Universal calibration for analysis of organic solutions of medium and low volatility by inductively coupled plasma-atomic emission spectrometry

Abstract

A novel chemometric technique is described to facilitate the use of a single organic solvent matrix standard to calibrate inductively coupled plasma atomic emission spectrometry (ICP-AES) for the accurate determination of trace elements in another organic solvent or complex mixture of several organic solvents. Analysis errors arising from the difference in solvent matrix vapor loading and chemical composition between standard and sample are corrected. The technique is intended for organic solvent mixtures for which the plasma vapor loading is tolerable with conventional sample introduction techniques (i.e., conventional nebulizer-spray chamber arrangement without a solvent desolvator). Simultaneous measurement of atomic and ionic spectral lines of the same analyte is required. A correction factor is estimated from its linear correlation with the line intensity ratio. For elements without a sensitive atom line, the correction is estimated from the correlation between their ionic line intensities and the ratio of ionic-to-atomic line intensities of another analyte in the same sample. Experimental tests with seven trace elements (Al, Be, Ca, Cu, Fe, Mg, and Mn) in different organic solvent mixtures (xylene, dichloromethane, hexane, carbon disulfide, acetone and 1,2,3,4-tetrahydronaphthalene) demonstrate the effectiveness of universal calibration.