Evaluation of a Lignin Bio-alkyd Resin for the Selective Determination of Molybdenum in Biological, Pharmaceutical, Fertilizer and Water Samples

A lignin-based bio-alkyd resin (LA-Resin) was synthesized by the polycondensation reaction of lignin with a mixture of palmitic acid and glycerol. The LA-Resin was characterized using many techniques, including scanning electron microscope, FTIR, X-ray diffraction and thermal analysis. LA-Resin was proven to have graphitized structures with enhanced surface functional groups, showing a slightly basic character (pHZCP = 7.8). It has a relatively better cation exchange capacity (0.70 mmol g-1) in addition to the ability for physical adsorption. The performance of LA-Resin was assessed for the uptake of molybdenum (Mo), followed by spectrophotometric determination, applying both batch and column techniques. Elevated sorption percentages of Mo were observed in acidic medium H2SO4 (1.5 mol L-1) in the presence of ascorbic acid (0.050 mol L-1) and NH4SCN (0.10 mol L-1). The method was successfully applied to the separation and determination of Mo in mice liver, pharmaceuticals, water and fertilizer samples. Validation showed good recovery (96.6-99.6%), sensitivity (LOD, 0.9-4.0 μg L-1), repeatability (RSD% ≤1.5%) and linearity (R2 = 0.984), demonstrating a good quantitative performance of the method. Mo in all investigated samples regardless of different matrices were well-separated and detected, indicating that the method is sensitive enough to detect low concentrations of Mo even in small samples such as mice liver.