AOAC methods

Initially, there was some ovedap on proposed analytical methods to accomplish a particular analysis. The Association of Official Analytical Chemists (AOAC) methods and Bacteriological Analytical Manual (BAM) methods in some cases dupHcated ASTA methods, but the procedures differed. Most spice companies, particulady those who are members of ASTA, use ASTA recommended methods. In an attempt to ensure that equivalent specifications are reported, the Technical Group of ASTA develops specifications and in some cases recommends that a BAM or AO AC method be used. 

Preferably, high pressure Hquid chromatography (hplc) is used to separate the active pre- and cis-isomers of vitamin D from other isomers and allows their analysis by comparison with the chromatograph of a sample of pure reference i j -vitainin D, which is equiUbrated to a mixture of pre- and cis-isomers (82,84,85). This method is more sensitive and provides information on isomer distribution as well as the active pre- and cis-isomer content of a vitamin D sample. It is appHcable to most forms of vitamin D, including the more dilute formulations, ie, multivitamin preparations containing at least 1 lU/g (AOAC Methods 979.24 980.26 981.17 982.29 985.27) (82). The practical problem of isolation of the vitamin material from interfering and extraneous components is the limiting factor in the assay of low level formulations. 

AOAC Method 985.29for TDF. This AO AC method (3), referred to as the method of Prosky and co-workers (4), was cited in the Nutritional Labeling and Education Act of 1990 as the general analytical approach for food labeling of dietary fiber content. The method has undergone several modifications for IDE and for the primary fractions, SDE and IDE. 

Nitric acid is also useful as an oxidant for the formation of sulphate from sulphones. Two such methods have been developed, firstly the established AOAC method which involves oxidation with a mixture of nitric acid and bromine221, and secondly the Carius method222. The latter is probably the oldest method used for the determination of sulphones as sulphate. This oxidation procedure involves heating the sulphone with concentrated nitric acid and sodium chloride at 280-300 °C in a sealed tube. The traditional method as described is prone to explosions. This problem may be alleviated by using less nitric acid whilst employing an oxygen atmosphere2 23,224. The Carius method is slower than the other oxidation methods described above but it usually yields the best results. 

Figure 1 shows narrow range high resolution scans of the molecular ion region of NDMA, recorded near the maximum of the GC peaks, present in one of the beer samples prepared in the AOAC collaborative study. The peak at m/z 74.0480 represents approximately 0.15 ng of NDMA injected on the column, corresponding to a concentration of 0.6 yg/kg of beer. Use of high resolution MS permitted confirmation of the identity and amount of nitrosamine without additional cleanup of the concentrate prepared by the AOAC method. Sample quantity requirements were comparable to those of the TEA. 

Promoting policy changes within AOAC to incorporate reference materials in AOAC methods. 

To identify and facilitate availability of reference materials needed for use with AOAC methods. 

The issue of data reproducibility had been the previous focus of the AOAC Official Methods Program. The TDRM will assist AOAC in responding to an expanded scope of it mission to include statements of accuracy with AOAC methods. This extra step requires independent verification of the accuracy of measurements generated by the method. Accuracy of an analytical method must be verified at three separate points ... 

The methods EN 1528 1996 and EN 12393 1998 comprise a range of old multiresidue methods of equal status, which are widely accepted throughout Europe. These are, e.g., the Luke method and the German Deutsche Forschungsgemeinschaft (DFG) methods S8 and S19 ° (all based on extraction with acetone), the Association of Official Analytical Chemists (AOAC) method 970.52 (using acetonitrile extraction and liquid-liquid partition combined with Horisil column cleanup) and the Dutch ethyl acetate extraction combined with GPC. All methods have been subjected to inter-laboratory studies, although not with all pesticide/matrix combinations, which would be impossible to achieve. 

AOAC Methods PAM211 and PAM 231, Association of Official Analytical Chemists, Arlington, VA (1984). 

Similar methods with modifications such as the one by Schutz et al.8 have been in use for over 20 years. In 1968, Ferren and Shane9 published a paper on the differential spectrometric determination of caffeine in soluble coffee and drug combinations. It had the advantage of eliminating a preliminary separation that was required by the earlier method. While the method was successful for coffee, it was not as successful in the determination of caffeine in acetaminophen/phenacetin/caffeine tablets. They proposed that phenacetin was a limiting factor. The official AOAC methods for these methylxanthines in coffee and tea still involve similar methods.10... 

Figure 8.1. Contribution of the various plant food groups to dietary fiber intake in the Spanish diet, according to AOAC method. Sources Saura-Calixto Goni 1993 Goni 2001.

Resistant starch will serve as primary source of substrate for colonic microflora and may have important physiological benefits. On this basis resistant starch can be classified as a dietary fibre. The Association of Official Agricultural Chemists (AOAC) method of determining dietary fibre will measure some resistant starch as dietary fibre. 

Dietary Fibre. An area of some contention is what should be included as dietary fibre. There are several different methods of measuring dietary fibre and all of them will give different results on the same sample. The EU favours the Association of Analytical Chemists (AOAC) method, which includes lignin and resistant starch, while the UK has preferred the Englyst method and has defined fibre as nonstarch polysaccharides from cell walls as the only substances that count as fibre. 

AOAC Method 986.15 Arsenic, cadmium, lead, selenium, and zinc in human and pet foods (1988)... 

AOAC Method 982.23 Cadmium and lead in food (not for fats and oils) (1988)... 

AOAC Method 979.17 Lead in evaporated milk and fruit juice (1984)... 

Standard analytical procedures were used to evaluate the composition of ingredients. Of the proximate analyses, nitrogen, lipids, and crude fiber were measured by American Oil Chemists Society (AOCS) methods (12) and moisture and ash by Association of Official Analytical Chemists (AOAC) methods (13). Amino acid analyses were performed by gas-liquid chromatography (14) except for tryptophan, which was analyzed colormetrically Tl5). In addition to these assays, certain tests of ingredient safety or spoilage were also performed, which space does not permit to be reported in this paper, to assure that ingredients met accepted standards for food safety (16). 

Forty natural liquid honey samples from Middle Anatolia and surrounding areas, marked as a red circle in the map of Turkey (Fig. 23. 1), were collected directly from different beekeepers during the months of January and February in 2003. The honey samples, stored in glass jars, were kept in the dark at room temperature until analyzed. Moisture was determined by measuring the refractive indices at 200°C with a refractometer (Abbe Refractometer NAR2T) and the corresponding moisture content (%) was calculated according to AOAC method [10]. 

AOAC (Method 977.01 Preparation of solution) extraction Weigh 1.000 g of the ground sample and transfer into a 9-cm filter paper in a funnel. Wash with successive small portions of water by directing a jet of water from a... 

The EC official method is described in the Official Journal of the European Communities (EC, 1992), and uses specialized glassware. We will base the method on that of MAEE/ADAS (1986, pp. 90-92), (with Crown Copyright permission), but replace the alcohol and diethyl ether (used for washing the residue) with acetone, which is safer and also used in the EC method. The AOAC method is described by Padmore (1990, pp. 80-82). The traditional method uses 0.313 M NaOH, free from carbonate, but the EC method uses 0.23 M KOH. The method is suitable for plant material or animal feeds, but the following pre-treatments may be necessary, especially for feedstuffs. 

Exact details of the method can be found in the total dietary fibre determination procedure AOAC Method 991.43 and AACC Method 32-07 (AOAC, 1995 AACC, 2000). 

AOAC International. (1995). AOAC Method 991.43, Total, Insoluble and Soluble Dietary Fiber in Food—Enzymatic-Gravimetrie Method, MES-TRIS Buffer. Official Methods of Analysis, 16th ed., Gaithersburg, MD. 

Reactivation of alkaline phosphatase is of considerable practical significance since regulatory tests for pasteurization assume the absence of phosphatase activity. An official AOAC method used to distinguish between renatured and residual native alkaline phosphatase is based on the increase in phosphatase activity resulting from addition of Mg2 + the activity of renatured alkaline phosphatase is increased about 14-fold but that of the native enzyme is increased only two-fold. 

Determination of Moisture. A modified AOAC method for ground spices was used for moisture determination of encapsulated orange oil (17). Twenty and 40 gram samples were refluxed in 150 ml anhydrous toluene for 3i hours. All samples were analyzed in duplicate. 

United States regulations on nutrition labeling of foods require that cholesterol content be given and that it be analyzed by GC measurement as shown in the AOAC method, which uses a packed column (Lewis et al., 1996 AOAC, 1990). The reference value, which is a set of recommended nutrient intake levels of cholesterol, is defined as 300 mg. However, the Codex guideline does not request labeling of cholesterol. Cholesterol contents in some foods and foodstuffs determined by GC measurement are summarized in Table Dl.3.3. 

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