Determination of Free and Total Choline and Free and Total Carnitine in Infant Formula and Adult/Pediatric Nutritional Formula by Liquid Chromatography/Tandem Mass Spectrometry (HPLC-MS/MS): A Multi-laboratory Testing Study, Final Action 2015.10.

BACKGROUND: A multi-laboratory study was conducted on AOAC First Action Method 2015.10 "Determination of Free and Total Choline and Free and Total Carnitine in Infant Formula and Adult/Pediatric Nutritional Formula by Liquid Chromatography/Tandem Mass Spectrometry (HPLC-MS/MS)." OBJECTIVE: In this study, nine laboratories participated in the performance testing of the method using ten nutritional products tested as blind duplicates. METHOD: Both free and total carnitine and free and total choline content of the samples were determined using separate extractions for the free and total results. For free choline and carnitine analysis, samples are diluted in water. For total choline and carnitine analysis, samples are extracted using acid-assisted microwave hydrolysis with nitric acid. For both the free and total methods, samples are then diluted with acetonitrile and analyzed using strong cation exchange (SCX) liquid chromatography coupled to a triple quadrupole tandem mass spectrometer (LCMS). Stable isotope labeled internal standards were utilized in all analyses to compensate for extraction inefficiencies and ionization suppression.

Compositional safety of herbicide-tolerant DAS-81910-7 cotton.

DAS-81910-7 cotton is a transgenic event that was transformed to contain the aad-12 and pat genes. These genes code for the AAD-12 and PAT proteins, which confer tolerance to the herbicides 2,4-D and glufosinate, respectively. Crop composition studies were conducted with DAS-81910-7 cotton (both nonsprayed and sprayed with 2,4-D and glufosinate) to comply with requirements of regulatory authorities responsible for evaluating crop safety. Results indicate compositional equivalence between DAS-81910-7 cottonseed and nontransgenic cottonseed and between sprayed and nonsprayed DAS-81910-7 cottonseed. This study builds on the results from many prior studies which support the conclusion that transgenesis is less likely to unexpectedly alter the composition of crops as compared with traditional breeding.

Compositional safety of event DAS-40278-9 (AAD-1) herbicide-tolerant maize.

Event DAS-40278-9 maize expresses the aryloxyalkanoate dioxygenase-1 enzyme, which was originally identified in the soil bacterium Sphingobium herbicidovorans. This enzyme degrades 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate herbicides (e.g., haloxyfop, cyhalofop, quizalofop, etc.); therefore, plants that contain this enzyme are tolerant to these herbicides. We employed the substantial equivalence approach to investigate the compositional safety of event DAS-40278-9 maize. A total of 82 different compositional analyses were conducted to evaluate the equivalence of event DAS-40278-9 and conventional maize. Analyte levels within the transgenic entries were either within literature ranges for non-transgenic maize or statistically indistinguishable from the non-transgenic near-isogenic hybrid, thus indicating substantial equivalence between event DAS-40278-9 and its conventional counterpart. These results agree with dozens of published studies for other transgenic events where input traits were found to have a negligible effect on crop composition compared with traditional breeding methods.

Progress on the development and single-laboratory validation of a high-performance liquid chromatographic method for the determination of carbadox and pyrantel tartrate in type B and C medicated feeds.

Carbadox, an antimicrobial agent, and pyrantel tartrate, an anthelmintic, are feed additives that are often used in combination in the United States. The current AOAC methods for these analytes are spectrophotometric, using standard addition techniques. These methods are labor-intensive and prone to variability as well as matrix interferences. Published methods for both analytes that use high-performance liquid chromatography were evaluated and a test method was developed. The method uses a water prewetting step to enhance extraction of pyrantel followed by extraction with acetonitrile-ethanol (50 + 50). Sample extracts are filtered through a glass fiber filter and purified using alumina solid-phase extraction columns. Chromatography is performed on a C18 column with a gradient mobile phase of dibutylamine acetate and acetonitrile. The data show that both analytes exhibit acceptable peak shape when a C18 column that is both acid- and base-deactivated is used. Linearity has been established and initial recovery studies on medicated swine feeds are promising.