Abstract The analytical methods adopted by the AOAC (Association of Official Analytical Chemists) are used by government agencies concerned with the analysis of fertilizers, foods, feeds, pesticides, drugs, cos‐metics, hazardous substances, and other materials related to agriculture, health and welfare, and the environment. AOAC methods are also used by indus‐try to check compliance of their products. The AOCS and AOAC have cooperated in the past in achieving common methodology for fatty acids, hydrocarbons and mineral oils, and monoglycerides. Present cooper‐ative effort centers primarily in the mycotoxins area. The various methods adopted by the AOAC appear in the book, Official Methods of Analysis, which is published every five years with annual supplements. The 12th edition was published in January 1975. Industrial scientists cannot be full or active members but they can serve as associate members of the AOAC. Active membership is limited to government scientists. Industry can and should, however, partici‐pate in the activities of the AOAC‐particularly in the key task of developing, testing, and validating methods of analysis. Uniform methodology should be the goal of all societies. The purpose of this paper is twofold: (a) to explain the structure, functions, and goals of the AOAC; and (b) to inform potential industrial representatives how they may participate in the Association’s activities.
AOAC Official Method 942.05, Ash in Animal Feed, has been applied in feed laboratories since its publication in the Official Methods of Analysis in 1942. It is a routine test with renewed interest due to the incorporation of "ash values" into modern equations for the estimation of energy content of dairy feed, beef feed, and pet food. As with other empirical methods, results obtained are a function of the test conditions. For this method, the critical conditions are the ignition time, ignition temperature, and any other furnace or weighing conditions. Complete ignition can be observed by the absence of black color (due to residual carbonaceous material) in the ash residue. To investigate performance of AOAC 942.05, 15 samples were chosen to be representative of a wide range of feed materials. These materials were tested at the conditions of AOAC 942.05 (ignition at 600 degrees C for 2 h) and similar or more rigorous conditions. The additional conditions investigated included: 600 degrees C for 4 h; 600 degrees C for 2 h, cool, and ignite 2 additional h; 600 degrees C for 2 h, cool, wet, dry, and ignite 2 additional h; 550 degrees C for 6 h; 550 degrees C for 3 h, cool, and ignite 3 additional h; and 550 degrees C for 3 h, cool, wet, dry, ignite 3 additional h. Results for all other conditions investigated were found to be significantly different from the current AOAC Method 942.05. All ignition conditions were significantly different from each other except two: 550 degrees C for 3 h, cool, ignite 3 additional h; and 550 degrees C for 3 h, cool, wet, dry, and ignite 3 additional h. Recommendations for modification to AOAC Official Method 942.05 are suggested based on statistical analysis of the data and a review of the literature.
In AOAC Official Method 955.04, Nitrogen (Total) in Fertilizers, Kjeldahl Method, fertilizer materials are analyzed using mercuric oxide or metallic mercury HgO or Hg) as a catalyst. AOAC Official Methods 970.02, Nitrogen (Total) in Fertilizers is a comprehensive total nitrogen (including nitrate nitrogen) method adding chromium metal. AOAC Official Method 978.02, Nitrogen (Total) in Fertilizers is a modified comprehensive nitrogen method used to measure total nitrogen in fertilizers with two types of catalysts. In this method, either copper sulfate or chromium metal is added to analyze for total Kjeldahl nitrogen. In this study, the part of AOAC Official Method 978.02 that is for nitrate-free fertilizer products was modified. The objective was to examine the necessity of copper sulfate as a catalyst for the nitrate-free fertilizer products. Copper salts are not environmentally friendly and are considered pollutants. Products such as ammonium sulfate, diammonium phosphate, monoammonium phosphate, urea-containing fertilizers such as isobutylene diurea (IBDU), and urea-triazone fertilizer solutions were examined. The first part of the study was to measure Kjeldahl nitrogen as recommended by AOAC Official Method 978.02. The second part of the study was to exclude the addition of copper sulfate from AOAC Official Method 978.02 to examine the necessity of copper sulfate as a catalyst in nitrate-free fertilizers, which was the primary objective. Our findings indicate that copper sulfate can be eliminated from the method with no significant difference in the results for the nitrogen content of the fertilizer products.
Subject Analytical Chemistry Collection: AOAC Publications, Official Methods of Analysis of AOAC INTERNATIONAL
A broad range of AOAC Official Methods of AnalysisSM (OMA) have been developed and approved for the measurement of dietary fiber (DF) and DF components since the adoption of the Prosky method (OMA 985.29). OMA 985.29 and other OMA were developed to support the Trowell definition of DF. However, these methods do not measure DF as defined by the "new," physiologically relevant, Codex Alimentarius definition. Methodology to support the Codex definition has been developed and updated in recent years. In this article, the relevance of each OMA in supporting the Codex definition of DF is described and suggestions are presented on the most appropriate method, together with proposals for changes in title and application statements for the "historic" OMA methods.
Official methods of analysis of AOAC International , Official methods of analysis of AOAC International , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
The LECO FP-228 "Nitrogen Determinator" was compared with the AOAC copper catalyst Kjeldahl method, 7.033-7.037, for the determination of crude protein in feed materials. The completely microprocessor-controlled instrument determines nitrogen by measuring the nitrogen gas following combustion of the sample; it was easy to operate and broadly applicable. A wide variety of feed materials of various nitrogen levels were analyzed in one mixed sequence. Results were precise, accurate, and rapid. Analysis time for one sample was approximately 3 min. Fourteen samples containing 2.5-15.5% N were selected for study and consisted of meals, grains, forages, and standard organic materials. The overall mean for the 14 samples by the LECO combustion method was 8.61% N compared with an overall mean of 8.58% N for the AOAC Kjeldahl method. Within-sample standard deviations for the LECO combustion method ranged from 0.013 to 0.052% N with a pooled standard deviation (SD) of 0.033% N for the 14 samples. Standard deviations for the AOAC Kjeldahl method ranged from 0.006 to 0.035% N with a pooled SD of 0.022% N. Combined average recovery of nitrogen from tryptophan, lysine-HCl, and EDTA determined by the LECO combustion method was 99.94% compared to 99.88% determined by the AOAC Kjeldahl method.
Abstract A historical and scientific account is given of the evolution of chemical methods of analysis for fertilizers, as recorded in the annals of AOAC. Meetings that preceded the formation of AOAC are recalled with evidence of their domination by fertilizer chemists. The development, study, and adoption procedures of AOAC pertaining to primary, secondary, and micro plant nutrients are reported in chronological order. Only those changes in methods of analysis that had significant impact on future developments are noted. No attempt is made to present an exhaustive review of all AOAC analytical methods for fertilizer.
Experiments were conducted to evaluate and compare several methods of egg yolk color analysis. Egg yolks of various colors and intensities were produced either by feeding known concentrations of synthetic xanthophylls to color depleted hens or by mixing the xanthophylls directly into depleted egg yolks. The yolk samples were then analyzed for color using the AOAC procedure, visual comparisons using the Roche Color Fan, and by reflectance colorimetry to describe color in the CIE and L*a*b* systems. The AOAC procedure of beta-carotene equivalents was found to be inadequate in describing yolk colors produced from different xanthophyll sources. Yolks blended to approximate the same total xanthophyll concentration from natural feed sources or from canthaxanthin resulted in about the same beta-carotene equivalent values of 14.3 and 14.2 μg/g, respectively. Visual scoring resulted in a Roche Color Fan value of 7 for the natural yolks and 15 for the canthaxanthin blended yolk. The colorimetric analysis indicated that the natural yolk was more yellow and less red (578.4 dominant wavelength, 2.74 a* and 56.7 b*) than the canthaxanthin yolk (591.9 dominant wavelength, 25.60 a* and 34.7 b*). The AOAC procedure, however, shows good agreement with increases in a monopigment source of color. These results would indicate that the AOAC procedure is an adequate procedure for describing egg yolk color from a monopigment source. However, it is a very poor procedure for describing egg yolk color from a variety of pigments.
Starch is a nutritionally important carbohydrate in feeds that is increasingly measured and used for formulation of animal diets. Discontinued production of the enzyme Rhozyme-S required for AOAC Method 920.40 invalidated this method for starch in animal feeds. The objective of this study was to compare methods for the determination of starch as potential candidates as a replacement method and for an AOAC collaborative study. Many starch methods are available, but they vary in accuracy, replicability, and ease of use. After assays were evaluated that differed in gelatinization method, number of reagents, and sample handling, and after assays with known methodological defects were excluded, 3 enzymatic-colorimetric assays were selected for comparison. The assays all used 2-stage, heat-stable, a-amylase and amyloglucosidase hydrolyses, but they differed in the gelatinization solution (heating in water, 3-(N-morpholino) propanesulfonic acid buffer, or acetate buffer). The measured values included both starch and maltooligosaccharides. The acetate buffer-only method was performed in sealable vessels with dilution by weight; it gave greater starch values (2-6 percentage units of sample dry matter) in the analysis of feed/food substrates than did the other methods. This method is a viable candidate for a collaborative study.
ABSTRACT The Codex Committee on Methods of Analysis and Sampling recently recommended 14 methods for measurement of dietary fiber, eight of these being type I methods. Of these type I methods, AACC International Approved Method 32‐45.01 (AOAC method 2009.01) is the only procedure that measures all of the dietary fiber components as defined by Codex Alimentarius. Other methods such as the Prosky method (AACCI Approved Method 32‐05.01) give similar analytical data for the high‐molecular‐weight dietary fiber contents of food and vegetable products low in resistant starch. In the current work, AACCI Approved Method 32‐45.01 has been modified to allow accurate measurement of samples high in particular fructooligosaccharides: for example, fructotriose, which, in the HPLC system used, chromatographs at the same point as disaccharides, meaning that it is currently not included in the measurement. Incubation of the resistant oligosaccharides fraction with sucrase/β‐galactosidase removes disaccharides that interfere with the quantitation of this fraction. The dietary fiber value for resistant starch type 4 (RS 4 ), varies significantly with different analytical methods, with much lower values being obtained with AACCI Approved Method 32‐45.01 than with 32‐05.01. This difference results from the greater susceptibility of RS 4 to hydrolysis by pancreatic α‐amylase than by bacterial α‐amylase, and also a greater susceptibility to hydrolysis at lower temperatures. On hydrolysis of samples high in starch in the assay format of AACCI Approved Method 32‐45.01 (AOAC method 2009.01), resistant maltodextrins are produced. The major component is a heptasaccharide that is highly resistant to hydrolysis by most of the starch‐degrading enzymes studied. However, it is hydrolyzed by the maltase/ amyloglucosidase/isomaltase enzyme complex present in the brush border lining of the small intestine. As a consequence, AOAC methods 2009.01 and 2011.25 (AACCI Approved Methods 32‐45.01 and 32‐50.01, respectively) must be updated to include an additional incubation with amyloglucosidase to remove these oligosaccharides.
Journal Article The History of Feed Analysis, as Chronicled in the Development of AOAC Official Methods, 1884-1984 Get access Valva C Midkiff Valva C Midkiff Retired, University of Kentucky, College of Agriculture, Lexington, KY 40546-0064 Search for other works by this author on: Oxford Academic Google Scholar Journal of Association of Official Analytical Chemists, Volume 67, Issue 5, 1 September 1984, Pages 851–860, https://doi.org/10.1093/jaoac/67.5.851 Published: 15 February 2020
ABSTRACT Total dietary fiber (TDF) was measured in 16 foods by three methods: a rapid enzyme‐NDF (neutral detergent fiber) procedure supplemented with a separate procedure for soluble (SOL) fiber, the AOAC TDF method and the comprehensive Englyst's procedure. The NDF+SOL method needed less operator time than the AOAC method and its TDF values were in agreement with the AOAC method (y = 0.98 ‐0.39; r = 0.997) and with the Englyst's method (y = 1.17 ‐0.19; r = 0.996). The constituent sugars of polysaccharides in NDF+SOL residues were similar to those by the Englyst's method, indicating an adequate estimation of dietary fiber in foods and food products.
AOAC Official Method(SM) 2005.06 for the determination of saxitoxin (STX)-group toxins in shellfish by LC with fluorescence detection with precolumn oxidation was previously validated and adopted First Action following a collaborative study. However, the method was not validated for all key STX-group toxins, and procedures to quantify some of them were not provided. With more STX-group toxin standards commercially available and modifications to procedures, it was possible to overcome some of these difficulties. The European Union Reference Laboratory for Marine Biotoxins conducted an interlaboratory exercise to extend AOAC Official Method 2005.06 validation for dc-GTX2,3 and to compile precision data for several STX-group toxins. This paper reports the study design and the results obtained. The performance characteristics for dc-GTX2,3 (intralaboratory and interlaboratory precision, recovery, and theoretical quantification limit) were evaluated. The mean recoveries obtained for dc-GTX2,3 were, in general, low (53.1-58.6%). The RSD for reproducibility (RSD(r)%) for dc-GTX2,3 in all samples ranged from 28.2 to 45.7%, and HorRat values ranged from 1.5 to 2.8. The article also describes a hydrolysis protocol to convert GTX6 to NEO, which has been proven to be useful for the quantification of GTX6 while the GTX6 standard is not available. The performance of the participant laboratories in the application of this method was compared with that obtained from the original collaborative study of the method. Intralaboratory and interlaboratory precision data for several STX-group toxins, including dc-NEO and GTX6, are reported here. This study can be useful for those laboratories determining STX-group toxins to fully implement AOAC Official Method 2005.06 for official paralytic shellfish poisoning control. However the overall quantitative performance obtained with the method was poor for certain toxins.
An AOAC official method for quantitating cholesterol in multicomponent foods, which was first published in the 13th edition of the Official Methods of Analysis, is rarely used. The method includes so many operations and manipulations--all described in excruciating detail--that most laboratories shun it altogether. Intent on finding an alternative, laboratories have developed their own methods for specific foods. As a result, new methods have proliferated, but still no practical method has been developed for the broader categories of multicomponent foods. The aim of AOAC, which is to promote greater accuracy and uniformity of analytical results primarily through collaborative testing, has not been well served under these circumstances. A different approach guided the work reported in the present paper. This approach was directed toward updating and dramatically simplifying the existing AOAC official method. The method's chloroform-methanol-water mixed-solvent extraction is preserved; however, all the remaining steps have been streamlined, updated, or eliminated by using newer technology. Cholesterol is quantitated with highly specific capillary gas-liquid chromatography using the internal standardization technique. The lipid extract is prepared for the chromatography step by a brief saponification carried out in a culture tube. The resulting method has been validated by using Standard Reference Materials and the standard addition method. Because a simplified method is now available for quantitating cholesterol in the lipid extracts, the expectation is that more attention can be given to the development of improved and efficient extraction methods. This step remains as the central difficulty in any number of methods of analysis for lipid analytes.
The increased focus on the accuracy of trans fatty acid data generated using current methodologies has resulted in research initiatives to optimize the quality of these assays. In this study, scientists combined the established methodology from AOAC 996.06 and the American Oil Chemists Society method Ce 1h-05, as well as other independent research. As a result, method modifications are proposed that could allow for a more accurate determination of trans fat than the current AOAC 996.06 method. Validation data from this study are presented. The authors encourage peer review and offer to facilitate a collaborative validation to update AOAC 996.06.
A modified version of the AOAC method of analysis for nitrite in meat and meat products was tested collaboratively by 23 laboratories. Results were compared with those obtained by the official AOAC method. Recommended modifications include: (a) substitution of N-(1-naphthyl) ethylenediamine and sulfanilamide for Griess reagent, (b) separate addition and 1:10 dilution of the above reagents, (c) 20 min color development and absorbance read at 540 nm, (d) substitutionstitution of NaNO2 for AgNO2 and NaCL, (e) omission of mercuric chloride, (f) screening of filter paper for nitrite contamination, (g) more precise dilution of sample aliquot, and (h) standard curve linear up to 10 microng N/50 ml. Results were statistically treated by Youden's technique for comparing 2 methods, using a matched pair sample scheme. The random error for the modified method was significantly lower than the random error for the official method. A t-test showed no difference in bias between the 2 methods.
Responding to a need for a guide for conducting Official Method validation studies of microbiological methods, AOAC utilized the experience of three microbiologists who have been active in the field of method validation. In collaboration, a document was prepared which covered the following areas: terms and their definitions associated with the Official Methods program (e.g., reference methods, alternative methods, and ruggedness testing), protocols and validation requirements for qualitative methods versus those for quantitative methods, the concept of the precollaborative study, ruggedness testing, tests for significant differences, performance indicators, and the approval process. After its preparation, this document was reviewed by the members of the Methods Committee on Microbiology and Extraneous Materials and by members of the Official Methods Board. Herein is presented the approved version of that document.
Pharmaceutical analytical chemistry, which ordinarily deals with the analysis of formulations containing from 0.1 to 100% of active ingredient, uses methods with a reproducibility (between-laboratory variability) of about 2.5% and a repeatability (within-laboratory variability) of about half that amount. The best between-laboratory precision attainable appears to be about 1.0% and within-laboratory precision, about 0.5%. On the basis of the results available, automated methods do not appear to be any more precise than manual methods, although the studies show fewer outlying data points. Replicates (preferably blind ones) should always be conducted in a collaborative interlaboratory study in order to obtain the important information as to whether efforts should be concentrated on improving the method itself or on the performance of laboratories and analysis in applying it.