液相色谱柱前衍生法检测水中无机一氯胺研究

采用高效液相色谱柱前衍生法建立了水中无机一氯胺(NH2Cl)的检测方法,该方法可以有效区分水中的无机氯胺和有机氯胺。以2-巯基苯并噻唑(2-MBTZ)作为衍生剂,以乙腈和水作为淋洗液,选取Sun FireTMC18分析柱,发现无机一氯胺的衍生产物(2-MBTZNH2)得到了良好的分离。结果表明,在优化衍生反应时间、衍生剂投加量和衍生反应温度条件下,无机一氯胺质量浓度与衍生产物峰面积在0.10~10.00 mg/L的范围内具有良好的线性关系(R2=0.999)。采用液相色谱柱前衍生法测定无机一氯胺的精密度为2.5%~3.4%,检出限为0.013 mg/L,在已知无机一氯胺质量浓度(0.26 mg/L)水样中的加标回收率为93.5%~113.4%,在实际水样中的加标回收率92.6%~106.0%。研究表明,该液相色谱柱前衍生法操作简单方便,测定的无机一氯胺浓度与衍生产物峰面积具有良好的线性关系,同时具有较好的精密度和加标回收率,可用于水中无机一氯胺的分析和检测。

Research of inorganic monochloramine detection by HPLC-pre-column derivatization method

The paper is inclined to introduce a so-called HPLC-pre-column derivatization method we have developed to identify and determine the inorganic monochloramine (NH2Cl) in treating micro-polluted water samples with ammonia nitrogen through experiments.The method we have developed known as the HPLC-pre-column derivatization method can be used to characterize the organic and inorganic chloramines effectively,and detect the colored samples through comparison with the spectrophotometric method,whereas the inorganic monochoramine standard solution can be prepared through the reaction of ammonium chloride and sodium hypochlorite.At the same time,we have also worked out the concentration of the standard solution through N,N-diethyl-1,4-phenylenediamine (DPD) spectrophotometric method.Furthermore,we have adopted 2-mercaptobenzothiazole (2-MBTZ) as the derivative agent,with 70％ of acetonitrile and 30％ of water being used as the mobile phases.And,next,we have successfully isolated and determined the derivatives of NH2Cl (2-MBTZ-NH2) through SunFireTM C18 column and the ultraviolet detector.In proceeding with the given study,we have conducted a series of comparative experiments to optimize the derivative reaction conditions,so as to maximize the concentration of the derivatives in the experimental condition when the reaction time length can be set up for 110 min,and 0.6 mL 1 g/L of the derivatization agent is enough for the reaction with the concentration of the inorganic monochloramine below 8.00 mg/L.However,the reaction temperature turns out not to have much effect on the concentration of the derivative,so the room temperature of 20 ℃ could be chosen.And,simultaneously,we have also found that it is possible to find a perfect linear relationship (R2 =0.999) of NH2Cl within the concentration range from 0.10 mg/L to 10.00 mg/L in the optimized derivative reaction conditions.The results of the aforementioned experiments have shown that the detection limit (MDL) of NH2Cl in the water should be 0.013 mg/L with the relative standard deviations (RSDs) being 2.5％-3.4％,whereas the recovery rates of 0.26 mg/L of the water sample and the real water account for 93.5％-113.4％ and 92.6％-106.0％,respectively.Thus,the method we have developed proves to be simple in processing,convenient in operation,and nice in the linear relationship,RSDs and recoveries,which can be applied to the analysis and determination of inorganic monochloramine in water treatment.