A sensitive vesicle mediated dispersive liquid-liquid microextraction of parts per quadrillion levels of beryllium from seawater samples prior to graphite furnace atomic absorption spectrometry determination

Abstract

A rapid and highly sensitive vesicle mediated dispersive liquid-liquid microextraction procedure is developed for the determination of parts per quadrillion level of beryllium in seawater and air filter samples for providing its natural background and contamination levels. In this procedure, dioctylsulfosuccinate, an anionic vesicular surfactant and acetylacetone are used as dispersing and chelating agents, respectively. At pH > 9.5, beryllium forms hydrophobic beryllium-acetylacetonate complex spontaneously at room temperature. This complex is selectively filled into the vesicular cavities of dioctylsulfosuccinate and is extracted into small chloroform phase from bulk aqueous phase. The beryllium present in the chloroform phase is back extracted with dilute nitric acid and is analyzed by graphite furnace atomic absorption spectrometry. This method is applied to groundwater, seawater, coal fly ash, air filter and sea sludge samples. Under the optimized conditions, the limit of detection, limit of quantification and linear dynamic range are 10 fg mL^-1, 33 fg mL^-1 and 40-500 fg mL^-1 for seawater; 0.15 ng g^-1, 0.5 ng g^-1 and 0.4-4 ng g^-1 for air filter and 1.5 ng g^-1, 0.39 ng g^-1 and 0.4-4 ng g^-1 for coal fly ash, respectively. For 1 L seawater sample an enrichment factor of 954 is achieved. Coefficient of determination (R²) is found to be 0.997. The recoveries are in the range of 94-105% at 200-500 fg mL^-1. The relative standard deviations are 20%, 11%, 8% for ppq, ppt and ppb levels of Be, respectively. The accuracy of the procedure is verified by analyzing NIST SRMs 1640 and 1640a trace elements in natural water.

Keywords: Beryllium dating; Liquid-liquid microextraction; Pre-concentration; Surfactant.