Application of ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (Orbitrap™) for the determination of beta-casein phenotypes in cow milk.

The objective of this study was to determine the ß-CN phenotypes in cow milk collected from HF and cross-bred HF dairy cattle in Phu Dong, Vietnam. In total, 85 samples of raw milk were collected from 85 individual cows. Beta-casein (ß-CN) phenotypes in cow milk were determined using ultra-high performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS). The results showed that three ß-CN variants A1, A2 and I were detected and identified in the milk samples. Five ß-CN phenotypes A1A1, A1A2, A1I, A2A2 and A2I were found with percentages of 0.035, 0.400, 0.059, 0.482 and 0.024, respectively. The higher proportion of ß-CN phenotype A2A2 compared to other phenotypes was expected because of changes in dairy cow breeding in Phu Dong, Vietnam.

High-Throughput Quantification of Monofluoroacetate (1080) in Milk as a Response to an Extortion Threat.

As a food defense measure against an extortion threat to poison infant formula with monofluoroacetate, a robust methodology for monofluoroacetate analysis in fluid milk and powdered dairy products was developed and optimized. Critical challenges posed by this situation required that the analytical methodology provide (i) high specificity, (ii) high throughput capable of analyzing thousands of samples of fluid milk per day, and (iii) trace-level detection of 1 ng/g or lower to achieve the maximum residue limit. Solid-phase extraction-purified acetone extracts of fluid milk were derivatized with aniline, and after ultrahigh-performance liquid chromatography using a Kinetex-C18 column packed with 1.3-µm shell particles, the resulting N-phenyl 2-fluoroacetamide could be determined by liquid chromatography-tandem mass spectrometry in a highly specific manner and with a limit of quantification of 0.5 ng/ml. By using 4-(4-chlorophenoxy)aniline as a derivatizing agent, the method could be extended to powdered dairy products with the same limit of quantification. Between January and July 2015, some 136,000 fluid milk samples were tested using this method. This analytical testing of fluid milk formed one element in a larger program of work by multiple agencies to ensure that consumers could continue to have confidence in the safety of New Zealand milk and dairy products.

A rapid, sensitive, and selective method for quantitation of lamprey migratory pheromones in river water.

The methodology of using fish pheromones, or chemical signatures, as a tool to monitor or manage species of fish is rapidly gaining popularity. Unequivocal detection and accurate quantitation of extremely low concentrations of these chemicals in natural waters is paramount to using this technique as a management tool. Various species of lamprey are known to produce a mixture of three important migratory pheromones; petromyzonol sulfate (PS), petromyzonamine disulfate (PADS), and petromyzosterol disulfate (PSDS), but presently there are no established robust methods for quantitation of all three pheromones. In this study, we report a new, highly sensitive and selective method for the rapid identification and quantitation of these pheromones in river water samples. The procedure is based on pre-concentration, followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. The method is fast, with unambiguous pheromone determination. Practical quantitation limits of 0.25 ng/l were achieved for PS and PADS and 2.5 ng/l for PSDS in river water, using a 200-fold pre-concentration, However, lower quantitation limits can be achieved with greater pre-concentration. The methodology can be modified easily to include other chemicals of interest. Furthermore, the pre-concentration step can be applied easily in the field, circumventing potential stability issues of these chemicals.