The application of antioxidant compounds to minimize matrix effects in flowing liquid anode atmospheric pressure glow discharge optical emission spectrometry

Abstract

To reduce matrix effects originating from concomitant elements (Al, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, and Zn) in flowing liquid anode atmospheric pressure glow discharge optical emission spectrometry (FLA APGD OES), the effect of antioxidant addition was investigated. Selected antioxidants, namely ascorbic acid, hydroquinone and its derivatives, i.e., tert-butylhydroquinone, resorcinol, and catechol, were added to the FLA solution and their impact on the analytical response from the analytes (Ag, Cd, Pb, Tl, and Zn) was thoroughly studied. It was established that the presence of the abovementioned foreign elements in a sample solution reduced analyte signals by ∼20–30% for Cd and Tl, ∼40–50% for Ag and Pb, and ∼60% for Zn. The addition of antioxidant compounds allowed to enhance the analyte signals by up to 4.5-fold. The improved analytical response was due to an efficiency increase in analyte transport from the liquid to the plasma phase. Based on these results, the possibilities of matrix effect reductions using antioxidants were summarized. To verify the suitability of the proposed approach, the analyses of simulated manganese steel and mineral water samples (with the use of 0.1% resorcinol) were conducted. Under these conditions, the detection limits (DLs) for Ag, Pb, and Zn were 0.006, 0.3–0.4, and 0.1–0.4 µg L−1, respectively. Measurement precision (expressed as RSD) for the analysis of these samples was approximately 1–2%, and analyte recoveries varied in the range of 99–108%.