Statistical comparison for assessing agreement between two mass spectrometric methods for the analysis of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs) in contaminated soils

A gas chromatography coupled to high-resolution mass spectrometry (GC-HR/MS) has been used as the standard method for the quantification of polychlorinated dibenzo-p-dioxins and furans (PCDDs/Fs), which are regulated at screening and action levels in the environment. However, several alternative methods have been attempted due to the disadvantage of its high cost. Although a gas chromatography with triple quadrupole mass spectrometry (GC-QqQ-MS/MS) has been used in a wide variety of sample matrices, showing that they are interchangeable, there has been a lack of comprehensive studies on statistical agreement with GC-HR/MS. In this study, a pairwise comparison of the total concentrations of PCDDs/Fs in 90 soil field samples obtained by two mass spectrometric methods was performed using the Passing-Bablok (P&B) regression and Bland-Altman (B&A) analysis for the method comparison. According to the result of the B&A analysis, the concentration range of PCDDs/Fs was between 98.2 and 1760 pg/g showed good agreement between two methods at the 95 % confidence level (CL). Although there was a large discrepancy between the two methods in the low concentrations (<16.5 pg/g of PCDDs/Fs), this result was similar to the P&B regression analysis. As the verification results by B&A and P&B regression analysis, the interchangeable concentration range between the two methods was confirmed to be adequate for the monitoring of PCDDs/Fs regulating levels in soils.