Evaluation of Optimal Conditions for Determination of Low Tin Content in Fresh and Canned Tomato Samples Using Hydride Generation Inductively Coupled Plasma Optical Emission Spectrometry

We propose a procedure for the determination of tin in tomatoes after wet digestion of the samples in HNO3 using hydride generation inductively coupled plasma optical emission spectrometry. The effect of acidity from HCl and HNO3 (0.01–4.0 mol L-1) as well as the presence of l-cysteine on the efficiency of SnH4 generation by reaction with the NaBH4 reductant was investigated. Optimal conditions were evaluated in terms of precision, accuracy (by recovery test) and limit of detection. The best results were obtained with l-cysteine and nitric acid for sample acidificitation. Addition of 1 % (m/v) l-cysteine enhanced the Sn signal and expanded the optimal range of HNO3 concentrations towards higher values; hence, strict control of the acidity could be avoided, up to 1.0 mol L-1. Under the optimized conditions, a detection limit of 1.2 ng mL-1 was achieved. The applicability of the proposed method was demonstrated by the determination of low tin contents in digests of fresh and canned tomato samples with satisfactory results.