Fig. 6: Representative chromatograms of the benzene polycarboxylic acids (BPCAs) derived from Chang’E 5 lunar soil samples measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS).

The chromatograms (mass-to-charge ratio: 44) are for direct LC-IRMS measurement of BPCAs extracts (A) and its corresponding blank sample (B); as well as for LC-IRMS measurement of B6CA and B5CA isolated from the BPCAs extracts of lunar soil samples with preparative liquid chromatography (prep-LC) (C, D).