磁性固相萃取-高效液相色谱-串联质谱法测定环境水样中12种喹诺酮类抗生素残留

自行制备了氧化石墨烯/零价纳米铁(GO@nZVI)磁性材料。称取此磁性材料15mg置于小烧杯中,依次用甲醇和水清洗和活化。将经过0.22μm滤膜过滤除去悬浮颗粒物的环境水样10mL加入于磁性材料中,用乙酸和氨水调节其酸度至pH 7.0,振荡5min,使磁性材料对水样中的喹诺酮抗生素充分吸附。用磁铁在烧杯外侧将磁性材料吸引在烧杯底部,弃去上清液,在磁性材料中加入氨水超声洗脱3次,每次用氨水1.0mL。合并洗脱液,并吹氮至近干,用100μL水溶解残留物,所得溶液过0.22μm滤膜过滤,滤液供高效液相色谱-串联质谱法(HPLC-MS/MS)在仪器工作条件下进行分析。在色谱分离中,选用ZORBAX Eclipse Plus C18色谱柱为固定相,和以不同比例的(A)甲醇和(B)1%(体积分数)甲酸溶液的混合液作为流动相进行梯度洗脱,并在电喷雾离子源、正离子(ESI+)模式和多反应监测(MRM)模式条件下进行MS/MS测定。测得12种喹诺酮类抗生素标准曲线的线性范围均在1~50μg·L-1之间,其检出限(3S/N)为1.6~9.6ng·L^-1。其测定值的相对标准偏差(n=5)为3.4%~6.1%(日内)和7.2%~13%(日间)。按标准加入法进行回收试验,测得回收率为90.3%~103%。经扫描电镜(SEM)和红外光谱(FTIR)两种方法对GO@nZVI磁性材料的表征,说明GO已紧密吸附在nZVI的表面;试验还证明此材料经重复使用10次,第10次的萃取回收率比第一次的数值降低约10%,说明此材料可重复利用。

Determination of Residual Amounts of 12 Quinolone Antibiotics in Evironmental Water by Magnetic Solid Phase Extraction-High Performame Liquid Chromatography-Tandem Mass Spectrometry

A magnetic material(GB@nZVI)was prepared from graphene oxide(GO)and zero valency nano iron(nZVI)by the authors and was used as magnetic adsorbent in SPE of 12quinolone antibiotics(QNLO)from water sample.A portion of the magnetic material(15mg)was placed in a small beaker,washed and activated with methanol and de-ionized water successively.10mL of the environmental water,which has been filtered through 0.22μm filtering membrane to remove the suspended particles,was then added to the activated adsorbent in the small beaker,and its acidity was adjested to pH 7.0with acetic acid and aq.ammonia.The mixture was then shaked for 5min to have the QNLOs in water fully adsorbed by the magnetic adsorbent,which was pulled and kept at the bottom of the beaker by the action of a magnet at outside beaker bottom.The supernatant was discarded,and the magnetic adsorbent was ultrasonicated thrice with 1.0 mL of aq.ammonia each.The ammoniacal eluates were combined and evaporated to near-dryness by N2-blowing.The residue was taken up with 100μL of water,and the solution was filtered through 0.22μm filtering membrane.The filtrate was used for HPLC-MS/MS analysis under the working condition of the instrument.In chromatographic separation,ZORBAX Eclipse Plus C18column was used as stationary phase,and mixtures of(A)methanol and(B)1%(volum fraction)formic acid solution in various ratios were used as mobile phase in gradient elution.And the 12QNLOs were determined by MS/MS under the conditions of ESI+and MRM modes.Linearity ranges of the standard curves for the 12QNLOs found were same between 1.0-50μg·L^-1.Their detection limits(3S/N)were found in the range of 1.6-9.6ng·L^-1.Values of RSDs(n=5)found were ranged from 3.4%-6.1%(intraday)and from 7.2%-13%(interday).Recovery was tested by standard addition method,giving results of recovery in the range of 90.3%-103%.The magnetic material was characterized by SEM and FTIR,showing that GO was tightly adsorbed on the surface of nZVI;and that the SPE recovery given by the GO@nZVI after using for 10times was about 10%lower than that given by the sample portion of GO@nZVI using for the first time.Hence it could be applied in repeated usage.