干法灰化-原子荧光光谱法测定植物样中痕量锗

锗是对人体有益的重要稀有元素，但锗在植物样中含量很低。目前锗的前处理方法主要采用湿法消解和微波消解两种，以上的前处理方法试剂用量大，称样量小，检出限难以满足植物样中锗的分析要求。氢化物发生-原子荧光光谱法测定锗等易形成共价氢化物的元素相对其他的方法具有明显的优势。为降低测定植物样中锗的检出限，准确测定植物中的锗。实验采用干法灰化法对植物样中锗进行富集，建立了植物样中痕量锗的氢化物发生-原子荧光光谱测定方法。实验了温度对植物样灰化的影响，结果表明，即使温度高达900 ℃也不会造成锗的挥发损失，进一步试验表明在600 ℃灼烧4 h，即可将植物样灰化完全。实验了灰化后样品的消解方法，确定了灰化后样品采用硝酸、氢氟酸和硫酸进行分解。采用大称样量高温灰化减少了试剂用量，有效降低了方法检出限，改善了方法精密度。方法检出限达到0.27 ng·g-1，方法精密度(RSD)在3.99%～6.81%，经生物国家一级标准物质验证方法准确可靠。

Determination of Trace Germanium in Plant Samples by Dry Ashing-Atomic Fluorescence Spectrometry

To reduce the limit of detection (LOD) and allow the accurate determination of Ge, a dry ashing method was performed to enrich the Ge in plant samples. A method for the determination of trace Ge in plant samples by HG-AFS was established. Study of the effect of temperature on the ashing of plant samples showed that no volatile loss of Ge occurred even at 900 ℃. Additional experiments indicated that a 4 h burning process at 600 ℃ would be sufficient to fully ash the plant samples. Various digestion methods (involving nitric acid, hydrofluoric acid, and sulfuric acid digestion methods) for ashed samples were investigated. High-temperature ashing with large sample weights was used, which could reduce the reagent doses and the method’s LOD effectively and simultaneously, the precision of the method was improved. The method’s LOD was 0.27 ng·g-1, and the relative standard deviation was 3.99%～6.81%. Verified with national biological reference materials (grade Ⅰ), the proposed method was accurate and reliable.