镉试剂正负峰加和法测定水中镉

Determination of Cd(Ⅱ) in water samples by spectropotometry with summation of positive-negative peaks and 1-(4-nitrophenyl)-3-(4-phenylazophenyl) triazene

研究了表面活性剂对Cd（Ⅱ）与1-（4-硝基苯基）-3-（4-苯基偶氮苯基）-三氮烯（镉试剂）显色反应的影响。实验结果表明,在非离子表面活性剂TritonX-100存在下,配合物出现正负两个最大吸收峰分别为478 nm和566 nm。采用正负峰加和法,Cd（Ⅱ）在0-8μg/25 mL范围内服从比尔定律,表观摩尔吸光系数为2.44×105L.mol^-1.cm^-1。该法可用于合成样品及池塘水样中痕量镉的测定。

The effect of surfactant on the colour reaction of cadion, 1-（4-nitrophenyl）-3-（4-phenylazophenyl）-triazene, with cadmimn（ Ⅱ ） was studied in this paper. In the presence of Triton X-100, the maximum absorption wavelength is at 478 nm and the maximum negative absorption wavelength is at 566 nm. The molar absorptivity is 2.44×105L.mol^-1.cm^-1 using positive-negative peak summation spectrophotometry, which the reference wavelength is 566 nm and detection wavelength is 478 nm. Beer＇s law is obeyed in the concentration range of 0 - 8 μg Cd（ Ⅱ ） in 25 mL solution. The method shows higher selectivity, and satisfactory results in detennineing trace amount of Cd（ Ⅱ ） in compound and pool water samples.