Abstract
y The sorption characteristics of phosphate ions from aqueous molybdate solution of pH <= 2 onto malachite green (MG) impregnated thiophenol (TP) functionalized Au nanoparticles based polyurethane foam (PUF) solid platform (MG-AuNPs-treated PUF) was studied. Phosphate uptakes followed Langmuir and Freundlich models. Based on the retention profile, a dual mechanism involving a weak base anion exchanger i.e. solvent extraction and a surface adsorption of phosphate retention as complex ion associate {[MG](+)(center dot)[H2PMo12O40](-)}(PUF) is anticipated. Complete retention of phosphate at various concentrations (0.01-100.0 mu g mL(-1)) onto the sorbent packed column at 35 mL min(-1) flow rate was achieved. A highly sensitive strategy for enriching, quantitative recovery and trace determination of phosphate in water using the sorbent packed column was developed. Under the optimized parameters, a linear concentration range of 0.07-25 mu g L-1 and limits of detection (LOD) and quantification (LOQ) of 0.02 and 0.07 mu g L-1 phosphate were achieved, respectively. The proposed and reference methods for analysis of phosphate in water samples were subjected to statistical treatment (student's t and F tests) at 95% confidence with no significant difference indicating the precision and accuracy of the proposed assay. The settled sorbent in flow mode was robust sufficient to be reused for five times without significant decrease in its performance. The intraday repeatability and interday stability of the established sorbent packed column towards phosphate (10.0 mu g L-1) determination was studied. An estimated coefficient of variation less than +/- 5% was achieved revealing the suitably of the modified PUFs in column mode. The established column enabled multiple enrichment of phosphate from water and expanded the range of phosphate level which can be determined in water.