深紫外分光光度检测系统的稳定性及灵敏度研究

Study on Stability and Sensitivity of Deep Ultraviolet Spectrophotometry Detection System

现有的国标光度法无法直接测定流程工业中连续反应单元生产过程的污染物,主要原因是氧气在深紫外区对紫外光的吸收干扰了紫外分光光度计对目标物质的检测,导致检测结果存在一定程度偏差。因此,解决这一问题的关键核心是稳定获取深紫外区不同特征波长物质的高灵敏光度信息。在紫外分光光度计基础上加装氮气输配系统,同时设计了自动进样流通池及进样托盘以实现检测间隙自动进样功能,减少检测间隙氮气消耗。为提高仪器稳定性,分别精准控制通入仪器内部光学系统区、样品室和数据接收区三个腔体的氮气流量,数值分别为6,2和3 L·min^(-1),使仪器基线平直度平均值由0.108降低至0.010,较空气条件削减了90.7%。通过对比空气与氮气两种气氛下直接测定SO^(2-)(-4)的吸光度、灵敏度、灵敏度变化量和线性范围的差异,发现氮气气氛下检测结果的吸光度和灵敏度在光程b=1~100 mm范围内均有提升,灵敏度变化量随b=1 mm时的10.42%增大至b=100 mm时30.65%,线性范围却随光程的增加由0.09 g·L^(-1)缩短至0.03 g·L^(-1)。说明氮气输配系统能够成功抑制检测过程中紫外光强度的衰减。与检测SO_(-4)^(2-)的常用方法之一的离子色谱法相比,该方法具有检测便捷、检测结果稳定可靠并且经济效益良好的优势,可为工业实际应用奠定基础。

The existing national standard photometric method can not directly determine the pollutants in the production process of continuous reaction units in the process industry.The main reason is that the absorption of ultraviolet light by oxygen in the deep ultraviolet region interferes with the detection of target substances by ultraviolet spectrophotometer,resulting in a certain degree of deviation in the detection results.Therefore,the key to solving this problem is to stably obtain the highly sensitive photometric information of substances with different characteristic wavelengths in the deep ultraviolet region.In this study,a nitrogen transmission and distribution system was installed based on a UV spectrophotometer.At the same time,an automatic injection flow cell and tray are designed to realize automatic sample injection between detection gaps.The nitrogen flows into the optical system area,sample room and data receiving area of the instrument is accurately controlled at 6,2 and 3 L·min^(-1) respectively,so that the average value of the baseline flatness of the instrument is reduced from 0.108 to 0.010,which is 90.7%less than the air conditioner.Comparing the differences in the absorbance,sensitivity,sensitivity change and linear range of SO_(-4)^(2-) between air and nitrogen atmospheres,reveals that the absorbance and sensitivity of detection results in nitrogen atmosphere are improved in the range optical pathlengths b=1~100 mm.The sensitivity change increases from 10.42%to 30.65%when b=1 mm to b=100 mm,but the linear range decreases from 0.09 to 0.03 g·L^(-1) with increasing of optical path lengths.It shows that the nitrogen transmission and distribution system successfully inhibits the attenuation of UV intensity in the detection process.Compared with ion chromatography,one of the common methods for detecting SO_(-4)^(2-),this method has the advantages of convenient detection,stable and reliable detection results and good economic benefits,laying a foundation for industrial application.