流动注射预富集─石墨炉原子吸收联用测定海水中痕量钼

用二乙基二硫代氨基甲酸钠作络合剂、乙醇作洗脱液的流动注射固相吸附萃取预富集─石墨炉原子吸收联用测定海水中痕量钼。设计了以固定体积取样法为基础的预富集装置。考察了实验参数对分析性能的影响。本法能在线分离干扰、富集被测物,当样品上柱体积为1.35mL时,富集倍数为13.3倍,检测下限为0.027μg/L,用于测定海水等标样中钼含量,精密度较好。

Determination of Ultfa-trace Amounts of Molybdenum in Seawater by Flow Injection On-line Preconcentration Graphite Furnace Atomic Absorption Spectrometry

Amethod for determination of ultra-trace amounts of molybdenum in seawater by flow injection on-line sorbent extraction preconcentration coupled with GFAASis described.An approach for introducting only the most concentrated fraction of the eluate into the graphite tube while discarding the rest was investigated. The experimental parameters of the FI-GFAASwere optimized. If miniflow (50 mL/min) in atomisation step was used, the memory effect in the determination of molybdenum by graphite furnace could be removed. By using the preheating step in furnace temperature program, diffusion losses of molybdnum ethanol solution could be prevented. On-line chelation of molybdenum with dithiocarbamate (NaDDTC) and sorption of the complex on C¹⁸ sorbent packed in a micro column ensure high group selectivity and enrichment. The closed nature of flow system reduced the risk of contamination significantly. The enrichment factor was 13. 3 using sample loading volume of only 1. 35 mL, detection limit achieved was 0.027μg/L. Results obtained for seawater and riverwater standards agreed well with certified values with a good precision.