Metabolite identification of DPHP and DINCH for exposure marker discovery by signal mining algorithm with isotope tracing (SMAIT) and mass spectrometry

Abstract

Di-2(propylheptyl) phthalate (DPHP) and di(isononyl) cyclohexane-1 2-dicarboxylate (DINCH) are substitutes for some phthalates like di-(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl-phthalate (DINP) The increase of DPHP and DINCH consumption suggests a possible exposure of the general population Exposure of DPHP and DINCH can be estimated by measuring concentration of metabolites The aim of this study is to identify biological markers of DPHP and DINCH exposure by using high resolution mass spectrometry (HRMS) and signal mining algorithm with isotope tracing (SMAIT) in the in vitro samples and validate the exposure-related markers in a rat model In vitro DPHP and DINCH incubation samples wew incubated with human liver enzyme (S9 fraction) for 24 hours and solid phase extraction (SPE) was used to clean up and condense those samples Those samples were analyzed by HRMS and the SMAIT program was used to identify metabolite marker candidates from the HRMS data The 12 DPHP and 18 DINCH metabolite marker candidates in negative ion mode and 5 DPHP and 8 DINCH candidates in positive ion mode were identified by using SMAIT and validated by rat model The rats were divided into seven groups (N=3) and the 24-hour urine were collected after the rats orally administerated with different dose (0 75 150 300 600 1200 2400 mg/kg body weight) The results of rat model showed that the intensity of 15 DPHP (11 in negative and 5 in positive) and 16 DINCH (9 in negative and 8 in positive) metabolite candidates were positively correlated with increasing administrated dose (r ? 0 7 p ? 0 001) The more metabolite candidates can be identified by Mass Defect Filter (324 DPHP and 299 DINCH) than SMAIT Nevertheless the efficiency of identify exposure markers in SMAIT (92% for DPHP and 50% for DINCH) was better than MDF (7% for DPHP and DINCH) The result suggested that the 15 DPHP and 16 DINCH metabolite signals can be used as exposure markers of DPHP and DINCH

Date of Award	2016 Aug 11
Original language	English
Supervisor	Pao-Chi Liao (Supervisor)