Background: Sarin is a nerve agent which is lethal to people due to its high toxicity. According to its extreme toxicity, sarin, relatively lack of color, highly toxic, miscible in water, poses viable threats to potable water sources. Therefore, there is an urgent need for portable, rapid and yet reliable methods to monitor for adulteration of potable water sources by sarin on spot.

Methods: A stock solution of 30 mg/L sarin was prepared daily by dissolving 300 μg of sarin in 10 mL isopropanol. A certain amount of sarin was added to the glass tube, and then o-dianisidine and hydrogen peroxide were added. The pH value of the solution was adjusted to 9.8. The solution was transferred to the test tube after 10 minutes. A test tube of 2 mL was placed between the light source and the RGB color sensor. The LED light source illuminates directly over the test tube while the RGB sensor obtained the generated spectral response. This RGB voltage output is connected to the ADC and microcontroller to convert these analog voltages to three digital data. This RGB digital data is linked to the microcomputer through the serial port that is interfaced with the user interface. The data thus obtained in the sensor can be processed to display the sarin concentration.

Results: Under the optimum conditions as described above, the calibration curve of chromaticity value versus sarin concentration was linear in the range of 0.15 mg/L to 7.8 mg/L. According to the IUPAC definition, theoretical detection limits of this method were 0.147 mg/L and 0.140 mg/L for R and B values, respectively. The practical detection limit was 0.15 mg/L. The sensor was successfully applied to the determination of sarin in artificial water samples and the recoveries were between 86.0% to 95.9%.

Conclusion: The results in the present work have demonstrated the feasibility to design a new portable colorimetric sensor based on the RGB chromaticity method for quantitative determination of sarin in water. The influences of chromogenic reagent, oxidant, reaction time, o-dianisidine concentration, hydrogen peroxide concentration, reaction temperature, pH on the chromaticity values were investigated. The results showed that the sensor possessed high selectivity, sensitivity and good repeatability. The method would be potentially applied to the analysis of other toxic compounds in environment, such as other chemical warfare agents.

背景：沙林是一种神经毒剂，由于其高毒性而对人致命。根据其极高的毒性，沙林蛋白（Sarin）相对缺乏颜色，剧毒，可与水混溶，对饮用水源构成了切实的威胁。因此，迫切需要一种便携式，快速而可靠的方法来现场监测沙林中饮用水的掺假情况。

方法：通过将300μg沙林溶于10 mL异丙醇中，每天制备30 mg / L沙林的储备溶液。向玻璃管中加入一定量的沙林蛋白，然后加入邻联二苯胺和过氧化氢。将溶液的pH值调节至9.8。10分钟后将溶液转移到试管中。将2 mL的试管放在光源和RGB颜色传感器之间。当RGB传感器获得生成的光谱响应时，LED光源直接照在试管上方。该RGB电压输出连接到ADC和微控制器，以将这些模拟电压转换为三个数字数据。RGB数字数据通过与用户界面连接的串行端口链接到微计算机。

结果：在上述最佳条件下，色度值与沙林浓度的校准曲线在0.15 mg / L至7.8 mg / L的范围内呈线性关系。根据IUPAC的定义，该方法的理论检出限R和B值分别为0.147 mg / L和0.140 mg / L。实际检出限为0.15 mg / L。该传感器成功应用于人造水样品中沙林的测定，回收率在86.0％至95.9％之间。

结论：本研究结果证明了基于RGB色度法设计一种新型便携式比色传感器用于定量测定水中沙林的可行性。考察了生色试剂，氧化剂，反应时间，邻二苯胺浓度，过氧化氢浓度，反应温度，pH值对色度值的影响。结果表明，该传感器具有较高的选择性，灵敏度和重复性。该方法将有可能应用于环境中其他有毒化合物的分析，例如其他化学战剂。