ASH

and

MIN

ERAL

CO

NTE

NTS

OF

FOO

DS

(Cha

pter

s 9-

10-2

8)I.

Ashi

ng P

roce

dure

s

a-C

onve

ntio

nal a

shin

g (d

ry,w

et, “

plas

ma”

or l

owT°

)

b-In

dire

ct m

etho

ds fo

r ash

det

erm

inat

ion.

II.Po

st-a

shin

g pr

oced

ures

:Pro

pert

ies

of

ash

(alk

alin

ity;

acid

-inso

lubl

e as

h; s

alt f

ree

ash)

III.Q

ualit

ativ

e sc

reen

ing

test

s fo

r met

als

IV.Q

uant

itativ

e el

emen

tal

anal

ysis

fo

r in

divi

dual

m

etal

s(si

ngle

or s

imul

tane

ous)

a-At

omic

Em

mis

sion

Spec

tros

copy

b-At

omic

Abs

orpt

ion

Spec

tros

copy

(with

fla

me,

with

out f

lam

e)

c-IC

P an

alys

es

Ash:

The

inor

gani

c re

sidu

e re

mai

ning

afte

r eith

er ig

nitio

n (b

urni

ng) o

r com

plet

e ox

idat

ion

of o

rgan

ic c

arbo

nace

ous

mat

ter(

tota

l min

eral

con

tent

).

Inor

gani

c el

emen

ts o

ccur

in fo

ods

:

1.As

nat

ural

con

stitu

ents

com

ing

from

the

soi

l, ce

rtai

n re

gion

s an

d pl

ants

, min

eral

con

tent

s ar

e sp

ecifi

c.

2.As

add

itive

s to

pre

pare

d fo

ods.

NaC

l→ad

ding

pre

pare

d fo

ods.

It is

als

o in

the

ash.

3.As

con

tam

inan

ts m

igra

ting

to fo

ods

durin

g pr

oces

sing

i.e.

From

mac

hine

ry→

met

al m

igra

tion,

whe

n pr

epar

ing

the

food

. M

igra

tion

can

com

e fr

om m

etal

licm

ater

ials

like

pipe

sor

silo

s.

Rat

io o

f as

hin

foo

ds i

s ve

ry m

uch

rela

ted

with

th

e m

oist

ure

cont

ents

of f

oods

. H

2O↓A

sh↑.

In f

resh

fru

its:a

roun

d %

0.3-

0.8,

but

in

dry

frui

ts l

ike

apric

ots

≅%3.

5; A

sh i

n m

ilk ≅

%0.

5-1

(mai

nly

Ca)

, In

no

n-fa

t dr

y m

ilk≅%

8;In

fre

sh m

eat,

arou

nd %

1,fr

ied

fish

fille

ts a

roun

d 2.

5%. I

n cu

red

mea

ts ≅

%12

(fro

m N

aCl

andN

a N

O2,

NaN

O3)

. In

cere

als,

0.6

-1.6

%.

In v

eget

able

oils

≅pp

mle

vels

(is

rem

oved

in p

repa

ring)

The

met

al c

onte

nt i

n na

ture

rem

ains

the

sam

e. B

ut

tran

sloc

atio

n oc

curs

by

wea

ther

con

ditio

n, l

ike

rain

s,

flood

. T

here

are

als

o ot

her

natu

ralf

acto

rs li

ke v

olca

nic

erup

tions

. M

an-m

ade

>fly

-ash

-bur

ning

oil,

fos

sil-f

uels

al

so t

rans

loca

tes

met

als.

W

e ac

cum

ulat

ehu

ge a

mou

nt

of

ash

from

m

an-m

ade

sour

ces

like

sew

age-

slud

ge→

excr

etio

n, m

iner

al m

inin

g ac

tiviti

es, a

gric

ultu

ral

prac

tises

like

irrig

atio

n an

d us

e of

fert

ilize

rs,

traf

fic+c

ars

and

mot

or v

ehic

le e

xhau

st g

asse

s .

Met

als/

min

eral

s in

food

cha

in

1.of

Nut

ritio

nal i

nter

est=

Ca,

P, N

a, K

, Mg,

Zn.

....

2.of

tox

icol

ogic

al c

once

rns,

als

o ca

lled

"con

tam

inan

t"

Hg,

Cd,

Pb

, As

3. B

oth:

Co,

Cr,

Cu,

Sn

Con

cent

ratio

ns:

•mac

rom

iner

alsR

equi

rem

ents

>100

mg/

day

[Ca,

P, N

a, K

,Mg,

Cl,

S,]

•mic

ro (

trac

e) m

iner

als:

requ

irem

ents

~1m

g/da

y(in

foo

ds

mcg

/100

g

[I,Fe

, Cu,

Zn,

Cu,

Cr,F

,Se]

Den

sitie

s:

•Lig

ht m

etal

s (d

<5 g

/cm

3 ) C

a (1

.5),

I (4,

6), P

(1.8

),

•Hea

vy m

etal

s (d

>5 g

/cm

3 ) Pb

(11.

3), F

e(7.

8)

Bot

h nu

triti

onal

and

toxi

colo

gica

l : F

e (7

.8) a

nd C

u (8

.9)

Fe w

hen

high

er t

han

a ce

rtai

n co

ncen

tratio

n,

will

be

of

toxi

colo

gica

l con

cern

. B

elow

a c

erta

in c

once

ntra

tion,

it w

ill

be o

f nut

ritio

nal c

once

rn.T

wo

way

s of

exp

ress

ing:

1. M

AC i

n fo

od:m

axim

um a

llow

ed c

once

ntra

tion(

mg/

100g

fo

od

2.

AWI

in

diet

= Al

low

ed

wee

kly

inta

ke

for

met

als

of

toxi

colo

gica

l con

cern

i.e. A

WI cd

= 0.

0067

-0.0

083

mg/

kg b

.w. o

f hum

ans

Det

erm

inin

g to

tal a

sh in

food

com

mod

ities

Mos

tlyth

e an

alyt

ical

in

tere

stis

in “

tota

l am

ount

of

ash”

, no

t in

its

det

aile

d co

mpo

sitio

n. F

or e

xam

ple,

a c

erea

l te

chno

logi

st w

ill ,

just

fro

mth

e am

ount

of

ash

in “

flour

”,

have

an

idea

abo

utth

e re

lativ

e br

an c

onte

nt o

f th

at f

lour

, si

nce

min

eral

s ar

e in

hig

her c

once

ntra

tion

in th

e br

an la

yer.

Ever

yPr

oxim

ate

Ana

lysi

ssh

ould

incl

ude

the

tota

l as

h co

nten

t. As

hing

is

dete

rmin

atio

n of

th

e re

sidu

e af

ter b

urni

ng o

rgan

ic m

ater

ials

at e

leva

ted

tem

pera

ture

s(>5

50°C

).

Whi

le b

urni

ng,o

rgan

icac

ids→

carb

onat

es→

oxid

es

of m

etal

s. T

he t

race

met

als

are

foun

d lin

ked

to

cert

ain

orga

nic

mat

eria

ls

Ash

ing

Proc

edur

es:

DR

Y AS

HIN

GYo

u us

e at

mos

pher

ic o

xyge

n as

the

oxi

dant

. W

hen

the

sam

ple

is b

urnt

in a

muf

fle f

urna

ce a

t ab

out~

550

°for

~2

hour

s, w

e ob

tain

ligh

t-gra

y as

h. If

the

re s

till i

s so

me

blac

k m

ater

ials

,it m

eans

tha

t or

gani

c m

ater

ials

w

ere

notc

ompl

etel

y bu

rnt.

Adv

anta

ges:

1.Sa

fe

2.M

ultip

le sa

mpl

es

3.O

nly

oven

and

dis

hes n

eede

d

Dis

adva

ntag

es:

Elem

ents

such

as F

e, S

e, P

b, A

s,, C

r , Z

n,N

i,Cd,

Cu,

an

d H

g m

ay p

artia

lly v

olat

ilize

.

Con

tam

inat

ion

risks

Alte

rnat

ive

"cru

cibl

e” m

ater

ials

:Q

uart

z: re

sist

ant t

o ac

ids

and

halo

gens

but

not

to a

lkal

i.

Porc

elai

n:

like

quar

tz,b

ut

will

cr

ack

easi

ly

at

rapi

d te

mpe

ratu

re

chan

ges.

Also

it a

ccum

ulat

es tr

ace

met

als

from

pre

viou

s an

alys

es; f

or

clea

ning

up,

put

it in

aci

dbe

fore

nex

t use

.

Stai

nles

s st

eel:

resi

stan

t to

bot

h ac

ids

and

alka

li, b

ut i

ts N

i an

d C

r co

mpo

nent

s m

ight

cau

se c

onta

min

atio

n.

Plat

inum

:ver

y in

ert

mat

eria

l, an

d he

at c

ondu

ctiv

ity is

idea

l-But

isve

ry

expe

nsiv

e, a

lso

it co

rrod

es e

asily

, nec

essi

tatin

g us

e of

woo

den

tong

s.

Cer

tain

ana

lysi

s re

quire

Pt.

Cru

cibl

e.

2.M

odifi

ed d

ry a

shin

gpr

oced

ures

:

a.In

itial

burn

ing

with

ope

n fla

me,

then

moi

sten

ing

with

dilu

te H

Cl(

1) +

H

NO

3(2

), D

ryin

g on

ste

am b

ath,

inc

iner

atin

g.U

se o

f "a

sh-a

ids“

for

acce

lera

ting

ashi

ng,

for

prev

entin

gsp

atte

ring

and

avoi

ding

sam

ple

loss

. [E

xam

ples

for

ash

-aid

s: a

lcoh

olic

sol

utio

n of

Mg

acet

ate;

a dr

op

of H

NO

3,pu

re c

otto

n, p

ure

glyc

erin

] [A

“Bla

nk”

for t

he a

sh-a

id s

houl

d al

so b

e ru

n in

par

alle

l with

the

sam

ple

is a

sh a

ids

are

used

.]

Low

Tem

pera

ture

Pla

sma

Ash

ing(

9.2.

4)

•Sp

ecia

l typ

e of

dry

ash

ing

met

hod

whe

re fo

ods a

re o

xidi

zed

in a

par

tial v

acuu

m b

y ox

ygen

form

ed b

y an

ele

ctro

mag

netic

fie

ld in

the

spec

ial i

nstr

umen

t.Muc

h lo

wer

tem

pera

ture

av

oids

vol

atili

zatio

n of

met

als.

Mic

row

ave

ashi

ng(9

.2.5

):Fa

ster

met

hod.

Can

be

used

for

both

dry

and

wet

app

licat

ions

.Sy

stem

s allo

w fo

r te

mpe

ratu

re p

rogr

amm

ing

Wet

-Ash

ing

(Wet

dig

estio

n)Pr

oced

ure:

9.2

.3.2

: O

xidi

sing

org

anic

sub

stan

ces

with

str

ong

oxid

izin

g ag

ents

. M

iner

al a

cids

ar

e us

ed

as

oxid

ants

(P

refe

rred

fo

r ap

plic

atio

nbe

fore

ana

lysi

s of

elem

enta

l tra

ce

met

als)

[H2S

O4+

HN

O3+

H2O

2]

•Pe

rchl

oric

acid

[HC

lO4]→

pow

erfu

l ox

idan

ts

Ex: A

shin

gW

heat

with

(HN

O3+

H2S

O4]→

8 ho

urs

With

(HC

lO4+

HN

O3]→

10 m

inut

esYo

u sh

ould

cont

rol

the

colo

r of

the

ash

solu

tion:

it m

ust

be

clea

r an

d tr

ansp

aren

t w

hen

oxid

atio

npr

oces

s is

com

plet

ed.

Dry

ash

ing

Wet

ash

ing

Slow

Rap

id

Sim

ple+

easy

Nee

ds s

kill

T° h

igh

(loss

due

toT°

low

(no

loss

es o

f vo

latil

izat

ion)

vola

tiliz

atio

n)

No

supe

rvis

ion

Nee

d su

perv

isio

n

Mor

e sc

ope

of a

pplic

abili

tyLa

rge

sam

ples

are

not

co

nven

ient

No

chem

ical

reag

ents

Cor

rosi

ve-e

xplo

sive

rea

gent

s

CO

MPA

RIS

ON

OF

TH

E A

SHIN

G P

RO

CE

DU

RE

S

B-In

dire

ct m

easu

rem

ents

of t

otal

ash

con

tent

1-C

ondu

ctom

etric

met

hods

rel

y on

det

erm

inat

ion

of

tota

l ele

ctro

lyte

con

tent

of fo

od s

ampl

e.

Exam

ple

Appl

icat

ion:

On

an a

cidi

fied

suga

r so

lutio

n,

min

eral

s di

ssoc

iate

whe

reas

sug

ar (

non-

elec

trol

yte)

do

es n

ot. T

he c

ondu

ctan

ce m

easu

red

befo

re a

nd a

fter

acid

ifica

tion

is a

n in

dex

of to

tal e

lect

roly

te (

or m

etal

) co

nten

t.

2-Io

n-ex

chan

ge

colu

mns

: Ac

idic

-cat

ion-

exch

ange

co

lum

ns a

re u

sed.

By

titra

tion

ofth

e lib

erat

ed a

cid

exch

ange

d on

the

colu

mn

by th

e ca

tions

, the

qua

ntity

of

tota

lele

ctro

lyte

s ca

n be

det

erm

ined

.

II. P

ost-

ashi

ng P

roce

dure

s :P

rope

rtie

s of

Ash

:1-

Acid

-inso

lubl

e as

h=

(~%

10

HC

l) .in

solu

ble

soil

met

al

cont

amin

ants

like

sili

cate

s( in

dex

of d

irt, s

and,

soi

l).

2-Sa

lt-fr

ee a

sh=

Inde

x of

add

ed N

aCl,

Tota

l ash

is d

isso

lved

in

dilu

te

HN

O3

and

titra

ted

with

Ag

NO

3so

lutio

n fo

r N

aCl

dete

rmin

atio

n.

3-Al

kalin

ity o

f as

h*:

Titr

atio

n w

ith 0

.1N

HC

l.Sho

ws

acid

-bas

e ba

lanc

e of

food

. Ind

exof

frui

t con

tent

sof

jam

s:O

rgan

ic a

cids

in

frui

ts a

re t

rans

form

ed t

o ca

rbon

ates

and

oxi

des,

res

ultin

g in

al

kalin

ity.A

lso

dete

cts

adul

tera

tions

with

min

eral

s.

4-W

ater

-sol

uble

ash

: Als

o an

Inde

xof

frui

t con

tent

s. S

ince

met

al

oxid

es a

re w

ater

-inso

lubl

e,lo

wer

ash

in w

ater

sol

uble

fra

ctio

n m

eans

ext

ra f

ruit

was

add

ed a

nd

indi

cate

hig

her

amou

nt o

f fr

uits

.

•*As

h of

frui

ts is

alk

alin

e(C

a,M

g,K

,Na)

•*As

h of

mea

ts+c

erea

lsis

aci

dic(

P,S,

Cl)

III. Q

ualit

ativ

e Sc

reen

ing

Test

s fo

r Met

als

Col

our

reac

tions

of

indi

vidu

al m

etal

s ar

e do

ne

on th

e as

h .

Ex:P

b+di

thiz

one(

gree

n)→

red

colo

ur

Fe+o

-phe

nant

role

ne→

red

P+m

olib

date

→ye

llow

As(a

rsen

ic)+

silv

er→

red

(die

thyl

dith

ioca

rbam

ate)

and

copp

er

Form

atio

n of

col

ored

com

plex

with

som

e lig

and.

A p

air

of u

nsha

red

elec

tron

s can

coo

rdin

ate

cert

ain

met

allic

ions

to g

ive

com

plex

es

Qua

litat

ive

elem

enta

l ana

lyse

s rel

y on

this

pri

ncip

le.

Exa

mpl

e: F

e++(F

erro

us Io

n) w

ith p

hena

nthr

olin

e(o

rtho

phen

anth

rolin

es) f

orm

inte

nse

red

colo

r. T

he fe

rrou

s or

thop

hena

nthr

olin

eco

mpl

ex is

qui

te st

able

and

is so

met

imes

cal

led

Ferr

oin

Col

orim

etric

or

Spec

troph

otom

etric

Met

hods

NN

Fe++

....

IV.Q

UAN

TITA

TIVE

Ele

men

tal a

naly

sis

This

is

do

ne

for

quan

tific

atio

n of

in

divi

dual

m

etal

lic

com

pone

nts.

How

ever

, en

richm

ent

of

trac

e m

etal

s is

alm

ost

alw

ays

requ

ired

befo

re

such

ana

lysi

s. Y

ou h

ave

to s

epar

ate

the

huge

am

ount

of

othe

r m

acro

ino

rgan

ic

com

pone

nts

(like

Ca,

Na

etc.

) tha

t can

inte

rfer

e w

ith tr

ace

met

al

anal

ysis

ste

pwis

e by

:

1.Io

n ex

chan

gere

sins

(spe

cific

)

2.C

once

ntra

tion

afte

r ex

trac

tion

with

sp

ecifi

c or

gani

c so

lven

ts.

Step

1:

Ash

ing

Step

2:

Solu

buliz

eas

h in

Con

c. H

Cl-

boil

and

evap

orat

e so

lutio

n to

dry

ness

.

Step

3:

Re-

diss

olve

resi

due

in 0

.5 N

HC

l.

Step

4:

Con

c. o

r dilu

te a

s des

ired

Step

5:

Det

erm

inat

ion

of in

divi

dual

com

pone

nts b

y su

itabl

e m

etho

ds

Maj

or S

tage

s in

Elem

enta

l Ana

lysi

s

Met

hods

for

Qua

ntita

tive

Min

eral

Ana

lyse

s(C

h. 1

0)

•G

ravi

met

ric•

EDTA

com

plex

omet

ric•

Red

ox re

actio

ns•

Prec

ipita

tion

Ttra

tion

•C

olor

imet

ric

•Io

n se

lect

ive

elec

trode

s •

Flam

e em

issi

on, A

tom

ic A

bsor

ptio

n an

d Em

issi

on

Spec

trosc

opy

(Cha

pter

28)

Gra

vmet

ric a

nd T

itrim

etric

M

etho

dsG

ravi

met

ry:

•In

solu

ble

salts

of m

iner

als a

re

prec

ipita

ted,

rin

sed,

dri

ed,

wei

ghed

. C

alcu

latio

ns a

re b

ased

on

mol

ecul

ar fo

rmul

a of

salt.

•E

xam

ple:

Ca+

+ in

ash

is

diso

lved

in H

Cl,

prec

ipita

ted

as C

aoxa

late

with

am

mon

ium

ox

alat

e so

lutio

n, th

en b

urnt

to

CaO

, the

n w

eigh

ed

+cal

cula

ted

usi

ng th

e M

W

ratio

s (M

WC

a/M

WC

aO).

Titr

imet

ry:

a.E

DT

A C

ompl

exom

etri

ctit

ratio

n: E

DT

A fo

rms s

tabl

e co

mpl

exes

with

met

als:

M+2

+H

2Y-2

mY

-2+2

H+

Exa

mpl

e:[ C

a++

with

asc

orbi

c ac

id+h

ydro

xyna

phto

l blu

e in

dica

tor]

is ti

trat

ed w

ith

0.01

M N

a E

DT

A so

lutio

n to

de

ep b

lue

endp

oint

.

Red

ox a

nd P

reci

pita

tion

Rea

ctio

nsLE

O_G

ER•

Oxi

datio

n:lo

sing

el

ectro

ns•

Red

uctio

n: g

aini

ng

elec

trons

•Pr

ecip

itatio

n tit

ratio

n:M

ohr a

nd V

olha

rd

Met

hods

for s

alt

dete

rmin

atio

n

(p. 1

56-7

)

The

inte

nsity

of t

he c

olor

of t

he c

olor

ed c

ompl

exfo

rmed

with

met

al

and

som

e sp

ecifi

c lig

and

is m

easu

red

by U

V-V

is sp

ectr

opho

tom

eter

an

d as

sess

ed b

y th

e us

e of

a c

alib

ratio

n gr

aph

usin

g kn

own

amou

nts o

f st

anda

rd m

etal

and

liga

nd.

Exa

mpl

e: F

e++(F

erro

us Io

n) w

ith p

hena

nthr

olin

e(o

rtho

phen

anth

rolin

es) f

orm

inte

nse

red

colo

r. I

nten

sity

of r

ed c

olor

ca

n be

mea

sure

d at

510

nm

by

spec

trop

hoto

met

er(F

ig.1

0.2)

.Bot

hred

oxan

d co

lori

met

ric

met

hod

Col

orim

etric

or

Spec

troph

otom

etric

Met

hods

NN

Fe++

....

Flam

e Em

issi

on S

pect

rosc

opy

is b

ased

upo

n th

ose

parti

cles

that

are

el

ectro

nica

lly e

xcite

d in

the

med

ium

.

The

Func

tions

of F

lam

e

1. T

o co

nver

t the

con

stitu

ents

of l

iqui

d sa

mpl

e in

to th

e va

por s

tate

.

2. T

o de

com

pose

the

cons

titue

nts i

nto

atom

s or s

impl

e m

olec

ules

:

M+

+

e-(f

rom

flam

e)

−>M

+

hν

3. T

o el

ectro

nica

lly e

xcite

a fr

actio

n of

the

resu

lting

ato

mic

or

mol

ecul

ar sp

ecie

s

M

−>M

*

Flam

e Em

issi

on S

pect

rosc

opy

p.43

3

Mea

sure

the

inte

nsity

of e

mitt

ed ra

diat

ion

Flam

e Em

issi

on S

pect

rosc

opy

Gro

und

Stat

e

Exci

ted

Stat

e

Emits

Spe

cial

El

ectro

mag

netic

Rad

iatio

n

Flam

e Em

issi

on S

pect

rosc

opy

hυ-h

υ

M+

−>

M0

−>M

* −

>M

0

Flam

eLe

ns

Slit

Filte

rer

Slit

Det

ecto

rEm

itted

1) T

he e

lem

ents

mus

t be

redu

ced

to th

e el

emen

tal,

neut

ral

grou

nd

stat

e by

the

flam

e.

2) T

he e

lem

ents

mus

t be

in v

apor

ized

stat

e.

3) T

he e

lem

ents

mus

t be

impo

sed

in th

e be

am o

f rad

iatio

n fr

om th

e so

urce

.

Adv

anta

ges:

Ver

y se

nsiti

ve.

Fast

.

Dis

adva

ntag

es:

Hol

low

cat

hode

lam

p fo

r eac

h el

emen

t.

Expe

nsiv

e el

emen

t.

TH

EO

RY

of A

tom

ic S

pect

rosc

opy:

Ato

mic

spec

tros

copy

req

uire

s tha

t the

ato

ms o

f ele

men

t ar

e in

“at

omic

” st

ate(

not c

ombi

ned

with

oth

er e

lem

ents

). “A

tom

izat

ion”

invo

lves

sepa

ratin

g th

e pa

rtic

les f

irst

into

in

divi

dual

mol

ecul

es b

y va

pori

zatio

n, a

nd b

reak

ing

mol

ecul

es in

to a

tom

s by

expo

sing

the

anal

yte

to v

ery

high

te

mpe

ratu

res i

n a

flam

e or

“pl

asm

a”.T

he a

tom

s the

n m

ade

to a

bsor

b th

e ra

diat

ion

of c

hara

cter

istic

wav

elen

gth

(AA

S), o

r ar

e m

ade

into

“ex

cite

d” st

ate,

thus

su

bseq

uent

ly e

mitt

ing

rad

iatio

n of

cha

ract

eris

tic

wav

elen

gth(

AE

S).

Atom

ic E

mm

issi

onSp

ectr

osco

py: (

AES)

(Ch.

28,p

.433

)M

easu

res

the

radi

atio

n em

itted

by

atom

s of

met

als

whe

n th

eir

plan

eter

yel

ectr

ons

that

are

dis

plac

ed (

i.e.

by h

eat

of

flam

e) f

rom

the

ir or

bits

fal

l ba

ck t

o th

eir

orig

inal

low

er

ener

gy l

evel

s. T

his

radi

atio

n is

ver

y ty

pica

l fo

r ea

ch m

etal

; fo

r eac

h, th

ere

is a

cha

ract

eris

tic e

mis

sion

wav

elen

gth(

for K

: 76

6nm

;for

Na:

330n

m).F

lam

e Ph

otom

etry

is e

ssen

tially

an

appl

icat

ion

of E

.S.

A ga

s-ai

r fla

me

(900

-120

0°C

)will

pro

vide

en

ough

radıa

tion

ener

gy f

or e

xciti

ng a

lkal

i an

d al

kali

eart

h m

etal

s.Th

e ph

otom

eter

mea

sure

s th

e in

tens

ity o

f lig

ht a

t the

ch

arac

teris

tic

wav

elen

gth,

w

hich

is

co

rrel

ated

w

ith

conc

entr

atio

n.

Rec

orde

r

Bur

ner

Mon

ochr

omat

orD

etec

tor(

Phot

osen

sitiv

e)

Atom

ic A

bsor

btio

nSp

ectr

omet

ry-A

AS(p

.428

)1.

AAS

With

Fla

me:

The

inst

rum

ent

cont

ains

a s

ourc

e of

rad

iatio

n (h

allo

w c

atho

de l

amp)

who

se w

avel

engt

h is

exa

ctly

the

sam

e as

tha

t re

quire

d to

exc

ite t

he a

naly

zed

met

al.

Elec

tron

s gi

ven

off

by

cath

ode

acce

lera

te to

war

ds th

e an

ode;

alon

g th

e w

ay, t

hey

ioni

ze a

rgon

ato

ms

whı

ch

are

then

attr

acte

d to

the

cath

ode.

The

ato

ms

exci

ted

by c

ollis

ion

with

fille

r ga

s io

ns gıv

e of

f theır

ener

gy, t

he e

mitt

ed r

adia

tion

bein

g ch

arac

teris

tic o

f th

e m

etal

the

HC

Lam

p is

mad

e of

.The

sam

ple

is a

spira

ted

into

the

bur

ner

gas

mix

ing

cham

ber

and

is m

ixed

wıth

a co

mbu

stib

le g

as mıx

ture

(air-

acet

ylen

e fla

me:

2300

°C,N

O-a

cety

lene

fla

me:

3080

°C).G

roun

d st

ate

met

al

atom

s in

the

flam

e ar

e de

tect

ed b

y th

e ab

sorp

tion

of e

nerg

y of

the

spec

ific

wav

elen

gth

furn

ishe

d by

the

hollo

w c

atho

de la

mp.

The

diff

eren

ce b

etw

een

the

radi

atio

n en

ergy

abs

orbe

d by

the

sol

vent

with

out

sam

ple

and

the

solv

ent

with

sam

ple

is d

ispl

ayed

ele

ctro

nica

lly.

Each

tim

e w

e an

alys

e a

diffe

rent

met

al,

we

have

to

repl

ace

the

resp

ectiv

e ha

llow

cat

hode

lam

p (F

orPb

→us

e Pb

lam

p,fo

r Cd

→us

e C

dla

mp)

. We

can

dete

ct e

ven

very

ver

y lo

w c

once

ntra

tions

like

10-6

Mol

ar s

olut

ions

.. Pl

ottin

g a

bs. v

s. c

onc.

giv

es u

s an

idea

of t

he c

once

ntra

tion

of th

e m

etal

in th

e sa

mpl

e

A

Con

cent

ratio

n(pp

m)

.A

tom

ic A

bsor

ptio

n Sp

ectro

met

ry

Hol

low

C

atho

de

Lam

p

Gra

phite

Fu

rnac

e

Slit

Mon

ochr

omat

or

Slit

Det

ecto

r

Ato

mic

Abs

orpt

ion

spec

trosc

opy

invo

lves

the

stud

y of

the

abso

rptio

n of

radi

ant e

nerg

y by

neu

tral a

tom

s in

the

gase

ous s

tate

.

•Fla

me

Emis

sion

−>

it m

easu

res t

he ra

diat

ion

emitt

ed b

y th

e ex

cite

d at

oms t

hat i

s rel

ated

to c

once

ntra

tion.

•Ato

mic

Abs

orpt

ion

-> it

mea

sure

s the

radi

atio

n ab

sorb

ed b

y th

e un

exci

ted

atom

s tha

t are

det

erm

ined

.

Ato

mic

abs

orpt

ion

depe

nds o

nly

upon

the

num

ber o

f une

xcite

d at

oms,

the

abso

rptio

n in

tens

ity is

not

dire

ctly

aff

ecte

d by

the

tem

pera

ture

of t

he fl

ame.

The

flam

e em

issi

on in

tens

ity in

con

trast

, bei

ng d

epen

dent

upo

n th

e nu

mbe

r of e

xcite

d at

oms,

is g

reat

ly in

fluen

ced

by te

mpe

ratu

re

varia

tions

.

Rel

atio

nshi

p B

etw

een

Ato

mic

Abs

orpt

ion

and

Flam

e Em

issi

on S

pect

rosc

opy

2.Fl

amel

ess

AAS:

(Als

o ca

lled

“car

bon-

rod

or g

raph

ite fu

rnac

e m

etho

d”) p

.430

.Th

is is

an

elec

trot

herm

alpr

oces

s us

ing

a si

mila

r AA

spec

trop

hoto

met

er, b

ut th

e di

ffere

nce

is th

at h

ere

the

burn

er

is e

lect

rical

ly h

eate

d. S

uch

insr

umen

ts a

re 1

0-10

0 tim

es m

ore

sent

itive

than

AAS

with

flam

e, th

us m

akin

g po

ssib

le to

de

tect

H

g at

0.0

01 p

pm c

once

ntra

tion

in f

ish.

Her

e th

e fu

rnac

e is

an

elec

tric

al re

sist

ance

-hea

ted

grap

hite

tube

(als

o ca

lled

a C

arbo

nro

d) a

nd th

ere

is n

o fla

me.

The

tem

pera

ture

can

reac

h

~500

0°K.

A sm

all a

mou

nt o

f sam

ple

is in

ject

ed w

ith a

syr

inge

into

the

gr

aphi

te tu

be,p

rogr

amm

ed fi

rst t

o dr

y th

en to

cha

r and

then

to

atom

ize

the

ash

to th

e pa

th o

f the

radi

atio

n fr

om th

e ho

llow

ca

thod

e so

urce

. Th

e re

st o

f ana

lysi

s(de

tectıo

n, g

raph

and

cal

cula

tions

etc

.) is

ex

actly

the

sam

e as

AAS

with

flam

e.

Sim

ulta

neou

s El

emen

tary

Ana

lysi

s: T

his

is m

ade

poss

ible

with

m

oder

n in

stru

men

ts,

like

“IC

P”,w

hich

is

shor

t fo

r “I

nduc

tivel

y co

uple

d pl

asm

a”.It

ha

s a

sim

ilar

prin

cipl

e w

ith

emm

issi

onsp

ectr

osco

py. T

he v

ery

expe

nsiv

e, h

ighl

y so

phis

ticat

ed b

ut a

lso

very

sen

sitiv

e in

stru

men

t mak

es u

se o

f a "

Plas

ma

torc

h”(p

.434

), w

hich

is a

n

elec

tric

al d

isch

arge

of h

igh(

>%1)

con

cent

ratio

n (+

) an

d (-)

ion

s.Th

e ar

gon

plas

ma

(T ~

100

00°C

) is

for

med

by

a st

ream

of

argo

n ga

s flo

win

g be

twee

n tw

o qu

artz

tub

es,

and

argo

n is

m

ade

cond

uctiv

e by

ex

posi

ng

it to

an

el

ectr

ical

di

scha

rge,

cre

atin

g se

ed e

lect

rons

and

ion

s.Th

e lig

ht(o

ptic

al)

ener

gy e

mitt

ed w

hen

sam

ple

is b

urnt

in p

lasm

a to

rch

is re

cord

ed

on a

pho

togr

aphi

c fil

m,

that

is

deve

lope

d an

d co

mpa

red

with

st

anda

rdiz

ed fi

lm.

Usi

ng t

his

met

hod,

ide

ntifi

catio

nof

the

orig

in o

f ag

ricul

tura

l co

mm

oditi

es is

mad

e p

ossi

ble,

sin

ce t

here

are

diff

eren

ces

,for

exam

ple,

in t

he c

once

ntra

tion

leve

ls o

f th

e in

divi

dual

met

als

in

Amer

ican

an

d Tu

rkis

h or

ange

s du

e to

di

ffere

nces

in

so

il co

mpo

sitio

n an

d m

iner

al u

ptak

e pa

ttern

s of

loca

l var

ietie

s..

Met

hod

Sele

ctio

n G

uide

FLA

ME

AA

ICPE

mis

sion

GFA

AIC

P_M

S

Hig

h

Num

ber o

f Ana

lyse

s

Low

Hig

h

Con

cent

ratio

n