng hnh:Chun so snh:

II.4. QA/QC trong tnh ton kt qu, ghi chp s liu phn tchCc kt qu phn tch trc khi ghi chp vo s phi c kim tra i chiu vi cc ssch gc nh: nht k thc a, s ghi kt qu phn tch. Vic kim tra c thc hin

bi t nht 1 ngi c trch nhim trong phng th nghim. Kt qu phn tch c ghivo biu kt qu phi cha ng c mt s thng tin quan trng di y:

Ngy thng phn tch, phng php phn tch. K hiu mu phn tch. K hiu v kt qu phn tch ca mu kim tra. Cc gii hn kim tra v cnh bo. Cc sc , th (nu c). H tn ngi phn tch, ngi tnh ton v ngi kim tra.

Sau khi s liu c i chiu, kim tra, lc mi c gi tr v c s dng vo ccmc ch khc nhau.

II.5. QA/QC trong bo co kt qu

Bn bo co kt qu phn tch m bo cht lng phi bao gm cc thng tin sau:- Tiu - Tn, a ch phng th nghim tin hnh phn tch

- Tn, a ch khch hng- Ngy, thng ly mu- Ngy, giphn tch- K hiu mu.- Tnh trng mu khi a vo phn tch- Phng php phn tch s dng- Sai s cho php- Kt qu phn tch mu trng thit b, mu trng phng th nghim, mu p v mulp

- Kt qu phn tch mu


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Ti liu tham kho

1. APHA, Standard Methods for the Examination of Water and Wastewater, 19thEdition, 1995

2. Britsh Columbia Field Sampling Manual, 1996 Edition3. Canadian Executive Agency, CPMS-II, Pollution Monitoring and Baseline

Studies- Environmental Monitoring Workbook 1997.

4. EPA Standard Methods, CD-ROM, Revision 1, July 19925. ISO 5667-14:1998, Water Quality- Sampling, Part 14: Guidance on Quality

Assurance of Enviromental Water Sampling and Handling

6. IUPAC, ISO, AOAC, Harmonised Guidlines for Internal Quality Control inAnalitycal Chemistry Laboratory, 1994

7. Jame P.Dux,Quality Assurance for the Anlytical Chemistry Laboratory, 2dEdition, Van Nostrand Reihold, 1991

8. Lawrence H.K. et all, Principles of Environmental Analysis, Ana.Chem, 1983,55, 2210-2218

9. TCVN 5993-1995, Cht lng nc-Hng dn bo qun v x l mu10.TCVN 5994-1995, Cht lng nc-Hng dn ly mu h ao t nhin nhn

to11.TCVN 5996-1995, Cht lng nc-Hng dn ly mu nc sng v sui12.TCVN 5998-1995, Cht lng nc-Hng dn ly mu nc thi13.

UN/ECE Task Force on Monitoring & Assessment, Guidelines on Water-Qualitymonitoring and Assessment of Tranboudary Rivers, May 1996

14.UN/ECE Task Force on Monitoring & Assessment, Volumn 4: QualityAssurance, Jaunuary 1996

15.Villars M.T. Monitoring water quality in the future, Executive summary, Deft, thenetherlands, May 1995.


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Ph lc 1: H thng qun l cht lng phng th nghim

H thng qun l cht lng ca phng th nghim/ hiu chun c quy nhtrong ISO/IEC 17025: 1999 gm hai nhm yu cu ln: cc yu cu v qun l v ccyu cu v k thut.

Cc yu cu vqun l bao gm:

1. T chc.

2. H thng cht lng.

3. Kim sot ti liu.

4. Xem xt cc yu cu, ngh v hp ng.

5. Hp ng ph v th nghim v hiu chun.

6. Cc dch v mua sm v ngun cung cp.

7. Dch vi vi khch hng.

8. Phn nn (hay kin ngh).

9. Kim sot vic th nghim v/hoc hiu chun khng ph hp.

10. Bin php khc phc.

11. Bin php phng nga.

12. Kim sot h s.

13. nh gi ni b.

14. Xem xt ca lnh o.

Cc yu cu vkthut bao gm:

1. Yu cu chung.

2. Nhn s.

3. Tin nghi v iu kin mi trng.

4. Phng php th nghim, hiu chun v ph duyt phng php.

5. Thit b.

6. Tnh lin kt chun o lng.

7. Ly mu.

8. Qun l mu th nghim, hiu chun.

9. m bo cht lng kt qu th nghim v hiu chun

10. Bo co kt qu.

Di y hng dn thc hin mt s vn then cht trong hot ng QA/QCca phng th nghim.

I. T chc v qun l phng th nghim


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t chc v qun l tt phng th nghim, cn thc hin mt s yu cu sau:

a/ Xc nh r ccu t chc ca PTN trong t chc m PTN trc thuc. Phnnh r nhim v, trch nhim ca tng cn b, nhn vin trong PTN. Xc nh c thngi l "cn b qun l k thut" chu trch nhim v cc hot ng k thut v ngil "cn b qun l cht lng" chu trch nhim m bo cho cc yu cu c quynh trong h thng cht lng c tun th v thc hin y .

b/ Phng th nghim phi thit lp mt h thng cht lng c th hin bng hthng cc vn bn, ti liu, gi chung l "h thng ti liu cht lng". H thng ti liucht lng ny bao gm: S tay cht lng; cc quy nh, th tc iu hnh nhng hotng, qu trnh c tnh cht chung ca phng th nghim; cc quy nh, ti liu c tnhcht ch dn cng vic c th.

C th hnh dung h thng ti liu cht lng trn bng s kim t thp diy. trn cng l S tay cht lng, cng mc di, s lng vn bn, ti liu cngyu cu nhiu hn.

c/ PTN phi nh k tin hnh vic nh gi ni b theo cc thi hn (thng l 1

nm) v th tc nh kim tra xem hot ng ca phng th nghim c lin tctun th cc yu cu ca h thng cht lng hay khng. Cn b qun l cht lng ctrch nhim lp k hoch v t chc nh gi theo chng trnh nh.

Khi vic nh gi pht hin ra nhng nghi ngv hiu qu ca cc hot nghoc v sng n ca cc kt qu phn tch, o, th, phng th nghim phi tin hnhcc hot ng khc phc kp thi, phi thng bo bng vn bn cho cc csc linquan bit v nhng sai st ny hiu chnh chng.

d/ Lnh o phng th nghim phi nh k, thng l 1 nm, xem xt li hthng qun l cht lng v cc hot ng phn tch, o, th ca phng th nghim

m bo s ph hp lin tc v tnh hiu qu ca chng v a ra nhng thay ihoc ci tin cn thit.

Cc thtc i u hnh

Cc ch dncng vic c th

S taycht lng


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II. Cc phng php phn tch, o th.

Yu cu chung l PTN phi s dng cc phng php v th tc ph hp vinhng yu cu c xc nh trong cc chng trnh quan trc v ph hp vi cc

php phn tch, o, th thuc phm vi hot ng ca PTN, bao gm c vic ly mu, xl, vn chuyn, lu kho v chun b mu.

a/ Chn la phng php

Tt nht l s dng cc phng php tiu chun ho, l cc tiu chun quct, tiu chun vng, tiu chun quc gia. Phi s dng nhng n phm mi nht ca cctiu chun. Khi cn thit, PTN phi hiu chnh cc tiu chun ny bng nhng chi tit bsung m bo s p dng thch hp.

PTN cng c th chn cc phng php thch hp c cng b trong cc tpch, cc sch khoa hc. Cc phng php ni b (do PTN t xy dng) cng c thcs dng nu ph hp vi yu cu quy nh v phi c th hin thnh vn bn, c

ph duyt theo th tc quy nh. i vi cc phng php cha c tiu chun ho nycn phi c s tho thun ca cquan qun l chng trnh quan trc. S tho thun nyc th hin bng mt vn bn quy nh r rng v cc yu cu v mc ch ca php

phn tch, o, th.

b/ Ph duyt phng php

PTN phi kim tra li cc phng php tiu chun, khng tiu chun v ccphng php mi khng nh cc phng php ny l ph hp vi mc ch s dng.


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Hnh 1. Hot ng QA/QC trong phng th nghim

Mc tiu cht lng

La chn phng php

Xy dng phng php

Bin son phng

Chp nhn phng php

- Kim tra hiu qu- nh gi hiu qu

Kim sot cht lng(bao gm bo tr thit b)

Sot xt/chp nhn li- Kim tra hiu qu- nh gi hiu qu

Tt Khng tt

Tt Khng tt


26/40

Phi ghi li cc kt qu ca vic ph duyt v th tc thc hin vic ph duyt ny.Vic ph duyt phi da trn cc thng s ca cc k thut phn tch c chn. Ccthng s v kt qu ph duyt phi c th hin bng vn bn v phi c lu tr.

S ph hp ca phng php c th kim tra bng cch so snh vi cc yu cuc trng cho vic s dng nh nh khng m bo ca kt qu, gii hn phthin, chn lc ca phng php, tuyn tnh, gii hn lp li hoc ti lp,kh nng chng li cc nh hng bn ngoi ...

Cc k thut c s dng ph duyt mt phng php c th l mt hoc mts trong cc cch sau: s dng cc chun o lng hoc mu chun; so snh kt qu vicc phng php khc; so snh lin phng; nh gi mt cch h thng nhng yu tnh hng n kt qu; nh gi khng m bo ca kt qu da trn hiu bit khoahc v cc nguyn tc l thuyt ca phng php v kinh nghim thc t.

c/nh gi khngm bo

PTN phi c th tc nh gi khng m bo ca tt c cc php phn tch,o, th.

Phi quan tm n tt c cc yu t gp phn vo khng m bo. Cc yu t l:

- Cc chun chnh, mu chun v trang thit b s dng;- Phng php phn tch, o thc la chn;

- iu kin mi trng;- c tnh ca i tng phn tch, o, th;- Ngi thao tc.Ti liu c bn nh gi, trnh by khng m bo o hin nay l

ISO/TAG4/WG3 "Guide to expression of uncertainty in measurement", 1993 v b tiuchun ISO 5725: 1994: chnh xc ( chnh xc v chm) ca phng php o vkt quo (ISO 5725: 1994 Accuracy (truness and precsion) of measurement methodsand results).

III. Trang thit b

a/ Trang thit b ca phng th nghim phi p ng cc yu cu ca tiu chunhoc phng php tng ng.

b/ Trang thit b phi c nh du, dn nhn phn bit v nhn dng cd dng, trong phn nh c tnh trng hiu chun, kim nh v thi hn hiuchun, kim nh tip theo ca n.

Phi duy tr v lu gi h sca tng loi trang thit b.

c/ Phi thit lp cc th tc bo dng v thc hin vic bo dng trang thit bthng xuyn hay nh k.


27/40

Trang thit b sai hng phi c dn nhn phn bit vi cc trang thit bbnh thng. Phi ngng s dng n cho n khi sa cha, hiu chnh xong v vic hiuchun hoc kim nh sau chng minh thit b hot ng tt.

Khi v l do no , trang thit b vt ra ngoi phm vi kim sot trc tip caPTN trong mt thi gian nht nh, PTN phi tin hnh kim tra m bo rng thit

b vn tt trc khi a vo hot ng trli trong PTN.

d/ Phi m bo tnh lin kt chun o lng ca tt c cc trang thit b caphng th nghim.

Thc cht ca yu cu m bo tnh lin kt chun chnh l vic thc hin mtchui php hiu chun k tip nhau i vi tt c trang thit b ca PTN, lm cho cctrang thit b ny u c so snh (trc tip hay gin tip), v tip l hiu chnh,

theo h thng chun o lng quc gia hay quc t, t m bo cho trang thit bo,th, phn tch lun tin cy v chnh xc. C th phng th nghim phi thc hin mt svic sau:

+ PTN phi xy dng v thc hin chng trnh hiu chun cho tt c cc trangthit b c nh hng r rt n gi tr v chnh xc ca cc kt qu phn tch, o, thtrc khi a chng vo s dng cng nh trong sut qu trnh s dng chng. Chngtrnh hiu chun phi bao gm c cc phng tin o dng cho cc php o ph tr, vdo cc iu kin mi trng.

+ i vi nhng trang thit b khng th thc hin c vic hiu chun nu trn,

PTN c th p dng cc bin php sau:- Tham gia mt chng trnh so snh lin phng hoc th nghim thnh tho c bng chng v s ph hp ca cc trang thit b lin quan.

- S dng cc mu chun m cc gi tr v thnh phn v tnh cht ca n c chng nhn kim tra trang thit b.

- S dng cc chun hoc cc phng php c cc bn lin quan tho thun.

IV. Tin nghi v iu kin mi trng

a/ Yu cu chung l tin nghi ca PTN, bao gm c cc iu kin v mi trng,chiu sng v cc ngun nng lng, phi ph hp c th d dng thc hin mt cchng n cc php phn tch, o, th theo yu cu. Cn c s quan tm c bit khi vicly mu, hoc vic phn tch, o, th c thc hin nhng ni ngoi a im cnh ca PTN. Phi quy nh thnh vn bn cc yu cu i vi cc tin nghi v iukin mi trng c thnh hng n kt qu phn tch, o, th.

b/ PTN phi c cc th tc v thc hin vic gim st, kim tra chc chn rngmi trng khng tc ng xu ti vic ly mu; vic tin hnh phn tch, o, th. Victhc hin cc php phn tch phi c dng li khi cc iu kin mi trng khng ph

hp. Cn c bit kim sot s ph hp vi cc yu cu ca cc yu t nh s v trng


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v mt sinh hc, bi bn, nhng tn hiu in t gy nhiu, cht phng x, vic cungng in, nhit , m, rung ng, ting n v.v...

c/ Trng hp c nhng hot ng nh hng ln nhau, PTN phi phn lp mtcch c hiu qu nhng khu vc ny trnh nhng nh hng xu qua li.

d/ PTN phi thc hin s kim sot i vi vic s dng v ra vo phng thnghim m khng c nhim v hn ch nhng nh hng xu n kt qu phn tch,c bit l nhng ni c nh hng trc tip n cht lng cc php phn tch.

V. Nhn s

a/ Ban lnh o PTN phi m bo rng tt c k thut vin vn hnh trang thit bc trnh v nng lc cn thit. Trong PTN cc k thut vin cn thng xuyn

c nng cao trnh p ng yu cu thc t.b/ Nhim v ca cn b lnh o v k thut vin phi c phn cng r rng vc th hin bng vn bn.

VI. Qun l mu phn tch, o, th

a/ PTN phi c cc th tc thch hp cho vic qun l mu i vi tng thng s.b/ PTN phi c cc cch nhn dng v phn bit mu. Nhng k hiu nhn

dng phi c duy tr trong sut thi gian tn ti ca mu trong PTN m bokhng gy ra s nhm ln cc mu khi phn tch o, th khi lun chuyn, k c khi a

vo h s, ti liu.c/ Khi tip nhn mu, PTN phi ghi li mi s khng bnh thng hoc sai lch

so vi s m t trong cc phng php phn tch, o, th m PTN s dng; phi thamkho kin ca cc b phn lin quan h cho cc hng dn c th khi c s nghingv s ph hp ca mu.

d/ PTN phi c cc th tc v tin nghi phng trnh cc h hng i vi mutrong qu trnh lu gi, x l, chun b v tin hnh phn tch, o, th. Phi tun th cchng dn km theo mu.

VII. m bo cht lng cc kt qu phn tch

PTN phi m bo cht lng kt qu phn tch bng cch theo di lin tc cckt qu. Vic theo di phi c lp thnh k hoch v c th bao gm cc cch sau:

Cc s kim tra cht lng ni b bng cch s dng k thut thng k. Tham gia cc chng trnh so snh lin phng hoc th nghim thnh tho. S dng u n cc mu chun c chng nhn. Ti to li cc php phn tch bng cc phng php ging hoc khc nhau. Phn tch nghim li cc mu c lu gi.


29/40

Xem xt s tng quan gia kt qu vi cc c trng khc nhau ca mu.VIII. Kim sot cht lng trong phng th nghim

QC phng th nghim chnh l mt chng trnh nh gi an xen vo cc hot

ng ti hin trng v trong phng th nghim nh gi chnh xc v ngn ca cc php phn tch o th (gi vn tt l cc php o).

Cc qu trnh QC c thc hin bng vic phn tch u n mu kim sot chtlng (mu QC) sau khi mt phng php c chng minh l thch hp cho vic sdng thng qua s ph duyt phng php.

Cc mu QC c dng trong phn tch mi trng gm hai loi: mu QC phngth nghim v mu QC hin trng.

Mu QC hin trng xem mc 1.4

1. Mu QC phng th nghim

Mu QC phng th nghim gm hai loi: mu QC phng php v mu QC thitb.

Mu QC thit bCc mu QC thit b dng nh gi v kim tra cht lng ca kt qu do thit

b mang li. Mu QC thit b bao gm: chun kim sot (control standard); chun thmtra (verification standard); mu trng thit b (instrument blank).

Mu QC hin trng

Mu QC

Mu QC phng th nghim

Mu QCphng th nghim

Mu QC phng phpMu QC thit b

Mu QC thit b


30/40

+Mu trng thit b: mt mu nh dung mi, thng l nc ct, c cho trctip vo thit bo s nhim do thit b gy ra. Mu ny thng dng nh gin nh v nhiu ca thit b.

+ Chun kim sot: l chun dng kim tra chnh xc ca cc chun cdng chun ho thit b.

+ Chun thm tra: l chun theo di n nh ca thit b theo thi gian.

Mu QC phng php:Mu QC phng php dng nh gi cht lng tt c tnh nng s dng ca

phng php trong phng th nghim. Mu QC phng php phng th nghim gm:mu trng phng php, mu lp phng th nghim, mu thm phng php, mu chunc chng nhn.

Mu trng phng php: L mu bng vt liu sch c tri qua cc bc x lging nh vi mu phn tch, o, th. Mu ny c dng nh gi s nhim to

ra trong ton b mt th tc phn tch, o, th.

Mu lp phng th nghim: Hai hoc nhiu hn cc phn ca cng mt mu tnhin c chun b v phn tch ring r bng cng mt phng php. Mu ny dngnh gi tp trung ca kt qu phn tch , o, th trong phng th nghim.

Mu thm phng php: Mu, vt liu sch hoc thuc thc cho thm vomt lng bit ca mt hay nhiu yu t phn tch v c x l ging nh khi phntch, o, th. Mu thm nh gi mc sai lch gy ra do nh hng ca nn v sais ca phng th nghim, cc sai s hiu chun, sai s chun b muv.v...

Mu chun c chng nhn:

Mu QCphng php

Mu chun cchng nhn

Mu lpphng th ghim

Mu thmphng php

Mu trngphng php

Chun thm traMu trng thit b Chun kim sot


31/40

Vic phn tch mu chun trong phng th nghim trc ht l nh gi sai s,ng, sai s h thng ca phng php c s dng.

2. Tiu ch chp nhn ca kim sot cht lng v bin php khc phc

Kim sot cht lng c thc hin thng qua vic phn tch, o hoc thnghim mt s loi mu QC nu trn nhn dng cc ngun sai s xc nh. Tuynhin kt qu phn tch, o, th cc mu QC s ch c ngha khi a ra c cc giihn so snh vi chng. V d khi phn tch mu trng hin trng, mu trng vnchuyn, mu trng thit b... cn c cc gi trnh mc thch hp bit mc nhim gy ra trong qu trnh ly mu, vn chuyn mu, hoc do thit b gy ra cn chpnhn c hay ti mc nguy him, cn truy tm nguyn nhn loi b n. Hoc khihiu chun thit b bng cch so snh vi chun, s xc nh c sai s s ch ca thit

b ny. Nhng cng vi n phi bit sai s cho php ln nht ca thit b l bao nhiu quyt nh xem c cn hiu chnh a sai s v phm vi cho php hay khng v.v...

Mt v din hnh l s dng cc "gii hn cnh bo" v "gii hn kim sot".Nh khi phn tch"mu lp phng th nghim", ta xc nh c lch chun s ctrng cho s phn tn ( tp trung) ca phng php (th tc) phn tch c s dng.Gii hn cnh bo c ly l 2s v gii hn kim sot c ly l 3s. Gi tr 2s v 3sgi l gii hn cnh bo v gii hn kim sot trn (k hiu l UWL v UCL). Gi tr -2s v -3s gi l gii hn cnh bo v gii hn kim sot di (k hiu l LWL v LCL).Khi s thnh tho ca PTN tng ln, gi tr ca cc gii hn ny s nh xung. Cc gii

hn 2s va 3s ng vi mc tin cy 95,45% v 99,73%. iu ny c ngha l vi 100php phn tch ta hy vng nhiu nht l ch c 5 php phn tch c gi tr vt qu giihn cnh bo v c 300 php phn tch hy vng ch c 1 gi tr vt qu gii hn kimsot. Vi mt gi tr nn xc nh ta c biu kim sot sau y:

Khi gi tr thu c vt ra khi gii hn cnh bo, ngha l bt u c nhngvn phi quan tm xem xt v khi gi tr thu c vt qu gii hn kim sot, cngha l vn trnn nghim trng v nguy him. Cc bin php khc phc phi

c ra v thc hin. Bng di y cho mt v d v cc hnh ng khc phc trongmt tnh hung c th.

UCL3s

UWL2s

Nn

LWL-2s

LCL-3s


32/40

K hoch khc phc cc sai st ca QC

A. Cc gi thit:

1.

Trung bnh c 1 trong 20 im o vt qu gii hn cnh bo (WL) 2 lchchun (2SD) v 1 trong 300 im o vt qu gii hn kim sot (CL) 3 lchchun (3SD).

2. ng trung tm l x ln gii hn pht hin ca phng php (MDL) vi x tnht l 20 ln MDL.

3. Tiu chun v cc hnh ng x l p dng cho cc im o nm trn v digii hn ca tham s v khng p dng nu cc im o nm trn hai cn catham s.

B. Bin php khc phc

Tham s thng k Tiu chun Hnh ngGii hn kim sot(CL) l 3SD (3s)

1. Mt im o vt qu CL2.a. Cc php phn tch lp li < CL2.b. Cc php phn tch lp li > CL

1. Lp li php phn tch2.a. Tip tc phn tch2. b. Dng li v hiu chnh

Gii hn cnh bo(WL) l 2SD (2s)

1. 2 hoc 3 im o > WL2.a. im o tip theo < WL 2. b.im o tip theo > WL

1. Phn tch mu khc2. a. Tip tc phn tch2. b. Dng liv hiu chnh

lch chun (SD) 1. 4 hoc 5 im o > 1 SD2.a. im o tip theo < 1SD2.b. im o tip theo > 1SD

1. Phn tch mu khc2. a. Tip tc phn tch2.b.Dng li v hiu chnh

ng trung tm(CTL)

1. im o trn CTL2.a. im o tip theo di CTL2.b. im o tip theo trn CTL

1. Phn tch mu khc2. a. Tip tc phn tch2. b. Dng li v hiu chnh

C. Sau khi tin hnh cc hot ng khc phc

Phn tch li mt na s mu nm gia im cui cng trong gii hn kim sotv im ngoi cng ngoi gii hn kim sot.

IX. So snh lin phng th nghim v thnghim thnh tho

Mt trong cc bin php kim sot cht lng PTN c hiu qu l vic t chc vtham gia so snh lin PTN v th nghim thnh tho.

* So snh lin phng th nghim (Interlaboratory compairison)L vic t chc v thc hin nh gi cc php phn tch i vi cc mu hoc vt

liu th hon ton ging nhau hoc tng t nhau bi hai hay nhiu PTN theo s thothun vi nhng iu kin c xc nh.


33/40

So snh lin PTN nhm cc mc ch: xc nh nng lc ca PTN i vi cc phpphn tch, o, th nghim; kim tra s tng thch v nht qun ca s liu i vi tngc nhn k thut vin ca PTN; thit lp cc phng php phn tch; o, th mi; giiquyt s khc nhau gia cc PTN; xc nh gi tr cc mu chun c chng nhnv.v...

* Thnghim thnh tho (proficiency testing)

L vic xc nh cht lng thc hin vic phn tch bng cch so snh lin PTN.

Mc ch ca vic th nghim thnh tho chnh l nhm xc nh nng lc caPTN i vi cc php phn tch do cc PTN cng b.

Th nghim thnh tho c thc hin bng chng trnh th nghim lin PTN.

* Chng trnh th nghim lin PTN (interlaboratory testing programmes)L vic so snh lin PTN trong cc mu ca mt vt liu thng nht c

phn pht thc hin cc php phn tch thch hp ti cc PTN tham gia.


34/40

Ph lc 2. X l s liu theo phn b chun

(phn b Gauss)

1. lch chun ca phng php bit

Kt qu ca php o 1 ln c trnh by nh sau:Q= X ts; vi P = 95%

Trong : Q l gi tr thc ca i lng;X l gi tr thu c t php o 1 ln, c coi l kt quo (l gi tr

ca i lng o);P l xc sut (mc tin cy);t l h s ph thuc P (bng 1 v bng 2 ca ph lc).

iu trn c ngha l vi xc sut tin cy P chn, sai s ca kt quo (X)nm trong gii hn ts, cng c ngha l gi tr thc Q ca i lng s nm trong

khong t X - ts n X + ts. Trng hp P c ly bng 95% (0,95), khi h s t = 2,c ngha l nu ta tin hnh 100 php o theo phng php y s hy vng ch c 5 lno c sai s vt ra ngoi gii hn 2s. Chn P bng bao nhiu l tu thuc vo yucu c th.

V d: Sai s ca php o mt ln c th bng bao nhiu nu phng php o cho c s =0,01 n v v c 100 ln o th trung bnh c 5 ln sai s vt qu gii hnquy nh. Bi ton ny cng c ngha l tm gii hn sai s ca php o vi s =0,01 vv P = 95%.

Bng 2 Ph lc I phn b chun cho ng vi P=95%, ta c t=2. Sai s ca phpo 1 ln trong trng hp ny l:

ts = 2 x 0.01v = 0,02 v

2. Trng hp cha bit lch chun s ca phng php

Thc hin n ln o (th, phn tch) lin tip cng mt i lng. Tnh gi trtrung bnh cng (x ) v lch chun thc nghim nh sau:

xn

x

n

nxxx

n

i

i==

++= 1

21 ...

trong : x1, x2 ....xn l gi tr thu c tng ln o;

n l s ln o lp li.

=s

( )

11

2

=

n

xxn

i

i

Gi tr trung bnh x c ly lm kt quo. lch chun s c trng cho sphn tn ca cc gi tro ring r xi xung quanh gi tr trung bnh x . Gi tr s ln cngha l cc gi tro ring r xi phn tn nhiu quanh x , tc php o c tp trungthp v ngc li.

Kt qu ca php o c trnh by nh sau:


35/40

Q = x sn

ts Vi P = ....

Trong : Q l gi tr thc ca i lng;x l gi tr trung bnh;

ts l h s ph thuc s ln o lp n v xc sut tin cy P chn c tratheo bng 1 v bng 2 phn b Student (ph lc)

s l lch chun thc nghim;P l xc sut tin cy.

iu trn c ngha l vi xc sut tin cy P chn sai s ca kt quo ( x )

nm trong gii hn

s

n

ts , c ngha l gi tr thc ca i lng s nm t

s

n

tx s n

+ s

n

tx s .

V d: xc nh chnh xc khi lng mt mu th, ta cn lin tip 6 ln mu, c cc kt qu sau (n v g):

72,631 72,34472,357 72,34673,352 72,340

Khi lng thc ca mu bng bao nhiu vi xc xut tin cy l 99%.

Tnh: x =6

ix = 72,350 g

=s( )

16

350,721

2

=

n

i

ix

8,06 x 10-3g

Tra bng 1 ph lc I, ng vi n = 6 v P = 99%, c ts = 4,03. Ta c:

sn

ts = gxgxx 33 10131086,06

03,4

Kt quo cui cng c th hin l:m =(72,350 0,013)g, vi P = 99%

3. Lm trn sKhi lm trn tr s ca kt quo, ngi ta cn c vo bc c ngha ca sai s. Tr

s ca kt quo phi tn cng bng con s cng bc vi tr s ca sai s. V d, khi sais l 5, con s tn cng s l con sng vi hng n v, khi sai s l 0,02, con stn cng s l s l phn trm...

lm trn s, p dng cc quy tc sau y:a. Nu k tip con s cui cng cn li khi quy trn l cc con s nh hn 5 th

khi quy trn, con s cui cng s khng thay i (quy trn xung hay gim).V d:

2,12 2,1

6,343 6,34


36/40

b. Nu k tip con s cui cng cn li khi quy trn l cc con s ln hn 5 thkhi quy trn, con s cui cng s tng thm 1 (quy trn ln hay quy trn tng).

V d: 3,14159 3,14168,248 8,25

c. Nu k tip con s cui cng cn li khi quy trn l con s 5 v sau con s 5c t nht mt con s khc khng th khi quy trn con s cui cng s tng thm 1(quy trn tng).

V d:4,3501 4,4

d. Nu k tip con s cui cng cn li khi quy trn l con s 5 v bit r con s5 ny c quy trn nh th no th con s 5 sc quy trn xung theo quy tca nu nh n c quy trn ln v sc quy trn ln theo quy tc b nu nh n c quy trn xung.

V d: 6,3149 c quy trn thnh 6,315 nu tip tc sc quy trn thnh

6,31. 4,1852 quy trn thnh 4,185, nu tip tc s quy thnh 4,19.e. Nu k tip con s cui cng cn li khi quy trn l con sng 5 (sau n ch

ton l s 0) th c th tu quy trn ln hay quy trn xung. Nhng nu cn s dng squy trn trong khi tnh ton th nn quy trn nh th no con s cui cng l con schn. Nh vy, con s cui cng s khng thay i nu n l con s chn v stng thm 1 nu n l con s l (quy tc s chn).

V d:

06200625016

1,, =

807504

3,, =

f. Nu k tip con s cui cng cn li khi quy trn l con s 5 nhng khngbit n l con sng 5 hay c quy trn, th xem con s 5 l con sng vquy trn theo quy tc e.

4. Loi b kt quo bt thng

Kt qu ca mt ln o ring r trong dy n php o cng mt i lng c coil bt thng nu n lch mt cch ng k so vi nhng gi tr cn li. Bng phn b

chun v phn b Student cho thy xc sut a = 1 - P mt kt quo ring r lch sovi gi tr trung bnh 3s hoc 4s l rt nh ( a ng vi xi - x > 3s l 0,3% v ng vixi - x > 4s l 0,01% ). Vy c kt qu no lch vi x qu gii hn 3s hoc 4s (tutheo P c chn) c th coi l mc sai s th v loi b chng trong qu trnh x l ktquo.


37/40

Bng 1

Gi tr tch phn xc sut dte)t(t t

=

0

2

2

2

2theo cc gi tr t cho trc

t F(t) t F(t) t F(t) t F(t)

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

0,55

0,60

0,55

0,65

0,60

0,75

0,80

0,85

0,90

0,0000

0,0399

0,0797

0,1192

0,1585

0,1974

0,2358

0,2737

0,3108

0,3473

0,3829

0,4177

0,4515

0,4843

0,5161

0,5467

0,5763

0,6047

0,6319

0,95

1,00

1,05

1,10

1,15

1,20

1,25

1,30

1,35

1,40

1,45

1,50

1,55

1,60

1,65

1,70

1,75

1,80

0,6579

0,6827

0,7063

0,7287

0,7499

0,7699

0,7887

0,8064

0,8230

0,8385

0,8529

0,8664

0,8798

0,8904

0,9011

0,9109

0,9199

0.9281

1,85

1,90

1,95

2,00

2,05

2,10

2,15

2,20

2,25

2,30

2,35

2,40

2,45

2,50

2,55

2,60

2,65

2,70

0,9357

0,9426

0,9488

0,9545

0,9596

0,9643

0,9684

0,9722

0,9756

0,9786

0,9812

0,9836

0,9857

0,9876

0,9892

0,9907

0,9920

0,9931

2,75

2,80

2,85

2,90

2,95

3,0

3,1

3,2

3,3

3,4

3,5

3,6

3,7

3,8

3,9

4,0

4,,5

5,0

0,9940

0,9949

0,9956

0,9963

0,9968

0,99730

0,99806

0,99862

0,99904

0,99932

0,99954

0,99968

0,99978

0,99986

0,99990

0,999936

0,999994

0,9999994


38/40

Bng 2Gi tr t theo gi tr tch phn xc sut cho trc

F(t) 1- F(t) t F(t) 1- F(t) t

0,50

0,60

0,70

0,75

0,80

0,85

0,900,95

0,96

0,97

0,98

0,99

0,991

0,50

0,40

0,30

0,25

0,20

0,15

0,100,05

0,04

0,03

0,02

0,01

0,009

0,675

0,842

1,036

1,150

1,282

1,440

1,6452,960

2,054

2,170

2,326

2,576

2,612

0,992

0,993

0,994

0,995

0,996

0,997

0,9980,999

0,9995

0,9999

0,99999

0,999999

0,9999999

0,008

0,007

0,006

0,005

0,004

0,003

0,0020,001

5.10-4

1.10-4

1.10-5

1.10-6

1.10-6

2,652

2,697

2,748

2,807

2,878

2,968

3,0903,219

3,481

3,891

4,417

4,892

5,327


39/40

Bng 3.

Gi tr tsng vi xc sut tin cy Ps v s ln o n khc nhau

Ps

n0,5 0,6 0,7 0,8 0,9 0,95 0,98 0,99 0,999

2

3

4

5

67

8

9

10

11

12

13

14

15

16

17

18

19

20

1,000

0,816

0,765

0,741

0,7270,718

0,711

0,706

0,703

0,700

0,697

0,665

0,694

0,692

0,691

0,690

0,689

0,688

0,688

0,674

1,376

1,061

0,978

0,941

0,9200,906

0,896

0,889

0,883

0,879

0,976

0,873

0,870

0,868

0,866

0,865

0,863

0,862

0,861

0,842

1,963

1,336

1,250

1,190

1,1561,134

1,119

1,108

1,110

1,093

1,088

1,083

1,079

1,076

1,074

1,071

1,069

1,067

1,066

1,036

3,08

1,886

1,638

1,533

1,4761,440

1,415

1,397

1,383

1,372

1,363

1,356

1,350

1,345

1,341

1,337

1,333

1,330

1,328

2,282

6,31

2,92

2,35

2,13

2,021,943

1,895

1,860

1,833

1,812

1,796

1,782

1,771

1,761

1,753

1,746

1,740

1,734

1,729

1,645

12,71

4,30

3,18

2,77

2,572,45

2,36

2,31

2,26

2,23

2,20

2,18

2,16

2,14

2,13

2,12

2,11

2,10

2,09

1,960

31,8

6,96

4,54

3,75

3,363,14

3,00

2,90

2,82

2,76

2,72

2,68

2,65

2,62

2,60

2,58

2,57

2,55

2,54

2,33

63,7

6,92

5,84

4,60

4,033,71

3,50

3,36

3,25

3,17

3,11

3,05

3,01

2,98

2,95

2,92

2,90

2,88

2,86

2,58

636,6

31,6

12,9

8,61

6,865,96

5,40

5,04

4,78

4,59

4,49

4,32

4,22

4,14

4,07

4,02

3,96

3,92

3,88

3,29


40/40

Bng 4

Gi tr xc sut tin cy Ps tng ng vi cc gi tr ts v n khc nhau

ts

n 2 2,5 3 3,5

2

3

4

5

6

7

8

9

10

11

12

13

14

1516

17

18

19

20

0,705

0,816

0,861

0,884

0,898

0,908

0,914

0,919

0,923

0,927

0,929

0,931

0,933

0,9350,936

0,937

0,938

0,939

0,940

0,955

0,758

0,870

0,912

0,933

0,946

0,953

0,959

0,963

0,966

0,969

0,970

0,972

0,974

0,9740,975

0,976

0,977

0,978

0,976

0,988

0,795

0,905

0,942

0,960

0,970

0,976

0,980

0,983

0,985

0,987

0,988

0,989

0,990

0,9900,991

0,992

0,992

0,992

0,993

0,997

0,823

0,928

0,961

0,975

0,983

0,987

0,990

0,992

0,993

0,994

0,995

0,996

0,996

0,9960,997

0,997

0,997

0,998

0,998

0,9995

quan trac & phan tich moi truong

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