水体中主要阴离子及pH值对双氯芬酸液相色谱定量的影响

双氯芬酸(DCF)是一种常用的非甾体消炎药,随着生产量和使用量的不断增大,其在环境中被频繁检出。DCF能在生物体内富集,对生物具有潜在毒性,已经引起了广大学者的关注。DCF的准确定量是开展其相关研究的基础,在应用液相色谱测试DCF的过程中,通常通过前处理消除样品基质干扰,但关于基质如何干扰DCF测量并没有详细研究。为了满足野外及实验室测试需要,本文针对高效液相色谱-紫外检测DCF过程中,水体中常见的阴离子SO_4~(2-)、Cl~-和NO_3~-,液相色谱流动相组成和水样pH对DCF准确定量的影响展开研究。结果表明:(1)SO_4~(2-)和Cl~-对DCF的最大吸收波长(277 nm)没有影响,但是NO_3~-的存在会使DCF的最大吸收峰发生偏移,产生红移现象,并且使吸光度略微增大;(2)同等条件下,在酸性介质(pH5)中DCF的定量结果比在碱性介质中的低。与碱性介质(pH=7.26)中DCF的峰面积相比,样品在pH=2.01的酸性介质中测得的峰面积减少73.14%,因此在碱性条件下DCF定量更为准确。

Effects of Anions and pH on the Determination of Diclofenac in Water Solutions by High Performance Liquid Chromatography

Diclofenac (DCF) is one of the widely used non-steroidal anti-inflammatory drugs. With the increased production and consumption, DCF is frequently detected in the environment. DCF can be enriched in organisms and has potential toxicity to several organisms, causing much concern. The accuracy determination of DCF is the basis for other studies. In a previous study, pretreatment methods were always used to eliminate matrix effects during the measurement of DCF, but how the sample matrix influences DCF measurement was not studied in details. In order to meet the need of field sample measurement and laboratory research, the effects of common anions SO₄^2-, Cl^- and NO₃^-, solution pH, and mobile phase constitutions on the determination of DCF using High Performance Liquid Chromatography with the UV-Vis detector (HPLC-UV) were investigated. The results show that SO₄^2- and Cl^- had no effect on the maximum absorption wavelength of DCF (277 nm), but NO₃^- changed the maximum absorption wavelength of DCF (277 nm) and resulted in the red shift phenomenon. Under the same condition, the measured concentration of DCF by HPLC in acidic medium (pH<5) was lower than that in an alkaline medium. Comparing with the peak area of DCF in alkaline medium (pH=7.26), the peak area of DCF in acidic medium (pH=2.01) decreased by 73.14%. Therefore, determination of DCF under alkaline conditions has greater accuracy.