Room temperature ionic liquids and ammonium pyrrolidine dithiocarbamate synergetically enhanced the determination of zinc by chemical vapor generation coupled with flame atomic absorption spectrometry

Abstract

A new method for the determination of zinc based on the synergetic enhancement effect of room temperature ionic liquids (RTILs) and ammonium pyrrolidine dithiocarbamate (APDC) by chemical vapor generation (CVG) coupled with flame atomic absorption spectrometry (FAAS) was developed. RTILs and APDC were used as synergetic enhancement reagents. The addition of RTILs led to a 3.6 times improvement in the CVG efficiency of zinc. Zinc hydride was effectively generated with a 48% vapor generation efficiency (the CVG efficiency was calculated on the basis of the concentrations of zinc before and after CVG) by mixing the acidified analyte solutions with KBH₄ in the presence of 0.02% (m/v) APDC and 0.1% (m/v) 1-butyl-3-methylimidazolium tetrafluoroborate ([C₄MIM]BF₄). Some parameters that influenced CVG and subsequent determination were evaluated in detail, such as the concentrations of RTILs, APDC, HNO₃ and KBH₄; flow rates of the carrier gas, lengths of the reaction tube and transfer tube, as well as interference from other elements. A detection of limit of 9 ng mL⁻¹ and a relative standard deviation (RSD) of 5.7% at 400 ng mL⁻¹ Zn(II) (n = 5) were obtained under optimal experimental conditions. The proposed method was successfully applied to the determination of zinc in real water samples and certified reference samples with satisfactory results.