Muscle Fatty Acids, Meat Flavor Compounds and Sensory Characteristics of Xiangxi Yellow Cattle in Comparison to Aberdeen Angus.

The objective of this study was to investigate meat quality of Xiangxi yellow cattle of different ages in comparison to Aberdeen Angus. At the ages of 6, 18, and 30 months, 10 female animals for both Xiangxi yellow cattle and Aberdeen Angus cattle were randomly selected and slaughtered. The proximate composition analysis, fatty acid profiles and flavor compounds were measured on the longissimus thoracis (LT) muscle samples. One boneless loin chop was dissected and used for sensory evaluation by a 10-persoon trained taste panel. The data obtained showed that Xiangxi yellow cattle deposited similarly high level of intramuscular fat as Angus at the age of 18 month and the polyunsaturated fatty acid in muscle along with the PUFA/SFA ratio reached the highest levels at this age. Inosine 5'-monophosphate (IMP) was the predominant umami compound in beef, which concentration was significantly higher (p < 0.05) at month 18, but not different between Angus and Xiangxi yellow cattle. Multiple volatile flavor compounds were higher (p < 0.05) in concentrations in meat from Xiangxi yellow cattle at ages of 18 and 30 months when compared to Angus. Sensory analysis revealed that Xiangxi yellow cattle (18 and 30 months) and Angus (30 months) were superior in meat overall eating quality to Xiangxi yellow cattle (6 months) and Angus (6 and 18 months). This study showed that Xiangxi yellow cattle are a fine cattle breed with equal or even better meat quality attributes when compared to Angus. It is proper to slaughter Xiangxi yellow cattle at the age of 18 months for high quality beef production.

[Rapid screening and determination of fentanyl and its analogues in drugs by liquid chromatography- quadrupole time-of-flight mass spectrometry].

A method based on liquid chromatography coupled with high-resolution quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) was developed for the simultaneous screening and determination of fentanyl and its 26 analogs in liquid and solid powder drugs. The established method involves successive extraction by 5 mL 75% (v/v) acetonitrile aqueous solution and 5 mL acetonitrile, followed by clean-up using the hydrophilic lipophilic balance (HLB) solid-phase extraction method. Detection was achieved by electrospray ionization (ESI) in the positive mode, TOF-MS, and information-dependent acquisition (IDA)-MS/MS acquisition; the external standard method was adopted for quantification. Two databases of accurate mass and fragment ions were created. The standard matrix-matched calibration curves of the 27 target compounds were linear in the range of 5.00-100 µg/L, with the correlation coefficients (r2)>0. 99. The limits of quantification for the 27 target compounds were 10.0 µg/kg. The recoveries for all the target compounds in vitamin C tablet, headache powder, cough syrup, and transdermal patch samples were in the ranges of 82.9%-106%, 84.8%-106%, 86.9%-109%, and 83.1%-106%, respectively, with relative standard deviations ranging from 0.38% to 8.71% (n=6). The results demonstrated that the developed method is rapid and sensitive for the simultaneous monitoring and determination of fentanyl and 26 its analogs in liquid and solid powder drugs.

[Determination of 105 pesticide residues in vegetables by QuEChERS-liquid chromatography-tandem mass spectrometry].

After optimization of the QuEChERS pretreatment method, combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology, a multi-residue determination method was established for 105 typical insecticides, bactericides, herbicides, and plant growth regulators in vegetables. The target compounds were extracted by acetonitrile, purified with 150 mg primary secondary amine (PSA), 150 mg EC-C18, and 30 mg graphitized carbon black (GCB) adsorbents. The standard curves of 105 target compounds were linear in the concentration range of 0.010-0.200 mg/L, with correlation coefficients (r)>0.99. The limit of quantification was 0.010 mg/kg, the recoveries were between 68.2% and 108% at three spiked levels, and the RSDs of the method were between 1.02% and 11.8%. The method is suitable for the rapid determination of the common pesticides in vegetables owing to its advantages of rapidity, simplicity, and better purification.