2008-2010 high throughput gc-ms and lc-ms-ms … throughput gc-ms and lc-ms-ms method for 668...

July 16, 2010

2008-2010High Throughput GC-MS and LC-MS-MS Method for 668 Multi-classes

and Multi-kinds of Residual Pesticides in Tea----AOAC OMA Collaborative Study Protocol (Draft)AOAC OMA Collaborative Study Protocol (Draft)

1. Study background: Challenge of food safety calls for the high throughput analytical techniques ofmulti-classes and multi-kinds of residual pesticides.

2 Characteristics of analysis method for 688 multi-classes and multi-kinds of residue pesticides in tea.3. Preparation of AOAC collaborative study in five stages:

(1)In stage I: stability study of 460 pesticides in the mixed standard solution(2)In stage II: stability study of 340 pesticides in tea(3)In stage III: stability study of 271 pesticides in tea Youden pair samples (4)In Stage IV: Investigation of the Ruggedness of the method by designing 8 different analytical procedures(5)In Stage V: Probe into the bias ratio of predicted value of kinetics degradative equation and the actual detected values

4. The tentative design of AOAC inter-collaborative study protocol.5.Work to do before this AOAC Annual Meeting in September and the final time of completion for the

study6. Historical experience is worth learning from7. Promote the spire of AOAC international and strive to raise AOAC collaborative study to a new level

( ) g g

Guo-Fang PangChinese academy of inspection and quarantine, Beijing, China

1

Email: [email protected]

1.Study background: Challenge of food safety calls for the high throughput

DDT pesticide came into the world in 1940, which was the break of dawn for the increase of

analytical techniques of multi-classes and multi-kinds of residual pesticides.

1.1 The present state of MRL of pesticide residue from different countries

agricultural production. 30 years later, it was banned in 1977 due to its toxicity to human food and thesurvival environment. With the advent of the standard for limit of residue in foods, agronomy and thescience of residue analysis came into being. Presently, the world countries attach great importanceto food safety, bringing severe challenges to the analytical techniques of pesticide residue andchemical contaminants.

Comparison of MRL for different countries(2010)

6071763888

70000

MR

Lqu

antit

y

30000

40000

50000

60000

M

109166194

4780

10000

20000

30000

2Source of literature: Journal of Pesticide Science :Song Wencheng et al. The Present State and Development Tendency of MRL Quantities for Domestic and External Pesticides

0USA EU Japan Canada China

1.2 The high threshold of international trade from MRL of pesticide residue in tea

At present, 17 countries and/or international organizations have formulated MRL for 800 pesticide residues in tea

Pesticide varieties Comparison of pesticide quantities with MRL for different countries

493

400

450

500

270250

300

350

81

50

100

150

200

EU, Germany, Holland, Switzerland, Hungry, Israel, Italy, CAC, China, Japan, Chinese Taiwan, South Korea, USA, Australia, India, Kenya and South Africa (till 2006)

8 13 240

50

美国欧盟日本德国 CAC 中国USA（2001） EU（2010） Japan（2010） Germany（2001）CAC（2009） China（2005）

3

Australia, India, Kenya and South Africa (till 2006)

Source of literature: http://ec.europa.eu/sanco_pesticides/public/index.cfmhttp://www.m5.ws001.squarestart.ne.jp/foundation/search.htmlhttp://www.tbtsps.com/foodsafe/xlbz/Pages/pesticide.aspxGB 2763-2005Doctoral Dissertation of Anhui Agricultural University Wu Xueyuan MRL of Pesticides in Tea and Risk Evaluation

1.3 There are more and more and stricter and stricter standards for MRL ofpesticides in tea required by world countries so the study of AOAC method forpesticides in tea required by world countries, so the study of AOAC method formultiresidues has become an absolute necessity.

270300493

450500Pesticide QuantitiesPesticide quantities

150

200

250

200250300350400

MRL for Japanese tea MRL for EU tea

3451

0

50

100

1986 1993 2010

6

134

050

100150200

1988 2004 2010More and more 1988 2004 2010More and more

4Stricter and Stricter

1.4 Development of the study of pesticide multiresidues in the author'sl b t th t tlaboratory over the past ten years

Pesticide varieties668

AOAC Collaborative Study

GC-MSLC-MS/MS

One-time prepared samples can satisfy both GC-MS and LC-MS/MS methods for simultaneous

20 China National Standards

Fruit, vegetable Grain Tea Medicinal herbs Edible fungi Animal tissue Fish, shrimp Milk, milk powder Honey Fruit juice, wine

5

One time prepared samples can satisfy both GC MS and LC MS/MS methods for simultaneous determination of 415-512 pesticide residues

Can be used for 10 kinds of edible agricultural products such as fruits and vegetables, grains, etc. Pesticide varieties that can be determined reach 806.

2. Characteristics of simultaneous determination of 668 pesticides multi-classes andmulti kinds of pesticides in tea (GB/T 23204 2008&GB/T 23205 2008）

Analytical program of nearly 668 pesticide residues in tea. The newly developed three groups, PC, NH2 and PS with different Cleanert TPT cleanup cartridgesmake possible the high-speed and highly efficient sample preparation of tea samples, with 20 samples

multi-kinds of pesticides in tea (GB/T 23204-2008&GB/T 23205-2008）

prepared per person per day.

5g tea sampleGC-MS&LC-MS/MSGC-MS&LC-MS/MS

Added 15 mL 1% acetic acid–acetonitrile

Elute with 25 mL acetonitrile+toluene(3+1) concentrate nearly to dryElute with 25 mL acetonitrile+toluene(3+1), concentrate nearly to dry

6

2.1 The first of the characteristics of the methods: the efficiency of GC-MS andC S/ SLC-MS/MS methods

(1) One-time prepared samples can be used for simultaneous determination of 668 residual pesticides; (2) Determination is made, based on time segment and groups, making the operation as simple as singleresidue

determination.GC MS(490) LC MS MS(448) GC MS(270) LC MS MS(270)

Item GC-MS(490) LC-MS-MS(448) GC-MS(270) LC-MS-MS(270)

Varieties % Varieties % Varieties % Varieties %

Rec. range(%)

60-120 424 94.0 400 91.1 239 95.6 249 93.6＜60 27 6.0 37 8.4 11 4.4 16 6.0＞120 0 0 2 0 0 0 1 0

Not added 39 / 9 / 20 / 4 /

RSD range(%)

＜20 348 77.2 333 75.9 188 75.2 211 79.3

20-30 86 19.0 77 17.5 56 22.4 42 15.8＞30 17 3.8 29 6.6 6 2.4 13 4.9

In terms of the 270 pesticides that can be bothdetermined by LC-MS/MS and GC-MS, there are

(3) Comparison of LOD of the two methods

Not added 39 / 9 / 20 / 4 /

LOD range (μg/kg) LC-MS-MS GC-MS

＜10 199(73.7%) 70 (25.9%) y ,207 pesticides with LOD of LC-MS/MS superiorto that of GC-MS, while there are 63 pesticideswith LOD of GC-MS superior to that of LC-MS/MS In general LC-MS/MS is superior to GC-

( ) ( )

10-50 39(14.4%) 182 (67.4%)

50-100 9 (3.3%) 9 (3.3%)

100-500 19 (7.0%) 8 (3.0%)

500 1000 1 (0 4%) 1 (0 4%)

7

MS/MS. In general, LC MS/MS is superior to GCMS in sensitivity.

500-1000 1 (0.4%) 1 (0.4%)

＞1000 3 (1.1%) -

2.2 The second of the characteristics of the method: multi-classes and multi-kinds,

300

350

with a determination totaling 668 pesticides (GB/T 23204-2008 &GB/T 23205-2008)

668 pesticides classified per compositions

293（43.9％）

100

150

200

250

Pest

icid

e va

rietie

s

93（13.9％）

125（18.7％）

3553 53

0

50

organohalogen organophosphorus pyrethroid carbamate organonitrogen organosulfur other

35（5.2％）

（7.9％） 16（2.4％）

（7.9％）

200

250

300

arie

ties

668 pesticides classified per functions258

（38.6％）

130

197（29.5％）

0

50

100

150

Pest

icid

e v （19.5％）

27（4.0％） 3

（0.4％）

14（2.1％）

39（5.8％）

8

0insecticide bactericide herbicide acaricide IGR PGR other

2.3 The third of the characteristics of the method: comparison of MRL with EU, Japan, USA and CAC

668

600

700

, p ,(1) Comparison in quantities

The method is capable of making a determination of 53% pesticides stipulated b EU

Pesticide varieties

493

270

200

300

400

500by EU.

The method is capable of making a determination of 63% pesticides stipulated by Japan

The sensitivity of the LOD can satisfy the requirements of international trade.

110

100

GC- MS&LC- MS/ MS EU Japan CAC

(2) Comparison of LOD values with MRL: the sensitivity of the method is mostly superior to that of EU and Japan

requirements of international trade.53％63％

394

300

350

400

450

etie

s

EUJapan

231

187

6389

219

59100

150

200

250

Pest

icid

e va

rie China

9

0 1 11 6 34 8 14 11 5029 19

00

50

N.D. ＜0.01 ≤ 0.01-0.1 ≤ 0.1-1 ≤ 1-10 ≤ 10-50 ≥ 50

2.4 The fourth of the characteristics of the method: low carbon and in2.4 The fourth of the characteristics of the method: low carbon and inconformance with environment, saving resources and satisfying theworld trend of being environmental friendly and the requirement forharmonious development.

(1) Disuse chlorine-free organic reagents.

Extraction:1% ascetic acid acetonitrile Cleanup:acetonitrile-toulene(3:1) Solvent exchange: hexane

GC-MSGC-MS/MSLC-MS/MS

(2) The newly-developed Cleanert TPT(graphite carbon, multi-amine-based silicone, and amide polystyrene) is superior to the traditional Envi-Carb+PSACarb+PSA

(3) One-time prepared samples can be used for GC-MS & LC-MS/MS determination of 668 pesticides

10

3.1 Why should these 5 stages of preparations be undertaken?

3. Preparation of AOAC collaborative study in five stages （Nov,2008-Aug.2010）

Participating laboratories of this AOAC collaborative study need to test various kinds ofpesticide spiked and incurred samples, which requires the organizer to solve three stabilitiesin the first place.p

(1) The stability of standard solutions contained in the ampoule bottle shipped to different participants

pesticide varieties suitable for es

(2) The stability of target pesticides in pesticide incurred Youden pair samples shipped to different countries

(3) The stability of the entire method

collaborative study are chosen from among them.

The good method ruggedness has been verified

①Draw a degradation curve and establish degradation equation

Thre

e St

abili

tie

① g g q②Conduct a comparative study on the predicted values and actual

values using kinetics equations

11

3.2 Stage I: Stability study of 460 pesticide in mixed standard solutions E i t l ti th th f N 26 2008 F b 26 2009

460 pesticides are divided into 6 groups of ABCDE and F6 for experiment with one GC-MS

Experimental time: three months from Nov.26,2008-Feb.26,2009

Experimental objective: to choose the pesticides with slower degradation in the mixed standard solutions.

460 pesticides are divided into 6 groups of ABCDE and F6 for experiment, with one GC MSdetermination every 2 days and parallel test for each group as well as 28520 analytical dataobtained from 31 circulative determinations over 3 months. The degradation kinetics exponentialequations have been established, and the relatively stable 340 pesticides in the standard solutionshave been chosen for the next stage of experiment.

The response value determined on the first day for each pesticide is set as 1, and the responsevalues obtained thereafter are compared and the ratio is calculated. This ratio change reflects thepesticide degradation rate.Nos. of pesticides

200

250

300

<0. 290. 29- 0. 400. 41- 0. 500 51- 0 60

Chart for the decomposition of 460 pesticides over three months

50

100

1500. 51 0. 600. 61- 0. 700. 71- 0. 800. 81- 0. 900. 90- 1. 00>1. 00

12

时间0半个月12. 10 1个月12. 26 1个半月1. 09 2个月 1. 26 2个半月2. 11 3个月 2. 26 15 days 12.10 30 days12.26 45 days 1.09 60 days 1.26 75 days 2.11 90 days 2.26 date

3.3 Stage II: Stability study of 340 pesticides in teaE i t l ti th th f M 31 2009 J 31 2009Experimental time: three months from Mar.31,2009-Jun.31,2009

Experimental objective: stability study is carried out on the 340 pesticides in Green Teaand Woolong Tea, and pesticide with slower degradations are chosen.

A GC-MS determination is made for 2 teas every 5 days, with 3 samples for parallel testing eachtime and four groups of ABCDE for 19 circulative determinations over three months, from which77520 data have been obtained. Exponential kinetics equations are established for 340 pesticides,and the relatively more stable 271 pesticides in tea have been chosen.

Degrading Chart for 340 pesticides in Green Tea within 3 months

180200 GC MS/MS

Nos. of pesticides Nos. of pesticides

80100120140160

100120140160180 GC-MSGC-MS/MS

≤ 0. 50≤ 0. 70- 0. 50≤ 0. 90- 0. 70>0 90

020406080

020406080 >0. 90

13

30天 45天 60天 75天 90天30天 45天 60天 75天 90天 Date 30 days 45days 60days 75days 90days 30 days 45days 60days 75days 90daysdate

3.4 Stage III: Stability study of 271 pesticides in tea Youden pair samplesE i t l ti th th f J l 2009 O t 2009Experimental time: three months from July 2009-Oct.2009

Experimental objective: to prepare for the design of inter-collaborative study protocol.

A GC-MS determination is made for 2 teas and two Youden pair samples every 5 days, with 3samples for parallel testing each time and 19circulative determinations over three months from whichsamples for parallel testing each time and 19circulative determinations over three months, from which123576data have been obtained. Kinetics degradation equations are established for Youden pairsamples.

Distribution of the fixed value content for 271 pesticides in Youden pair samplesDistribution of the fixed value content for 271 pesticides in Youden pair samplesNos of pesticides

100

120≤ 50≤ 100- 50

ppb

20

40

60

80≤ 100- 50≤ 150- 100≤ 200- 150≤ 300- 200≤ 400- 300＞400

0

20

A B A B C D C D

绿茶GC- MS 绿茶GC- MS/ MS 乌龙茶GC- MS 乌龙茶GC- MS/ MS

＞400

Green Tea GC-MS Green Tea GC-MS/MS Wu LongTea GC-MS/MSWu LongTea GC-MS

14

The study of above-mentioned 3 stages has led to the preliminary selection of 201 pesticides for inter-collaborative study, and the ruggedness of the method has been verified accordingly.

3.5 Stage IV: 8 different analytical procedures have been designed to investigate the Ruggedness of the method （Nov.09,2009-Feb.7,2009）Ruggedness of the method （Nov.09,2009 Feb.7,2009）

Tea sample

3.5.1 8 analytical procedures:(1) two teas (2) two Youden pair samples (3) two cartridges (4) two testing methods

Green tea Woolong tea

Cleaner TPT

Youden PairYouden Pair

Envi-Carb+PSA


Cleaner TPT


Envi-Carb+PSA


Cleaner TPT


Envi-Carb+PSA


Cleaner TPT


Envi-Carb+PSA


GC-MSGC-MS

A B A B A B A B A B A B A B A B

GC-MS/MSGC-MS/MS GC-MSGC-MS GC-MS/MSGC-MS/MS

8 Green tea Youden Pair samples8 Green tea Youden Pair samples 8 Woolong tea Youdnen Pair samples8 Woolong tea Youdnen Pair samples

15

189744 data have been obtained (2 teas X 2 cartridges X 2 testing methods X 2 Youden pair samples X one determination every 5 days with 3 parallel samples X 19 determinations over 3 months X 201 pesticides

3 5 2 Statistical analysis of 8 analytical procedures

Statistical analysis of 183312 data is carried out (201 X 944 samples)

3.5.2 Statistical analysis of 8 analytical procedures

Original data( p )

The first fixed value (parallel 5 times) is established, after which 19 circulative values over three months ( three parallels each time) are statistically calculated.

Statistical data I

The first fixed value is established, after which the average content of pesticides in samples are tested each time 18 circulative

The first fixed RSD value is established, after which RSD of each pesticide is

tested each time in 18 circulativeStatistical

data IIsamples are tested each time 18 circulative determinations over 3 months

tested each time in 18 circulative determinations over 3 months.

Calculate the Youden pari ratios of each pesticide for each sample

RSD of Youden pair tested from 18 circulative determinations over three

monthsStatistical

data III

Conclusion

（1）The Ruggedness of the method is satisfactory.（2）The major source of errors have found in five aspects.（3）The key control points in five aspects have been confirmed.

16

（） y p p

3.5.3 The agreement of the first fixed value of 201 pesticides in Youden pair incurred samples from 8 analytical procedures with the detected values from 19 circulative determinations proves that the method is of good Ruggedness.

(1) 2 teas X 2 Youden pair samples X 2 cartridges X 2 instruments X 201 pesticides X 19 determinations over 3months, with 30552 Youden pair ratio data obtained.

Table 1 Comparison of 201 pesticide incurred Youden pair sample fixed value range with that of 18 circulative determinations over 3 months

Youden pair Ratio Range

Cleanert TPT GC-MS Cleanert TPT GC-MS/MS Envi-Carb+PSA GC-MS Envi-Carb+PSA GC-MS/MS

Fixed value ratio

(making up %)

Total of 18 times

(making up %)

Fixed value ratio

(making up %)Total of 18 times(making up %)

Fixed value ratio

(making up %)

Total of 18 times

(making up %)

Fixed value ratio

(making up %)

Total of 18 times

(making up %)

Green Tea

≤0.80 2（1.0） 76 (2.1 ) 1（0.5） 35（1.0） 4（2.0） 32(0.9) 13（6.5） 53(1.5)

0.80~1.00 45（22.4） 652 (18.0 ) 39（19.4） 819（22.6） 58（28.9） 615(17.0) 65（32.3） 781(21.6)

1.00~1.20 150（74.6） 2840 (78.5 ) 154（76.6） 2660（73.5） 131（65.2） 2614(72.2) 121（60.2） 2367(65.4)

1.20~1.40 2（1.0） 47 ( 1.3 ) 3（1.5） 84（2.3） 6（3.0） 299(8.3) 1（0.5） 345(9.5)

1.40~1.60 2（1.0） 3 (0.1) 1（0.5） 12（0.3） 0（0.0） 38(1.1) 0（0.0） 32(0.9)

＞1.60 0（0.0） 0 (0.0 ) 0（0.0） 2（0.1） 2（1.0） 17(0.5) 0.00 23(0.6)

No value 0（0.0） 0 (0.0 ) 3（1.5） 6（0.2） 0.00 3(0.1) 1（0.5） 17(0.5)No value 0（0.0） 0 (0.0 ) 3（1.5） 6（0.2） 0.00 3(0.1) 1（0.5） 17(0.5)

Totalling 201.00 3618 201.00 3618 201.00 3618 201.00 3618

Woolong Tea

≤0.80 0.00 4（0.1） 0（0.0） 9(0.2) 0（0.0） 23(0.6) 0（0.0） 8（0.2）0.80~1.00 10（5.0） 225（6.2） 22（10.9） 189(5.2) 9（4.5） 398(11.0) 7（3.5） 309（8.5）1.00~1.20 164（81.6） 2462（68.0） 158（78.6） 2436(67.3) 124（61.7） 2196(60.7) 102（50.7） 2339（64.6）

Experiment has found that the first Youden pair fixed value from 8 analytical procedures basically agree with the ratio distributions

1.20~1.40 26（12.9） 867（24.0） 15（7.5） 908(25.1) 65（32.3） 858(23.7） 72（35.8） 866（23.9）1.40~1.60 1（0.5） 35（1.0） 4（2.0） 44(1.2) 3（1.5） 90（2.5） 14（7.0） 62（1.7）

＞1.60 0（0.0） 24（0.7） 0（0.0） 20(0.6) 0（0.0） 52（1.4） 5（2.5） 23（0.6）No value 0（0.0） 1（0.0） 2（1.0） 12(0.3) 0（0.0） 1（0.0） 1（0.5） 11（0.3）Totalling 201.00 3618 201.00 3618 201.00 3618 201.00 3618

17

Experiment has found that the first Youden pair fixed value from 8 analytical procedures basically agree with the ratio distributionsfrom 19 circulative determinations over 3 months. Youden pair ratios will not change with degradation of pesticides over three months,which is a constant. Test results prove the first fixed value agree basically with the ratio range from the 18 circulative determinationsover 3 months thereafter, which demonstrates that the test results are accurate, and the method is of good Ruggedness.

(2) The percentage of pesticides within the optimum ratio range (1.00-1.20) of Youden pair from 8 analytical proceduresanalytical procedures

（The chart is drawn on the data of 1.00-1.20 range of Youden pair ratios in the above table）

①Single class statistical analysis ② Clustering statistical analysis

1) For each of the 4 procedures of Green Tea, there is an average difference of 4.6% for the percentages of1) For each of the 4 procedures of Green Tea, there is an average difference of 4.6% for the percentages ofpesticide varieties falling within the optimum range of Youden pair 1.00-1.20 between the first fixed value andthe 18 determined values thereafter; there is an average difference of 9.4% for Woolong Tea

2) The fact that pesticide quantities within the optimum range of Youden ratios for Cleanert TPT cartridge arehigher than those for Envi-Carb+PSA by 10% proves once again that the former is superior to the later incleanup results.

3) The comparison of the two teas shows that there are certain deviations for different consignments of spraying

18

3) The comparison of the two teas shows that there are certain deviations for different consignments of sprayingpesticides, with small deviations for Green Tea and big deviations for Woolong Tea.

4) The analytical results from these two instruments are very close.

3.5.4 The reproducibility of the first determination of 201 pesticide content in the pesticide incurred Youden pair samples from 8 analytical procedures agrees with that of 18 circulative determinationsYouden pair samples from 8 analytical procedures agrees with that of 18 circulative determinations, which proves the method is of good Ruggedness.

（1）61104 RSD data from 8 analytical procedures (2 teas X 2 Youden pair X 2 cartridges X 2 instrumentsX 201 pesticides X 19 determinations over 3 months

RSDRange（%）

TPT cartridge GC-MS TPT cartridge GC-MSMS Cartridge in Tandem GC-MS Cartridge in Tandem GC-MSMS

Fixed value RSD (making

up%)

RSD from 18 times

(making up %)


up%)

RSD from 18 times

(making up %)


up%)

RSD from 18 times

(making up %)


up%)

RSD from 18 times

(making up %)

RSD distribution of Youden pair sample ratio from 8 analytical procedures

p ) ( g p ) p ) ( g p ) p ) ( g p ) p ) ( g p )

Green tea

≤10 368(91.5) 6348(87.7) 370(92) 6374(88.1) 256(63.7) 5544(76.6) 242(60.2) 5392(74.5)

10.1-15 25(6.2) 801(11.1) 21(5.2) 638(8.8) 77(19.2) 908(12.5) 48(11.9) 1020(14.1)

Total 393(97.7) 7149(98.8) 391() 7012 (96.9) 333 (85.9) 6452 (89.1) 290 (72.1) 6412 (88.6)

15 1-20 6(1 5) 63(0 9) 5(1 2) 147(2) 35(8 7) 308(4 3) 43(10 7) 396(5 5)15.1 20 6(1.5) 63(0.9) 5(1.2) 147(2) 35(8.7) 308(4.3) 43(10.7) 396(5.5)

>20 3(0.7) 24(0.3) 4(1) 65(0.9) 34(8.5) 470(6.5) 67(16.7) 404(5.6)No value 0(0) 0(0) 2(0.5) 12(0.2) 0(0) 6(0.1) 2(0.5) 24(0.3)Totaling 402(100) 7236(100) 402(100) 7236(100) 402(100) 7236(100) 402(100) 7236(100)

Woolong tea

≤10 362(90) 6537(90 3) 355(88 3) 6576(90 9) 340(84 6) 5848(80 8) 319(79 4) 5947(82 2)≤10 362(90) 6537(90.3) 355(88.3) 6576(90.9) 340(84.6) 5848(80.8) 319(79.4) 5947(82.2)

10.1-15 29(7.2) 545(7.5) 29(7.2) 441(6.1) 40(10) 956(13.2) 52(12.9) 874(12.1)

Total 391(97.2) 7082 (97.8) 384 (95.5) 7017(97.0) 380 (94.6) 6804 (94.0) 371 (92.3) 6821 (94.3)

15.1-20 5(1.2) 93(1.3) 6(1.5) 116(1.6) 14(3.5) 283(3.9) 17(4.2) 233(3.2)

>20 6(1.5) 59(0.8) 8(2) 81(1.1) 8(2) 147(2) 12(3) 160(2.2)N l 0(0) 2(0) 4(1) 22(0 3) 0(0) 2(0) 2(0 5) 22(0 3)

19

No value 0(0) 2(0) 4(1) 22(0.3) 0(0) 2(0) 2(0.5) 22(0.3)Totaling 402(100) 7236(100) 402(100) 7236(100) 402(100) 7236(100) 402(100) 7236(100)

（2）Percentage of pesticides with RSD≤15％ for the first fixed value determination and 18 determinations thereafter from the 8 analytical procedures

（The chart is drawn on the basis of data of RSD ≤15％）


① The differences of the percentage of pesticides with RSD falling within the optimum range (≤15％) for the first determination and 18 determinations thereafter from the 8 analytical procedures do not exceed 16.5%, demonstrating the Ruggedness is acceptable.

20

②The differences of the percentage of pesticide with RSD falling with the optimum range (≤15％) for two SPE Cartridges, two teas and two instruments do not exceed 6%, suggesting the Ruggedness is acceptable.

3 5 5 RSD of parallel samples from 19 circulative determinations agrees with RSD of3.5.5 RSD of parallel samples from 19 circulative determinations agrees with RSD ofYouden pair ratios from 19 circulative determinations, which proves once again thatthe method is of good Ruggedndess.

①Si l l t ti ti l l i ② Clustering statistical analysis

97.791.5 93.3 95.8 95 94.2

97.3

89.392.6 93.9 93.5 93.1

80

100

Parallel sampleYouden Pair ratios

98.8 96.7

89.1 88.6

97.8 97.094.0 94.3

100.095.5

90.185.1

97.0 96.5

87.0

95.0

80.0

100.0

Parallel sampleYouden Pair ratios


20

40

60

％

20.0

40.0

60.0

％

0Cleanert TPT Envi-Carb+PSA Green tea Woolong tea GC-MS GC-MS/MS

Two cartridges Two tea samples Two instruments

0.0GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS

Cleanert TPT Cleanert TPT Envi-Carb+PSA Envi-Carb+PSA Cleanert TPT Cleanert TPT Envi-Carb+PSA Envi-Carb+PSA


Sub-conclusions:①Single-class analysis shows that no matter whether it is Green tea or Woolong tea,or be it GC-MS or

GC-MS/MS determination Clearnet TPT cartridge is superior to Envi-Carb+PSA in cleanup results.②Clustering analysis also proves that no matter whether it Green Tea or Woolong tea or be it GC-MS or

GC-MS/MS determination Cleanert TPT is superior to Envi-Carb+PSA in cleanup results.

21

GC MS/MS determination Cleanert TPT is superior to Envi Carb PSA in cleanup results.③For this inter-collaborative study, Cleanert TPT is recommended to be the cleanup cartridge.

Using both GC-MS/MS and GC-MS 19 circulative determinations over three months are conducted

3.5.6 Statistical analysis of RSD of Green Tea and Woolong tea Youden pairs samples in Stage III and IV

Using both GC MS/MS and GC MS, 19 circulative determinations over three months are conductedon the 271 pesticides and 201 pesticides in both Green Tea and Woolong tea Youden pairs samplesin stage III and IV respectively (3 samples for every parallel testing), with 41192 and 30552 RSDvalues. RSD distribution in different values and the proportion saw the table and column.

Stage III RSD （making up %） Stage IV RSD （making up %

RSD%Green tea Woolong tea Green tea Woolong tea

Statistical analysis of RSD of Green Tea and Woolong tea Youden pairs samples in Stage III and IV

RSD%GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS

≤10 8004（77.9） 7217（70.2） 7697（75.5） 6830（67.9） 6716（87.9） 6744（88.5） 6899（90.3） 6931（91.1）

10.1~15 1465（14.3） 1825（17.8） 1461（14.3） 1707（17.0） 826（10.8） 659（8.6） 574（7.5） 470（6.2）

≤15 9469(92.1) 9042(88.0) 9158(89.8) 8537(84.9) 7542(98.7) 7403(97.1) 7473(97.9) 7401(97.2)

15.1~20 343（3.3） 561（5.5） 421（4.1） 699（6.9） 69（0.9） 152（2.0） 98（1.3） 122（1.6）

＞20 466（4.5） 675（6.6） 619（6.1） 824（8.2） 27（0.4） 69（0.9） 65（0.9） 89（1.2）

22

Statistical analysis of RSD of Green Tea and Woolong tea Youden pairs samples in Stage III and IVStatistical analysis of RSD of Green Tea and Woolong tea Youden pairs samples in Stage III and IV (RSD≤15％)

92 1 89 898.7 97.1 97.9 97.2100.0

120.0

92.1 88.0 89.884.9

60.0

80.0

00.0

%

20.0

40.0

0.0GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS GC-MS GC-MS/MS

Green tea Woolong tea Green tea Woolong tea

St III RSD ( ki %) St IV RSD ( ki %)

The table and the figure show that in terms of RSD ≤15%, RSD data obtained from different teas and differentinstrument determinations in these two stages are all acceptable. However, pesticide quantities with RSD≤10%account for 72.9% in Stage III and 89.5% in Stage IV; pesticide quantities with RSD≤15% account for nearly88.7% in Stage III and nearly 97.8% in Stage IV. Apparently, RSD data obtained in Stage IV are superior to those

Stage III RSD (making up %) Stage IV RSD (making up %)

23

in Stage III, and the cause of such differences have something to do with different operators and differentinstruments in these two stages.

3.6 Stage V: to establish ppb level degradation kinetics exponential equations for 201pesticides in two teas（2010.5.13-8.13）

3.6.1 Comparative study of predicted value and the actual values of kinetics degradaton euations.In the evaluation process of the Ruggedness of the method using two teas and 16 analytical

procedures and based on the test results from 19 circulative determinations over 3 months, 1608 ppblevel residual pesticide degradation kinetics exponential equations have been established (201pesticides X 8 analytical procedures X 2 teas). These exponential equations are only provided for thisAOAC collaborative study. Utilizing these exponential equations will enable one to predict how muchthe content of target pesticide for Youden pair samples will degrade in different time frames.

The index of the equation is for AOAC International collaborative research using GC-MS和GC-MS/MS

24

3.6.2 Calculation method for the deviation rate of predicted values and actual values

The comparative study of the predicted and actual values of collaborative study Youden pair samplesbegan on May 13, 2010, with a duration of 3 months, and will end on Aug.12, 2010, which is still in theprocess of work. A test is conducted every 5 days, with 3 parallel samples each time. The average valueis taken as the testing value, which is compared with the predicted value before the deviation is worked

│A-B │×100％Deviation D＝

D：DeviationA：Predicted value

g , p pout per the following equation:

（A+B）/2 B：Actual value

25

3.6.3 A comparative analysis of the predicted values taken at 5 time points with actual valuesThe comparative results of predicted values with actual values on Days 20 30 40 50 and 60 forThe comparative results of predicted values with actual values on Days 20, 30, 40, 50 and 60 for

Green Tea and Woolong Tea by GC-MS and LC-MS/MS are tabulated in the table below:

Comparison of actual and predicted values for Green Tea

TestingGC-MS GC-MS/MS

Testing time 20 days

(Jun.04,2010)30 days

(Jun.14, 2010)40days

(Jun.24, 2010)50days

(July 04,2010)60days

(July 13,2010)20 days

(Jun.04,2010)30 days

(Jun.14, 2010)40days

(Jun.24, 2010)50days

(July 04,2010)60days

(July 13,2010)

deviation rate

%

quantities (percentage)










<20 126(62 7) 102(50 7) 123(61 2) 74(36 8) 86(42 8) 141(70 1) 73(36 3) 109(54 2) 69(34 4) 82(40 8)<20 126(62.7) 102(50.7) 123(61.2) 74(36.8) 86(42.8) 141(70.1) 73(36.3) 109(54.2) 69(34.4) 82(40.8)

<30 173(86.1) 160(79.6) 170(84.6) 116(57.7) 131(65.2) 180(89.6) 143(71.1) 141(70.1) 133(66.2) 139(69.2)

<40 191(95) 184(91.5) 189(94) 159(79.1) 175(87.1) 197(98) 186(92.5) 186(92.5) 183(91.0) 185(92.0)

>40 10(5) 17(8.5) 12(6) 41(20.4) 26（12.9) 3(1.5) 15(7.5) 15(7.5) 18(9.0) 16(8.0)

Testing time

GC-MS GC-MS/MS

20 days (Jun.04,2010)

30 days (Jun.14, 2010)

40days(Jun.24, 2010)

50days(July 04,2010)

60days (July 13,2010)

20 days (Jun.04,2010)

30 days (Jun.14, 2010)

40days(Jun.24, 2010)

50days(July 04,2010)

60days (July 13,2010)

deviati

Comparison of actual and predicted values for Woolong Tea

deviation rate

%











<20 168(83.6) 141(70.1) 172(85.6) 165(82.1) 169(84.1) 174(86.6) 148(73.6) 150(74.6) 159(79.1) 170(84.6)

<30 185(92) 180(89.6) 188(93.5) 185(92) 188(93.5) 193(96) 188(93.5) 186(92.5) 186(92.5) 190(94.5)

<40 194(96 5) 195(97) 194(96 5) 193(96) 194(96 5) 195(97) 194(96 5) 192(95 5) 192(95 5) 193(96 0)

26

<40 194(96.5) 195(97) 194(96.5) 193(96) 194(96.5) 195(97) 194(96.5) 192(95.5) 192(95.5) 193(96.0)

>40 7(3.5) 6(3) 7(3.5) 8(4) 7(3.5) 5(2.5) 6(3) 8(4) 8(4) 7(3.5)

3.6.4 The tentative probe into the prediction value of target pesticide in Green Tea and Woolong tea (because this study is not over yet)and Woolong tea (because this study is not over yet)

A bar chart of the deviation of predicted and actual values is drawn based on the five time points of Days 20,30, 40, 50 and 60 in the above-mentioned table. (This chart is based on the data of Youden pair ratiodeviation<30% in the above-mentioned table)

100

120 Green teaWoolong tea

86.1(173)

92.0(185)

79.6(160)

89.6(180) 84.6

(170)

93.5(188)

92.0(185)

93.5(188)

89.6(180)

96.0(193)

93.5(188)

92.5(186)

92.5(186)

94.5(190)

40

60

80

％

( )

57.7(116)

65.2(131)

71.1(143)

70.1(141) 66.2

(133)

69.2(139)

0

20

40

20 30 40 50 60 20 30 40 50 60

GC-MS GC-MS/MS

date

The above table and the chart show that for Woolong Tea the deviation of predicted values<30% makes upabout 90%;for Green tea, deviation is greater than that for Woolong, but deviation is <30%. Except for the

27

predictions on Days 50 and 55, deviation of other time points<30 still reaches above 70%. Therefore, theaccuracy of predicted values is above 70% no matter whether it is for Green Tea or Woolong Tea or be it for GC-MS or GC-MS/MS.

3.6.5 Summary of the study in five stages

(1)Test dataStage I （Nov.26,2008-Feb.26,2009）28520 test data have obtained (31 times×2 parallel samples ×460

pesticides )Stage II（Mar.31,2009-Jun.31,2009）81420 test data have obtained (2 teas×2 kinds of instruments×19

times×3 parallel samples ×345 pesticides)S III （J l 09 2009 O 9 2009）129800 d h b i d (2 2 i 2 ki d fStage III （July 09,2009-Oct.9,2009）129800 test data have obtained (2 teas×2 concentrations ×2 kinds of

instruments×19 times×3 parallel samples ×275 pesticides ）Stage IV（Nov.9,2009-Feb.7,2010）189744 test data have obtained (2 teas X 2 cartridges X 2 kinds of

instruments X 2 Youden pair samples, one time every 5 days, 3 parallel samples each time, and 19 determinations conducted over three months X 201 pesticides)

Stage V (May 13 2010-Aug 13 2010) 47216 test data have obtained （ 2 teas×2 kinds of instruments×2Stage V (May 13,2010-Aug.13,2010) 47216 test data have obtained （ 2 teas×2 kinds of instruments×2 cartridges×2 parallel samples（the first 5）×13 times×227pesticides ）

(2)Five papers① The tentative study of the analytical techniques for multiresidues in tea (already submitted to J.AOAC)② Comparative study of efficiencies of three sample preparation techniques (already submitted to J.AOAC)p y p p p q ( y )③ Evaluation of efficiencies of newly-developed cleanup cartridges for multiresidues in tea④ Error analysis and key control points of AOAC collaborative study ( is being written)⑤ The establishment of pesticide degrading kinetics equations for AOAC collaborative study and

predictions for testing values of multiresidues from collaborative study samples (The study of Stage V, which is to written after the completion of test on Aug.13, 2010.)

(3) The expected objective has been reached① Best efforts are made to hone up this expertise to a perfect mastery so as to create successful conditions for collaborators. Also experience is accumulated for our guaranteeing to answer the questions from the collaborators within 24 hours during collaborative study period.② The Scientific Association Dedicated to Analytical Excellence Promoting AOAC spirit: The Scientific

28

② The Scientific Association Dedicated to Analytical Excellence，Promoting AOAC spirit: The Scientific Association Dedicated to Analytical Excellence. A solid foundation has been laid for raising AOAC collaborative study to a new level and establishing a high quality AOAC official method.

4 The tentative plan of AOAC collaborative study protocol4. The tentative plan of AOAC collaborative study protocol

4 1 Content of AOAC collaborative study4.1 Content of AOAC collaborative study(1) The 227 pesticides for collaborative study represent the 668 pesticides for GC-

MS and LC-MS/MS determination. (2) Residual level (concentration) range of target pesticides (see table below)(3) Collaborative study samples: Green Tea and Woolong Tea(4) Analytical techniques: GC-MS, GC-MS/MS and LC-MS/MS

Plan: collaborative study is to finished in two termsThis year : GC-MS and GC-MS/MS methodNext year : LC-MS/MS method or tea method or Chinese herbal medicine method

29

4 2 Classifications of 227 pesticides and residual levels4.2 Classifications of 227 pesticides and residual levels

LOD

LOD concentrations distributions of 227 pesticides

LODug/kg

＜10.0 10.1-50.0 50.1-100.0 100.1-150.0 150.1-200.0 ＞200.0 total

GC-MS 85 129 4 5 2 2 227

LC-MS/MS 101 23 5 2 5 4 140

Per functions

organonitrogen

organohalogen

organophosphorus carbamate pyrethroid organosulfur other total

Classfications

functions rogen alogen osphorus

Quantities96 48 33 18 6 4 22 227

Per compositi herbicid insectici

dbacterici

d acaricide Insects growth l t

Plant growth l t other totalcompositi

ons e de de acaricide regulators regulators other total

Quantities 75 68 48 10 2 2 22 227

In terms of compositions, functions and LOD of the above 227 pesticides, choosing the 227

30

pesticides to stand for 668 pesticides for AOAC collaborative study is representative.

4.3 Sample quantities for collaborative studyp q y

Collaborative study samples: 227 pesticide spiked and incurred Youden pair samples1）Sample types: Green Tea and Woolong Tea2）16 samples for each collaborative study


Spray pesticides of A group

Blank sample Matrix

A B C D

Youden pair samples with spray pesticides of

A group Blank sample Matrix

A B C D

Youden pair samples with spray pesticides of

B group

Spiked pesticides of B&C group

Green tea

Blank sample Matrix

Woolong tea

Youden pair samples with spiked pesticides of

B group Blank sample MatrixYouden pair samples with

spiked pesticides of C group

31A B C D A B C D

4.4 The participating laboratories for this inter-collaborative study (tentative plan)

Three schemes to choose from

I（15）: China (3), USA (3), Canada (2), EU (5), Japan (1) and Taiwan (1)II（20）: China (5) USA (5) EU (5) Canada (2) Japan (2) and Taiwan (1)II（20）: China (5), USA (5), EU (5), Canada (2), Japan (2) and Taiwan (1)III（18-19）：China (8), USA (2), EU (5), Canada (1), Japan (1), Oceania (1-2) and

Africa (1-2)

32

4.5 Statistical calculation method of the collaborative study results

Th d t f thi ll b ti t d t ti ti ll l l t d St ti ti l M l fThe data from this collaborative study are statistically calculated per Statistical Manual ofthe AOAC (Youden,W.J.,&Steiner,E. H.,1975, Arlington,VA), and outliner shall be eliminatedthrough Dixon testing. The repeatability (in-lab errors) and reproducibility (between-lab errors)of the method shall be calculated through the analytical results from Youden pair samples.This traditional method is the one we used for the previous two inter-collaborative studies.p

33

4.6 Error analysis of the method

(1)Sample extraction: monograph Manuscript ID：10-0215 J.AOAC Int.Major errors come from:

(2) Sample cleanup: monograph Manuscript ID：10-0251 J.AOAC Int.(3) Chromatographic resolutions: 944 X 201 chromatograms were obtained from 19

circulative determinations over three months of 8 analytical procedures in Stage IV,and chromatographic resolutions were all conducted for retention time, abundance

ti d b li l ti i d i th 1608 d d ti f 201ratio and baseline selection; in drawing the 1608 degradation curves for 201pesticides (8 analytical procedures X 2 testing means), specific outliners wereanatomized and 9 kinds of chromatographic resolutions have been summed,causing the errors.

(4) I t t l t t (i d li i t b ) t t f d th t th 12 5 28 4%(4) Instrumental state (ion source and lining tube) tests found that there are 12.5-28.4%automatic integration errors from GC-MS and 4.0-9.6% from GC-MS/MS regardingboth Woolong Tea and Green Tea. The errors from the poor state of instruments arenot to be ignored.

(5) Level of participants: capability skill residue analytical experience and sense of(5) Level of participants: capability, skill, residue analytical experience and sense ofresponsibility as well as the conscientious attitude on the part of participants willmake a big difference on the testing results. So the errors from the level of technicalpersonnel are not to be ignored, either.

34

4 7 Key control points of the method4.7 Key control points of the method

① Rotary evaporation temperature shall not exceed 40② Cleanup cartridges: two kinds with negative pressure free or negative pressure applied③ Chromatographic resolutions are checked in the following three Aspects:

a. Check the retention time of each pesticide (including internal standards) to make sure it is within the integration window.

b. Check ion abundance ratio of each pesticideCh k h h i f i i li bc. Check the choice of integration lines to be correct.

④ Make sure that the instrument is the optimum working condition: check in the following three aspects before testing begins

a Check peak’s asymmetrical factors: ±0 1；a. Check peak s asymmetrical factors: ±0.1；b. Check instrumental reproducibility: RSD<0.1% (n=3) (retention time);

RSD<5% (n=3) (peak area)c. Check instrumental sensitivity: calculation of internal matters’ noise signal

⑤ Operators’ technical level and capability shall reach two criteria through conducting tests.a. Spike recovery60-100%, RSD<15%b. Practice blind samples to fall within the range of

predicted values

35

predicted values

4.8 Self-examination acceptance criteria for participants of collaborative study or laboratories(Only for discussion)

Organizers of this inter-collaborative study shall provide participants with twopractice samples, one of which is the spiked sample, the other prepared teaincurred sample. Before conducting official testing of collaborative studysamples, participants should test the spiked sample for self-examination, andcriteria for self examination should meet the following two conditions:

1 When the average recoveries of target pesticides in the 5 parallel spiked samples in the

criteria for self-examination should meet the following two conditions:

1. When the average recoveries of target pesticides in the 5 parallel spiked samples in thelaboratory fall within the range of 70-120% and RSD is <15%, testing of the incurredpractice sample can be started.

2. You will be kindly requested to advise us of your test results from the practice samples.We will inform you within 24 hours if your test results comply with the requirements. Ify y p y qnot, we will try to figure out the cause jointly. Only after the test results comply withrequirements can testing of official collaborative study samples be undertaken.

36

Due to the constant degradations of 227 pesticide incurred samples

4.9 The best testing time of AOAC inter-collaborative study

g p pduring their storage under laboratory conditions, values tested atdifferent time are changing, which is a dynamic value, with which theexponential equations have been established for prediction. Tests foundp q pthat from the date of preparing the incurred samples 70% of the actualvalues and predicted values within 90 days are in conformity with eachother. Therefore, the time of collaborative study is decided to be 90 days,, y y ,which is to say that participating laboratories will have finish testingwithin two months from the day of reception of collaborative studysamples. The best testing time is finishing the test within 45-75 days afterp g g ysample preparation.

37

4.10 Organizers’ promises and requests for participants

1 ） During collaborative study, organizers will make a reply to anytechnical questions concerning the study from participants within 24hours and other questions as well if possible.

2）P ti i t ill h t fi i h t ti th ll b ti t d l2）Participants will have to finish testing the collaborative study sampleswithin the time limit, and conduct the test in one breath without anystops in the middle, preferably finish the test within 5 working days byrunning the test continuously from within 45-75 days after sampleg y y ppreparation.

3）Participants will have to meet the technical requirements for practicebefore testing collaborative study samples officially, and shouldi f i ti i f b i bl t ti i t d tinform us in time in case of being unable to participate due to somereasons.

38

5. Work to do before this AOAC Annual Meeting in September and thefinal time of completion for the study

1.Continue to finish summing up the study of Ruggedness of the method in Stage IV andwrite a monograph;

2.Continue to finish the comparative study of predicted and actual values of targetresidual pesticides of AOAC collaborative study samples in Stage V and write aresidual pesticides of AOAC collaborative study samples in Stage V, and write amonograph.

3. Design AOAC collaborative study protocol and submit to AOAC before the AnnualMeeting

4 Recruit collaborative study laboratories in August and train the domestic4. Recruit collaborative study laboratories in August, and train the domesticparticipating laboratories.

5. If AOAC approves this AOAC collaborative study protocol by the end of Septemberwithin the conditions of our preparations, we will strive to this AOAC collaborativestudy by the end of this yearstudy by the end of this year.

39

6. Historical experience is worth learning from

In the years of 1998 and 2003, I organized two AOAC collaborative studiesy , gattended by 33 laboratories from 12 countries and regions such as China, USA, UK,Japan, Italy, Switzerland, Greece, Slovak, Lithuania, Argentina and Chinese Taiwan,both of which won tremendous success under the guidance of the then AOAC firstreferee, Dr. Parfitt (FDA) and Dr. MacNeil from Canadian Food Agency. Some

i l t d b t th l l D t f l b texperience was accumulated, but there were also lessons. Data from one laboratoryfor the first study and two laboratories for the second study were all eliminated onaccount of test data deviations. This is both historical experience and lessons. Tominimize the occurrences of the above-mentioned problems, one word said it all inthe notice for our attending the meeting: “A pre-collaborative study by thethe notice for our attending the meeting: A pre collaborative study by theparticipating laboratories to ensure the laboratories are qualified to run the method”What is mentioned here is very important. If the pre-collaborative study test isorganized well and performs well, through which participants have got good trainingand mastered the necessary skills, the above-mentioned problems can be preventedf h i Th f I h th t ll th t t thi ti i dfrom happening. Therefore, I hope that all the experts at this meeting raise goodsuggestions so as to organize this pre-collaborative study well, which is key point toensure the success of the study.

40

7. Promote the spire of AOAC international and strive to raise AOAC collaborative study to a new level

Dr. Harvey W. Wiley, founder of AOAC, launched a federal legislative campaign when he wasthe first chemist of American Bureau of Chemistry in 1883. His study on the adulterations infoods caused the serious concern of American government at that time. In 1906, USA

l i d h fi P F d d D A d h l i ll hi f h f

a new level

proclaimed the first Pure Food and Drug Act, and the later generations call him father ofPure Food and Drug Act. Today after over 100 years, reminiscing his contributions to thelegislations of food and drug standards, his strategic eyesight for founding AOAC and hisinnovative and scientific spirit are still of important instructional significance for the studyof our present AOAC standards. Therefore, we should carry on the innovative and scientifico ou p ese t O C sta da ds e e o e, e s ou d ca y o t e o at e a d sc e t cspirit of Dr. Wiley, implement AOAC’s objective of the Scientific Association Dedicated toAnalytical Excellence, organize this collaborative study well, perform it well and strive toraise it to a new and high level.

Harvey W. Wiley IssueWil d hi " i t l" i t t lWiley and his "poison patrol" were instrumental in the passage of the Pure Food and Drug Act. this stamp commemorates the 50 anniversary of the signing of the act which began an era of consumer protection.

41

In a word, we hope to get above 10 countries from five continents ofAmerica, Europe, Asia, Oceania and Africa to participate in this AOACcollaborative study. MacNeil praised us in 2003 for organizing a globalstudy true to its name I hope to do a better job this time For thisstudy true to its name. I hope to do a better job this time. For thispurpose, I sincerely hope that laboratories who are interested in thisstudy will participate in this inter-collaborative study positively and makenew contributions for the development of AOAC OMA methods.p

Qinhuangdao EntryQinhuangdao Entry Exit Inspection and Quarantine Bureau of P R ChinaExit Inspection and Quarantine Bureau of P R ChinaQinhuangdao EntryQinhuangdao Entry--Exit Inspection and Quarantine Bureau of P. R. ChinaExit Inspection and Quarantine Bureau of P. R. ChinaAddress: No. Address: No. 39 Haibin Road, Qinhuangdao China PC: 06600239 Haibin Road, Qinhuangdao China PC: 066002

Fax: +86Fax: +86--335335--5997608 Tel: +865997608 Tel: +86--335335--5997609 Email: [email protected] Email: [email protected]

42

2008-2010 high throughput gc-ms and lc-ms-ms … throughput gc-ms and lc-ms-ms method for 668...

Documents