Production of matrix certified reference material for analysis of salbutamol residue in mutton

Development of a Purity Certified Reference Material for Vinyl Acetate

Vinyl acetate is a restricted substance in food products. The quantification of the organic impurities in vinyl acetate is a major problem due to its activity, instability, and volatility. In this paper, while using the mass balance method to determine the purity of vinyl acetate, an improved method was established for the determination of the content of three impurities in vinyl acetate reference material, and the GC-FID peak area normalization for vinyl acetate was calibrated. The three trace organic impurities were identified by gas chromatography tandem high-resolution mass spectrometry to be methyl acetate, ethyl acetate, and vinyl propionate. The content and relative correction factors for the three organic impurities were measured. The purity of vinyl acetate determined by the mass balance method was 99.90% with an expanded uncertainty of 0.30%, and the total content of organic impurities was 0.08% with a relative correction factor of 1.23%. The vinyl acetate reference material has been approved as a national certified reference material in China as GBW (E) 062710.

Quick and high-throughput quantification of 22 β-agonists residues in animal-derived foods using enzymatic probe sonication

A high demand exists in veterinary drug residual analysis for rapid, automatic and high-throughput analytical techniques that produce data simultaneous and faster. Here, we describe a combined automated solid-phase extraction (SPE) and enzymatic probe sonication (EPS), subsequently ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for the quick extraction, automated clean-up as well as simultaneous quantification of 22 β-agonists residues in animal-derived foods. Enhanced by the ultrasonic probe, only 2 min was needed for exhaustively extraction of β-agonists from foods of animal-origin; whereas traditional enzymatic digestion methods require hours or even days, which making it more appropriate for high-throughput biomonitoring. Moreover, the clean-up and pre-concentration procedures were conducted on the automatic SPE, which allowed 36 samples being performed simultaneously within 30 min. The method was successfully applied for analyzing 56 animal-derived food samples, 53.6 % of which contained detectable levels of at least one kind of β-agonists. Interestingly, both the detection rate and residual level of β-agonists in the ruminants (bovine and sheep) were higher as compared with the swine. Concerning the real food samples analyzed, the findings of this study suggest that stricter measures should be adopted to control the illegal usage of β-agonists on the farm animals, particularly for the ruminants.

Development of matrix certified reference material for accurate determination of docosahexaenoic acid in milk powder

A novel matrix certified reference material (CRM) of docosahexaenoic acid in milk powder [GBW (E) 100641] was first developed. The CRM candidates was prepared by adding appropriate levels of docosahexaenoic acid to cow's milk, then powder sprayed, lyophilized, mixed, dispensed and sterilized. An optimized acetylchloride-methanol method was proposed and used for the characterization. The CRM characterization was carried out in six laboratories in accordance with ISO Guide 35 requirements. The certified value of CRM was 0.69 mg/g with an uncertainty of 0.08 mg/g (k = 2). The CRM was sufficiently homogeneous between and within bottles and stable up to 6 month at -20℃ and 7 days below 50 ℃. The uncertainty was evaluated by combing the contributions from characterization, homogeneity and stability. Thus, the CRM can be used for quality control and method validation to ensure the accurate and reliable measurements of docosahexaenoic acid in milk for quality monitoring.

Production of a matrix certified reference material for measurement and risk monitoring of clenbuterol in mutton

A novel matrix certified reference material (CRM) for clenbuterol in mutton (GBW 10216) was developed to assist measurement and risk monitoring of clenbuterol in mutton. The candidate CRM raw samples were obtained by oral administration of clenbuterol and investigating the pharmacokinetics of clenbuterol in sheep. A high-precision isotope dilution coupled with liquid chromatography tandem mass spectrometry (LC-ID-MS/MS) method was established and assigned the value of clenbuterol in mutton powder through combined detection of nine inter-laboratories. The certified value with expanded uncertainty was 21.1 ± 2.2 μg/kg (k = 2, 95% confidence) for clenbuterol in mutton. The prepared matrix CRM was sufficiently homogeneous between and within bottles. The long-term stability of clenbuterol in mutton powder was evaluated for 12 months at -20℃ and short-term stability for 7 days at 4℃ and 50℃. The uncertainties originating from characterization, homogeneity, and stability were systematically analyzed and evaluated. The prepared matrix CRM can be applied for proficiency testing and nationwide risk monitoring programs to guarantee the accuracy and comparability of clenbuterol measurement results in mutton.