还原分离-原子荧光光谱法测定镀锌板涂镀层中痕量汞

Determination of trace mercury in the coating of galvanized sheet by reduction separation-atomic fluorescence spectrometry

建立了以六次甲基四胺-盐酸溶液褪去镀锌层后用还原分离-原子荧光光谱法测定镀锌板涂镀层中痕量汞的方法。研究了六次甲基四胺用量、溶液酸度对测定的影响,优化了硼氢化钾浓度、灯电流、光电管负高压、屏蔽气和载气流量、原子化器高度、原子化器温度、试样注入量等测试条件,并对共存元素干扰情况进行了考察。研究结果表明,在灯电流为10mA,负高压为-320V,载气流量为400mL/min,屏蔽气流量为1 000mL/min,原子化器高度为8.0mm,积分时间为10.0s,断续流动注入溶液为1.0mL,载流溶液为盐酸(1+19),以20.0g/L硼氢化钾浓度(含5.0g/L氢氧化钠)为还原剂的条件下进行测定,荧光强度与汞浓度在0.20～40.0ng/mL呈良好线性关系。汞的检出限为0.10μg/g,样品测定结果的相对标准偏差为1.3%,加标回收率在98%～100%之间。

A method for determining trace mercury in galvanized sheet by reduced separation-atomic fluorescence spectrometry was established after hexamethylenetetramine-hydrochloric acid solution was used to get rid of galvanized sheet.A study was conducted on the effect of hexamethylenetetramine amount and acidity on the determination.Testing conditions including potassium borohydride concentration,lamp current,photoelectric tube with negative pressure,shield gas and carrier gas flow rate,the height of atomizer,atomizer temperature,and sample injection volume were optimized.And the interference caused by coexistent elements was studied.The result indicated the fluorescence strength had excellent linear relationship with mercury concentration of 0.20-40.0 ng/mL when mercury was determined under following conditions： lamp current of 10 mA,negative pressure of-320 V,carrier gas flow rate of 400 mL/min,shield gas flow rate of 1 000 mL/min,atomizer height of 8.0 mm,integration time of 10.0s,1.0 mL of intermittent flow injection solution,and with hydrochloric acid（1＋19） as current carrying solution and 20.0 g/L potassium borohydride solution（containing 5.0 g / L sodium hydroxide） as reducer.The detection limit of mercury was 0.10 μg/g.The RSD for determination result of sample was 1.3 % and the standard addition recovery was 98%-100%.