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A method of ultra high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) combined with modified QuEChERS purification technology was developed for the simultaneous determination of 25 veterinary medicine residues including four classes (sulfonamides, quinolones, chloramphenicols and amantidines) in chicken and egg. The samples were hydrolyzed by dilute hydrochloric acid, extracted by acetonitrile. Sodium chloride was added into the extracting solution to salt out. The acetonitrile was took out and degreased by n-hexanecyclohexane solution (1∶1,V/V) after stratification of acetonitrile and aqueous phase and concentrated to dry. The residues were dissolved with 0.2% formic acid ethyl acetate to remove the sodium chloride by filtrating and the filtrate was concentrated to dry again, then the sample was purified with a mixture of 30 mg of C18 and 60 mg PSA after adding 0.2% formic acid methanol. The target compounds were separated by ZORBAX C18 chromatography column (50 mm×2.1 mm×1.8 μm), the mass spectrometer data were acquired under multiple reaction monitoring (MRM) of positive and negative modes at the same time, and the residues were quantitated by isotope internal standard method. The results showed that the linear of 25 veterinary medicines is good in the range of 0.2~250 μg/L. The linear correlation coefficients are more than 0.99, and the detection limits are in the range of 0.1~0.9 μg/kg. The limits of quantification are 0.3~3.0 μg/kg. The average recoveries at three spiked levels (about 1, 5 and 20 folds of quantitative limits) are 79.5%~119% with the relative standard deviations of 0.9%~9.2%. The method is rapid,simple, accurate, sensitive and cheap, which is suitable for simultaneous determination of multiple vererinary medicine residues in eggs and chicken.

Poor efficiency of current SSRs on a plant-by-plant basis makes it hesitate to accept SSRs as an alternative for routine DUS test. The present study testified the availability of two-dimensional bulked DNA sampling in uniformity assessment of 8 inbred rice lines with commonly-used SSR markers. Our results showed that, (1) bulked sampling was suggested as 10 individuals, thus in a 10-row 10-column matrix, the bulked samples could save 80% cost compared with routine SSRs; (2) the way to identifying true off-types from putative ones was modified and optimized as that all the intersections were considered as putative off-types, and further identifications were based on bulked SSR profiles or individual ones; (3) a putative off-type could be detected using 1 markers, or in some cases, 15 markers, and each marker equally detected 12.5 true off-types, ranged from 6 to 20; (4) true off-types were generally detected using 4 or more markers, so the strategy should be based on a group of markers rather than one to reduce the interfere of residual heterozygosity; (5) the very significant correlations (0.553 equally, concluded from the data of off-types) between results of the strategy and traditional morphological test made it prospective to indicate an exclusive acceptable uniformity baseline for SSRs. The reported strategy is available to evaluate uniformity of inbred rice lines with 20% cost of routine SSRs taking advantage of two-dimensional bulked DNA sampling (in a 10-row 10-column matrix) and 24 commonly-used SSR markers. It could also be interest for the determination of stability and distinctness of inbred rice lines, as well as other non-hybrid plant varieties. However, we found the strategy couldn't effectively discriminate self-pollinated off-types from those true hybrid individuals. [ABSTRACT FROM AUTHOR]

Two sequencing batch reactors were established at bench-scale, with one used as an in-situ sludge ozone-reduction system and the other as a control system. Both systems were continuously operated for 90 days to comparatively investigate the elimination of nine typical antibiotics (i.e., tetracycline, oxytetracycline, doxytetracycline, norfloxacin, ofloxacin, ciprofloxacin, lomefloxacin, enrofloxacin, and azithromycin) during the in-situ sludge ozone-reduction process. Results indicated that the presence of target antibiotics in the influent (100 μg·L -1 each) had an insignificant influence on the removal of COD, total nitrogen, ammonia, and total phosphorus by the activated sludge. The antibiotic concentrations in the effluent of the reduction system remained fairly stable over the entire operation period, and were similar to those in the effluent of the control system; however, the antibiotic concentrations in the sludge of the reduction system were obviously lower than those in the control system sludge. Mass balance calculations revealed that the input and output of target antibiotics gradually approached balance in both the systems. Ozone degradation and excess sludge discharge were the main pathways for target antibiotic removal in the reduction and the control systems, respectively. The influent antibiotics could be degraded by 83% in the sludge ozonation module of the reduction system, while 82% of the influent antibiotics were discharged with excess sludge in the control system. Therefore, the in-situ sludge ozone-reduction process could greatly reduce the release of antibiotics from the activated sludge system, which is of great importance in practice.