摘要:
传统的原子吸收光谱和分光光度法测定土壤有效态钴和有效态铅,操作繁琐,且分析效率低,不适用于大量样品的测定;利用先进仪器测定虽然提高了分析效率,但由于浸提剂的浓度影响仪器灵敏度,测定结果不准确。本文用DTPA溶液浸提,电感耦合等离子体质谱法测定石灰性土壤中有效态钴和有效态铅的含量。稀释倍数实验表明,浸提液稀释2倍时,石灰性土壤国家标准物质的测定值与标准值基本一致;稀释5倍或10倍时,测定值较标准值偏高;不稀释时,由于浸提液的浓度较高,受到基体干扰,测定值偏低。本方法确定对浸提液稀释2倍进行实验,有效态钴的检出限为0.0130 μg/g,有效态铅的检出限为0.0142 μg/g,精密度(RSD,n=9)小于8%。用土壤国家标准物质进行验证,测定值与标准值的相对误差小于9%(n=9),满足了DD 2005-03对土壤样品中有效态钴和有效态铅的测定要求。
Abstract:
The traditional methods for determining available cobalt and lead in soils by Atomic Absorption Spectrometry and Spectrophotometry have complicated operation and low analysis efficiency and are not applicable to large batches of samples. Advanced equipment has been applied to improve the analysis efficiency, however, the interferences from the extracted fluid affected the sensitivity of the instruments, which resulted in inaccurate determination. In this paper according to the method for determination of available forms of heavy metals in calcareous soil extracted with DTPA, the amounts of available cobalt and lead in soils are determined with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). A control test was simultaneously conducted with several dilution factors experiments. The results indicate that the measured values of lime standard substances are consistent with the certified values when the extract solution is diluted twice. The measured values are higher than the certified values when the dilution factors for extract solution are 5-10 times higher. If there is no dilution, the measured values are lower than the certified values due to matrix interference. Based on 2 times dilution for extract solution, the detection limit for available cobalt and lead are 0.0130 μg/g and 0.0142 μg/g, respectively. Both the accuracy and precision of the method were validated by analyzing National Standard Reference Materials with RSD (n=9) less than 8% and relative error (n=9) less than 9%. It has been indicated that the method can be used to analyze the calcareous soil and its precision and criterion error were also in line with the limit by geological specification DD2005-03.
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