Correlation-based detection of spectral information using microliter volumes, in-torch vaporization (ITV) sample introduction and inductively coupled plasma atomic emission spectrometry with photodiode array detection

Abstract

The application of Fourier transform-based cross-correlation techniques for automatic detection of spectral information using 10 μl volumes is presented. The basic approach involves interrogation of a spectral pattern from a multielement mixture for the presence of spectral features obtained by running single element standard(s). In essence, the multielement mixture is “interrogated” for the presence of the sought-for element and, thus, automatic interpretation of spectral information is obtained. Spectral patterns from 10 μl volumes of single element standards and multielement mixtures were acquired using an electrically heated wire-loop, in-torch vaporization (ITV) sample introduction system and an inductively coupled plasma (ICP) spectrometer equipped with a photodiode array detector (Leco Plasmarray). The wavelength region from about 280 nm to about 410 nm was covered. Spectral patterns for 10 elements (Al, Be, Co, Ni, Sc, Sr, V, Y, Yb and Zr) obtained using 10 μl volumes of single element standards were converted to spectral interference-free and noise-free binary software masks. Cross-correlation of these binary software masks with spectral patterns obtained from 10 μl volumes of multielement mixtures is discussed and a graphical user interface that utilizes a color-coded periodic table to present the likely composition (i.e. qualitative and semi-quantitative analysis) of a mixture on the computer screen is described.