Baseline correction for solution cathode glow discharge (SCGD) atomic emission spectroscopy (AES) using an iterative shift difference algorithm based on fitting-accuracy

Abstract

Solution cathode glow discharge atomic emission spectroscopy (SCGD-AES) is an excellent analytical technique for detecting trace metal elements, yet its quantitative analysis accuracy is severely affected by spectral interference and continuum background. Here, an algorithm based on iterative shift difference was proposed for simultaneous correction of these interference effects and continuum background. The method applies a wavelength shift to the spectrum, subtracts the shifted spectrum from the original unshifted one to minimize background fluctuations, and subsequently restores the spectral profile using a deconvolution. Additionally, iterative shift step optimization based on calibration curve fitting-accuracy is introduced to accommodate spectral differences across elements. This method was applied for SCGD-AES analyses of Zn, Fe, Mg, Cu and Ca with continuum backgrounds and spectral interference in aqueous solution samples. Experimental results demonstrate that the ISDF algorithm eliminates the need for repeated blank background measurements. It achieves a fitting accuracy (R²) for calibration curves exceeding 0.995 for Zn, Fe, Mg, Cu and Ca and reduces measurement errors to approximately 5 %. These metrics surpass those of matrix-matched calibration, moving-average corner-cutting (MA-CC), and achieves equivalent effect to the subtraction of adjacent spectral background (adjacent-background). The results demonstrated that the developed algorithm contributed to accuracy improvement for SCGD-AES quantitative analyses with the presence of spectral interference.