Determination Of Parabens In Personal Care Products And Its Application For Human Exposure Assessment

Parabens(PBs)are widely used in many fieds,such as personal care products(PCPs),food,pharmaceuticals,etc.due to their low toxicity,low cost and excellent anti-corrosion and anti-mildew properties.In the past,these chemicals were considered as safe and effective antiseptic antibacterial agents.The results from recent literatures indciated that PBs can be found in many environmental and biological samples,which exhibit reproductive toxicity,developmental toxicity and estrogen active.Therefore,it is necessary to determine parabens in environmental samples and then to assess human exposure level.(1)In general,PCPs are the main pathway to expose PBs.However,it is difficult to completely remove the sample matrix by the common sample pretreatment technology.Residuce of matrix decrease the sensitivity of analytical method and increase the damage.Molecular imprinted polymer is an artificial receptor made by imprinting molecules of a template in a polymer matrix followed by removing the template molecules via thorough washing to give the permanent template grooves.They show favored affinity to the template molecule compared to other molecules,and this property is the basic driving force for such diverse application of this techniques.(2)Due to the short metabolic time,the variation of PBs contents in the randomly collected urine is high.There is a significant difference in the estimate does between external exposure and internal exposure of parabens.This has led to an interest in developing a simultaneous and high-precision study in the environmental monitoring of parabens and human exposure,based on the Chinese young adult population.Based on this,the study is divided into two parts:Part ?: Determination of parabens in personal care products using molecularly imprinted polymers open-tubular columnObjective: In this study,a coiled molecularly imprinted open-tubular column was prepared to selectively determine PBs and decrease matrix interference.Then,it was used as extraction device to directly extract parabens in PCPs and develop an efficient analytical method.Methods: In this study,molecularly imprinted polymer(MIPs)was prepared using ethylparaben as a template and methacrylic acid/isobutyl vinyl ether(mol/mol,1/1)as functional monomers.Then,the epoxy group was modified on the surface of the MIPs using glycidyl methacrylate as a monomer.In addition,dopamine self-polymerization was applied to modify the hydroxyl group on the internal surface of Teflon tube.Amino groups were grafted on the tube using silylating reagent and polyethyleneimine.Finally,MIPs were grafted on the internal surface of Teflon tube to develop a coiled molecularly imprinted open-tubular column.The characterizations of materails and the recognition mechanism were studied.The performance of this open-tubular column was evaluated by adsorption capacity,adsorption kinetics and extraction efficiency.Finally,an efficient analytical method was developed to determine PBs in different types of PCPs samples.Results: MIPs have been successfully prepared and modified on the internal surface of Teflon tubes.The molecularly imprinted open-tubular column showed superior selective recognition ability to PBs.The adsorption equilibrium was obtained within 35 minutes.The maximum adsorption capacity was 74 mg/g and the imprinting factor was 2.07.Under the optimal conditions,the PBs in PCPs can be directly extracted from the complex samples,and the enrichment factor reached 126-168.The linear range was 0.5-600 ?g/L and the limit of detection was 0.2-0.3?g/L.The results indicated that the performance of molecularly imprinted open-tubular column was better than the standard method.Most of creams,lotions,toners,and body washes samples have methylparaben and propylparaben,and the level of methylparaben was higher than that of propylparaben.Conclution: Coiled molecularly imprinted open-tubular column showed high selectivity and recognition ability for PBs.A novel approach was developed to directly extract PBs from the complex PCP samples with excellent purification and high enrichment effects.Part ?: Urinary concentrations of parabens in Chinese young female adults: implications for human exposureObjective: The pathways and information of exposure by the young female adults to parabens were investigated in detail.It is used to estimate the external exposure doses and draw the whole picture for human exposure to parabens.Methods: Based on the results of part I,two types of skin care products were identified and applied to the three-stage population study(days 1-7,low-dose skin care products exposure period;days 8-14,high-dose skin care products exposure period;day 15-21,low-dose exposure period exposure period).Urine samples(24h)of 10 young women(n=1260)were collected each day,and the information of collection time,volume and specific gravity were recorded.The concentrations of PBs in skin care products samples(n=9),dietary samples(n=287),dust samples(n=9),atmospheric samples(n=6),and tap water samples(n=9)were detected on the 6th,10 th and 17 th days.Concentrations of PBs were determined in the urine samples and the corresponding environmental samples.Results: High contents of methylparaben,ethylparabens and propylparaben were found in dietary samples and the contribution rate of vegetables,staple food,snacks and dairy products were 48.3%,14.2%,15.5% and 8.8%,respectively.There were no significant difference in dietary exposure duting the three days.The average daily dose of young female adults was largely attributed to skin care products exposure(88-98%)and dietary food(1-12%).The levels of PBs in the dust and atmospheric samples were expected to be very low.The concentration of PBs in urinary samples collected from the high-dose exposure period was significantly higher than that from the low-dose exposure period(P<0.05).However,the exposure level of PBs in China were much lower than those from other countries.Temporal variability of the urinary concentration of PBs showed an obvious change with time.Conclusion: PCPs was the most important pathway and was greater than exposure by food ingestion.The concentrations of PBs in Chinese young female adults were much lower than those in other countries.The high variability observed in the urinary levels suggested that a single measurement provides only a brief snapshot in time of the exposure levels of an individual.