Preconcentration of selenium by living bacteria immobilized on silica for microwave induced plasma optical emission spectrometry with continuous powder introduction

The analytical potential of living bacteria Lactobacillus plantarum for the preconcentration of selenium from mineral water and beer samples followed by the selenium determination by continuous powder introduction microwave induced plasma-optical emission spectrometry (CPI-MIP-OES) has been investigated. The use of the bacteria immobilized on silica permits on-column preconcentration of selenium with minimum sample pretreatment by the pH adjustment. Experimental conditions for the preconcentration were optimized and the mechanism of the biosorption was investigated. Results showed that the use of the preconcentration stage leads to the substantial lowering of the detection limit of selenium by OES. The detection limit of 52 ng g(-1) by the CPI-MIP-OES was achieved which corresponds to 0.06 ng mL(-1) in the sample solution regarding the preconcentration factor of 1000. Precision of 5 replicate measurements expressed as relative standard deviation was about 3%. The utility of the method was demonstrated in the determination of selenium in hard drinking water ERM-CA011a as well as in mineral water and beer samples.