Determination of Total Aflatoxin Levels in Peanut Butter by Enzyme-Linked Immunosorbent Assay: Collaborative Study

1992 ◽  
Vol 75 (4) ◽  
pp. 693-697 ◽  
Author(s):  
Alan L Patey ◽  
Matthew Sharman ◽  
John Gilbert
Keyword(s):  
Immunosorbent Assay ◽  
Aflatoxin B1 ◽  
Peanut Butter ◽  
Collaborative Study ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Total Aflatoxin ◽  
Aflatoxin Level ◽  
Relative Standard

Abstract Laboratories in Australia, Japan, Spain, the United Kingdom, and the United States participated in a collaborative study to evaluate a commercial enzyme- linked immunosorbent assay for the determination of total aflatoxin. Collaborators were sent 10 randomly numbered samples (5 blind duplicates) of roasted peanut butter. Two pairs were "blank" peanut butters to which aflatoxin B1, B2, G1, and G2 standards had been added. The other 3 pairs of peanut butters were 1 low aflatoxin level sample and 2 naturally contaminated samples. The assay is based on indirect competition. Test samples containing (free) aflatoxin, added to aflatoxin-coated microwells, compete for specific monoclonal rat anti-aflatoxin. As the concentration of aflatoxin in the test samples increases, the amount of rat antiaflatoxin binding to the aflatoxin attached to the well decreases. After a wash step to remove unbound material, the amount of rat anti-aflatoxin bound to the well is determined by its reaction with peroxidase conjugated rabbit anti-rat globulin. Bound peroxidase activity is then determined by the addition of a substrate, whose color development is inversely proportional to the aflatoxin concentration and is measured by absorbance. Coefficients of variation (CV) for total aflatoxin concentrations, for mean levels of 9,30, and 89µg/kg, were between 28 and 37% for the low level and 2 naturally contaminated samples, which contained mainly aflatoxin B1. CVs for the spiked samples were lower (24-25%) for mean levels of 11 and 20 µg/kg; recoveries were 84 and 89%, respectively. Ranges for relative standard deviations for repeatabilty and reproducibility were 9-30% and 25-37%, respectively. The method has been adopted first action by AOAC International.

scholarly journals Determination of Total Fumonisins in Corn by Competitive Direct Enzyme-Linked Immunosorbent Assay: Collaborative Study

2002 ◽  
Vol 85 (2) ◽  
pp. 404-410 ◽  
Author(s):  
Chuck B Bird ◽  
Bruce Malone ◽  
Larry G Rice ◽  
P Frank Ross ◽  
Robert Eppley ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Fusarium Species ◽  
Collaborative Study ◽  
The United States ◽  
Enzyme Linked Immunosorbent Assay ◽  
Test Portion ◽  
Relative Standard ◽  
Standard Deviations ◽  
Different Levels

Abstract Fumonisins—mycotoxins produced by some Fusarium species—have been shown to be the causative agent of diseases in horses and other domesticated animals as well as possible carcinogens in humans. A collaborative study was conducted to evaluate the effectiveness of a competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for the determination of total fumonisins (B1, B2, and B3) in corn. The test portion was extracted with methanol–water (7 + 3), filtered, diluted, and tested on the CD-ELISA. Naturally and artificially contaminated corn test portions were sent to 13 collaborators in the United States. Naturally contaminated field test portions were prepared at 3 different levels. Artificially contaminated test portions were spiked at 1.0, 3.0, and 5.0 mg/kg total fumonisins (B1, B2, and B3). Average recoveries of total fumonisins were 120, 100, and 90%, respectively. The relative standard deviations for repeatability ranged from 13.3 to 23.3% and the relative standard deviations for reproducibility ranged from 15.8 to 30.3% across all levels tested. HORRAT values, calculated for each individual sample, ranged from 1.24 to 1.94. This method demonstrated acceptable intra- and interlaboratory precision at the levels tested.

scholarly journals Determination of Cry9C Protein in Corn-Based Foods by Enzyme-Linked Immunosorbent Assay: Interlaboratory Study

2001 ◽  
Vol 84 (6) ◽  
pp. 1891-1902 ◽  
Author(s):  
Mary W Trucksess ◽  
T Artis ◽  
C Diaz ◽  
C Fernandez ◽  
K Harkin ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Specific Interaction ◽  
Strong Acid ◽  
The United States ◽  
Interlaboratory Study ◽  
Enzyme Linked Immunosorbent Assay ◽  
Corn Flour ◽  
Relative Standard ◽  
Standard Deviations

Abstract The performance of a commercially available enzyme-linked immunosorbent assay kit (Enviro-Logix) was assessed for the determination of Cry9C protein, which is produced by the genetically modified corn StarLink, in 8 types of corn-based foods (starch, refined oil, soft tortillas, tortilla chips, corn flakes, corn puffs, corn muffins, and corn bread) in an interlaboratory study involving 7 laboratories in the United States. The assay kit is a double antibody sandwich and is based on the specific interaction between antibody and antigen. The Cry9C protein analyte is sandwiched between 2 antibodies, one to capture the analyte and the other is conjugated to the enzyme, horseradish peroxidase. The enzyme uses tetramethylbenzidine/peroxide for color development. A strong acid stopping reagent is then used to change the color from blue to a stable yellow. The intensity of the color is proportional to the concentration of the Cry9C protein. In this study blind duplicates of control samples (blank material prepared from non- StarLink corn), spiked samples (blank material with the addition of Cry9C protein), and samples containing incurred analyte (products prepared with StarLink corn) were analyzed. Cry9C protein from 2 different sources was used to spike the food products. Cry9C protein produced and purified from a bacterial host was used to prepare spiked test samples at 2.72 and 6.8 ng/g. Cry9C protein from StarLink corn flour was used to prepare spiked samples at 1.97 ng/g. Average recoveries for samples spiked with corn flour Cry9C protein at 1.97 ng/g ranged from 73 to 122%, within-laboratory relative standard deviations (RSDr) ranged from 6 to 22%, and between-laboratories relative standard deviations (RSDR) ranged from 16 to 56%. Average recoveries for samples spiked with bacterial Cry9C protein at 2.72 and 6.8 ng/g ranged from 27 to 96% and from 32 to 113%, respectively; RSDr values ranged from 10 to 35%and from 7 to 38%, respectively; and the RSDR ranged from 28 to 84%and 15 to 75%, respectively. The incurred test samples were found to contain Cry9C protein at levels ranging from 0.8 to 3187 ng/g depending on the product, RSDr values ranged from 5 to 16% and RSDR values ranged from 11 to 71%. Results of the statistical analysis indicate that this method is applicable to the determination of Cry9C protein in the 8 types of collaboratively studied corn-based products containing Cry9C protein (from StarLink ) at levels of ≥2 ng/g.

Enzyme-Linked Immunosorbent Assay for Detection of Zearalenone in Corn, Wheat, and Pig Feed: Collaborative Study

1994 ◽  
Vol 77 (6) ◽  
pp. 1500-1508 ◽  
Author(s):  
Glenn A Bennett ◽  
Terry C Nelsen ◽  
Brjnton M Miller
Keyword(s):  
Immunosorbent Assay ◽  
Collaborative Study ◽  
Screening Method ◽  
The United States ◽  
False Positives ◽  
Enzyme Linked Immunosorbent Assay ◽  
Elisa Method ◽  
False Negatives ◽  
Relative Standard ◽  
Pig Feed

Abstract A direct competitive enzyme-linked immunosorbent assay (ELISA) screening method for zearalenone in corn, wheat, and feed at 500 ng/g was evaluated by 23 collaborators (22 laboratories) in an international collaborative study. Eighteen samples of spiked or naturally contaminated corn, wheat, and pig feed were prepared by the sponsoring laboratory and sent for testing with complete test kits to participating collaborators in Canada, Italy, Sweden, The Netherlands, and the United States. Test samples were extracted with methanolwater solution (70 + 30) by shaking on a wrist-action shaker for 3 min. A portion of the extract was mixed with an equal volume of zearalenone-enzyme conjugate, and the mixture was incubated with zearalenone-specific monoclonal antibodies coated onto microtiter wells. All test samples were assayed in duplicate. One of 52 (2%) blanks was reported positive. Thirty-nine of the 52 (75%) samples that were spiked at 500 ng/g were reported as positive. Forty-nine of the 51 (96%) samples with concentrations at or above 1000 ng/g were reported as positive. The overall incidence of false negatives was 6.0% and the incidence of false positives was 22.7% by the ELISA method. Only one (3.4%) false negative was reported for samples containing ≥800 ng/g. In the spectrophotometric method, 8 collaborators determined approximate levels of zearalenone in test samples from standard curves constructed from spiked extracts (0–3000 ng/g of each commodity tested). This method gave and overall incidence of false negatives of 5.7% and false positives of 17.8%. Average relative standard deviations, RSDr (repeatability) and RSDR (reproducibility), were 11.6 and 25.1% for spiked samples and 11.7 and 33.1% for naturally contaminated samples, respectively. Standard curves were constructed with each set of samples assayed. Comparison of absorbance values from these standard curves indicate the performance of reagents and antibody used in the assay. The ELISA method has been adopted first action by AOAC INTERNATIONAL as a screening method for zearalenone at ≥800 ng/g in corn, wheat, and pig feed.

Solvent-Efficient Thin-Layer Chromatographic Method for the Determination of Aflatoxins B1, B2, G1, and G2 in Corn and Peanut Products: Collaborative Study

1994 ◽  
Vol 77 (3) ◽  
pp. 637-646 ◽  
Author(s):  
Douglas L Park ◽  
Mary W Trucksess ◽  
Stanley Nesheem ◽  
Michael Stack ◽  
Richard F Newell
Keyword(s):  
Thin Layer ◽  
Peanut Butter ◽  
Collaborative Study ◽  
The United States ◽  
High Recovery ◽  
Relative Standard ◽  
Aoac Method ◽  
Repeatability And Reproducibility ◽  
Contamination Levels

Abstract An interlaboratory study of a solvent-efficient thin-layer chromatographic (TLC) method for the determination of aflatoxins B1, B2, G1, and G2 was conducted in laboratories located in the United States, France, Tunisia, and Denmark. Eighteen artificially contaminated samples plus blanks of raw peanuts and peanut butter and corn containing varying amounts of aflatoxins B1, B2, G1, and G2 were distributed to participating laboratories. The method consists of elements of the U.S. Food and Drug Administration (FDA), Contaminants Branch (CB) (AOAC Method 968.22) and FDA, Best Foods (BF) (AOAC Method 970.45) methods with reduced requirements for solvents. Participating laboratories used either visual or densitometric techniques during the final determinative step. Statistical analysis of the data was performed to determine or confirm outliers and to compute repeatability and reproducibility of the method using either visual or densitometric techniques for the determinative step. Reported results from laboratories using a densitometer showed that, for corn, the relative standard deviation for repeatability (RSDr) for aflatoxin Bi ranged from 56.6 to 41.7% for contamination levels ranging from 5 to 50 ng/g. For raw peanuts and peanut butter, the RSDr values for aflatoxin Bi ranged from 21.3 to 37.3% and 65.9 to 42.1%, respectively, for the contamination levels ranging from 5 to 25 ng/g. RSDr ranges for anatoxins B2, Gi, and G2 were similar. For reproducibility (R), the RSDr ranges for aflatoxin Bi were 41.7-56.6%, 56.6-84.8%, and 26.4-37.3% for corn, peanut butter, and raw peanuts, respectively. Average re-coveries for all aflatoxins at all levels were 95.3, 139.0, and 95.6% for corn, peanut butter, and raw peanuts, respectively. When analysts determined af latoxin concentrations in corn by visual comparison to standards, the RSDr values for aflatoxin Bi were 47.8-11.4% for contamination levels ranging from 5 to 50 ng/g. For raw peanuts and peanut butter, the RSDr values for aflatoxin Bi were 76.3-12.6% and 33.4-8.8%, respectively, for the contamination levels ranging from 5 to 25 ng/g. RSDr values for aflatoxins B2, G1, and G2 were similar. The RSDr values for aflatoxin Bi were 34.6-90.2%, 45.5-59.3%, and 31.8-78.3% for corn, peanut butter, and raw peanuts, respectively. Average recoveries for all anatoxins at all levels were 111.0,157.6, and 92.3% for corn, peanut butter, and raw peanuts, respectively. High recoveries were noted for anatoxins in peanut butter determined by either a densitometer or comparison to standards. Generally, increased precision was observed with the method at higher contamination levels. On the basis of the results obtained in this AOAC/IUPAC collaborative study, the solvent-efficient TLC method using densitometry for the quantitative step was adopted first action by AOAC for the determination of aflatoxins B1, B2, G1, and G2 in corn at levels within the range of 5-50 ng/g, 3-15 ng/g, 10-50 ng/g, and 3- 15 ng/g, respectively, by densitometry; for anatoxins B1 and B2 in raw peanuts at levels ranging from 5 to 25 ng/g and from 1.5 to 7.5 ng/g, respectively, by densitometry; and for aflatoxins B1 and G1 in corn at 10-50 and 50 ng/g, respectively, and aflatoxins B1, B2, and G1 in raw peanuts at 10-25 ng/g, 7.5 ng/g, and 10-25 ng/g, respectively. Because of high recovery values, additional study is recommended for peanut butter. The solvent-efficient TLC method for determination of aflatoxins B1, B2, G1, and G2 in corn and peanuts has been adopted first action by AOAC INTERNATIONAL.

Liquid Chromatographic Method for Determination of Aflatoxins B1, B2, G1, and G2 in Corn and Peanut Products: Collaborative Study

1990 ◽  
Vol 73 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Douglas L Park ◽  
Stanley Nesheim ◽  
Mary W Trucksess ◽  
Michael E Stack ◽  
Richard F Newell
Keyword(s):  
Chromatographic Method ◽  
Peanut Butter ◽  
Collaborative Study ◽  
The United States ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Standard Deviations ◽  
Contamination Levels ◽  
Liquid Chromatographic

Abstract A collaborative study of a liquid chromatographic method for the determination of aflatoxins B1, B2, G1, and G2 was conducted in laboratories located in the United States, Canada, South Africa, and Switzerland. Twenty-one artificially contaminated raw peanuts, peanut butter, and corn samples containing varying amounts of aflatoxins B1, B2, G1, and G2 were distributed to participating laboratories. The test portion was extracted with methanol-0.1N HCl ( 4 + 1 ) , filtered, defatted with hexane, and then partitioned with methylene chloride. The concentrated extract was passed through a silica gel column. Aflatoxins B1 and G1 were derivatized with trifluoroacetic acid, and the individual aflatoxins were determined by reverse-phase liquid chromatography with fluorescence detection. Statistical analysis of the data was performed to determine or confirm outliers, and to compute repeatability and reproducibility of the method. For corn, relative standard deviations for repeatability (RSDr) for anatoxin B1 ranged from 27.2 to 8.3% for contamination levels from 5 through 50 ng/g. For raw peanuts and peanut butter, RSDr values for aflatoxin Bi were 35.0 to 41.2% and 11.2 to 19.1 %, respectively, for contamination levels from 5 through 25 ng/g. RSDr values for aflatoxins B2, G1, and G2 were similar. Relative standard deviations for reproducibility (RSDR) for aflatoxin B1 ranged from 15.8 to 38.4%, 24.4 to 33.4%, and 43.9 to 54.0% for corn, peanut butter, and raw peanuts, respectively. The method has been adopted official first action for the determination of aflatoxins B1, B2, G1, and G2 in peanut butter and corn at concentrations ≥13 ng total aflatoxlns/g.

Immunoaffinity Column Coupled with Solution Fluorometry or Liquid Chromatography Postcolumn Derivatization for Determination of Aflatoxins in Corn, Peanuts, and Peanut Butter: Collaborative Study

1991 ◽  
Vol 74 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Mary W Trucksess ◽  
Michael E stack ◽  
Stanley Nesheim ◽  
Samuel W Page ◽  
Richard H Albert ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Peanut Butter ◽  
Collaborative Study ◽  
The United States ◽  
Affinity Column ◽  
Immunoaffinity Column ◽  
Relative Standard

Abstract An AOAC/IUPAC (International Union of Pure and Applied Chemistry) collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column for the determination of af latoxin. The test portion Is extracted with methanol- water (7 + 3), filtered, diluted to ⦟30% methanol with water, and applied to the affinity column. The column Is washed with water and the concentrated aflatoxins are eluted with methanol. Total aflatoxins are determined by solution fluorometry with bromine (SFB), and Individual toxins are determined by reverse-phase liquid chromatography with postcolumn derlvatizatlon with Iodine (PCD). Corn naturally contaminated with aflatoxins, and peanuts, peanut butter, and corn containing added aflatoxins ( B1:B2:G1G2 = 7:1:3:1) were sent to 24 collaborators In the United States, France, Canada, and the Republic of South Africa. Twelve collaborators used the SFB method, 9 used the PCD method, and 3 used both SFB and PCD methods. Twenty collaborators completed the study (10 used the SFB method, 7 used the PCD method, and 3 used both SFB and PCD methods). Test portions were spiked at 10, 20, and 30 ng/g. For SFB analyses, recoveries of total aflatoxins were 123,105, and 107%, respectively; the relative standard deviation for repeatability (RSDr) ranged from 11.75 to 16.57%, and the relative standard deviation for reproducibility (RSDR) ranged from 10.97 to 33.09%. For PCD analyses, recoveries were 81, 81, and 83%, respectively; the RSDr ranged from 5.20 to 17.22%, and the RSDR ranged from 4.68 to 50.77%. The RSDr for aflatoxins B1, and G1 for spiked test portions ranged from 5.45 to 23.55%, and the RSDR ranged from 4.21 to 57.28%. The RSDr and RSDR for aflatoxins B2 and G2 were higher because of the small amounts added. Analyses by both SFB and PCD methods showed acceptable within-laboratory and betweenlaboratories precision. The method has been adopted official first action by AOAC as an AOAC-IUPAC method.

scholarly journals Immunoaffinity Column Cleanup with Liquid Chromatography Using Post-Column Bromination for Determination of Aflatoxins in Peanut Butter, Pistachio Paste, Fig Paste, and Paprika Powder: Collaborative Study

2000 ◽  
Vol 83 (2) ◽  
pp. 320-340 ◽  
Author(s):  
Joerg Stroka ◽  
Elke Anklam ◽  
Urban Jörissen ◽  
John Gilbert ◽  
Anna Barmark ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Aflatoxin B1 ◽  
Peanut Butter ◽  
Collaborative Study ◽  
Immunoaffinity Column ◽  
Sample Extract ◽  
Relative Standard

Abstract A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for the determination of aflatoxin B1 and total aflatoxins at European regulatory limits. The test portion is extracted with methanol–water (8 + 2) for dried figs and paprika, and with methanol–water (8 + 2) plus hexane (or cyclohexane) for peanut butter and pistachios. The sample extract is filtered, diluted with phosphate buffer saline, and applied to an immunoaffinity column. The column is washed with water and the aflatoxins are eluted with methanol. Aflatoxins are quantitated by reversed-phase LC with post-column derivatization (PCD) involving bromination. PCD is achieved with either an electrochemical cell (Kobra cell) and addition of bromide to the mobile phase or pyridinium hydrobromide perbromide. Determination is by fluorescence. Peanut butter, pistachio paste, dried fig paste, and paprika powder samples, both naturally contaminated with aflatoxins and containing added aflatoxins, were sent to 16 collaborators in 16 European countries. Test portions of samples were spiked at levels of 2.4 and 9.6 ng/g for total aflatoxins which included 1.0 and 4.0 ng/g aflatoxin B1, respectively. Recoveries for total aflatoxins ranged from 71 to 92% with corresponding recoveries for aflatoxin B1 of 82 to 109%. Based on results for spiked samples (blind duplicates at 2 levels) as well as naturally contaminated samples (blind duplicates at 4 levels, including blank), the relative standard deviation for repeatability ranged from 4.6 to 23.3% for total aflatoxins and from 3.1 to 20.0% for aflatoxin B1. The relative standard deviation for reproducibility ranged from 14.1 to 34.2% for total aflatoxins, and from 9.1 to 32.2% for aflatoxin B1. The method showed acceptable within-laboratory and between-laboratory precision for all 4 matrixes, as evidenced by HORRAT values <1, at the low levels of determination for both total aflatoxins and aflatoxin B1.

Simultaneous Determination of Aflatoxin B1 and Aflatoxin M1 in Food Matrices by Enzyme-Linked Immunosorbent Assay

2012 ◽  
Vol 6 (3) ◽  
pp. 767-774 ◽  
Author(s):  
Wenxiao Jiang ◽  
Zhanhui Wang ◽  
Greta Nölke ◽  
Jing Zhang ◽  
Lanlan Niu ◽  
...  
Keyword(s):  
Simultaneous Determination ◽  
Immunosorbent Assay ◽  
Aflatoxin B1 ◽  
Aflatoxin M1 ◽  
Enzyme Linked Immunosorbent Assay ◽  
Food Matrices

scholarly journals Interlaboratory Evaluation of Two Enzyme-Linked Immunosorbent Assay Kits for the Determination of Crustacean Protein in Processed Foods

2008 ◽  
Vol 91 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Shinobu Sakai ◽  
Rieko Matsuda ◽  
Reiko Adachi ◽  
Hiroshi Akiyama ◽  
Tamio Maitani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Immunosorbent Assay ◽  
Soluble Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Processed Foods ◽  
Relative Standard ◽  
High Level

Abstract The labeling of foods containing material derived from crustaceans such as shrimp and crab is to become mandatory in Japan because of increases in the number of allergy patients. To ensure proper labeling, 2 novel sandwich enzyme-linked immunosorbent assay (ELISA) kits for the determination of crustacean protein in processed foods, the N kit (Nissui Pharmaceutical Co., Ltd, Ibaraki, Japan) and the M kit (Maruha Nichiro Holdings, Inc., Ibaraki, Japan), have been developed. Five types of model processed foods containing 10 and/or 11.9 g/g crustacean soluble protein were prepared for interlaboratory evaluation of the performance of these kits. The N kit displayed a relatively high level of reproducibility relative standard deviation (interlaboratory precision; 4.08.4 RSDR) and sufficient recovery (6586) for all the model processed foods. The M kit displayed sufficient reproducibility (17.620.5 RSDR) and a reasonably high level of recovery (82103). The repeatability relative standard deviation (RSDr) values regarding the detection of crustacean proteins in the 5 model foods were mostly <5.1 RSDr for the N kit and 9.9 RSDr for the M kit. In conclusion, the results of this interlaboratory evaluation suggest that both these ELISA kits would be very useful for detecting crustacean protein in processed foods.

Gas Chromatographic-Thermal Energy Analysis Method for Determination of Volatile N-Nitrosamines in Baby Bottle Rubber Nipples: Collaborative Study

1987 ◽  
Vol 70 (1) ◽  
pp. 64-68 ◽  
Author(s):  
J Ian Gray ◽  
Michael A Stachiw
Keyword(s):  
Thermal Energy ◽  
Energy Analysis ◽  
Collaborative Study ◽  
Internal Standard ◽  
Analytical Techniques ◽  
The United States ◽  
Baby Bottle ◽  
Relative Standard ◽  
Better Than

Abstract A collaborative study was conducted on the U.S. Food and Drug Administration (FDA) dichloromethane extraction method for determining volatile N-nitrosamines in baby bottle rubber nipples. Following dichloromethane extraction, A'-nitrosamines were determined by gas chromatography-thermal energy analysis. Six pairs of blind duplicate rubber nipple samples representing 6 lots were analyzed by 11 collaborating laboratories. All samples were portions taken from equilibrated composites of cut-up rubber nipples obtained from manufacturers in the United States. Recoveries of the internal standard (N-nitrosodipropylamine) at approximately 20 ppb ranged from 10 to 120%. Reproducibility relative standard deviations (RSDJ were between 35 and 45% for N-nitrosamine levels from 10 to 20 ppb. However, when data from laboratories with recoveries less than 75% were excluded (this is now specified in the method), RSD„ values were between 11 and 32% for N-nitrosamine levels from 6 to 26 ppb. Values were consistent with or better than those reported for other analytical techniques designed to quantitate trace contaminants at the low ppb level, e.g., afiatoxin in foods. The method has been adopted official first action for the quantitation of volatile N-nitrosamines in baby bottle rubber nipples.

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