Development of a sensitive method for lead determination by flame atomic absorption spectrometry using slotted quartz tube in-situ atom trapping and metal coatings

Abstract

Flame atomic absorption spectrometry (FAAS) still keeps its importance despite the relatively low sensitivity, because it is a simple and economical technique for determination of metals. In recent years, atom traps have been developed to increase the sensitivity of FAAS. Although the detection limit of FAAS is only at the level of mgL−1, with the use of atom traps it can reach to the level of ngmL−1. Slotted quartz tube (SQT) is one of these atom traps; it is applied for determination of volatile elements. It is economical, commercially available and easy to use. In this study, a sensitive analytical method has been developed for the determination of lead with the help of SQT. 1472 fold sensitivity enhancement was obtained using the uncoated slotted quartz tube atom trap flame atomic absorption spectrometry (SQT-AT-FAAS) method at a sample suction rate of 7.4mLmin−1 for 4.0min collection with respect to FAAS. To obtain a further sensitivity enhancement, the inner surface of SQT was coated with several kinds of transition metals. The best sensitivity enhancement, 4600 fold, was obtained by the Ta-coated-SQT-AT-FAAS. In addition, the chemical nature of Pb trapped on quartz and Ta surface, and the chemical nature of Ta on quartz surface were investigated by X-ray photoelectron spectroscopy (XPS).