A novel method wasdeveloped for the determination oflevamisole in animal livers by liquid-liquid extraction and gas chromatography-mass spectrometry. Levamisole hydrochloride was transferred to levamisole in alkalinesolution, andthen extracted intoethyl acetate. Two liquid-liquid extraction steps were carried out with HCI aqueous solution and potassium hydroxide-dichloromethane system in turn, and the liposoluble substances and the water-soluble substances were removed, respectively. The qualitative and quantitative analyses of levamisole were achieved by gas chromatography-mass spectrometry (GC-MS) system. The characteristic fragments m/z 148, 176 and 204 were selected and m/z 204 was used as the quantitative ion. A good linear relationship was obtained between the peak area and the mass concentration of levamisole from 0.25 mg/L to 3.0 mg/L with the correlation coefficient of 0.999. The limit of quantitation (LOQ) for levamisole was 5 microg/kg, which was much lower than the international maximum residue limit. The average recoveries of levamisole spiked in chicken liver, duck liver, rabbit liver and pig liver samples at three spiked levels ranged from 76% to 106% with the relative standard deviations less than 9%. The method is simple and stable without tedious sample preparation, and suitable for the determination of levamisole in animal livers.
With the development of economy and the continuous improvement of living standard, the contradiction between the rapid growth of electric load and the untimely renewal of power grid equipment is increasingly prominent. Power supply reliability issues or frequent power outages and customer complaints exist in many areas. Due to the limited human and material resources of power supply companies, the problems existing in the distribution transformer service areas cannot be resolved timely and thoroughly. As the direct service objective of electric power, customer’s experience of using electricity will reflect the power quality of the distribution transformer service areas to a great extent. Therefore, this paper will start with work orders from customer sides, find out the existing problems in distribution transformer service areas based on the data association rules, and help make informed decisions. The proposed method not only reduces the investment of capital and manpower, but also reduces the number of power outages, and improves the customer satisfaction.
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