Food analysis method comparison

Several methods have been discussed for the determination of method limitations when evaluating procedures for the determination of pesticides in food. A brief comparison of the methods discussed for the determination of the detection and quantification limits of methods used for the analysis of food products can be found in Table 2. 

Di Pinto A, Forte VT, Guastadisegni MC, Martino C, Schena FP, TantiUo G (2007). A comparison of DNA extraction methods for food analysis. Food Control, 18 76-80. 

Abugri, D. A., McElhenney, W. H., Willian, K. R. (2012). Comparison of Transesterification Methods for Fatty Acid Analysis in Higher Fungi Application to Mushrooms. Food Anal Methods, 5(5), 1159-1166. 

Parallel method comparisons are used to establish the validity of a new method developed for five organic pharmaceutical compovmds, food colors, and color additives. The standard methods such as the Japanese Standard Food Additives and Japanese Standard of Cosmetic Ingredients method, based on volumetric and gravimetric titration, have been used to establish new methods developed for the determination of I, Cl, Br, and SO4 in food colors. The results obtained indicate good agreement in both accuracy and precision for procedures based on the oxygen flask method as compared with the standard methods. In addition to anion elemental analysis, method validation has also been carried out for metal analysis such as that of Ce(III), Th(IV), and U(VI), with the results showing acceptable limits of variation. 

NUUTILA A M, KAMMioviRTA K and OKSMAN-CALDENTEY K-M (2002) Comparison of methods for the hydrolysis of flavonoids and phenolic acids from onion and spinach for HPLC-analysis, Food Chem, 76, 519-25. 

Demeke, T., Clear, R. M., Patrick, S. K., and Gaba, D. (2005). Species specific PCR-based assays for the detection of Fusarium species and a comparison with the whole seed agar plate method and trichothecene analysis. Int. J. Food Microbiol. 103, 271-284. 

Stanker, L. Ft., Kamps-Holtzapple, C., Beier, R. C., Levin, C. E., Friedman, M. (1997). Detection and quantification of glycoalkaloids comparison of enzyme-linked immunosorbent assay and high-performance liquid chromatography methods. In L. H. Stanker (Ed.). Immunoassays for Residue Analysis for Food Safety, ACS Symp. Ser, Vol. 621 (pp. 243-255). American Chemical Society, Washington, DC. 

Packard, V. S., Jr., Ginn, R. E. and Rosenau, J. R. 1973. A comparison of Babcock, Mojonnier, and Milko tester Mark III methods in the analysis of milkfat in cream. J. Milk Food Technol. 36, 523-525. 

For a compound to contribute to the aroma of a food, the compound must have odor activity and volatilize from the food into the head-space at a concentration above its detection threshold. Since aroma compounds are usually present in a headspace at levels too low to be detected by GC, headspace extraction also requires concentration. SPME headspace extraction lends itself to aroma analysis, since it selectively extracts and concentrates compounds in the headspace. Some other methods used for sample preparation for aroma analysis include purge-and-trap or porous polymer extraction, static headspace extraction, and solvent extraction. A comparison of these methods is summarized in Table Gl.6.2. 

Gas chromatography (GC) for amino acid analysis is the alternative to HPLC that has found the greatest acceptance. It requires the preseparation derivatization of the amino acids to render them volatile. For this purpose, amino acids are frequently converted into acylated esters. N-Trifluoroacetyl-n-butyl esters and /V-heptafluorobutyrylisobutyl esters are most commonly employed. There have been comparative studies (3,4) that document similar (if not equivalent) analytical results for GC and the classic ion-exchange chromatographic method applied to a variety of food samples. Comparison (5) of GC to the reversed-phase HPLC determination of amino acids (phenylisothiocyanate derivatized) also shows excellent agreement. 

J Landry, S Delhaye, DG Jones. Determination of tryptophan in feedstuffs comparison of two methods of hydrolysis prior to HPLC analysis. J Sci Food Agric 58 439-441, 1992. 

Recent interlaboratory comparisons of HPLC and microbiological methods for vitamin B6 revealed significant variability among laboratories (42,70). The extraction and hydrolysis of the B6 vitamers, especially the pyridoxine-/ -glucoside (PNG) in plant-based foods, were cited as problem areas. Other sources of analytical error included HPLC (mis)identification of the individual B6 vitamers, and vitamer interconversion during extraction and analysis. 

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