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水溶性卟啉是超高灵敏度显色剂之一,在pH9.6～10.5范围内与铅定量络合并立即显色。波长470毫微米时络合物有最大吸收峰,克分子吸光系数ε=26×10~5。卟啉与铅的络合物进行分光光度测定时以pH=10.2的四硼酸钠为缓冲溶液,适量的甘露醇、柠檬酸钠、氰化钾为掩蔽剂,允许一定量的常见干扰元素存在。室温30℃络合物稳定时间短,室温低于30℃时稳定时间超过2小时。本法测定矿石中的铅最低检出量是0.2微克,精密度在2%左右。测定样品结果与打萨宗目视比色法比较相对偏差一般在4～5%。
Water-soluble porphyrin is one of the ultra-high sensitivity color developing agents, complexed with Pb quantitatively in the range of pH9.6 ~ 10.5 and immediately colored. When the wavelength is 470 nm, the complex has the maximum absorption peak and the molecular extinction coefficient ε = 26 × 10 ~ 5. Porphyrin and lead complexes spectrophotometric determination of sodium tetraborate pH = 10.2 as a buffer solution, an appropriate amount of mannitol, sodium citrate, potassium cyanide masking agent, allowing a certain amount of common interference elements exist. Room temperature 30 ℃ complex stability time is short, at room temperature below 30 ℃ when the stability of more than 2 hours. Determination of the law of lead in the ore minimum detection volume is 0.2 micrograms, precision of about 2%. The relative deviation between the measured sample results and the colorimetric method of Sazan visual observation is generally 4 ~ 5%.