离子色谱法-光度检测天然水中铬(Ⅵ)

IC Determination of Chromium(Ⅵ) in Natural Water with VIS-Photometric Detection

应用离子色谱法测定了天然水中六价铬,给出了试验装置及分析流程的图解。水样经0.22μm滤膜过滤后分取500μL进样,经保护柱（IonPac AG7）及分离柱（IonPac AS7）分离,由流量为0.25 mL.min-1的淋洗液（300 mmol.L-1硫酸铵和120 mmol.L-1氨水的混合溶液）洗脱。洗脱液与以流量为0.15 mL.min-1二苯羰酰二肼显色液在混合器中混合后,在反应圈中显色,在540 nm波长处作光度检测。线性范围在0.02-50μg.L-1之间,检出限（3S/N）为0.010μg.L-1。对一水样作了12次测定,测定结果的相对标准偏差为1.22%。

Ion chromatography was applied to the determination of Cr（Ⅵ） in natural water.Testing installation and flow diagram for the analysis was given.Water sample was filtered with 0.22 μm filtering membrane and an aliquot of 500 μL was introduced into the instrument.The protective column（IonPac AG7） and separation column（IonPac AS7） were used for separation.A mixture of 300 mmol·L-1（NH4）2SO4 solution and 120 mmol·L-1 aq.ammonia was used as eluant passing through the columns at the flow-rate 0.25 mL·min-1 to elute Cr（Ⅵ） from the column.The eluate was mixed with the color reagent（diphenylcarbazide） solution which was introduced at the flow-rate of 0.15 mL·min-1,at the mixing cell,reacted in the reaction coil to form the colored complex and measured photometrically at the wavelength of 540 nm.Linearity range was found between 0.02-50 μg·L-1,and detection limit（3S/N） was found to be 0.010 μg·L-1.Precision was tested by analyzing a water sample for 12 determinations,value of RSD found was 1.22%.