Biological evaluation of occupational exposure to nickel and lead with the solid-phase extraction method using Chromosorb-102 resin

The aim of this study was to assess exposure of workers in a metal industry to nickel and lead. Extraction was done using the solid-phase extraction on Chromosorb-102 resin to prepare, concentrate and purify biological samples of urine, hair and nails of workers working in metal industries. The variables influencing response (pH, loading flow rate, elution solvent, and amount of resins, elution volume, and sample volume) were examined and the procedure was optimized. The optimized procedure was, then, validated based on the “within-day” and “day-to-day” reproducibility experiments, using low, medium and high concentrations, leading to a satisfactory accuracy and precision. Finally, lead and nickel samples were taken from the workers and their concentrations determined voltammetrically. The optimum values for the examined parameters were as follows: pH = 9, ligand concentration = 0.05%, loading flow rate = 5 ml/min, elution solvent = 2M HNO3, amount of resins = 500 mg, elution volume = 15 ml, and sample volume up to 500 ml. A good reproducibility and repeatability was obtained for the optimized method under the existing conditions. Lead and nickel could be extracted with recoveries in the range of 94-100%. On the whole, the concentrations of nickel and lead in the workers’ biological samples were above the respective maximum permitted levels. Solid-phase extraction procedure is a fast and simple method for preconcentrating and isolating analytes from biological samples. Considering the low concentrations of the analytes and presence of confounding factors in such samples, the procedure can be very effective for their preparation. The application of the developed method indicates that trace metal ions can be effectively purified and preconcentrated from different matrices like urine, hair and nail samples to assess occupational exposures.