内部萃取电喷雾电离质谱技术快速检测饮用水中的铅

Rapid Detection of Lead in Drinking Water by Internal Extractive Electrospray Ionization Mass Spectrometry

重金属铅排放造成的水资源污染长期受到高度关注,监测水中铅含量对于保障饮水安全具有重要意义。本文基于内部萃取电喷雾电离质谱(iEESI-MS)技术,发展了一种快速检测饮用水中铅含量的方法。首先,将水样滴加在聚四氟乙烯滤膜上烘干,然后用邻菲罗啉(Phen)溶液对滤膜上的铅进行在线络合萃取,质谱仪实时检测。结果表明,在Pb^(2+)浓度低至1μg/L时,仍可获得明显的质谱信号;在1~500μg/L浓度范围内的线性关系良好,相关系数(R^(2))为99.4%,加标回收率为117%。该方法具有检测速度快、灵敏度高、准确性好等优点。此外,在获得Phen-Pb络合物信号的同时,还能观察到阴离子(如NO_(2)^(-)、Cl^(-)、SO_(4)^(2-))以及有机组分的质谱信号,表现出高通量的优势,有望用于水中多指标的同时检测。

Lead is a toxic heavy metal with widespread industrial using.The pollution of water resources caused by lead emissions has been highly concerned for a long time.Monitoring the concentration of lead in drinking water is of great significance for preventing its deleterious effects on human health.The main methods for determination of lead in water include graphite furnace atomic absorption spectrometry(GFAAS),flame atomic absorption spectrometry(FAAS),atomic fluorescence spectrometry(AFS),inductively coupled plasma mass spectrometry(ICP-MS),anodic stripping voltammetry(ASV),dithizone spectrophotometry and so on.These methods generally need cumbersome pre-treatments of samples and have the disadvantages of time consuming,large amount of reagents,high energy consumption,and high risk of environmental pollution,which are hard to satisfy the increasing requirements of rapid detection.Although the emerging biosensor technology has the advantages of fast reaction speed and low detection limit,it cannot cope with the presence of multiple ions,and its application of practical samples still needs a further exploration.At present,the rapid analysis of metal ions can also be achieved by using organic mass spectrometry.Based on some previous researches,a method of internal extractive electrospray ionization mass spectrometry(iEESI-MS)was developed for rapid determination of lead in drinking water in this study.Firstly,a drop of 50μL water sample was dropped onto the polytetrafluoroethylene filter membrane and then sent into an oven at 100℃for 15 min until the water completely evaporated.o-Phenanthroline(Phen)solution was selected as a complexing agent to extract lead on the dry filter membrane,and the Phen-Pb complexes were analyzed in real time by mass spectrometer.The results indicated that the concentration of Pb 2+can be detected as low as 1μg/L.Meanwhile,the calibration curve had a good linear relationship between the intensity of mass spectrum peaks and the concentration of Pb^(2+)in the range of 1-500μg/L with the correlation coefficient(R^(2))of 99.4%,and the recovery was 117%.This fully demonstrates that the method has the advantages of fast detection,high sensitivity and good accuracy.Following this example,other metal ions in water can be further analyzed.In addition,when signals of Phen-Pb complexes were obtained,the signals of anions(such as NO_(2)^(-),Cl^(-),SO_(4)^(2-))and organic components in the mass spectrum could also be observed synchronously,showing the outstanding advantage of high throughput.In a word,this method has great potential to be used for implementing the simultaneous detection of multiple indicators in water.