Optimization of a NH4PF6-enhanced, non-organic solvent, dual microextraction method for determination of phthalate metabolites in urine by high performance liquid chromatography

An eco-friendly sample preparation procedure based on air-assisted liquid-liquid microextraction for the rapid determination of phthalate metabolites in urine samples by liquid chromatography-tandem mass spectrometry

Urinary phthalate metabolite (mPAEs) analysis is a reliable tool for assessing human exposure to phthalates. With growing interest in urinary biomonitoring of these metabolites, there is a need for fast and sensitive analytical methods. Therefore, a simple, rapid procedure for simultaneous determination of fifteen phthalate metabolites in human urine samples by liquid chromatography-tandem mass spectrometry was developed. The novelty of the present procedure is based on the use of diethyl carbonate as a green biobased extraction solvent and air-assisted liquid-liquid microextraction (AALLME) as a sample preparation step. A Plackett-Burman design was used for screening the factors that influence the AALLME extraction efficiency of mPAEs. The effective factors were then optimized by response surface methodology using a central composite rotatable design. Under the optimized conditions, good linearity can be achieved in a concentration range of 1.0-20.0 ng mL-1 with correlation coefficients higher than 0.99. The repeatability and reproducibility precision were in the range of 2-12% and 1-10% respectively. Recoveries ranging from 90% to 110%. This, and the low limits of detection, ranging from 0.01 to 0.05 ng mL-1, make the proposed procedure sensitive and suitable for human biomonitoring of phthalate exposures. For proof-of-principle, the new method was used to measure the urinary concentrations of mPAEs in 20 urine samples from Brazilian women. The high frequency of detections and in part high concentrations of mPAEs indicate to widespread exposure to several phthalates among Brazilian women.

A critical review on human internal exposure of phthalate metabolites and the associated health risks

Phthalates (PAEs) are popular synthetic chemicals used as plasticizers and solvents for various products, such as polyvinyl chloride or personal care products. Human exposure to PAEs is associated with various diseases, resulting in PAE biomonitoring in humans. Inhalation, dietary ingestion, and dermal absorption are the major human exposure routes. However, estimating the actual exposure dose of PAEs via an external route is difficult. As a result, estimation by internal exposure has become the popular analytical methods to determine the concentrations of phthalate metabolites (mPAEs) in human matrices (such as urine, serum, breast milk, hair, and nails). The various exposure sources and patterns result in different composition profiles of PAEs in biomatrices, which vary from country to country. Nevertheless, the mPAEs of diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), and di-(2-ethylhexyl) phthalate (DEHP) are predominant in the urine. These mPAEs have greater potential health risks for humans. Children have been observed to exhibit higher exposure risks to several mPAEs than adults. Besides age, other influencing factors for phthalate exposure are gender, jobs, and residential areas. Although many studies have reported biological monitoring of PAEs, only a few reviews that adequately summarized the reports are available. The current review appraised available studies on mPAE quantitation in human biomatrices and estimated the dose and health risks of phthalate exposure. While some countries lack biomonitoring data, some countries' data do not reflect the current PAE exposure. Thence, future studies should involve frequent PAE biomonitoring to accurately estimate human exposure to PAEs, which will contribute to health risk assessments of human exposure to PAEs. Such would aid the formulation of corresponding regulations and restrictions by the government.

A rapid method for the quantification of urinary phthalate monoesters: A new strategy for the assessment of the exposure to phthalate ester by solid-phase microextraction with gas chromatography and tandem mass spectrometry

In the following work, a new method for the analysis of the phthalate monoesters in human urine was reported. Phthalate monoesters are metabolites generated as a result of phthalate exposure. In compliance with the dictates of Green Analytical Chemistry, a rapid and simple protocol was developed and optimized for the quantification of phthalate monoesters (i.e., monoethyl phthalate, monoisobutyl phthalate, mono-n-butyl phthalate, mono-(2-ethylhexyl) phthalate, mono-n-octyl phthalate, monocyclohexyl phthalate, mono-isononyl phthalate) in human urine, which entails preceding derivatization with methyl chloroformate combined with the use of commercial solid phase microextraction and the analysis by gas chromatography-triple quadrupole mass spectrometry. The affinity of the derivatized analytes toward five commercial coatings was evaluated, and in terms of analyte extraction, the best results were reached with the use of the divinylbenzene/carboxen/polydimethylsiloxane fiber. The multivariate approach of experimental design was used to seek for the best working conditions of the derivatization reaction and the solid phase microextraction, thus obtaining the optimum response values. The proposed method was validated according to the guidelines issued by the Food and Drug Administration achieving satisfactory values in terms of linearity, sensitivity, matrix effect, intra- and inter-day accuracy, and precision.

Phthalate exposure in Thai children and adolescents

Background

Phthalates are found in products made of plastic. Because of concerns regarding the hazards of phthalate exposure, including endocrine disruption, many countries have regulations to restrict their use in products used by children. However, in Thailand, no such restrictions exist, and data relating to phthalate exposure are scarce.

Objectives

To determine the level of exposure of Thai children and adolescents to phthalates, and study its associations with sociodemographic data and the exposure to potential sources of phthalates.

Methods

Healthy children aged 2–18 y were enrolled into the present cross-sectional study between January 2016 and December 2016 inclusive. Their anthropometric indices and Tanner staging were determined. Urinary concentrations of the phthalate metabolites, monomethyl phthalate (MMP) and mono-n-butyl phthalate (MBP), were determined in spot samples by high-performance liquid chromatography to estimate the level of phthalate exposure. Associations between sociodemographic data, exposure to potential sources of phthalates, and phthalate metabolite concentrations were analyzed.

Results

We included 103 boys and 118 girls with a mean age of 9.4 ± 3.64 (range 2.8–17.1) y and detected MMP in 28.5% and MBP in 88.6%. The geometric means (interquartile range) of urinary MMP and MBP were 3400 (2489, 4642) and 214.4 (164, 279) μg/g creatinine (Cr), respectively. Significant associations were found between exposure to floor cleaning products and Cr-adjusted urinary MMP level (P < 0.05), and paint and Cr-adjusted urinary MMP and MBP levels (P < 0.05). Prepuberty was significantly associated with urinary Cr-adjusted MMP level.

Conclusion

Urinary phthalate metabolite levels were high in a proportion of Thai children and adolescents. Exposure to floor cleaning products and paint is associated with phthalate exposure, and advanced Tanner stage is negatively associated with urinary Cr-adjusted MBP.

Higher phthalate concentrations are associated with precocious puberty in normal weight Thai girls

BACKGROUND

The cause of precocious puberty may be associated with genetics and other conditions such as central nervous system (CNS) insults, or the exposure to endocrine disrupting chemicals (EDCs). Phthalates is known to be one of the EDCs and have estrogenic and antiandrogenic activities, and may be associated with advanced puberty. The objective of the study was to determine the association between urinary phthalate metabolites and advanced puberty.

METHODS

A cross-sectional study was conducted in patients with precocious puberty (breast onset <8 years, n=42) and early puberty (breast onset 8-9 years, n=17), compared to age-matched controls (n=77). Anthropometric measurements, estradiol, basal and gonadotropin releasing hormone (GnRH)-stimulated follicle stimulating hormone (FSH) and luteinizing hormone (LH) levels, uterine sizes, ovarian diameters and bone ages (BA) were obtained. Urine samples were collected and mono-methyl phthalate (MMP) and mono-ethyl phthalate (MEP) were analyzed by high performance liquid chromatography (HPLC) and adjusted with urine creatinine.

RESULTS

The median adjusted-MEP concentration in girls with precocious puberty, was greater than in normal girls (6105.09 vs. 4633.98 μg/g Cr: p<0.05), and had the same trend among early puberty and normal puberty (5141.41 vs. 4633.98 μg/g Cr: p=0.4), but was not statistically significant.

CONCLUSIONS

Precocious puberty girls had an association with increased MEP concentration. This is the first report of the association between urinary phthalate levels and precocious puberty in Thai girls.