Determination of lithium in serum and whole blood by graphite furnace atomic absorption spectrometry

Abstract

A method has been developed for the direct determination of lithium in serum and whole blood by graphite furnace atomic absorption spectrometry using tantalum carbide coated graphite tubes in combination with ammonium nitrate matrix modification. The maximum permissible charring temperature for lithium was raised from 1050 to 1500 "C and the lifetime of the tube was also prolonged for ca. 200 more firings using the tantalum carbide coated graphite tube compared with the conventional pyrolytic graphite coated graphite tube. Matrix interferences from chlorides present in human blood samples were eliminated using the proposed method, which has been used for the determination of lithium in serum and whole blood of normal healthy individuals.

Interference of Sodium Chloride in the Determination of Lithium by Atomic Spectrometry

“…LiCl did not lose during the ash step: Severe interferences caused by the chloride matrices were considered one of the major problems encountered in the GFAAS determination of Li. It was believed that the suppression of the atomic absorption signal for Li in the presence of chloride was probably due to the formation of volatile LiCl and much of Li was lost from the graphite furnace in the form of gaseous molecular compound without contributing to the atomic absorption signal 18 . Katz and Taitel 25 pointed out that the observed signal decrease was caused by the reaction between gaseous Li and Cl and consequent formation of LiCl, which was swept out in the gaseous state from the graphite tube by the purge gas.…”

“…Therefore, it is very important to determine Li accurately in biological samples for clinical and medical research investigations. Several analytical methods have been developed for the determination of Li in biological samples, such as flame atomic emission spectrometry (FAES) [7][8][9] , flame atomic absorption spectrometry (FAAS) 8,10 , graphite furnace atomic absorption spectrometry (GFAAS) 1,[11][12][13][14][15][16][17][18] , inductively coupled plasma atomic emission spectrometry (ICP-AES) [19][20][21] , inductively coupled plasma mass spectrometry (ICP-MS) 13,22 , isotope dilution mass spectrometry (IDMS) 23 , ionselective electrode (ISE) 8 etc.…”

Strategies to increase selectivity of analytical methods for As, Cr and Se speciation in biological samples: A review

“…Although problems presented above regarding the use of sample introduction through suspension, there is still a great advantage as the introduction of direct analysis of solid samples in equipment. The direct determinations of solids require a calibration [57][58][59] patterns solids [57,58], the availability of these standards [57], which requires more cost, difficulty in obtaining a representative portion of the sample [60,61], sampling error in the portion to be analyzed, and the non homogeneous distribution of the analyte [59]. Besides, equipment for direct solid analysis needs samplers suitable for such analysts.…”