Determination of chlorine in coal via the SrCl molecule using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis

• A simple and fast method for the determination of chlorine via the SrCl molecule.
• Chlorine has been determined in coal using direct solid sample analysis.
• Calibration has been carried out against aqueous standard solutions.
• Zirconium was successfully employed as permanent chemical modifier.

In this study, the determination of chlorine in coal is described via molecular absorption of the strontium mono-chloride (SrCl) molecule at 635.862 nm using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) and direct solid sample analysis. The pyrolysis and vaporization temperatures were optimized and the measurements are accomplished with a platform coated with zirconium as a permanent chemical modifier in order to increase the sensitivity of the gaseous SrCl molecule generated in the graphite furnace. The optimum pyrolysis and vaporization temperatures were 700 °C and 2100 °C, respectively. Under optimized conditions, the limit of detection and characteristic mass of the method were 0.85 and 0.24 ng, respectively. The accuracy of the method has been verified using four certified reference materials and one not certified reference material of coal, and the results were in good agreement with the certified or reference values.