High-Throughput Analysis of Selected Urinary Hydroxy Polycyclic Aromatic Hydrocarbons by an Innovative Automated Solid-Phase Microextraction

A review of bioanalytical applications of microextraction techniques combined with derivatization

Microextraction techniques have attracted the attention of many researchers working in the field of bioanalysis due to their unique advantages, mainly in downsizing the scale of sample preparation steps. In parallel, analytical derivatization offers a powerful combination in terms of additional sensitivity, selectivity and compatibility with modern separation techniques. The aim of this review is to discuss the most recent advances in bioanalytical sample preparation based on the combination of microextraction and analytical derivatization. Both innovative fundamental reports and analyte-targeted applications are included and discussed. Dispersive liquid-liquid extraction and solid-phase microextraction are the most common techniques that typically combined with derivatization, while the development of novel and greener protocols is receiving substantial consideration in the field of analytical chemistry.

Low-Dose Benzene Exposure Monitoring of Oil Refinery Workers: Inhalation and Biomarkers

Airborne benzene in workplaces has progressively decreased due to preventive actions and the redesigning of facility processes. Professionals who assess occupational exposure should select techniques to detect benzene levels comparable to ambient air exposure. Thus, sensitive biomarkers are needed to discriminate the effects of confounding factors, such as smoking or sorbic acid (SA). In order to identify sensitive biomarkers and to study their correlation with confounding factors, 23 oil refinery workers were enrolled in the study; their airborne benzene exposures and biomarkers were monitored. Urinary benzene (U-B), t,t-muconic acid (t,t-MA), and S-phenylmercapturic acid (SPMA) were quantified. Urinary cotinine (U-C) and t,t-sorbic acid (t,t-SA) were evaluated to flag smoking and SA intake, respectively. The benzene measured in personal inhalation sampling ranged from 0.6 to 83.5 (median 1.7) µg/m3. The concentration range of the biomarkers, U-B, t,t-MA, and SPMA, were 18–4893 ng/m3, <10–79.4 µg/g creatinine, and <0.5–3.96 µg/g creatinine, respectively. Pearson tests were carried out; the best correlations were between airborne benzene and U-B (µg/L r = 0.820, p < 0.001) and between benzene and SPMA (g/L r = 0.812, p < 0.001), followed by benzene and t,t-MA (mg/L r = 0.465, p = 0.039). From our study, U-B and SPMA result to be the most reliable biomarkers to assess the internal number of low doses of benzene exposure, thanks to their specificity and sensitivity.

Advanced Solid-Phase Microextraction Techniques and Related Automation: A Review of Commercially Available Technologies

The solid-phase microextraction (SPME), invented by Pawliszyn in 1989, today has a renewed and growing use and interest in the scientific community with fourteen techniques currently available on the market. The miniaturization of traditional sample preparation devices fulfills the new request of an environmental friendly analytical chemistry. The recent upswing of these solid-phase microextraction technologies has brought new availability and range of robotic automation. The microextraction solutions propose today on the market can cover a wide variety of analytical fields and applications. This review reports on the state-of-the-art innovative solid-phase microextraction techniques, especially those used for chromatographic separation and mass-spectrometric detection, given the recent improvements in availability and range of automation techniques. The progressively implemented solid-phase microextraction techniques and related automated commercially available devices are classified and described to offer a valuable tool to summarize their potential combinations to face all the laboratories requirements in terms of analytical applications, robustness, sensitivity, and throughput.

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.

Polycyclic Aromatic Hydrocarbons and the Risk of Kidney Stones in US Adults: An Exposure-Response Analysis of NHANES 2007-2012

Background

Polycyclic aromatic hydrocarbons (PAHs) exposure may cause various diseases. However, the association between PAHs exposure and kidney stones remains unclear. The purpose of this study was to examine the relationship between PAHs and the risk of kidney stones in the US population.

Methods

The study included a total of 30,442 individuals (≥20 years) from the 2007–2012 National Health and Nutrition Examination Survey (NHANES). Nine urinary PAHs were included in this study. Logistic regression and dose–response curves were used to evaluate the association between PAHs and the risk of kidney stones.

Results

We selected 4385 participants. The dose–response curves showed a significant positive association between total PAHs, 2-hydroxynaphthalene, 1-hydroxyphenanthrene, 2-hydroxyphenanthrene, 9-hydroxyfluorene and the risk of kidney stones after adjusting for confounding factors. Compared with the low group, an increased risk of kidney stones was observed in the high group of total PAHs [OR (95% CI), 1.32 (1.06–1.64), P=0.013], 2-hydroxynaphthalene [OR (95% CI), 1.37 (1.10–1.71), P=0.005], 1-hydroxyphenanthrene [OR (95% CI), 1.24 (1.00–1.54), P=0.046] and 9-hydroxyfluorene [OR (95% CI), 1.36 (1.09–1.70), P=0.007].

Conclusion

High levels of PAHs were positively associated with the risk of kidney stones in the US population.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.

Assessment of kitchen emissions using a backpropagation neural network model based on urinary hydroxy polycyclic aromatic hydrocarbons

Kitchen emissions are mixed indoor air pollutants with adverse health effects, but the large-scale assessment is limited by costly equipment and survey methods. This study aimed to discuss the application of backpropagation (BP) neural network models in the assessment of kitchen emissions based on the exposure marker. A total of 3686 participants were recruited for the kitchen survey, and their sleep quality was measured by the Pittsburgh sleep quality index (PSQI). After excluding the confounders, 365 participants were selected to assess their urinary hydroxy polycyclic aromatic hydrocarbons (OH-PAHs) concentrations by ultra-high-performance liquid chromatography/tandem mass spectrometry. Two BP neural network models were then set up using the survey and detection data from the 365 participants and used to predict the total urinary OH-PAHs concentrations of all participants. The total urinary OH-PAHs and 1-hydroxy-naphthalene (1-OHNap) concentrations were significantly higher among the 365 participants with poor sleep quality (global PSQI score > 5; P < 0.05). Results from internal and external validation showed that our model has high credibility (model 2). Further, the participants with higher predicted total urinary OH-PAHs concentrations were associated with the global PSQI score of >5 (odds ratio (OR) = 1.284, 95% confidence interval (CI) = 1.082-1.525 for participants with predicted total urinary OH-PAHs concentrations of over 1.897 μg/mmol creatinine in model 1, and OR = 1.467, 95% CI = 1.240-1.735 for participants with predicted total urinary OH-PAHs concentrations of over 2.253 μg/mmol creatinine in model 2) after adjusting for the confounders. Findings suggest that the BP neural network model is suitable for assessing kitchen emissions, and the urinary OH-PAHs concentrations can be taken as the model outlay.

Application of an agitation-assisted dispersed solvent microextraction for analysis of naphthalene and its derivatives from aqueous matrices

Agitation-assisted dispersive liquid-liquid extraction without a dispersing solvent is lately receiving considerable attention owing to the low to no solvent loss relative to its predecessor, which suffers severe extracting solvent loss. Herein, we report the application of a simple agitation-assisted dispersive liquid-liquid microextraction method, without a disperser solvent, for the extraction of naphthalene and its derivatives from aqueous solutions. Under the optimised conditions, namely, 25 μL 3:1 mixture of dichloroethane and ethylacetate with 20 s agitation, in 2-mL aqueous solutions containing 10% NaCl, the method demonstrated acceptable figures of merit: linearity-R² ≥ 0.9914 in the concentration range 0.5-50 ng/mL, repeatability (%RSD ≤ 12.9 for n = 15) and limits of detection (0.034-0.081 ng/mL). The recoveries obtained from the spiked dam water sample were also satisfactory (94-103%). These parameters are comparable with those reported in literature, especially for dispersive liquid-liquid microextraction techniques albeit for different analytes. Despite only naphthol being detected in one of the three sampled sites, the method shows considerable promise for routine monitoring of river and dam water quality subject to accuracy validation using certified reference materials.

New fully automated gas chromatographic analysis of urinary S-phenylmercapturic acid in isotopic dilution using negative chemical ionization with isobutane as reagent gas

The determination of urinary S-phenylmercapturic acid (S-PMA) represents the most reliable biomarker to monitor the intake risk of airborne benzene. Recently, the European Chemical Agency deliberated new occupational exposure limits for benzene and recommended an S-PMA biological limit value of 2-μg/g creatinine. This limit is an order of magnitude lower than the previous one, and its determination constitutes a challenge in the analytical field. We developed and validated a method that allows the fully automated and sensitive determination of S-PMA by the use of gas-chromatography negative chemical ionization tandem mass spectrometry in isotopic dilution. For negative chemical ionization, we selected a mixture of 1% isobutane in argon as reactive gas, by studying its chemical ionization mechanism and optimal parameters compared with pure isobutane or pure methane. This gas mixture produces a more abundant signal of the target analyte than isobutane or methane, and it extended the operative lifetime of the ion source, enabling us to start a high-throughput approach of the S-PMA analysis. Moreover, energy-resolved mass spectrometry experiments were carried out to refine the MS/MS analysis conditions, testing nitrogen and argon as collision gases. The method optimization was pursued by a chemometric model by using the experimental design. The quantification limit for S-PMA was 0.10 μg/L. Accuracy (between 98.3% and 99.6%) and precision (ranging from 1.6% to 6.4%) were also evaluated. In conclusion, the newly developed assay represents a powerful tool for the robust, reliable, and sensitive quantification of urinary S-PMA, and because of its automation, it is well suited for application in large environmental and biological monitoring.

Determination of Urinary Hydroxyl PAHs Using Graphene Oxide@Diatomite Based Solid-Phase Extraction and High-Performance Liquid Chromatography

A diatomite supported graphene oxide composite (GO@Dt–NH₂) was fabricated and explored as a solid-phase extraction adsorbent coupled with high performance liquid chromatography to determine the trace hydroxyl polycyclic aromatic hydrocarbons (2-hydroxy-naphthalene, 2-hydroxy-fluorene, 1-hydroxy-phenanthrene, and 1-hydroxy-pyrene) in urine samples. The fabricated composites were characterized by X-ray powder diffractometry and scanning electron microscopy. GO@Dt–NH₂ offered enhanced adsorption affinity towards the analytes compared with the bare diatomite. The amount of graphene oxide and the factors affecting solid-phase extraction were investigated in detail. Under the optimized conditions, the method gave good linearity (0.30–200 ng/mL) and a low detection limit (0.10–0.15 ng/mL) for the hydroxyl polycyclic aromatic hydrocarbons. The average recovery for spiked urine samples with three levels ranged from 90.6% to 100%. The intra-day and inter-day relative standard deviations were in the range of 1.8–6.4% and 2.7–11.8%, respectively. Besides, the GO@Dt–NH₂ provided enrichment factors of 18–20 and superior purification ability. The developed method was successfully applied to the determination of hydroxyl polycyclic aromatic hydrocarbons in urine samples from smoking volunteers.

Durable molybdenum oxide coated solid-phase microextraction fiber for highly selective and efficient extraction of polycyclic aromatic hydrocarbons in water

A bonding method was developed for coating molybdenum oxides onto a steel wire substrate, which was used as a solid-phase microextraction fiber, was coupled with gas chromatography. Based on the characterization, it is found that the as-prepared molybdenum oxides material contained a nanobelt structure with a uniform size and good dispersibility. In addition, there were a large number of small protrusions on the surface of the nanobelts. These characteristics provided a large specific surface area for extraction. Molybdenum oxides exhibited a high extraction selectivity for polycyclic aromatic hydrocarbons owing to its moderate coordination. After the optimization of the factors, method detection limits of < 1.25 μg/L were achieved, and the calibration curves were linear within the range of 2-600 μg/L. In addition, repeatability was demonstrated, and the relative standard deviation < 6.4%. The molybdenum oxides coating had a high scratch resistance, which could effectively prevent coating wear and failure. Combined with the high thermal and chemical stability, the service life of the coating was improved and could be used 150 times without a significant reduction in the extraction performance. Finally, the as-prepared fiber had a comparable extraction capacity and higher partition coefficients that those of commercial polyacrylate fibers.