A "three-in-one" sample preparation method for simultaneous determination of B-group water-soluble vitamins in infant formula using VitaFast(®) kits.

VitaFast(®) test kits designed for the microbiological assay in microtiter plate format can be applied to quantitative determination of B-group water-soluble vitamins such as vitamin B12, folic acid and biotin, et al. Compared to traditional microbiological methods, VitaFast(®) kits significantly reduce sample processing time and provide greater reliability, higher productivity and better accuracy. Recently, simultaneous determination of vitamin B12, folic acid and biotin in one sample is urgently required when evaluating the quality of infant formulae in our practical work. However, the present sample preparation protocols which are developed for individual test systems, are incompatible with simultaneous determination of several analytes. To solve this problem, a novel "three-in-one" sample preparation method is herein developed for simultaneous determination of B-group water-soluble vitamins using VitaFast(®) kits. The performance of this novel "three-in-one" sample preparation method was systematically evaluated through comparing with individual sample preparation protocols. The experimental results of the assays which employed "three-in-one" sample preparation method were in good agreement with those obtained from conventional VitaFast(®) extraction methods, indicating that the proposed "three-in-one" sample preparation method is applicable to the present three VitaFast(®) vitamin test systems, thus offering a promising alternative for the three independent sample preparation methods. The proposed new sample preparation method will significantly improve the efficiency of infant formulae inspection.

Development of a simple method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs in milk and dairy products by ultra-performance liquid chromatography with tandem mass spectrometry.

A multi-residue analysis method for simultaneous determination of nine subclasses of non-steroidal anti-inflammatory drugs (NSAIDs) in milk and dairy products by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) has been established. The sample was initially extracted and deproteinized with ascorbic acid buffer (0.01M, pH 3) and acetonitrile-ethyl acetate mixture, followed by centrifugation and evaporation, then reconstituted with acetonitrile-0.1% formic acid (1+1, v/v). After removal of lipid material by n-hexane, the sample was analyzed by UPLC-MS/MS with electro-spray ionization (ESI) interface in Multiple Reaction Monitoring (MRM) mode. The range of limits of detection (LODs) and limits of quantification (LOQs) were 0.03-0.30µg/kg and 0.10-1.00µg/kg, respectively. The recoveries in milk, milk powder, yogurt, processed cheese and milk beverage ranged from 61.7% to 117%, and the relative standard deviations (RSDs) were less than 17.9% at three spiked levels (1, 10 and 100 times of the LOQ). Matrix effects were also investigated and it was determined the signals of the analytes were suppressed from 9.4% to 76.6% in processed cheese. The proposed method was also applied to incurred sample analysis. The results proved that this method was suitable for the simultaneous determination of nine subclasses of NSAIDs residues in milk and dairy products.

Simultaneous determination of thirty non-steroidal anti-inflammatory drug residues in swine muscle by ultra-high-performance liquid chromatography with tandem mass spectrometry.

An ultra-high-performance liquid chromatography with tandem mass spectrometric detection (UHPLC-MS/MS) method was established for the simultaneous determination of residues of thirty non-steroidal anti-inflammatory drugs (NSAIDs) in swine muscle. The samples were extracted with acetonitrile and phosphoric acid. The extracts were defatted with n-hexane, and then purified by HLB solid-phase extraction cartridge. Analysis was carried out on UHPLC-ESI-MS/MS working with multiple reaction monitoring mode with polarity switching. Limits of detection were between 0.4 µg/kg and 2.0 µg/kg, and limits of quantification were between 1.0 µg/kg and 5.0 µg/kg. The recoveries of NSAIDs were between 61.7% and 125.7% at spiked levels of 1.0-500 µg/kg. The repeatability was less than 8% and the within-laboratory reproducibility was not more than 12.3%. The method was reliable, convenient and sensitive.