Estimation of lead in biological samples of oral cancer patients chewing smokeless tobacco products by ionic liquid-based microextraction in a single syringe system

Several studies have reported that the chewing habit of smokeless tobacco (SLT) has been associated with oral cancer. The aim of the present study was to evaluate the trace levels of lead (Pb) in biological samples (blood, scalp hair) of oral cancer patients and referents of the same age group (range 30–60 years). As the concentrations of Pb are very low in biological samples, so a simple and efficient ionic liquid-based microextraction in a single syringe system has been developed, as a prior step to determination by flame atomic absorption spectrometry. In this procedure, the hydrophobic chelates of Pb with ammonium pyrrolidinedithiocarbamate (APDC) were extracted into fine droplets of 1-butyl-3-methylimidazolium hexafluorophosphate [C₄MIM][PF₆] within a syringe while using Triton X-114 as a dispersant. Factors influencing the microextraction efficiency and determination, such as pH of the sample, volume of [C₄MIM][PF₆] and Triton X-114, ligand concentration, and incubation time, were studied. To validate the proposed method, certified reference materials were analyzed and the results of Pb²⁺ were in good agreement with certified values. At optimum experimental values of significant variables, detection limit and enhancement factor were found to be 0.412 μg/L and 80, respectively. The coexisting ions showed no obvious negative outcome on Pb preconcentration. The proposed method was applied satisfactorily for the preconcentration of Pb²⁺ in acid-digested SLT and biological samples of the study population. It was observed that oral cancer patients who consumed different SLT products have 2–3-fold higher levels of Pb in scalp hair and blood samples as compared to healthy referents (p < 0.001). While 31.4–50.8 % higher levels of Pb were observed in referents chewing different SLT products as compared to nonconsumers (p < 0.01).