A liquid chromatography tandem mass spectrometric method was developed for the determination of two β-agonists (ractopamine and salbutamol) in pig hair samples. An isotope of ractopamine-d5 or salbutamol-d6 as an internal standard was used to carry out quantitative analysis. Concentrated sodium hydroxide was used to pretreat hair samples and then purified by the solid phase extraction (SPE) procedure. The extracted solution was evaporated and reconstituted for injection in the instrument with electrospray ionization (ESI) operating in a positive multiple-reaction-monitoring (MRM) mode. Ractopamine and salbutamol separation were performed on C18 analytical column under gradient condition. The internal standard calibration curve was linear in the range of concentration from 0.5 to 100 ng mL (R > 0.995). Recoveries of this method estimated at three spiked concentrations of 100, 250 and 500 ng mL in pig hair samples, were 79-82% for ractopamine and 77-96% for salbutamol. The corresponding inter-day and intra-day precisions expressed as relative standard deviation (RSD %) were 3.8-6.4% and 3.8-8.6%, respectively. The analytical time for one sample was 8 min. The detection limit of this method was 0.6 and 8.3 ng mL for ractopamine and salbutamol, respectively. This developed method can be applied for monitoring the use of the β-agonists salbutamol and ractopamine in swine feed incurred pig hair.
SHRs) to evaluate the efficacy on regulating hypertension. In vivo results were showed that the body weight in each group was not significantly different with or without the Chinese yam extracts. The mean blood pressure (MBP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) of SHRs were monitored once two weeks. Data were presented that MBP was decrease at 6 th week administration. After oral administration with the Chinese yam extracts for 6 weeks, the trend of the decrease MBP of SHR can be found that compared to the beginning of this experiment. Additionally, the liver and kidney functional indexes were all at the safety level after 6 weeks administration with the Chinese yam extracts. Taken these results together, the supercritical fluid CO 2 extracted-Chinese yam (Dioscorea polystachya) extracts has a potential ability to regulate hypertension.
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