Simultaneous determination of 1- and 2-naphthol in human urine using on-line clean-up column-switching liquid chromatography-fluorescence detection

Quantitative analysis of naphthalene, 1-naphthol and 2-naphthol at nanomol levels in geothermal fluids using SPE with HPLC

Naphthalene (NAP), 1-naphthol (1-NAP) and 2-naphthol (2-NAP) are the thermal decomposition products of naphthalene sulfonates making them potentially new geothermal reservoir permeability tracers, however, to date, no sensitive and fast detection method for these compounds has been developed. In order to facilitate sensitive and rapid analysis of these compounds in geothermal brines and associated steam condensates, a high-performance liquid chromatography (HPLC) method combined with solid-phase extraction (SPE) has been developed.•A method for determination of naphthalene, 1- and 2-naphthol from brines has been developed.•These compounds have been detected in steam samples from three New Zealand geothermal fields.•As breakdown products of NDS/NSA, these compounds have potential use as geothermal tracers.

N-doped mesoporous carbon as a new sorbent for ultrasonic-assisted dispersive micro-solid-phase extraction of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene, from urine samples

This study aimed to optimize a new sample preparation method using N-doped mesoporous carbon sorbent for simultaneous measurement of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene. The samples were analyzed using high-performance liquid chromatography supplied with ultraviolet detector (HPLC-UV). N-doped mesoporous carbon sorbent was obtained via the hard template procedure. The synthesized nanosorbent was then characterized by transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and elemental analysis (CHN). The effective factors in the extraction of the studied biomarkers were examined by the Box-Behnken (BBD) methodology. Regarding the optimum conditions, the sketched calibration curve for naphthols was linear in the concentration levels of 1-600 µg L^-1 for human urine samples. The accuracy and reproducibility of the introduced method were determined using the relative recovery (RR %) and relative standard deviation (RSD %) tests on the fortified urine samples. RR% and RSD% were found to be 97.0-101.2% and 3.1-9.0%, respectively. The calculated method detection limit of the optimized procedure was 0.3 µg L^-1 and 0.5 µg L^-1 for 1-naphthol and 2-naphthol, respectively.

Simple and reliable method to simultaneously determine urinary 1- and 2-naphthol using in situ derivatization and gas chromatography-mass spectrometry for biological monitoring of naphthalene exposure in occupational health practice

OBJECTIVES

The aim of this study was to develop and validate a simple and reliable gas chromatography-mass spectrometry (GC-MS) method to simultaneously determine urinary 1-naphthol (1-NAP) and 2-naphthol (2-NAP) for biological monitoring of occupational exposure to naphthalene.

METHODS

NAPs were derivatized in situ with acetic anhydride after enzymatic hydrolysis, extracted with n-hexane, and analyzed using GC-MS. Validation of the proposed method was conducted in accordance with US Food and Drug Administration guidance. A final validation was performed by analyzing a ClinChek® -Control for phenolic compounds.

RESULTS

The linearity of calibration curves was indicated by a high correlation coefficient (>0.999) in the concentration range 1-100 μg/L for each NAP. The limits of detection and quantification for each NAP were 0.30 and 1.00 μg/L, respectively. The recovery was 90.8%-98.1%. The intraday and interday accuracies, expressed as the deviation from the nominal value, were 92.2%-99.9% and 93.4%-99.9%, respectively. The intraday and interday precision, expressed as the relative standard deviation, was 0.3%-3.9% and 0.4%-4.1%, respectively. The ClinChek® values obtained using our method were sufficiently accurate.

CONCLUSIONS

The proposed method is simple, reliable, and appropriate for routine analyses, and is useful for biological monitoring of naphthalene exposure in occupational health practice.

Quantification of Genotoxic Impurities in Key Starting Material of Sertraline Hydrochloride by Simple and Sensitive Liquid Chromatography Technique

Background:

Schiff base is an advanced key starting material of Sertraline hydrochloride. Schiff base is synthesized using two raw materials 1-Naphthol and 1,2-Dichlorobenzene which are potentially genotoxic impurities.

Objective:

Genotoxic impurities need to be controlled in key starting material to avoid carry forward in the active pharmaceutical ingredient. For trace level quantification of impurities a sensitive, accurate and cost effective method is developed by simultaneous estimation of both impurities.

Methods:

Reverse phase high performance liquid chromatography (HPLC) method was developed and validated for determination of both impurities in Schiff base. HPLC column Cosmosil MS-II C18, 100 mm X 4.6 mm, 3 μm particle size with ultra-violet detector (UV) was used.

Results:

The calibration curve of 1-Naphthol and 1,2-Dichlorobenzene showed good linearity over the concentration range of 0.25 µg/g to 7.5 µg/g and 1.5 µg/g to 7.5 µg/g and the regression coefficient was 0.999 and 0.998 respectively. Method had very low limit of detection (LOD) and limit of quantification (LOQ) of both analytes which proves that the method is sensitive and suitable for quantification of compounds at trace level.

Conclusion:

The proposed method is specific, linear, accurate, rugged and precise. Genotoxic impurities 1-Naphthol and 1,2-Dichlorobenzene are quantified and controlled in the key starting material of Sertraline hydrochloride. The validated method can be used in quality control unit in pharmaceutical industry.

Zeolitic imidazolate framework 8 (ZIF-8) reinforced macroporous resin D101 for selective solid-phase extraction of 1-naphthol and 2-naphthol from phenol compounds

Macroporous resin has been attracting intensive attention due to its critical role in separation and purification of natural products. Herein, a zeolitic imidazolate framework 8 reinforced macroporous resin D101 was prepared via a room temperature growth method and used for dispersive SPE of 1-naphthol and 2-naphthol. The parameters affecting the adsorption and desorption efficiency such as the sample pH, adsorbent amount, extraction time, desorption solvent, and desorption time were investigated. The as-prepared adsorbent showed selectivity for 1-naphthol and 2-naphthol compared to other phenols. Under the optimum dispersive SPE conditions, the detection of 1-naphthol and 2-naphthol coupled with a CZE method was conducted and the LODs for 1-naphthol and 2-naphthol were 1.37 and 1.43 ng/mL, respectively. Moreover, the results of urine sample analysis showed the spiked recoveries to be in the range of 96.2-106.9%. This study indicated that D101@ZIF-8 (where ZIF is zeolitic imidazolate framework) is a promising selective adsorbent for the analysis of 1-naphthol and 2-naphthol in urine samples.

Biological monitoring of environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage, in Southern China

The study was undertaken to evaluate the environmental exposure to polycyclic aromatic hydrocarbons in subjects living in the area of recycling electronic garbage in Southern China and research the influence of environment smoke tobacco (EST) to people through active and passive smoking. Urinary concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene were determined in 141 randomly selected voluntary residents aged 13 to 81 years in two polycyclic aromatic hydrocarbon (PAH)-exposed groups, two control groups, and an EST research group. The concentrations of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in PAH-exposed groups are significantly higher (p<0.05) than those of control groups. Mean value of 1-hydroxypyrene in the residents living in the area of recycling electronic garbage (1.1 μmol/mol creatinine) is a little higher than those of iron foundry workers, automobile repair workers, and firefighters. Mean value of 2-hydroxynaphthalene (11.3 μmol/mol creatinine) is much higher than that of shipyard and aircraft maintenance and much lower than some occupational exposure, such as coking batteries, sorting department, and distillation department in coking plant. Some metabolites of PAHs (PAHm) are significantly elevated through active and passive smoking, while the influence of EST to other PAHm is not statistically significant. 2-Hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene in the urine of smokers are, respectively, 3.9, 1.9, 1.4, and 1.9 times to those of nonsmokers. In nonsmokers, passive smokers excreted 1.1, 1.5, 1.9, and 1.5 times of 2-hydroxynaphthalene, 2-hydoxyfluorene, 9-hydroxyphenanthrene, and 1-hydroxypyrene compared to nonpassive smokers.

A community study of the effect of polycyclic aromatic hydrocarbon metabolites on heart rate variability based on the Framingham risk score

OBJECTIVES

To investigate the effects of the urinary metabolite profiles of background exposure to the atmospheric pollutants polycyclic aromatic hydrocarbon (PAH) and Framingham risk score (FRS), which assesses an individual's cardiovascular disease risk, on heart rate variability (HRV).

METHODS

The study conducted from April to May 2011 in Wuhan, China, included 1978 adult residents with completed questionnaires, physical examinations, blood and urine samples, and 5-min HRV indices (including SD of all normal to normal intervals (SDNN), root mean square successive difference (rMSSD), low frequency (LF), high frequency (HF) and their ratio (LF/HF), and total power) obtained from 3-channel Holter monitor. 12 urinary PAH metabolites were measured by gas chromatography-mass spectrometry. FRS was calculated by age, sex, lipid profiles, blood pressure, diabetes and smoking status. Linear regression models were constructed after adjusting for potential confounders.

RESULTS

Elevated total concentration of hydroxynaphthalene (ΣOHNa) was significantly associated, in a dose-responsive manner, with decreased SDNN and LF/HF (ptrend=0.014 and 0.007, respectively); elevated total concentration of hydroxyfluorene (ΣOHFlu) was significantly associated with reduced SDNN, LF and LF/HF (ptrend=0.027, 0.003, and <0.0001, respectively); and elevated total concentration of all PAH metabolites (ΣOH-PAHs) was associated with decreased LF and LF/HF (ptrend=0.005 and <0.0001, respectively). Moreover, increasing quartiles of FRS were significantly associated with decreased HRV indices, except LF/HF (all ptrend<0.0001). Interestingly, individuals in low-risk subgroups had greater decreases in SDNN, LF and LF/HF in relation to ΣOH-PAHs, ΣOHNa and ΣOHFlu than those in high-risk subgroups (all p<0.05).

CONCLUSIONS

Environmental PAH exposure may differentially affect HRV based on individual coronary risk profiles.

The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing

Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

Highly sensitive detection of α-naphthol based on G-DNA modified gold electrode by electrochemical impedance spectroscopy

A highly sensitive, reusable G-rich DNA sensor was reported for the detection of α-naphthol by electrochemical impedance spectroscopy (EIS). Specifically, a single-stranded G-rich DNA was self-assembled on the electrode and transformed into K(+)-stabilized G-quadruplex, which could catalyze H2O2-mediated oxidation of α-naphthol (with hemin as a cofactor) to 1, 4-naphthoquinone precipitated on the DNA films. Due to the insolubility of 1, 4-naphthoquinone, the charge transfer resistance (RCT) was increased to maximum within 15 min. Depending on the difference in charge transfer resistance change (ΔRCT), the α-naphthol could be detected with the detection limit of 0.1 nM in Tris-ClO4 buffer solution (20mM, pH=7.4). Moreover, the sensor demonstrated a high selectivity over other selected phenolic compounds. The performance of the sensor in the real lake water was also explored with the detection limit of 0.8 nM. Finally, the regeneration of the sensor was investigated, which allowed for reuse more than 4 cycles with a mean recovery of 94% of the original signal.

Urinary metabolites of polycyclic aromatic hydrocarbons in workers exposed to vapours and aerosols of bitumen

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons (PAH) were investigated as potential biomarkers of bitumen exposure in a cross-shift study in 317 exposed and 117 non-exposed workers. Personal measurements of the airborne concentration of vapours and aerosols of bitumen during a working shift were weakly associated with post-shift concentrations of 1-hydroxypyrene (1-OHP) and 1-, 2+9-, 3- and 4-hydroxyphenanthrenes (further referred to their sum as OHPHE), but not 1- and 2-hydroxynaphthalene (OHNA). Smoking showed a strong influence on the metabolite concentrations, in particular on OHNA. Pre-shift concentrations of 1-OHP and OHPHE did not differ between the study groups (P = 0.16 and P = 0.89, respectively). During shift, PAH metabolite concentrations increased in exposed workers and non-exposed smokers. Statistical modelling of post-shift concentrations revealed a small increase in 1-OHP by a factor of 1.02 per 1 mg/m(3) bitumen (P = 0.02) and 1.04 for OHPHE (P < 0.001). A group difference was observed that was diminished in non-smokers. Exposed non-smokers had a median post-shift 1-OHP concentration of 0.42 μg/l, and non-smoking referents 0.13 μg/l. Although post-shift concentrations of 1-OHP and OHPHE were slightly higher than those in the general population, they were much lower than in coke-oven workers. The small content of PAHs in vapours and aerosols of bitumen, the increasing use of additives to asphalt mixtures, the strong impact of smoking and their weak association with airborne bitumen limit the use of PAH metabolites as specific biomarkers of bitumen exposure.

Determination of endocrine disruptors in honey by CZE-MS using restricted access materials for matrix cleanup

An analytical method based on CZE coupled to ESI-MS is proposed for the identification and simultaneous quantification of several endocrine-disrupting chemicals in honey. The target compounds were the chlorophenols: 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol, and bisphenol-A, 4-tert-butylphenol, and 4-tert-butylbenzoic acid. A two-step optimization of the ESI-MS detection was carried out. First, the organic solvent present in the sheath liquid was selected and its effect on the analytical signal was studied. The best results in terms of the intensity of the MS signals were obtained with methanol. Thus, an experimental design technique (Doehlert type) was used for the optimization of the other parameters: the NH(3) concentration in the sheath liquid, the flow of the sheath liquid, the nebulizer pressure in ESI, and the drying gas temperature and flow. Here, we developed a new sample treatment based on the combined use of a restricted access material and a polymeric sorbent for SPE. The LOD achieved were in the range of 5-31 ng/g. The intraday precision of the proposed method was determined from replicate analyses (n=4) at a concentration level of 50 ng/g, with RSD values in the range of 15-23%. The results revealed that the proposed method is suitable for the reliable quantification of endocrine-disrupting chemicals in honey at nanograms per gram levels.

Simultaneous quantification of sulfamethoxazole and trimethoprim in whole egg samples by column-switching high-performance liquid chromatography using restricted access media column for on-line sample clean-up

This work reports the application of restricted access media (RAM) column, in a multidimensional configuration, for simultaneous analysis of sulfamethoxazole (SMX) and trimethoprim (TMP) in whole eggs with ultraviolet detection. The proteins were partially precipitated by adding 0.5 mL of acetonitrile into 1.0 mL of blended egg followed by centrifugation. The supernatant was injected (250 microL) directly into the multidimensional system. At the first dimension, a restricted access medium (RAM) bovine serum albumin (BSA) octadecyl column (100 mm x 46 mm I.D., Luna silica, 10 microm particle size and 100 A pore size), was used for extraction and concentration of the analytes and at second dimension, an octadecyl column (150 mm x 46 mm I.D., Luna silica, 10 microm particle size and 100 A pore size), for analysis. The developed method showed good selectivity, accuracy and precision for quantification of these different compounds in eggs, and the limits of quantification were 80 ng/mL, for both compounds. The validated method is reliable and sensitive for monitoring residues in whole eggs samples and thus, to determine withdraw period for laying hens using veterinary medicine having SMX-TMP combination.

Automated on-line liquid chromatography–photodiode array–mass spectrometry method with dilution line for the determination of bisphenol A and 4-octylphenol in serum

A novel on-line liquid chromatography-photodiode array detection-mass spectrometry (LC-DAD-MS) system was established with restricted-access media (RAM) pre-column and dilution line combined with a column-switching valve. The serum samples were injected directly onto pre-column under diluted condition by dilution line. After elution of proteins in the serum, the analytes were backflushed onto an ODS analytical column using a six-port column-switching device. The influence of the composition of the mobile phase, for instance, organic modifer, ionic strength, pH, dilution times and the rotation time of the switching valve have been investigated using bisphenol A (BPA) and 4-octyphenol (4-OP) as analytes. The evaluations for peak responses and sensitivity were conducted by MS, and proteins were removed by RAM-column with DAD monitoring at 280 nm. The peak shape was improved by adding a dilution line, especially in the case of large volume injection (LVI), which increased the sensitivity of the analysis. The selective and sensitive quantification of BPA and 4-OP in serum sample could be finished within 25 min. The method had linearity in the range 0.1-500 ng/mL with a limit of quantification for BPA and 4-OP of 0.1 and 0.5 ng/mL, respectively. The recoveries were in the range of 80-101% with less than 9.0% RSDs. This on-line LC-MS method demonstrates potential application to evaluating the exposure and risk of BPA and 4-OP in human.

Development of restricted-access media supports and their application to the direct analysis of biological fluid samples via high-performance liquid chromatography

A quick overview of published methods for analyzing compounds in complex biological samples reveals that the most difficult step is the clean-up or extraction of a required compound from the matrix. The strategy required to analyze exogenous compounds in biological fluids depends greatly upon the nature of the compound and upon the biomatrix. Coupled-column separation using restricted-access media as the first dimension in order to exclude macromolecules and retain micromolecules has been successfully used for a number of biological fluids. This paper presents the history of the development of restricted-access media supports and of their application to the direct injection of biological fluid samples in high-performance liquid chromatography.

Gas chromatographic–tandem mass spectrometric method for the quantitation of carbofuran, carbaryl and their main metabolites in applicators’ urine

A new gas chromatographic-tandem mass spectrometric method has been developed and validated for the determination of two N-methylcarbamates, carbofuran and carbaryl and their metabolites in applicators' urine specimens. Mild conditions were used for sample preparation based on enzymic hydrolysis and solid-phase extraction using Oasis HLB sorbent cartridges. Amides, phenols and ketones were first converted to volatile derivatives of trifluoroacetic acid anhydride (TFAA) and afterwards were quantitated using tandem mass spectrometry. Linear calibration equations (1-200 ng mL(-1) urine) were obtained from fortified urine samples for all eight compounds, carbaryl, 1-naphthol, 2-naphthol, and carbofuran, 3-hydroxycarbofuran, 7-phenol, carbofuran-3-keto, 3- hydroxycarbofuranphenol. For all compounds, the limit of detection was lower than 0.1 ng mL(-1). Precision for all compounds, at the concentrations of 1, 10 and 100 ng mL(-1) (n = 5) in-fortified urine samples ranged from 0.7% to 18%. Accuracy was calculated at two concentrations 8 and 80 ng mL(-1) (n = 5) and ranged from -8.4% to 8.2%. Relative recoveries at concentrations of 1, 10 and 100 ng mL(-1), ranged from 71% to 116%. The method was successfully applied to five male applicators and 10 non-applicators (including both smokers and non-smokers).

Decreasing urinary PAH metabolites and 7-methylguanine after smoking cessation

OBJECTIVE

Humans are exposed to various carcinogens by smoking. Urinary metabolites of polycyclic aromatic hydrocarbons (PAH), one of the major carcinogens in cigarette smoke, were measured as the environmental carcinogen exposure marker for humans. We evaluated urinary exposure markers for smoking cessation.

METHOD

In this study, we measured cigarette smoke exposure markers, such as urinary cotinine, PAH exposure markers, such as urinary 1-hydroxypyrene (1-OHP), 2-naphthol (2-NP) and 1-naphthol (1-NP), as well as a methylating chemical exposure marker, 7-methylguanine (7-MeG). The before smoking cessation levels of these markers, and the after smoking cessation levels were then compared. Eighteen subjects participated in this smoking cessation program.

RESULTS

Levels of all of four markers were found to have decreased by 19-54% after smoking cessation. Urinary cotinine, 1-OHP, 2-NP and 7-MeG levels were found to have significantly decreased after smoking cessation. There were positive correlations between cotinine and three urinary PAH markers and between 1-OHP, 2-NP and 7-MeG.

CONCLUSION

PAH metabolites were better biomarkers of smoking cessation than 7-MeG. Analyzing urinary metabolites or urinary DNA adducts is suitable for epidemiological studies.

Biomonitoring of inhaled complex mixtures--ambient air, diesel exhaust and cigarette smoke

Human biomonitoring comprises the determination of biomarkers in body-fluids, cells and tissues. Biomarkers are generally assigned to one of three classes, namely, biomarkers of exposure, effect or susceptibility. Since biomarkers represent steps in an exposure-disease continuum, their application in epidemiological studies ('molecular epidemiology') shows promise. However, to be a predictor of disease, a biomarker has to be validated. Validation criteria for a biomarker include intrinsic qualities such as specificity, sensitivity, knowledge of background in the population, existence of dose-response relationships, degree of inter- and intra-individual variability, knowledge of the kinetics, confounding and modifying factors. In addition, properties of the sampling and analytical procedures are of relevance, including constraints and non-invasiveness of sampling, stability of sample as well as simplicity, high sensitivity, specificity and speed of the analytical method. It is of particular importance to prove by suitable studies that the biomarker of exposure indicates the actual exposure, the biomarker of effect strongly predicts the actual risk of disease and the biomarker of susceptibility actually modifies the risk. Biomonitoring of the exposure to complex mixtures such as polluted ambient air, diesel exhaust or tobacco smoke is a particular challenge since these exposures have many constituents in common and many people were exposed to more than one of these mixtures. Data on the exposure to polycyclic aromatic hydrocarbons (PAH) and benzene from ambient air, diesel exhaust and tobacco smoke will be presented. In addition, some source-specific biomarkers such as nitro-arenes and nicotine metabolites as well as their application in population groups will be discussed. The second part of the presentation addresses the application of biomarkers for assessing so called 'potentially reduced exposure products' (PREPs). According to a recent report of the Institute of Medicine (USA), "reducing risk of disease by reducing exposure to tobacco toxicants is feasible" and "surrogate biological markers that are associated with tobacco-related diseases could be used to offer guidance as to whether or not PREPs are likely to be risk-reducing." In general, the same validation criteria apply as discussed above. In addition, it is suggested that a panel of biomarkers should be used, representing both smoke phases (gas and particulate phase) and the various chemical classes of smoke constituents (e.g., carbonyls, benzene, PAH, tobacco-specific nitrosamines, aromatic amines). Also, a panel of biomarkers of effect should cover the major known adverse effects of smoking (e.g., oxidative stress, inflammatory processes, lipid peroxidation, lipometabolic disorders, mutagenic effects). Biomarkers of nicotine and carbon monoxide uptake are of interest for evaluating the smoking and inhalation behavior, respectively. Finally, suitable study designs for evaluating PREPs are discussed. It is concluded that suitable biomarkers for assessing the exposure to complex mixtures such as ambient air, diesel exhaust and tobacco smoke as well as for evaluating the exposure-reducing properties of PREPs are already available. Future efforts should focus on the development and validation of biomarkers of effect.

Quantification of several monohydroxylated metabolites of polycyclic aromatic hydrocarbons in urine by high-performance liquid chromatography with fluorescence detection

A high-performance liquid chromatographic method with fluorescence detection has been developed to determine the urinary polycyclic aromatic hydrocarbon metabolites 2-hydroxynaphthalene, 2-hydroxyfluorene, 9-hydroxyphenanthrene, 1-hydroxypyrene and 3-hydroxybenz[a]pyrene. Solid phase extraction (SPE) was used to clean up the samples, and washing with 30% methanol was found to be the best way to remove interferences in the matrix. The method detection limits ranged from 0.044 microg/L for 1-hydroxypyrene to 1.615 microg/L for 3-hydroxybenz[a]pyrene, and the recoveries ranged between 40% for 3-hydroxybenz[a]pyrene and 99% for 2-hydroxynaphthalene. The within-day relative standard deviation was lowest for 2-hydroxynaphthalene at 0.67% and went up to 2.42% for 3-hydroxybenz[a]pyrene, and the between-day relative standard deviation ranged from 3.84% for 9-hydroxyphenanthrene to 10.42% for 2-hydroxyfluorene. The correlation coefficients were between 0.9962 and 0.9998. The developed method was successfully used to analyze samples from student volunteers in a high school.

Current external and internal exposure to naphthalene of workers occupationally exposed to polycyclic aromatic hydrocarbons in different industries

OBJECTIVES

External and internal exposure to naphthalene was examined in the most important industries that are typically concerned with polycyclic aromatic hydrocarbon (PAH)-induced diseases (cancer). Furthermore, a control collective from the general population was investigated.

METHODS

External naphthalene was determined by personal air sampling (n = 205). The internal exposure was examined by urinary metabolites 1-naphthol and 2-naphthol (n = 277).

RESULTS

Highest median concentrations of naphthalene in air were found in converter infeed (93.2 microg/m3) and coal-tar distillation (35.8 microg/m3). Moderate and low levels were determined in coking plants (14.5 microg/m3) and in the production of refractories (6.1 microg/m3) and graphite electrodes (0.7 microg/m3). Biological monitoring revealed concentrations of the sum of both metabolites [(1+2)-NOL] in smokers to be increased by 1.6-6.4 times compared with that in non-smokers at the same workplaces. Among non-smokers we found high median (1+2)-NOL levels in converter bricklayers (120.1 microg/l), in coal-tar distillation workers (56.0 microg/l) and in coking plant workers (29.5 microg/l). (1+2)-NOL concentrations around 10 microg/l were found in the production of refractories and graphite electrodes. There was a rough coherency between external and internal naphthalene exposure. In the controls, median (1+2)-NOL concentrations were 10.9 microg/l in non-smokers' urine and 40.3 microg/l in smokers' urine samples.

CONCLUSIONS

Actual conditions of occupational hygiene at the workplaces investigated in this comprehensive study are better than those that current limit values of 50,000 microg/m3 (TLV, TRK) seem to induce. It has become obvious that tobacco smoking is a crucial confounding factor in biological monitoring of naphthalene-exposed humans, making interpretation of occupationally increased naphthol excretions very difficult at low exposure levels.

Genotoxic risk assessment in white blood cells of occupationally exposed workers before and after alteration of the polycyclic aromatic hydrocarbon (PAH) profile in the production material: comparison with PAH air and urinary metabolite levels

OBJECTIVE

Workers in various industries can be exposed to polycyclic aromatic hydrocarbons (PAHs). The relationship between biomarkers of genotoxic risk, PAH compounds in air (ambient monitoring) and PAH metabolites in urine (internal exposure) were studied in 17 workers exposed to PAHs in a fireproof-material producing plant before and 3 months after the PAH profile was altered in the binding pitch.

METHODS

Two biomarkers of exposure, specific DNA adducts of (+/-)-r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (anti-BPDE) and non-specific DNA adduct of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) were determined in white blood cells (WBCs). In addition, DNA strand breaks were analysed in lymphocytes by single-cell gel electrophoresis in a genotoxic risk assessment. Sixteen PAH compounds in air were determined by personal air sampling, and hydroxylated metabolites of phenanthrene, pyrene and naphthalene were determined in urine.

RESULTS

After substitution of the binding pitch the concentrations of benzo[a]pyrene in air decreased (P<0.01). No changes could be observed for pyrene, while levels of phenanthrene (P=0.0013) and naphthalene (P=0.0346) in air increased. Consequently, median DNA adduct rates of anti-BPDE decreased after alteration of the production material (from 0.9 to <0.5 adducts/10(8) nucleotides). No changes in the excretion of 1-hydroxypyrene in urine could be determined, whereas increased levels of 1-, 2+9-, 3- and 4-hydroxyphenanthrene (P<0.0001) and 1-naphthol and 2-naphthol (P=0.0072) were found in urine. In addition, a statistically significant increase in DNA strand break frequencies (P<0.01) and elevated 8-oxodGuo adduct levels (P=0.7819, not statistically significant) were found in the WBCs of exposed workers 3 months after the PAH profile in the binding pitch had been altered.

CONCLUSION

The results presented here show that the increased concentration of naphthalene and/or phenanthrene in the air at the work place could induce the formation of DNA strand breaks and alkali-labile sites in WBCs of exposed workers.

Biological monitoring of the five major metabolites of di-(2-ethylhexyl)phthalate (DEHP) in human urine using column-switching liquid chromatography–tandem mass spectrometry

We present a fast and reliable on-line clean-up HPLC-method for the simultaneous determination of the five major urinary metabolites of di-(2-ethylhexyl)phthalate (DEHP) namely mono-(2-ethyl-5-carboxypentyl)phthalate (5carboxy-MEPP), mono-[2-(carboxymethyl)hexyl]phthalate (2carboxy-MMHP), mono-(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP), mono-(2-ethyl-5-oxohexyl)phthalate (5oxo-MEHP) and mono-(2-ethylhexyl)phthalate (MEHP). These metabolites represent about 70% of an oral DEHP dose. We for the first time succeeded to reliably quantify 5carboxy-MEPP and to identify 2carboxy-MMHP as major metabolites in native urines of the general population. The analytical procedure consists of an enzymatic hydrolysis, on-line extraction of the analytes from urinary matrix by a restricted access material column (RAM), back-flush transfer onto the analytical column (betasil phenylhexyl), detection by ESI-tandem mass spectrometry and quantification by isotope dilution (limit of detection (LOD) 0.25 microg/l). Median concentrations of a small collective taken from the general population (n=19) were 85.5 microg/l (5carboxy-MEPP), 47.5 microg/l (5OH-MEHP), 39.7 microg/l (5oxo-MEHP), 9.8 microg/l (MEHP) and about 37 microg/l (2carboxy-MMHP). The presented method can provide insights into the actual internal burden of the general population and certain risk groups. It will help to further explore the human metabolism of DEHP-an occupational and environmental toxicant of great concern.

Pilot study on the naphthalene exposure of German adults and children by means of urinary 1- and 2-naphthol levels

Concentrations of 1- and 2-naphthol were measured in urine of 72 adults and 35 young children from Germany to assess the internal exposure to naphthalene of the general population. Naphthols could be detected in more than 90% of the urine samples. Levels of naphthols (sum of 1- and 2-naphthol) were 4-fold higher in smokers (median: 37.6 microg/g creatinine) compared to non-smoking adults (8.2 microg/g creatinine). On a creatinine basis young children had slightly lower naphthol levels in urine compared with adults (7.5 microg/g creatinine). Preliminary reference values for the sum of 1- and 2- naphthol in urine as means of the 95th percentile are proposed: 41.2 microg/g creatinine (non-smoking adults) and 23.5 microg/g creatinine (young children). It is concluded that 1- and 2-naphthol levels in urine are suitable for human biomonitoring of the naphthalene exposure in environmental medicine.