Development of a SPE-HPLC-PDA Method for the Quantification of Phthalates in Bottled Water and Their Gene Expression Modulation in a Human Intestinal Cell Model

Phthalates are ubiquitous pollutants that are currently classified as endocrine disruptor chemicals causing serious health problems. As contaminants of food and beverages, they come into contact with the epithelium of the intestinal tract. In this work, a SPE-HPLC-PDA method for the determination of phthalates in water from plastic bottles was developed and validated according to the food and drug administration (FDA) guidelines. A chromatographic separation was achieved using a mobile phase consisting of ammonium acetate buffer 10 mM pH 5 (line A) and a mixture of methanol and iso-propanol (50:50 v/v, line B) using gradient elution. Several SPE cartridges and different pH values were investigated for this study, evaluating their performance as a function of recovery. Among these parameters, pH 5 combined with the SPE sep pack C18 cartridge showed the best performance. Finally, the proposed method was applied to the analysis of real samples, which confirmed the presence of phthalates. A colonic epithelial cell model was used to evaluate the effects of these phthalates at the concentrations found in water from plastic bottles. In cells exposed to phthalates, the increased expression of factors, which control the signaling pathways necessary for intestinal epithelium homeostasis, inflammatory response, and stress was detected. The proposed method falls fully within the limits imposed by the guidelines with precision (RSD%) below 7.1% and accuracy (BIAS%) within −4.2 and +6.1.

High-sensitivity photo-electrochemical heterostructure of the cuprous oxide-metal organic framework for a dioctyl phthalate molecularly imprinted sensor

This work designed a novel dioctyl phthalate (DOP) photoelectrochemical (PEC) sensor based on a molecularly imprinted polymer (MIP) modified Cu₃(BTC)₂@Cu₂O heterostructure. In this work, a metal organic framework (MOF), Cu₃(BTC)₂, was coated on Cu₂O through a simple immersion method to form a Cu₃(BTC)₂@Cu₂O heterostructure. The heterostructure exhibited strong light adsorption ability, good stability and enhanced photocurrent under visible light irradiation. Using the Cu₃(BTC)₂@Cu₂O heterostructure as the photoelectric converter, a PEC sensor was constructed by imprinting DOP on the heterostructure. Under the optimal experimental conditions, the PEC sensor showed a wide linear range from 25.0 pM-0.1 μM and a low detection limit of 9.15 pM. This method with good sensitivity, stability, selectivity and reproducibility in actual sample analyses showed promising applications of the MOF-based heterostructure in photoelectrochemical analysis fields.

Novel strategy for disposable pipette extraction (DPX): Low-cost Parallel-DPX for determination of phthalate migration from common plastic materials to saliva simulant with GC-MS

In widespread use in commercial products as plasticizers, phthalic acid esters (phthalates) have worried researchers and society in general, given the negative impacts on living organisms, especially human health. Since they are not chemically linked to the polymeric matrix, their migration is evident for samples that come into contact with plastics that contain them, such as water, food and saliva. In this work, a new strategy is described, named parallel-disposable pipette extraction (Pa-DPX), in a fast, efficient and robust analytical method using five simultaneous extractions for the determination of migration of 6 phthalates from common plastic materials (children's toys, school supplies, dog toys and oral contact items) to saliva simulant, using gas chromatography-mass spectrometry (GC-MS). The optimized conditions were 5 extraction cycles with 1600 μL of saliva simulant and desorption with 200 μL of ethyl acetate using 5 cycles with the same aliquot. The calibration curves resulted in determination coefficients higher than 0.9915, limits of detection at 1.5 μg L^-1, and the quantification limits were 5.0 μg L^-1. Excellent results were obtained for repeatability (relative standard deviation ranging from 8.7% to 20.1% for 5 μg L^-1) and intermediate precision, varying the day of analyses (7.9%-16.2%). The analyte recovery ranged from 75% to 114% for two different samples, in four different levels of concentration. The Pa-DPX-GC-MS method was successfully applied to determine the migration of PAE from 21 samples. At least one PAE was detected in 81% of samples, and di-n-octyl phthalate was found in higher concentration, achieving the migration of almost 30 μg per g of sample.

Magnetic Graphene Dispersive Solid-Phase Extraction for the Determination of Phthalic Acid Esters in Flavoring Essences by Gas Chromatography Tandem Mass Spectrometry

In the present study, a sensitive, efficient and repeatable method for the simultaneous extraction and determination of 13 types of phthalic acid esters (PAEs) in flavoring essence samples using magnetic graphene solid-phase extraction coupled with gas chromatography tandem mass spectrometry was developed. Due to the unique structure of magnetic graphene, it has several advantages, such as large surface area and fast separation ability. This unique structure not only provided strong magnetic responsiveness for the separation but also prevented the self-aggregation of graphene. The large delocalized p-electron system of graphene can form strong π-stacking interactions with the benzene ring. Thus, graphene may be also a good candidate adsorbent for the adsorption of benzenoid-form compounds. Several magnetic soild-phase extraction parameters, such as elution solvents, amounts of sorbents, enrichment time and desorption time were optimized. The optimized procedures for this method were performed by ultrasonication using ethyl acetate as elution solvent for 5 min. Under the optimal conditions, the developed method provided spiked recoveries of 75.0–105.3% with relative standard deviations of ~5.6% and limits of detection were 0.011–0.091 mg/kg. Good linear relationships were observed with the coefficient of determination (R2) > 0.993 for all the analytes. Finally, the validated method was successfully applied to the analysis of PAEs in real samples.

In situ construction of metal–organic framework (MOF) UiO-66 film on Parylene-patterned resonant microcantilever for trace organophosphorus molecules detection

UiO-66 film is directly grown on the sensing area of a resonant microcantilever for toxic organophosphorus molecules detection.

Distribution and contamination status of phthalic acid esters in the sediments of a tropical monsoonal estuary, Cochin - India

Phthalic acid esters (PAEs) are a group of endocrine-disrupting chemicals listed as priority pollutants by United States Environmental Protection Agency (USEPA, 2009). This study provides baseline information on seasonal distribution and contamination status of six phthalic acid esters (∑₆PAEs) in sediments of a tropical estuary (Cochin-India). In general, the sediments accumulated more PAEs during the post monsoon (mean 2325 ngg^-1; between 1402 and 3121 ngg^-1) and monsoon (mean 1372 ngg^-1; between 331 and 4015 ngg^-1) periods indicating land run off as the major transport pathway. Moderate run off and comparatively high residence time lead to effective sorption and settling of PAEs in the surface sediments during post monsoon season. Despite a high discharge of PAEs in to the water column, their deposition on to the sediments occurs at a lower rate during monsoon than that post monsoon season. PAEs were (mean 810 ngg^-1; between 44 and 1722 ngg^-1) lowest in pre monsoon season. The pre monsoon season is characterized by a minimal runoff consequent to the trapping of these organic pollutants in the river catchment area. The mid and high molecular PAEs (DEHP-Di ethylhexyl phthalate, BBP-Benzyl butyl phthalate and DnBP-Di-n-butyl phthalate) were the dominant congeners relative to the low molecular weight congeners (DMP-Dimethyl phthalate and DEP-Diethyl phthalate). DEHP and BBP levels exceeded permissible risk levels indicating a serious ecological hazard to the estuarine ecosystem.

Determination of phthalate esters in seawater of Chabahar Bay using dispersive liquid-liquid microextraction coupled with GC-FID

Phthalate esters (PEs), a group of environmental pollutants which are possibly carcinogenic to humans, have been detected in seawater. Seven PEs in seawater were quantitatively determined by using gas-chromatography flame ionizing detection after executing dispersive liquid-liquid microextraction. The suggested method is optimized for microextraction and determination of PEs in artificial sea water. Factors affecting the microextraction procedure such as the type and volume of extracting and dispersive solvents (carbon tetrachloride, 20 μL; methanol, 0.5 mL), extraction time and pH (7) were investigated. Under optimum conditions, the limit of detection of the analytes were obtained between 0.04 and 4.52 μg·L^-1, and linearity and linear range were of 0.999 ≥ R² ≥ 0.994 and 10-560 μg·L^-1 respectively. Enrichment factors were found in the range of 761-827 fold, while the relative standard deviations of the analytes were between 0.17 and 7.5% (n = 6) for real sea water samples. Using this method, total PEs content of seawater from several locations in Chabahar Bay (the southeast part of Iran) was estimated 2.33-90.45 μg·L^-1.

Sensitive Detection of Organophosphorus Pesticides in Medicinal Plants Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with Sweeping Micellar Electrokinetic Chromatography

A simple, rapid, and sensitive method using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) combined with sweeping micellar electrokinetic chromatography (sweeping-MEKC) has been developed for the determination of nine organophosphorus pesticides (chlorfenvinphos, parathion, quinalphos, fenitrothion, azinphos-ethyl, parathion-methyl, fensulfothion, methidathion, and paraoxon). The important parameters that affect the UA-DLLME and sweeping efficiency were investigated. Under the optimized conditions, the proposed method provided 779.0-6203.5-fold enrichment of the nine pesticides compared to the normal MEKC method. The limits of detection ranged from 0.002 to 0.008 mg kg(-1). The relative standard deviations of the peak area ranged from 1.2 to 6.5%, indicating the good repeatability of the method. Finally, the developed UA-DLLME-sweeping-MEKC method has been successfully applied to the analysis of the investigated pesticides in several medicinal plants, including Lycium chinense, Dioscorea opposite, Codonopsis pilosula, and Panax ginseng, indicating that this method is suitable for the determination of trace pesticide residues in real samples with complex matrices.

Development of an air-flow-assisted extractive electrospray ionization source for rapid analysis of phthalic acid esters in spirits

RATIONALE

Although traditional analytical techniques like gas chromatography (GC) and GC/mass spectrometry (MS) offer satisfactory sensitivity and good reproducibility for the detection of phthalic acid esters (PAEs) in a variety of matrices, they involve laborious sample pretreatment, are time-consuming, and some are expensive and environmentally unfriendly. Furthermore, there are thousands of spirits on the market; therefore, rapid and high-throughout methods suitable for the consistent detection and quantification of PAEs in spirits are urgently required.

METHODS

A new atmospheric pressure ionization method, named air-flow-assisted extractive electrospray ionization (EESI), has been developed. It is a variant on EESI and possesses the advantages of both EESI and air-flow-assisted ionization for direct analysis of samples without pretreatment. Combined with a quadrupole time-of-flight (QTOF) mass spectrometer, the method was used to directly analyze four PAEs, i.e., dipentyl phthalate, diethyl phthalate, benzyl butyl phthalate and didecyl phthalate, in spirits.

RESULTS

The method exhibits excellent sensitivity, stability and convenience. Four different brands of spirits have been successfully analyzed. The total analysis time for one sample was within 1 min, and the limits of detection and limits of quantification of the samples are located in the range 0.011-0.035 and 0.038-0.087 µg g(-1), respectively. Very good linearities, with correlation coefficients of 0.9758-0.9990, are observed for the samples in the range of 0.035 to 10 µg g(-1).

CONCLUSIONS

The results indicate that the air-flow-assisted EESI combined with tandem mass spectrometry is an effective method for rapid and direct determination of PAEs in spirits without sample pretreatment.

Sensitive liquid chromatography-tandem mass spectrometry method for the simultaneous determination of benzyl butyl phthalate and its metabolites, monobenzyl phthalate and monobutyl phthalate, in rat plasma, urine, and various tissues collected from a toxicokinetic study

This study describes the development of a sensitive liquid chromatography-electrospray-tandem mass spectrometry method for the simultaneous determination of benzyl butyl phthalate (BBP) and its major metabolites, monobenzyl phthalate (MBzP) and monobutyl phthalate (MBuP), in rat plasma, urine, and 10 different tissues. The method was validated with regard to the specificity, linearity, precision, accuracy, lower limit of quantification (LLOQ), recovery, and stability by using the matrix-matched quality control samples. The assay achieved LLOQ of 1 ng/ml of BBP for plasma and urine, 4 ng/g for kidney and liver, 10 ng/g for fat, and 20 ng/g for all other tissues. For MBzP and MBuP, the assay achieved LLOQ of 5 ng/ml for plasma and urine, 10 ng/g for fat, and 20 ng/g for all other tissues. The disposition of BBP was characterized by a large volume of distribution (71.1-82.9 l/kg) and a high clearance (838.7-871.0 ml/min/kg). It was extensively metabolized to MBzP and MBuP, with their levels consistently exceeding the BBP levels. The distribution of BBP, MBzP, and MBuP to tissues of kidney, liver, stomach, small intestine, large intestine, spleen, brain, testis, thyroid, and fat was determined under steady-state conditions. For BBP, the steady-state tissue-to-plasma partition coefficient (K p) was the highest for fat (25.0) followed by small intestine (2.6), thyroid (2.0), and stomach (1.1). In contrast, for MBzP and MBuP, it was the highest for kidney (2.0 and 4.3, respectively) and liver (4.3 and 2.1, respectively) but was less than unity for all other tissues. The developed assay method and findings of this study may be useful to evaluate the exposure and toxic potential of BBP and its metabolites in risk assessment.

Reliable quantification of phthalates in environmental matrices (air, water, sludge, sediment and soil): a review

Because of their widespread application, phthalates or phthalic acid esters (PAEs) are ubiquitous in the environment. Their presence has attracted considerable attention due to their potential impacts on ecosystem functioning and on public health, so their quantification has become a necessity. Various extraction procedures as well as gas/liquid chromatography and mass spectrometry detection techniques are found as suitable for reliable detection of such compounds. However, PAEs are ubiquitous in the laboratory environment including ambient air, reagents, sampling equipment, and various analytical devices, that induces difficult analysis of real samples with a low PAE background. Therefore, accurate PAE analysis in environmental matrices is a challenging task. This paper reviews the extensive literature data on the techniques for PAE quantification in natural media. Sampling, sample extraction/pretreatment and detection for quantifying PAEs in different environmental matrices (air, water, sludge, sediment and soil) have been reviewed and compared. The concept of "green analytical chemistry" for PAE determination is also discussed. Moreover useful information about the material preparation and the procedures of quality control and quality assurance are presented to overcome the problem of sample contamination and these encountered due to matrix effects in order to avoid overestimating PAE concentrations in the environment.

Extraction and GC-MS analysis of phthalate esters in food matrices: a review

According to the Scopus database, using “phthalate” and “GC” as keywords, 758 papers have been found between 1990 and 2014, showing strong and increasing interest in this class of compounds from the scientific community.

Ultra sound assisted one step rapid derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometric determination of amino acids in complex matrices

A rapid and economical method for the simultaneous determination of 20 amino acids in complex biological and food matrices (hair, urine and soybean seed samples) has been developed using ultrasound assisted dispersive liquid-liquid micro extraction (UA-DLLME). The method involves simultaneous derivatization and extraction followed by gas chromatography-mass spectrometric (GC-MS) analysis of amino acids. The parameters of UA-DLLME were optimized with the aid of design of experiments approach. The procedure involves the rapid injection of mixture of acetonitrile (disperser solvent), trichloroethylene (TCE) (extraction solvent) and ethylchloroformate (derivatization reagent) into the aqueous phase of sample extract containing pyridine. The Plackett-Burman design has indicated that, the factors such as volume of disperser and extraction solvents and pH were found to be significantly affects the extraction efficiency of the method. The optimum conditions of these factors based on central composite design were found to be 250μL of acetonitrile, 80μL of TCE and pH of 10. The limit of detection and limit of quantification were found to be in the range of 0.36-3.68μgL(-1) and 1.26-12.01μgL(-1) respectively. This is the first application of DLLME for the analysis of amino acids in any matrices. The advantages like (i) in situ derivatization and extraction of amino acids without any prior lyophilization and cleanup of sample, (ii) low consumption of extraction solvent, (iii) fast and simple, (iv) cost-effective and (iv) good repeatability make the method amenable for the routine analysis of amino acids in clinical, toxicological, nutritional and quality control laboratories.

Occurrence of thyroid hormone activities in drinking water from eastern China: contributions of phthalate esters

Thyroid hormone is essential for the development of humans. However, some synthetic chemicals with thyroid disrupting potentials are detectable in drinking water. This study investigated the presence of thyroid active chemicals and their toxicity potential in drinking water from five cities in eastern China by use of an in vitro CV-1 cell-based reporter gene assay. Waters were examined from several phases of drinking water processing, including source water, finished water from waterworks, tap water, and boiled tap water. To identify the responsible compounds, concentrations and toxic equivalents of a list of phthalate esters were quantitatively determined. None of the extracts exhibited thyroid receptor (TR) agonist activity. Most of the water samples exhibited TR antagonistic activities. None of the boiled water displayed the TR antagonistic activity. Dibutyl phthalate accounted for 84.0-98.1% of the antagonist equivalents in water sources, while diisobutyl phthalate, di-n-octyl phthalate and di-2-ethylhexyl phthalate also contributed. Approximately 90% of phthalate esters and TR antagonistic activities were removable by waterworks treatment processes, including filtration, coagulation, aerobic biodegradation, chlorination, and ozonation. Boiling water effectively removed phthalate esters from tap water. Thus, this process was recommended to local residents to reduce certain potential thyroid related risks through drinking water.