Fig. 4: UHPLC-CAD and UHPLC-HRMS chromatograms of the second organosulfate-containing fraction.

The HRMS chromatogram is the sum of the extracted ion chromatograms (EICs) of the organosulfate-specific ions HSO4−, HSO3−, SO4•− and SO3•− recorded in the all ion fragmentation (AIF) mode. This correlation is demonstrated by using results from the Handan 1 aerosol filter. Graph a shows the UHPLC-CAD chromatograms of the Handan ambient aerosol sample (black) and the ambient aerosol filter blank (orange), b the UHPLC-HRMS chromatograms of the Handan ambient aerosol sample (blue) and the ambient aerosol filter blank (pink), c correlation of the blank-subtracted OS concentration (determined by the external calibration of the UHPLC-CAD) and the UHPLC-HRMS signal of the OS-specific ions recorded in the AIF mode, and (d) same as (c), but with the mass spectrometric signal being divided by the methanol content to correct for the ionization efficiency. The peak numbering in (a, b) represents the eight spiked internal standards. The color bar of (c, d) shows the retention time (min).