固相萃取-高效毛细管电泳法同时分离测定水体和土壤中13种抗生素

采用固相萃取(SPE)纯化、富集,高效毛细管电泳(HPCE)分离和紫外光谱检测同时分离并测定水体和土壤样品中13种抗生素的含量。所采得的土壤样品需先经规定方法制成固态分析样品,并取此样品4.000g,用二乙胺四乙酸二钠0.8g、Mcllvacine缓冲溶液和乙腈(1+1)混合液提取样品3次(每次加入混合液20.0mL)。合并3次所得提取液(上清液),用0.22μm滤膜过滤后,按与水的体积比为1∶2.5加水稀释。此溶液待SPE纯化及富集。所采集的水样经0.22μm滤膜过滤后,用0.1mol·L^-1HCl溶液调节pH至5.0。此溶液继续进行SPE纯化及富集。分取上述土壤(或水样)样品溶液150mL,流经HLBSPE柱,用甲醇-水(10+90)混合液淋洗SPE柱除去杂质,随即用甲醇-乙腈(1+1)混合液2mL洗脱柱上吸附的抗生素,收集洗脱液,吹氮至近干,加入水300μL溶解残渣,所得溶液进入HPCE柱进行电泳分离,选择由65.0mmol·L^-1硼砂和50.0mmol·L^-1硼酸组成的pH9.0的缓冲溶液和甲醇及异丙醇(88+10+2)的混合液作为电泳介质,在分离电压为19kV,柱温为23℃,压力为3.45kPa条件下进样7s,13种抗生素可在25min内完全分离。选择在波长210nm处进行检测。13种抗生素的线性范围均在150μg·L^-1以内,检出限(3S/N)在0.40~1.0μg·L^-1之间。以空白基质进行加标回收试验,测得回收率在78.5%~107%之间。

Simultaneous Separation and Determination of Thirteen Antibiotics in Soil and Water by High Performance Capillary Electrophoresis with Pretreatment by Solid Phase Extraction

13 antibiotics in soil or water samples were enriched and purified on SPE column and then separated and determined simultaneously by HPCE with UV-spectrometric detector. Soil sample collected should be pretreated according to a definite process to give analytical sample in solid state, from which 4.000 g were taken and extracted thrice with Na2 EDTA 0.8 g and a mixture of mcllvacine buffer and acetonitrile (1 + 1), using 20.0 mL in each extraction. The extracts (i. e., the supernatants) were combined and filtered through 0. 22 μm filtering membrane. The filtrate was diluted with water according to the ratio of volume of the filtrate to water of 1 to 2.5. This solution was ready to be used for SPE treatment. Water sample collected was first filtered through 0.22 μm filtering membrane, and the filtrate was acidified to pH 5.0 with 0.1 mol·L^-1 HC1 solution. This water sample solution was ready for SPE treatment. A portion of 150 mL of the soil sample solution or the water sample solution (as obtained above) was passed through HLB SPE column, and the column was rinsed w.h CH3OH-H2O (1 + 9) to eliminate impurities, and then eluted with 2 mL of a mixture of CH3OH and CH3CN (1 + 1) to elute the antibiotics from the column. The eluate was collected and evaporated to near dryness by N2-blowing. 300 μL of water were added to dissolve the residue, and the solution was introduced into the HPCE system for electrophoresis. A mixture of (A) pH 9.0 buffer solution composed of 65.0 mmol·L^-1 of borax and 50.0mmol·L^-1 of boric acid,(B) methyl alcohol and (C)iso-propyl alcohol mixed in the ratio of A : B : C = 88 : 10 : 2, was used as electrophoretic medium. The 13 antibiotics could be well separated within 25 min under the following conditions ,(a) separation voltage: 19 kV;(b) column temperature: 23 °C;(c) pressure of sample introduction: 3.45 kPa;(d) time of sample injection: 7 s. UV-detection was performed at 210 nm. Linearity ranges for the 13 analytes were obtained all within 150 μg·L^-1. Detection limits (3S/N) found were in the range of 0.40-1.0μg·L^-1. Tests for recovery were carried out by addition of standard solution to matrixes of blank solutions, values of recovery found were ranged from 78.5% to 107%.