石墨炉原子吸收光谱法测定土壤及农产品中痕量铍

GF-AAS Determination of Trace Amount of Beryllium in Soil and Agricultural Products

土壤试样用浓硝酸及过氧化氢在ETHOS 1型微波消解仪中按预设程序进行消解,所得消解溶液蒸发至近干后定容为25.0 mL供石墨炉原子吸收光谱法(GF-AAS)分析用。农产品试样先置于浓硝酸及高氯酸中浸泡过夜,然后置于电热板上加热消解至溶液呈深棕色,再加入硝酸-高氯酸(3+1)混合酸适量,加热蒸发至冒高氯酸烟,冷却,定容为25.0 mL供GF-AAS分析。分取10μL试样溶液,按预设的仪器工作条件测定其含铍量。在试样溶液中加入氯化钙溶液作为基体改进剂,铍(Ⅱ)的质量浓度与相应的吸光度值在4.0μg.L-1范围内呈线性关系。方法的检出限(3s/k)为0.4 pg。应用此方法测定了土壤及菠菜标准物质,测定结果均与证书值一致,测定值的相对标准偏差(n=6)均小于5%。

Soil sample was digested with conc.HNO3 and H2O2 in the ETHOS 1 microwave digestor under the prescribed program.The solution obtained was evaporated to near dryness and its volume was made up to 25.0 mL,which is ready for the GF-AAS analysis.Sample of agrucultural products was soaked in conc.HNO3 and HClO4 over night,and then heated on an electric hot plate until color of the solution became dark brown.A definite amount of mixed acid of HNO3 and HClO4（3＋1） was added to the solution and evaporated to fumes of HClO4 acid.The solution was cooled,diluted to 25.0 mL and ready to be used for GF-AAS analysis.Ten μL of sample solution were taken and its beryllium content determined by GF-AAS under the prescribed instrumental working condition.Calcium salt solution was added as matrix modifier.Linear relationship between values of absorbance and mass concentration of Be（Ⅱ） was obtained in the range within 4.0 μg· L-1 with the detection limit（3s/k） of 0.4 pg.The proposed method was used in the determination of beryllium in CRM′s of soil and spinach,giving results in consistency with the certified values,with RSD′s（n=6） less than 5%.