A combined volume correction and standard addition step to simplify environmental chemical analysis

Abstract

A simple standard addition calibration procedure is described theoretically to allow both quantification of the unknown component of interest in an environmental sample and, simultaneously, measurement of the volume of that sample. The method relies on the addition to the standard solution of an internal standard containing an analyte that is not expected in the sample itself or at such a low concentration as to make no difference. The underpinning mathematics of the technique is described, including the complex correction for variable volume standard addition techniques. The method would be most suitable for the measurement of environmental samples requiring a digestion or extraction step (leading to variable sample volumes) prior to the analysis. Theoretical consideration of this new approach is made with reference to the measurement of metals in ambient particulate matter, where it would dramatically reduce analysis time and the requirement for analyst intervention.