次靈敏線火焰原子吸收光譜法測定
鄧 翔
摘 要：以鋰的次靈敏線323.3 nm為分析譜線，采用火焰原子吸收光譜法測定磷酸鐵鋰中的高含量鋰。通過研究酸介質、消電離劑和基體離子對鋰測定的影響，以及進行共存離子干擾實驗發現：在2%的硝酸介質中方法的靈敏度最佳；在標準溶液中加入基體離子，可以消除基體對鋰測定的干擾；常見共存離子不干擾鋰的測定。在優化的實驗條件下，鋰的檢測線性范圍為4～140 μg·mL-1，檢出限（3σ）為2.0 μg·mL-1，對20.0 μg·mL-1的鋰標準溶液連續測定11次，其RSD為0.05%。方法簡便、快速、準確，檢測線性范圍廣，避免了稀釋操作帶來的誤差，可用于高含量鋰的直接測定；方法用于磷酸鐵鋰樣品測定，回收率在94%~103.7%之間，相對標準偏差（n=7）在1.04%~1.16%之間。
關鍵詞：火焰原子吸收光譜法；磷酸鐵鋰；鋰；次靈敏線
中圖分類號：O657.31；TQ131.1+1；O614.111；TM930.12 文獻標志碼：A 文章編號：1674-5124（2013）05-0046-03
Flame atomic absorption spectrophotometric determination of lithium in lithium
ferric phosphate using sub-sensitive spectral line
DENG Xiang1，2
（1. Engineering Research Center in Biomaterials，Sichuan University，Chengdu 610064，China；
2. Sichuan Testing Center for Biomaterials and Medical Devices，Chengdu 610064，China）
Abstract: The high-content of lithium in lithium ferric phosphate was determined by flame atomic absorption spectrophotometry using sub-sensitive spectral line at 323.3 nm. The effects of acid medium， disionizer and matrix ions had been studied. The effects of concomitant ions had been studied too. The results proved that the sensitivity was the best in 2% HNO3 aqueous solution， and the matrix effect could be eliminating with addition of matrix ions in standard solutions. The concomitant ions did not affect the determination of lithium. Under the optimized conditions， the linearity range of lithium was kept from 4 μg·mL-1 to 140 μg·mL-1 and the detection limit（3σ）was 2.0 μg·mL-1. The relative standard deviation （n=11） was 0.05% for 20.0 g·mL-1 lithium. This was a simple， rapid， accurate method with wide linearity range. It could avoid the error produced in the dilution operation， so it could be applied to determine high-content lithium in samples directly. The content of lithium in lithium ferric phosphate was determined by this method， giving values of recovery in the range of 94%-103.7% and RSD （n=7） in the range of 1.04%-1.16%.
Key words: flame atomic absorption spectrophotometry; lithium ferric phosphate; lithium; sub-sensitive spectral line
