Pesticide and Disinfectant Formulations
Drugs and Related Topics

• Liquid Chromatographic Determination of Flumequine, Nalidixic, Oxolinic, and Piromidic Acid Residues in Catfish (Ictalurus punctatus)
• Simultaneous Determination of Water and Ene-diols or Thiols in Chemical Products and Drugs Not Amenable for Direct K. Fischer Titration

• Determination of Deoxynivalenol in White Flour, Whole Wheat Flour, and Bran by Solid-Phase Extraction/Liquid Chromatography: Interlaboratory Study

Food Nutrition

• Capillary Gas Chromatographic Determination of Fat in Olestra Savory Snack Products
• pH-Metric Determination of the Acid Value of Vegetable Oils without Titration
• Determination of Total Fat in Foods and Feeds byt the Caviezel Method, Based on a Gas Chromotographic Technique
• pH-Metric Determination of the Acid Value of Oilseeds without Titration
• pH-Metric Acid Number Determination in Petroleum Oils without Titration

• Fluorometric Determination of Acid Phosphatase in Cooked, Boneless, Nonbreaded Broiler Breast and Thigh Meat
• Measurement of Bromate in Bread by High Performance Liquid Chromatography with Post-Column Flow Reactor Detection Residues

• Determination of Fluoride in Bovine Urine
• Thin Layer Chromatographic Determination of Monensin in Feeds: Screening Method
• Liquid Chromatographic Determination of Ivermectin in Feed Environmental Quality

Drugs and Related Topics
AOAC® PEER-VERIFIED METHOD PVM 1:1995
Liquid Chromatographic Determination of Flumequine, Nalidixic, Oxolinic, and Piromidic Acid Residues in Catfish (Ictalurus punctatus)
Abstract: A peer-verified, liquid chromatographic (LC) method for simultaneous determination of residues of flumequine (FLU), nalidixic acid (NAL), oxolinic acid (OXO), and piromidic acid (PIR) in catfish muscle is presented. Sample workup involves homogenizing tissue with acetone, defatting with hexane, and extracting quinolones into chloroform. Sample is purified further by partitioning into base and then subsequently back-extracting into chloroform after acidifying the aqueous phase. After solvent is evaporated, the residue is diluted with mobile phase, and analytes are introduced into an LC system where separations are made with a 5 µm, reversed-phase polymer column and an isocratic, buffered acetonitrile-tetrahydrofuran mobile phase. Determinations are made by UV detection at 280 nm for PIR and by fluorescence detection (excitation at 325 excitation and emission at 365 nm) for the other 3 analytes. Each quinolone was used to fortify catfish muscle at 5, 10, 20, 40, and 80 ng/g. The following recoveries and relative standard deviation (RSD) values represent an average of the 5 levels for each analyte: FLU, 79.7% (RSD = 5.7%); OXO, 80.8% (RSD = 6.3%); PIR, 75.0% (RSD = 5.9%); and NAL, 87.1% (RSD = 10%). Assay of 5 levels (base incurred catfish, plus 4 dilutions with control catfish) of catfish muscle incurred with the 4 quinolones gave the following averages:FLU: base, 198 ng/g (RSD = 2.3%); dilutions, 98.0 ng/g (RSD = 4.2%), 61.6 ng/g (RSD = 4.4%), 21.6 ng/g (RSD = 2.8%), 9.24 ng/g (RSD = 8.7%); OXO, base, 257 ng/g (RSD = 6.9%); dilutions, 146 ng/g (RSD = 5.5%), 95.0 ng/g (RSD = 4.1%), 30.7 ng/g (RSD = 3.8%), 13.7 ng/g (RSD = 4.6%); PIR, base, 22.1 ng/g (RSD = 4.2%); dilutions, 13.7 ng/g (RSD = 6.7%), 6.49 ng/g (RSD = 15%), 2.65 ng/g (RSD = 15%); and NAL, base, 75.1 ng/g (RSD = 3.8%); dilutions, 42.3 ng/g (RSD = 5.1%), 24.1 ng/g (RSD = 6.3%), 8.59 ng/g (RSD = 4.8%). A second multiresidue analysis of the 4 quinolones was performed by an outside analyst. Average recoveries from catfish fortified at 5, 10, 20, and 40 ng/g were FLU, 75.9% (RSD = 4.0%); OXO, 84.0% (RSD = 5.5%); NAL, 85.6% (RSD = 8.9%); and PIR, 66.2% (RSD = 8.7%). The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 1:1998 Simultaneous Determination of Water and Ene-diols and Thiols in Chemical Products and Drugs Not Amenable for Direct K. Fischer Titration
Abstract: Method for the determination of water and ene-diols and thiols is based on the consecutive titration, first of the ene-diols or thiols by the novel reagent, and then of water by the conventional K.Fischer reagent in the same cell. The time necessary for both titrations is 8-20 min. The novel reagent consists of iodine, sodium acetate as a base, and potassium iodide in a nonaqeous solvent system. The method is applicable for quality control of chemical products and drugs during their production and trade. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form. Return to Category List/ AOAC® Methods Validation and Technical Programs / AOAC INTERNATIONAL Home Page

Natural Toxins
AOAC® PEER-VERIFIED METHOD PVM 2:1997
Determination of Deoxynivalenol in White Flour, Whole Wheat Flour, and Bran by Solid-Phase Extraction/Liquid Chromatography: Interlaboratory Study
Abstract: A liquid chromatographic (LC) method for determining deoxynivalenol (DON) in white flour, whole wheat flour, and bran at or above the U.S. Food and Drug Administration advisory level of 1 µg/g was evaluated by an interlaboratory study. Test samples of processed wheat (flour and bran) were extracted by blending with acetonitrile-water (84 + 16). Extracts were filtered and passed through a solid-phase extraction (SPE) column. The eluate was then chromatographed on a reversed-phase LC column with a water-methanol gradient. DON was measured at 220 nm. Naturally contaminated white flour, whole wheat flour, and bran samples and spiking solutions of DON to be added to the 3 commodities at 0.5, 1.0, and 2.0 µg/g were sent to 4 collaborators in Kansas, Louisiana, Missouri, and Washington states. Three collaborators completed the study. Average recoveries of DON from the 3 commodities spiked at 0.5, 1.0, and 2.0 µg/g were 94, 87, and 97%, respectively. Within-laboratory relative standard deviations for repeatability (RSDr) ranged from 3.1 to 21.7% and between-laboratory relative standard deviations for reproducibility (RSDR) ranged from 10.8 to 38.7%. On the basis of the results of this study, the SPE/LC method for DON in white flour, whole wheat flour, and bran was adopted as a peer-verified method by AOAC INTERNATIONAL. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.Return to Category List/ AOAC® Methods Validation and Technical Programs / AOAC INTERNATIONAL Home Page

Food Nutrition
AOAC® PEER-VERIFIED METHOD PVM 4:1995
Capillary Gas Chromatographic Determination of Fat in Olestra Savory Snack Products
Abstract: A quantitative method to determine fat in olestra-containing savory snack products has been validated within the AOAC Peer-Verified Methods Program. The results of the method may be used to demonstrate compliance with the U.S. Nutrition Labeling and Education Act (NLEA) guidelines for "fat free" and "low fat" labeling. The method is applicable to the measurement of total and saturated fat in savory snacks, when present at levels from 0.2 to 10 g total fat and 0.1 to 3 g saturated fat per 30 g serving. The method is standardized to measure C6-C24 fatty acids. Olestra savory snack samples are extracted with chloroform-methanol solution (modified AOAC® Official Method 983.23), yielding a lipid extract which contains the total fat and olestra. The extracted lipid is hydrolyzed by lipase, yielding fatty acids and unreacted olestra. The fatty acids are then precipitated as calcium soaps. Olestra is extracted from the insoluble soaps with hexane and then discarded. The isolated soaps are converted back into fatty acids with hydrochloric acid and extracted to hexane. The isolated fatty acids are converted to methyl esters with boron trifluoride-methanol solution and quantified by capillary gas chromatography using internal standard. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 1:1997
pH-Metric Determination of the Acid Value of Vegetable Oils without TitrationAbstract: The acid value (AV) of vegetable oils is determined without titration by using a new reagent consisting of triethanolamine in a solution of water and isopropyl alcohol. When the oil sample is mixed with the reagent in the pH-metric cell, free fatty acids from the sample are extracted into the reagent (3-4 min). The initial pH, called conditional pH´1, is measured, a standard acid (HCl) is added, and the final pH, pH´2, is measured. AV is calculated from the difference between pH´1 and pH´2. The method is applicable for quality control of vegetable oils during their production, trade, and use. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 4:1997
Determination of Total Fat in Foods and Feeds byt the Caviezel Method, Based on a Gas Chromotographic TechniqueAbstract: This peer-verified method specifies a fast, easy, and reliable quantitative method to determine total fat in foods and feeds in compliance with the new definition of fat from the U.S. Food and Drug Administration. The method takes into consideration all fatty acids, from C4 to C24, and when fat is present at 0.3-100%. The validation study included 9 matrixes, with fat levels ranging from 1 to 79%. Sample and internal standard (IS; tridecanoic acid) are added to solvent (n-butyl alcohol). Fat is extracted and simultaneously saponified by potassium hydroxide. The fatty acid potassium salts are converted to fatty acids by adding an acidic aqueous salt solution, which produces a 2-phase system. The upper phase, containing the fatty acids and IS, is injected into the fat determination system. After gas chromatographic separation, the fat content is calculated from IS and fatty acid peak areas. The fat content is automatically converted to triglyceride content with a predetermined factor. Ten replicates of 9 different food samples, which cover the whole range of different contents in fat, proteins, and carbohydrates, were analyzed by the submitting and the peer laboratories. Repeatability relative standard deviation (RSDr) values ranged from 0.47 to 4.62%. Reproducibility relative standard deviation (RSDR) values ranged from 0.85 to 9.52%. These estimates include between-run variability. The method shows good accuracy. Values for standard reference materials (SRMs) are in agreement with certified values. Regression analysis of the correlation between observed fat and certified value over all matrixes and fat levels indicated good precision and absence of method bias (5 SRMs; 1-30% fat; correlation coefficient, R2 = 99.98%). The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 1:1999
pH-Metric Determination of the Acid Value of Oilseeds without TitrationAbstract: A pH-metric method for determining the acid values (AVs) of oilseeds in the range 0.6-10 mg KOH/g oil or more has been developed. The method is based on raid (1-2 min) and complete extraction of free fatty acids from an oilseed test portion into a special reagent A, transfer of an aliquot of the reagent into pH-metric cell with another reagent B, and then measurements of the conditional pH in the mixture of reagents by a glass electrode. Total time for the determination including calculation is 9-10 min. The method is rapid, cheap, simple for sutomation, and not labor intensive. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 3:1999
pH-Metric Acid Number Determination in Petroleum Oils without TritrationThe pH-metric method using a special reagent [2] is intended for determination of low acid numbers (AN) in oils without titration. It can be applied to analysis of White oils used in pharmacy and perfumery, Transformer and Basic oils, where control of AN is important for safety, and other similar oils. The method has the following advantages in comparison to standard titration methods [3-6 ]: is not time and labor consuming, is cheap and simple for automation, uses non-toxic reagent. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form. Return to Category List/ AOAC® Methods Validation and Technical Programs / AOAC INTERNATIONAL Home Page

Commodity Foods and Commodity Products
AOAC® PEER-VERIFIED METHOD PVM 3:1997
Fluorometric Determination of Acid Phosphatase in Cooked, Boneless, Nonbreaded Broiler Breast and Thigh Meat
Abstract: This method is applicable for determining activity of acid phosphatase (ACP), a heat-labile enzyme, in cooked, boneless, nonbreaded broiler marinated (83.65% meat) and nonmarinated (100% meat) breast and thigh and in a 50:50 blend of breast and thigh meat. The assay uses a self-indicating substrate that, when acted upon by ACP, loses a phosphate radical and becomes a highly fluorescent compound. Cooked meat is added to deionized distilled water in a 1:3 ratio, blended with a hand-held homogenizer, and then centrifuged at 2500 relative centrifugal force for 5 min. ACP activity in the filtrate is measured after shaking on a Vortex mixer 75 µL of the extract with a pH 5.00 acetate buffer containing a nonfluorescent aromatic monophosphoric ester substrate. The rate of fluorophore formation is monitored during a 3 min incubation period (38°C) in a fluorometer, and ACP enzyme activity (mU/kg sample) is calculated. Three laboratories analyzed 6 cooked poultry products (marinated and nonmarinated breast, thigh, and 50:50 breast/thigh blend). Five cooking temperatures were used to generate different ACP activity levels, which were replicated twice with duplicate samples and duplicate sample tests representing 720 data points. Log10 ACP activity (mU/kg sample) performance repeatability and reproducibility standard deviations (sr and sR) and relative standard deviations (RSDr and RSDR) over 5 cooking treatments for 6 products were as follows: marinated breast: sr = 0.02, sR = 0.08, RSDr = 0.60%, RSDR = 2.12%; nonmarinated breast: sr = 0.02, sR = 0.04, RSDr = 0.66%, RSDR = 1.29%; marinated thigh: sr = 0.01, sR = 0.01, RSDr = 0.37%, RSDR = 0.37%; nonmarinated thigh: sr = 0.02, sR = 0.05, RSDr = 0.53%, RSDR = 1.43%; marinated 50:50 breast/thigh blend: sr = 0.01, sR = 0.05, RSDr = 0.36%, RSDR = 1.31%; nonmarinated 50:50 breast/thigh blend: sr = 0.01, sR = 0.04, RSDr = 0.32%, RSDR = 1.12%. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 2:1999
Measurement of Bromate in Bread by High Performance Liquid Chromatography with Post-Column Flow Reactor DetectionAbstract: This method is suitable for the determination of bromate residues in a variety of baked goods. The Peer-Verified Method trial was carried out with white bread, multi-grain bread and coffee cake. The results demonstrate that the method provides adequate accuracy with low fat as well as high fat foods. Bromate at levels as low as 5 ppb (5 x 10 -9 g/g) can be detected with this method. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form. Return to Category List/ AOAC® Methods Validation and Technical Programs / AOAC INTERNATIONAL Home Page

Feeds, Fertilizers, and Agricultural Related Topics
AOAC® PEER-VERIFIED METHOD PVM 2:1995
Determination of Fluoride in Bovine Urine
Abstract: Fluoride concentration is determined in bovine urine using a selective ion electrode. Urine is buffered and measured against known fluoride (F) standards. The method is applicable to 2-40 mg F/L, without further dilution. Typical normal urine contains less than 10 mg F/L. Concentrations greater than 10 mg/L support a clinical diagnosis of fluorosis in cattle. The repeatability coefficient of variation (CV) ranged from 1.6-3.5% for F concentrations of 3.2-43 mg/L. The reproducibility CV ranged from 0.3-7.3% for F concentrations of 7.0-17.2 mg/L. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 3:1995
Thin Layer Chromatographic Determination of Monensin in Feeds: Screening Method
Abstract: Monensin is extracted from feed with methanol and purified using solvent partitioning solid phase extraction. After solvent reduction, monensin is separated by TLC on silica gel and visualized by color development with vanillin. No false positive results were obtained in the validation studies by the submitting or peer laboratories when blank samples were analyzed. Three of 20 samples spiked with 5 ppm monensin were reported as containing no monensin. All samples spiked with 10 ppm monensin were reported positive for monensin. The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.

AOAC® PEER-VERIFIED METHOD PVM 1:1996
Liquid Chromatographic Determination of Ivermectin in Feed
Abstract: An analytical method for determining ivermectin in feed at 0.50-3 ppm is presented. The method is based on liquid chromatographic measurement after sample preparation by adsorption chromatography on alumina and solid-phase extraction. Two complete, final, finished medicated feeds and the corresponding control feeds used in their preparation were analyzed. Recoveries from feeds fortified at 50-150% of the 2 ppm ivermectin use concentration also were determined. Mean recoveries from replicate analyses ranged from 90 to 100%, and coefficients of variation (CVs) were less than 4.5%. No significant interferences were found in control feeds. The pooled distribution of individual analytical results (n = 100) gave a mean recovery of 100%, a recovery range of 90-111%, and an overall CV of 5.5%. Resolution of the total variance into its 2 components gave a within-laboratory CV of 4.1% and a between-laboratory CV of 3.4%. There was no significant difference in recoveries among laboratories, days, concentrations, and feed base or between fortified and medicated feeds (P > 0.2). The cost is $35.00 per Peer-Verified Method. Members: subtract 10% discount. Available in print and electronic formats. Peer-Verified Methods can be ordered through the Publications Order Form.