土壤中土霉素残留的高效液相色谱检测方法

为有效测定土壤中土霉素残留量，建立了固相萃取－高效液相色谱法提取以及测定潮土、红壤、紫色土中土霉素残留量的方法。土壤中土霉素残留经提取缓冲溶液进行有效提取，经过DVB固相萃取小柱纯化、无水甲醇洗脱和氮气流浓缩后，经HPLC测定。对提取缓冲液、流动相以及流动相pH值、有机相与无机相的比例以及流速等测定条件进行优化研究。结果表明：提取液为Na2EDTA-Mcllvaine，流动相为乙腈∶0.01mol/L磷酸二氢钠（pH值2.5，V∶V=10∶90），温度25℃，流速1.2ml/min，检测波长350nm对3种不同性质的土壤中土霉素残留量的测定最为合适。应用本方法进行土壤中土霉素残留量的测定，土霉素含量与峰面积具有良好的线性关系，相关系数（n=9）分别为红壤0.997，紫色土0.995，潮土0.987；检出限分别为红壤0.11mg/kg，紫色土0.17mg/kg，潮土0.09mg/kg；回收率(n=18)分别为红壤80.7%~128.8%，紫色土70.5%~100.0%，潮土61.5%~103.9%;相对标准偏差(RSD, n=18)分别为红壤7.1%~28.2%，紫色土11.9%~38.1%，潮土4.1%~17.0％。本方法简便、准确，适合于测定不同土壤中土霉素残留量，结果可靠。

DETERMINATION OF OXYTETRACYCLINE IN SOILS WITH HIGH PERFORMANCE LIQUID CHROMATOGRAPGY

In order to accurately determine the content of oxytetracycline (OTC) resiudes in soils, the combination method of soild phase extraction and high performance liquid chromatography (HPLC) was developed in the present paper. The fluvo-aquic soil, red soil, and purplish soil were used as materials. OTC was extracted from soil samples by extraction buffer, purified by solid phase extraction column followed by elution with anhydrous methanol, and then concentrated by nitrogen flow. OTC in the solution was determined by HPLC. In this study, separation parameters were optimized including the extraction buffer solution, the buffer pH value, the rate of organic phase over inorganic phase, and flow rate. The results were present as follows. The optimal extraction buffer solution was Na2EDTA-Mcllvaine, and the optimal mobile phase was acetonitrile -NaH2PO4 with pH 2.5, V∶V=10∶90.The column temperature was 25℃, and the flow rate was 1.2ml/min. The determine wavelength was 350nm. The significant linearity correlation was observed between OTC concentration in soils and peak area. The correlation coefficient values (n=9) were 0.997 for red soil, 0.995 for purplish soil, and 0.987 for fluvo-aquic soils, respectively. The values of detection limit of the developed method were 0.11mg/kg for red soil, 0.17mg/kg for purplish soil, and 0.09mg/kg for fluvo-aquic soil respectively. Recoveries of oxytetracycline in three soils were 80.7%~128.8% for red soil, 70.5%~100.0% for purplish soil, and 61.5%~103.9% for fluvo-aquic soil, respectively. The values of relative standard deviations (RSD) were 7.1%～28.2% for red soil, 11.9%～38.1% for purplish soil, and 4.1%～17.0％ for fluvo-aquic soil, respectively. The developed method was simple and accurate, which was suitable for OTC determinine in soils.