State Key Laboratory of Marine Environmental Science, Environmental Science Research Center, Xiamen University, Xiamen, Fujian Province 361005, PR China.
Talanta. 2011 Apr 15;84(2):443-50. doi: 10.1016/j.talanta.2011.01.048. Epub 2011 Jan 26.
An automatic gas-phase molecular absorption spectrometric (GPMAS) system was developed and applied to determine nitrite and total nitrate in water samples. The GPMAS system was coupled with a UV-light emitting diode photodiode (UV-LED-PD) based photometric detector, including a 255 nm UV-LED as the light source, a polyvinyl chloride (PVC) tube of 14 cm as the gas flow cell, and an integrated photodiode amplifier to measure the transmitted light intensity. The UV-LED-PD detector was compact, robust, simple and of low heat production, comparing with detectors used in other GPMAS works. For nitrite measurement, citric acid was used to acidify the sample, and ethanol to catalyze the quantitative formation of NO(2). The produced NO(2) was purged with air flow into the UV-LED-PD detector, and the gaseous absorbance value was measured. The total nitrate could be determined after being reduced to nitrite with a cadmium column. Limits of detection for nitrite and nitrate were 7 μmol/L and 12 μmol/L, respectively; and linear ranges of 0.021-5 mmol/L for nitrite and 0.036-4 mmol/L for nitrate were obtained. Related standard deviations were 1.81% and 1.08% for nitrite and nitrate, respectively, both at 2 mmol/L. The proposed method has been applied to determine nitrite and total nitrate in some environmental water samples.
开发了一种自动气相分子吸收光谱（GPMAS）系统，并将其应用于水样中亚硝酸盐和硝酸盐总量的测定。GPMAS 系统与基于紫外发光二极管光电二极管（UV-LED-PD）的光度检测器耦合，包括作为光源的 255nm UV-LED、14cm 长的聚氯乙烯（PVC）管作为气流池，以及集成的光电二极管放大器，用于测量透射光强度。与其他 GPMAS 工作中使用的检测器相比，UV-LED-PD 检测器具有紧凑、坚固、简单和低热产生的特点。对于亚硝酸盐的测量，使用柠檬酸酸化样品，并使用乙醇催化定量形成 NO(2)。产生的 NO(2)用气流吹扫到 UV-LED-PD 检测器中，测量其气态吸收值。硝酸盐可以用镉柱还原为亚硝酸盐后进行测定。亚硝酸盐和硝酸盐的检出限分别为 7μmol/L 和 12μmol/L；亚硝酸盐的线性范围为 0.021-5mmol/L，硝酸盐的线性范围为 0.036-4mmol/L。在 2mmol/L 时，亚硝酸盐和硝酸盐的相关标准偏差分别为 1.81%和 1.08%。该方法已应用于一些环境水样中亚硝酸盐和硝酸盐总量的测定。
