Study On Preparation Of Magnetic Molecularly Imprinted Composite And Its Application In The Rapid Detection Of Diphenyl Phosphate In Urine Samples

Organophosphate flame retardants?OPFRs?are chemicals for reducing the flammability of numerous commercial products,including electronic products,building materials,home decorations,plastics and textiles,et al.Previous studies have demonstrated that OPFRs have some toxic effects,such as endocrine disruption,neurotoxicity,genotoxicity and carcinogenicity.Long-term exposure to plastics,furniture,electronics or even food containing OPFRs may result in the potential health risks to human beings.OPFRs have been detected with high frequency in different biological samples?such as urine,blood,human milk and hair?,therefore,the effective detection of trace OPFRs in biological samples is important in the field of environmental health.OPFRs metabolites in urine are biomarkers for the evaluation of human exposure to OPFRs.Diphenyl phosphate?DPHP?is one of the most often detected OPFRs metabolites in urine samples.Considering the complicated matrix and the low concentration of DPHP?generally at ng/mL level?in urine samples,it is necessary to build an effective pretreatment method for improving the sensitivity and accuracy of analytical method,which can provide the technical support for OPFRs exposure assessment.In this work,a kind of magnetic molecularly imprinted polymers?MMIPs?with specific recognition ability and high adsorption capacity for DPHP was synthesized as the new sorbent of magnetic solid-phase extraction?MSPE?,and then an ultrahigh-performanceliquidchromatography-tandemmassspectrometry?UPLC-MS/MS?system was employed for the rapid detection of trace DPHP in urine samples.The whole study is composed of the following three parts:Chapter I Preparation of magnetic molecularlyimprinted composite and its adsorption performance fordiphenyl phosphateObjective:We prospectively prepared the MMIPs composite with specific recognition ability and high adsorption capacity for DPHP and the adsorption properties of the MMIPs composite were evaluated.Methods:Fe₃O₄ nanoparticles?Fe₃O₄ NPs?with good dispersion and super magnetism were prepared.Sol-gel method was used to synthesize MMIPs on the surface of Fe₃O₄NPs with dibenzyl phosphate?DBHP?as dummy template,3-Aminopropyl triethoxysilane?APTES?as functional monomer,Tetramethoxysilane?TEOS?as cross-linker,ammonia as catalyst,respectively.MMIPs showed specific recognition ability and high adsorption capacity for DPHP.The materials were characterized by scanning electron microscopy,transmission electron microscope,infrared spectroscopy,hysteresis loops and X-ray diffraction.The absorption properties were evaluated with static,dynamic and selective adsorption experiments.Results:The results obtained demonstrated the successful preparation of MMIPs.The maximum adsorption capacity of MMIPs and magnetic non-imprinted polymers?MNIPs?for DPHP fitted by scatchard model were 311.09 mg/g and 17.13 mg/g,respectively.The imprinting factor?IF?was 5.47.The adsorption of DPHP on MMIPs can reach equilibrium in 30 minutes and MMIPs had good selectivity for DPHP.Conclusions:The MMIPs composite is successfully synthesized with specific recognition ability and high adsorption capacity for DPHP,and it has the potential as a novel sorbent for the separation and enrichment of trace DPHP in urine samples.Chapter?Rapid detection of diphenyl phosphate in urine samples by magnetic solid-phase extraction coupled with ultrahigh-performance liquid chromatography–tandem massspectrometryObjective:Using MMIPs prepared as the sorbent,a rapid,convenient and effective MSPE procedure was established for the selective separation and enrichment of DPHP,and then UPLC-MS/MS system was employed for the rapid detection of trace DPHP in urine samples.Methods:The MSPE method was established to purify DPHP from urine samples with MMIPs as the sorbent,under the optimized mass of sorbent,pH of loading solution,eluting solution,extraction time and eluting time conditions.Then,MSPE coupled with UPLC-MS/MS?MSPE-UPLC-MS/MS?method was established for the efficient extraction and rapid detection of trace DPHP in urine samples.Results:Under the optimized conditions of MSPE,the linear range of this method for DPHP in urine samples was ranged from 0.1 to 50 ng/mL,with the limit of detection?LOD?of 0.035 ng/mL.The spiked recovery was 85.8%-108.9%and the relative standard deviation?RSD?was 5.1%-13.3%.Conclusions:The proposed MSPE-UPLC-MS/MS method is simple,rapid,sensitive and selective,which can be used for the efficient extraction and rapid detection of trace DPHP in urine samples.Chapter?Investigation of the levels of urinary diphenylphosphate among university studentsObjective:The study aimed to evaluate urinary DPHP levels among college students,analyze their influencing factors and investigate the variability of DPHP levels in spot and first morning urine collections over the whole sampling period,which could provide scientific basis for human exposure assessment to OPFRs.Methods:30 college students?15 males,15 females?were selected as survey subjects,and 300 urine samples for 5 consecutive days were collected.Urinary levels of DPHP were measured by the establish MSPE-UPLC-MS/MS technique.The intraclass correlation coefficient?ICC?was calculated to assess the reproducibility of DPHP measurements in spot and first morning urine collections.The students were surveyed with questionnaires,which included by demographic indicators?sex,weight and height?,lifestyles,dietary habits and other information.The influencing factors of urinary DPHP levels were analyzed by univariate analysis and linear regression model.Results:The level of urinary DPHP adjusted by creatinine in females was relatively high,with the median of 0.61?g/g Cr,the geometric mean of 0.69?g/g Cr,the concentration range of 0.43-3.33?g/g Cr.The median and geometric mean of urinary DPHP in males were 0.54?g/g Cr and 0.56?g/g Cr,relatively,with the concentration range of 0.38-1.36?g/g Cr.Moderate reproducibility was observed for the serial measurements of DPHP in first morning urines?ICC>0.40?,whereas the serial measurements of DPHP in spot urines showed poor reproducibility?ICC<0.40?.The results of univariate analysis and linear regression model showed that there was a significant correlation between urinary levels of DPHP and variable factors,such as gender??=0.72;95%CI:0.48⁰.96?,sampling time??=0.36;95%CI:0.08⁰.65?and frequency for take-out food??=0.45;95%CI:0.07⁰.74?.Conclusions:College students are generally exposed to OPFRs in daily life,and the levels of urinary DPHP among college students were relatively high,which could be related to their unhealthy lifestyles and dietary habits...