Population-based Study On Detection Of Phthalates In Human Serum By Gas Chromatography

ObjectivePhthalic acid esters, PAEs for short, are a kind of plasticizers and softeners widely used inthe industry. It has great significance to carry on biological monitoring for PAEs. There are manypretreatment methods, such as liquid-liquid extraction (LLE), solid phase extraction (SPE),solid-phase microextraction (SPME), enzymolysis and solid phase extraction after enzymolysis;and many determination methods, such as gas chromatography (GC), gas chromatography-mass spectrography (GC-MS), high performance Liquid chromatography (HPLC), Liquidchromatography-mass spectrography (LC-MS). In our country, this research is still in its infancy.The purpose of the present study was to set a method for determination of DBP and DEHP inserum and provide supports in the technology for the next research of bio-exposure limits ofserous DBP、DEHP.MethodTo minimize the interference of impurities and increase the detection limits of the method,LLE and gas chromatograph method with FID detector was adopted to extract and separateDBP、DEHP from the serum for qualitative and quantitative analysis. Pursuant to demands ofGuide for Establishing Occupational Health Standards, the best determination conditions of LLEand GC were tested and chosen, and then the performance of each indicator was assessed anddiscussed for the established method. This method was used to compare the effect of serumpreservation between EP tube and centrifuge glass tube.ResultsAs pretreatment,1.0mL of serum and1ml n-hexane were put into a centrifuge glass tube of10mL and vortexed. The mixture was centrifuged at3000r/min for40minutes to collectedthe organic phase and the aqueous phase was extracted twice again with n-hexane. The combinedorganic phase was evaporated completely by90℃(20min) and the residue was redissolved in1.0mL n-hexane. The column temperature was kept at100℃for2min and then increased at50℃/min to260℃and then increased at3℃/min to270℃and then increased at10℃/min to300℃for5min. The regression equations of standard curves of the method was satisfactory with Y ＝1467.9X+581.18and Y＝1478.2X+541.49(r=0.9996and r=0.9993) in the concentrationrange from0.10mg/L to10.0mg/L for DBP and DEHP separately. The lowest detectableconcentration was0.10mg/L and0.08mg/L for DBP and DEHP separately. The results showedthat, for DBP and DEHP, the recovery percentages range at three levels of concentration were96.76%～104.99%and94.78%～99.91%, respectively. The relative standard deviation (RSD)which expressed the precision for inter-and intra-day, were DBP：3.05%～4.81%and3.23%～6.50%，DEHP：2.40%～3.63%and2.93%～8.67%. Stability test found that serum samples werestable for at least14days when stored at4℃and-20℃. The result showed that the differencebetween EP tube and centrifuge glass tube has no statistical significance(P>0.05).126serumsamples from TianYou hospital were detect by the established method, the result showed that therelevance ratios of DBP and DEHP were5.6%and15.1%while the concentration ranges wereND～3.58mg/L and ND～13.52mg/L and means were0.105mg/L and0.386mg/Lrespectively.ConclusionThe LLE—GC method built in this study was simple and easy of use with good precisionfor determination of DBP and DEHP. The accuracy of the method can be improved if GC—MSwas used. EP tube can be used to substituted for glass tube at4℃or-20℃in2weeks.