“…To deconjugate the DINP metabolites in the biofluid, most studies add enzymes in the pretreatment procedure. However, in hair extraction, few studies use enzymes in the extraction procedure (Takayama et al, 2003), and most do not add enzyme (Takayama et al, 2003;Miyaguchi et al, 2007Miyaguchi et al, , 2009Favretto et al, 2011;Li et al, 2012;Chang et al, 2013). Because extraction of DINP metabolites from hair has not been previously reported, we based our methodologies on procedures from earlier studies and modified them (Miyaguchi et al, 2007;Chang et al, 2013).…”