天然水体中颗粒物吸附抗生素特征分析

为了研究抗生素在天然水体中的固、液相分配规律,分析了水体中颗粒物对7种典型抗生素的吸附特征,并通过环境扫描电镜测定了颗粒物的表面结构及元素组成.同时,采用高效液相色谱与质谱串联(HPLC-MS/MS)的检测方法对抗生素进行测定,以Simeton为内标物,得到抗生素的检出限为15~25 ng·L-1,定量下限为50~83 ng·L-1.连续吸附实验结果表明:初始的20 min颗粒物对抗生素的吸附比较快,达到过量吸附;吸附达到过饱和后会进行10 min的解吸反应;实验进行30 min后,吸附与解吸过程的变化会趋于稳定,2 h后达到吸附平衡.抗生素的平衡吸附量在1616~15568 ng·g-1之间,其吸附量及吸附曲线的变化与抗生素的pKa值密切相关.

Adsorption of antibiotics on the surface of aquatic particles

In order to investigate the distribution of antibiotics between the truly dissolved and the non-aqueous phases in nature water, the adsorption of 7 kinds of typical antibiotics on the surface of the particles was analyzed. Environmental scanning electron microscopy (ESEM) was used to examine the surface structure and elements of aquatic particles. A high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed for simultaneous determination of 7 antibiotics. Simeton was used as an internal standard. The limit of detection(LOD) of 7 compounds ranged from 15 ng·L^-1 to 25 ng·L^-1 and the limit of quantification (LOQ) ranged from 50 ng·L^-1 to 83 ng·L^-1.The continuous adsorption experiments show that adsorption of antibiotics on particles is fast, even to the excess adsorption in the initial 20 minutes; the desorption reaction lasts for 10 minutes after the adsorption saturation; after 120 min, the adsorption and desorption variations tend to be stable. Equilibrium adsorption capacity of antibiotics by particles is between 1616 ng·g^-1 and 15568 ng·g^-1. The adsorption amount and adsorption curve changes with antibiotics is closely related to pK_a of the antibiotics.