Determination of trace hydroxyl polycyclic aromatic hydrocarbons in urine using graphene oxide incorporated monolith solid-phase extraction coupled with LC-MS/MS

Determination of hydroxypolycyclic aromatic hydrocarbons in urine by electromembrane extraction coupled with liquid chromatography

Polycyclic aromatic hydrocarbons (PAHs) have been classified as the earliest discovered class of environmental carcinogens, seriously endangering human health and ecological safety, and the hydroxylpolycyclic aromatic hydrocarbons (OH-PAHs) in human urine are considered as the main biomarkers to evaluate the exposure levels of PAHs in human body. Therefore, it is necessary to develop an accurate and sensitive method for the determination of urinary OH-PAHs. Herein, we proposed electromembrane extraction (EME) as a simple, effective and ecofriendly sample pretreatment technique for selective extraction, purification and enrichment of four typical OH-PAHs (2-naphthol, 2- and 3-phenanthrol, 2-hydroxyfluorene) in human urine for the first time. Under the optimum conditions, an analytical method of EME coupled with HPLC was established, which provided wide linear ranges for four OH-PAHs from 1 to 500 ng mL-1 with low LODs of 0.05-0.3 ng mL-1. The average recoveries of four OH-PAHs at three spiked levels in human urine were 81.6-102.5% with RSDs all below 9.4%. The present method has been successfully applied for the sensitive determination of trace four OH-PAHs in urine samples from non-smokers and smokers with a maximum concentration of 2.24 and 3.56 ng mL-1, respectively, which showed a great potential for the analysis of trace OH-PAHs in biological samples.

Surface molecularly imprinted polymers based on magnetic multi-walled carbon nanotubes for the highly selective purification of resveratrol from crude extracts of Vitis vinifera, Arachis hypogaea, and Polygonum cuspidatum

In this work, surface molecularly imprinted polymers based on magnetic multi-walled carbon nanotubes were prepared for the specific recognition and adsorption of resveratrol. The functionalization of magnetic multi-walled carbon nanotubes and the synthesis process of surface molecularly imprinted polymers were optimized. Characterizations were performed to demonstrate the successful synthesis of the imprinted materials. The imprinted materials showed satisfactory adsorption capacity of resveratrol (45.73 ± 1.72 mg/g) and excellent selectivity (imprinting factor 2.89 ± 0.15). In addition, the imprinted materials were used as adsorbents in molecularly imprinted solid-phase extraction for the purification of resveratrol from crude extracts of some food and medicinal resources, achieving recoveries of 93.69%-95.53% with high purities of 88.37%-92.33%. Moreover, the purified products exhibited extremely strong free radical scavenging activity compared with crude extracts. Overall, this work provided a promising approach for the highly selective purification of resveratrol from natural resources, which would contribute to the application of this valuable compound in the food/nutraceutical fields.

Characterization of the internal working-life exposome using minimally and non-invasive sampling methods - a narrative review

During recent years, we are moving away from the 'one exposure, one disease'-approach in occupational settings and towards a more comprehensive approach, taking into account the totality of exposures during a life course by using an exposome approach. Taking an exposome approach however is accompanied by many challenges, one of which, for example, relates to the collection of biological samples. Methods used for sample collection in occupational exposome studies should ideally be minimally invasive, while at the same time sensitive, and enable meaningful repeated sampling in a large population and over a longer time period. This might be hampered in specific situations e.g., people working in remote areas, during pandemics or with flexible work hours. In these situations, using self-sampling techniques might offer a solution. Therefore, our aim was to identify existing self-sampling techniques and to evaluate the applicability of these techniques in an occupational exposome context by conducting a literature review. We here present an overview of current self-sampling methodologies used to characterize the internal exposome. In addition, the use of different biological matrices was evaluated and subdivided based on their level of invasiveness and applicability in an occupational exposome context. In conclusion, this review and the overview of self-sampling techniques presented herein can serve as a guide in the design of future (occupational) exposome studies while circumventing sample collection challenges associated with exposome studies.

Monitoring of hydroxylated polycyclic aromatic hydrocarbons in human tissues: Targeted and untargeted approaches using liquid chromatography-high resolution mass spectrometry

Hydroxylated polycyclic aromatic hydrocarbons are metabolites of persistent organic pollutants which are formed during the bioactivation process of biological matrices and whose toxicity is being studied. The aim of this work was the development of a novel analytical method for the determination of these metabolites in human tissues, known to have bioaccumulated their parent compounds. Samples were treated by salting-out assisted liquid-liquid extraction and the extracts were analyzed by ultra-high performance liquid chromatography coupled to mass spectrometry with a hybrid quadrupole-time-of-flight analyzer. The proposed method achieved limits of detection in the 0.15-9.0 ng/g range for the five target analytes (1-hydroxynaphthalene, 1-hydroxypyrene, 2-hydroxynaphthalene, 7-hydroxybenzo[a]pyrene, and 9-hydroxyphenanthrene). The quantification was achieved by matrix-matched calibration using 2,2´-biphenol as internal standard. For all compounds, relative standard deviation, calculated for six successive analyses, was below 12.1%, demonstrating good precision for the developed method. None of the target compounds was detected in the 34 studied samples. Moreover, an untargeted approach was applied to study the presence of other metabolites in the samples, as well as their conjugated forms and related compounds. For this objective, a homemade mass spectrometry database covering 81 compounds was created and none of them was detected in the samples.

Application of a novel nylon needle filter-based solid-phase extraction device to determination of 1-hydroxypyrene in urine

In this work, a simple and miniaturized solid-phase extraction device was constructed by connecting a commercial nylon needle filter to a syringe, which was applied for extracting 1-hydroxypyrene from urine sample via hydrophobic and hydrogen bond interactions. The nylon membrane in the needle filter acted as the solid-phase extraction adsorbent, meanwhile, it filtered the particles in the urine sample. To obtain high extraction efficiency, key parameters influencing extraction recovery were investigated. The entire pretreatment process was accomplished within 5 min under the optimal conditions. By coupling HPLC-UV, a rapid, low-cost, and convenient nylon needle filter-based method was established for the analysis of 1-hydroxypyrene in complex urine matrix. Within the linearity range of 0.2-1000 μg/L, the method exhibited a satisfactory correlation coefficient (R = 0.9999). The limit of detection was 0.06 μg/L, and the recoveries from urine sample spiked with three concentrations (5, 20, and 100 μg/L) ranged from 105.8% to 113.1% with the relative standard deviations less than 6.7% (intra-day, n = 6) and 8.9% (inter-day, n = 4). Finally, the proposed method was successfully applied for detecting 1-hydroxypyrene in urine samples from college students, smokers, gas station workers, and chip factory workers. The detected concentration in actual urine samples ranged from 0.46 to 5.26 μg/L. Taken together, this simple and cost-effective nylon needle filter-based solid-phase extraction device showed an excellent application potential for pretreating hydrophobic analytes from aqueous samples. This article is protected by copyright. All rights reserved.

Development of a highly efficient in-tube solid-phase microextraction system coupled with UHPLC-MS/MS for analyzing trace hydroxyl polycyclic aromatic hydrocarbons in biological samples

Hydroxyl polycyclic aromatic hydrocarbons are considered active mutagenic and carcinogenic substances and are found in extremely low levels (ng/g) in biological samples. As a result, their determination in urine and blood samples is challenging, and a sensitive and effective method for the analysis of trace hydroxyl polycyclic aromatic hydrocarbons in complex biological matrices is required. In this work, a novel macroporous in-tube solid-phase microextraction monolith was prepared via a thiol-yne click reaction, and a highly efficient analytical method based on in-tube solid-phase microextraction coupled with UHPLC-MS/MS was developed to determine hydroxyl polycyclic aromatic hydrocarbons with low detection limits of 0.137-11.0 ng/L in complex biological samples. Four hydroxyl polycyclic aromatic hydrocarbons, namely, 2-hydroxyanthraquinone, 1-hydroxypyrene, 1,8-dihydroxyanthraquinone, and 6-hydroxychrysene, were determined in the urine samples of smokers, non-smokers, and whole blood samples of mice. Satisfactory recoveries were achieved in the range of 83.1-113% with relative standard deviations of 3.2-9.7%. It was found that implementation of the macroporous monolith gave a highly efficient approach for enriching trace hydroxyl polycyclic aromatic hydrocarbons in biological samples.

A polymer-based dispersive solid phase extraction combined with deep eutectic solvent based-dispersive liquid-liquid microextraction for the determination of four hydroxylated polycyclic aromatic hydrocarbons from urine samples

A new and efficient extraction procedure was proposed and used for the simultaneous extraction of four hydroxylated metabolites polycyclic aromatic hydrocarbons from urine samples. The extraction procedure was started by dissolving an organic polymer into a water-miscible organic solvent (iso-propanol) and its injection into the sample solution. The sorbent was re-precipitated in all parts of the solution as tiny particles and the analytes were adsorbed onto the sorbent. After that, the sorbent was separated and the adsorbed analytes were eluted by choline chloride: dichloroacetic acid deep eutectic solvent. The elution solvent was mixed with choline chloride-3,3-dimethyl butyric acid deep eutectic solvent and the mixture was applied in dispersive liquid-liquid microextraction procedure for more concentration of the analytes. After optimization, the method validation was followed according to International Council Harmonization guidelines and the results showed that wide linear ranges (26-500 000 ng/L) and low limits of detection (3.6-7.2 ng/L) and quantification (11-26 ng/L) were obtained. Satisfactory enrichment factors (435-475) and extraction recoveries (87-95%), and acceptable relative standard deviations (equal or less than 8.6%) were obtained. Finally, the introduced method was successfully applied for determination of the analytes in urine samples obtained from tobacco smokers.

[Fabrication of nanomaterials incorporated polymeric monoliths and application in sample pretreatment]

Polymeric monolithic columns are fabricated by in situ polymerization of the corresponding monomer, crosslinkers, porogenic solvents and radical initiators within a mold. Compared with the conventional packed solid phase extraction adsorbents, polymeric monolithic columns with a continuous porous structure process distinctive advantages of rapid mass transfer and excellent permeability, which facilitates the extraction of trace amounts of the target from the matrix even at high flow velocities. Besides, these materials can be easily fabricated in situ within various cartridges, avoiding a further packing step associated with packed particulate adsorbents. Additionally, the abundant monomer availability, flexible porous structure, and wide applicable pH range make monoliths versatile for use in separation science. Thus, polymeric monolithic columns have been increasingly applied as efficient and promising extraction media for sample pretreatment food, pharmaceutical, biological and environmental analyses. However, these materials usually have the difficulty in morphology control and their interconnected porous micro-globular structure, which may result in low porosity, limited specific surface area and poor efficiency. In addition, polymeric monoliths suffer from the swelling in organic solvents, thus decreasing the service life and precision while increasing the cost consumption. Recently, the development of nanomaterial-incorporated polymeric monoliths with an improved ordered structure, enhanced adsorption efficiency and outstanding selectivity has attracted considerable attention. Nanoparticles are considered as particulates within the size range of 1-100 nm in at least one dimension, which endows them with unique optical, electrical and magnetic properties. These materials have a large surface area, excellent thermal and chemical stabilities, remarkable versatility, as well as a wide variety of active functional groups on their surface. With the aim of exploiting these advantages, researchers have shown great interest in applying nanomaterial-incorporated polymeric monoliths to separation science. Accordingly, significant progress has been achieved in this field. Nanomaterials can be entrapped via the direct synthesis of a polymerization solution that contains well dispersed nanomaterials in porogens. In addition, nanoparticles can be incorporated into the monolithic matrix by copolymerization and post-polymerization modification via specific interactions. Therefore, nanomaterial-incorporated polymeric monoliths combined the different shapes, chemical properties, and physical properties of the polymers with those of the nanoparticles. The presence of nanoparticles can improve the structural rigidity as well as the thermal and chemical stabilities of monolithic adsorbents. Besides, nanoparticles are capable of increasing the specific surface area and providing multiple active sites, which leads to enhanced extraction performance and selectivity of polymeric monolithic materials. In recent years, diverse types of nanomaterials, such as carbonaceous nanoparticles, metallic materials and metal oxides, metal-organic frameworks, covalent organic frameworks and inorganic nanoparticles have been extensively explored as hybrid adsorbents in the modes of solid phase extraction, solid phase microextraction, stir bar sorption extraction and on-line solid phase extraction. This review specifically summarizes the fabrication methods for nanomaterial incorporated polymeric monoliths and their application to the field of sample pretreatment. The existing challenges and future possible perspectives in the field are also discussed.