Extraction of trace amounts of silver on various amino-functionalized nanoporous silicas in real samples

Abstract

Aminopropyl-functionalized mesoporous silicas, NH2-MCM-41 and NH2-SBA-15, as absorbents were utilized for rapid extraction, preconcentration and determination of trace amounts of silver. Flow rates of sample and eluent, pH, eluent solution, type, concentration and the least amount of eluent for desorption of silver ions were optimized; moreover, break through volume and the effect of various cationic interferences on the sorption of silver were evaluated. The extraction efficiency of silver ions was greater than 95% for MCM-41-NH2 and 85% for SBA-15-NH2 and the limit of detection (LOD) was less than 4 ng mL−1 for both functionalized mesoporous silicas. The preconcentration factor was greater than 210 and the relative standard deviation (RSD) was <2%. The adsorption capacity of the mesoporous silicas is higher than 143 mg g−1 for NH2-MCM-41 and 137 mg g−1 for NH2-SBA-15. Under similar experimental conditions the results for these solid phases were compared with each other. NH2-SBA-15, in spite of larger pore size diameter and adsorption of silver ions in higher flow rates has lower recovery and a higher RSD compared to MCM-41. This method has been applied to determine silver in photographic emulsions and real samples.