Analytical method for the sensitive determination of major di-(2-propylheptyl)-phthalate metabolites in human urine

Di-(2-propylheptyl)-phthalate (DPHP) is a specific phthalic acid ester of isomeric C10 alcohols. It is classified as high molecular weight phthalate and marketed as plasticizer for polyvinyl chloride (PVC). The increase of its production volume and its wide field of application suggest a possible background exposure of the human population as found for other phthalates, making suitable analytical methods necessary. The aim of the presented analytical report is the sensitive and selective determination of the three major DPHP metabolites mono-2-(propyl-6-hydroxy-heptyl)-phthalate (OH-MPHP), mono-2-(propyl-6-oxoheptyl)-phthalate (oxo-MPHP) and mono-2-(propyl-6-carboxy-hexyl)-phthalate (cx-MPHxP) in human urine. Most of the published analytical methods for phthalate metabolites use high pressure liquid chromatography tandem mass spectrometry (HPLC–MS/MS). The methods presented here allow a comparison of chromatographic separation between HPLC–MS/MS and gas chromatography high resolution mass spectrometry (GC–HRMS), which is useful to distinguish between DPHP and DIDP. The enhanced detection limits range between 0.05–0.1 μg/L for GC–HRMS and 0.1–0.2 μg/L for HPLC–MS/MS.