Optimization of an improved analytical method for the determination of 1-nitropyrene in milligram diesel soot samples by high-performance liquid chromatography–mass spectrometry

Detection of Nitrated, Oxygenated and Hydrogenated Polycyclic Aromatic Compounds in Smoked Fish and Meat Products

Polycyclic aromatic hydrocarbons (PAHs) are present in smoked food products. More toxic nitrated (NPAH) and oxygenated (OPAH) PAHs derivatives are found concomitantly to PAHs and are therefore believed to be found in smoked food products. However, only a few PAH analyses on food include these derivatives. We adjusted and successfully validated a GC-QTOFMS method including 13 NPAHs and 2 OPAHs as well as the 4 regulated PAHs for analysis of 14 smoked (13 fish and one bacon) and one pan fried fish samples.OPAHs were detected in the highest concentrations in 13 of 15 samples. Non-target screening revealed the presence of an additional four OPAHs and two methylated PAHs. Future food analysis should, based on these results, focus on PAH and oxygenated derivatives.

Quantitation of ultra-trace nitrated polycyclic aromatic hydrocarbons isomers in water by online solid-phase extraction coupled-liquid chromatography-mass spectrometry

An online solid-phase extraction (SPE)-coupled liquid chromatography-mass spectrometry (LC-MS) method was established for the determination of 10 nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in water. Water samples were mixed with methanol to generate 40% methanol solutions (v/v), and filtered by 0.45 μm membrane. The filtration with polytetrafluoroethylene(PTFE) membrane got higher recovery rates than nylon membrane, especially for 4-ring and 5-ring nitro-PAHs. 2.5 mL solution was directly injected into online SPE flow path to allow for online purification and enrichment of target analytes in the SPE column. The nitro-PAHs eluted from the SPE column were automatically transferred to the analytical flow path by a well-designed valve-switching system. With the optimization of LC and MS condition, ten nitro-PAH isomers was separated and detected from each other by LC-MS/MS with negative atmospheric pressure chemical ionization (APCI). It was firstly found that nitro-PAHs could produce strong [M-H]^- precursor ions in the primary MS besides [M+e]^- and [M+15]^-. In the secondary MS, the precursor ions mainly lose NO neutral molecule (30 Daltons) to produce daughter ions. The online SPE and LC-MS analysis process was completed in 15.5 min. The linear correlation coefficients of 10 nitro-PAH standard curves were higher than 0.99. The detection limits of nitro-PAHs were about 1.2~22.2 ng/L (S/N=3). The intra-day and inter-day reproducibility (RSD, n=6) were 1.6%~8.4% and 5.3%~16.9%, respectively. The recoveries of 10, 40 and 200 ng/L in tap water were 71.7%~106.4%, 79.7%~100.9% and 73.0%~105.5%, with the corresponding RSD of 2.4%~10.5%, 2.1%~8.6% and 2.7%~6.2%, respectively.

Solid-Phase Extraction Combined with Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry for the Determination of 5 Trace Nitro-Polycyclic Aromatic Hydrocarbons in Barbecued Foods

BACKGROUND

Nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) are the derivatives of polycyclic aromatic hydrocarbon which are direct mutagens and carcinogens to human. Nitro-PAHs can be produced in the process of food barbecuing/grilling. At present, there are few studies for the determination of nitro-PAHs in food.

OBJECTIVE

To assess the effect of barbecued food to human health, we have established a method for the determination of 5 nitro-PAHs in barbecued foods.

METHODS

The target nitro-PAHs were extracted with the mixture of methanol/acetone and then purified with an HLB SPE cartridge and finally analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry. Two pairs of target multiple reaction monitoring (MRM) ion pairs have been successfully identified for the target nitro-PAHs, and confirmed by high-resolution mass spectrometry to explore their formation mechanism.

RESULTS

The method had linear ranges of 2.0-500 µg/L (except 1-nitronaphthalene 20-5000 µg/L) with the correlation coefficients greater than 0.995. The extraction recoveries were between 70.1% and 85.6% with the relative standard deviations less than 10.0%. The limits of detection of the method were less than 0.60 µg/L (except 1-nitronaphthalene 6.0 µg/L).

CONCLUSIONS

The method has been successfully applied to the analysis of 5 nitro-PAHs in barbecued foods. 1-nitronaphthalene, 1,8-dinitropyrene , 1-nitropyrene were detected in some charcoal grilled samples with the contents of 1.35-12.9 µg/kg. 1,8-Dinitropyrene was detected in some oil-fried samples with the contents of 2.12-5.12 µg/kg.

HIGHLIGHTS

This work presents an ultra-high-performance liquid chromatography-tandem mass spectrometry method for the determination of 5 nitro-PAHs in barbecued foods for the first time. The method has been successfully applied to the analysis of 5 nitro-PAHs in various barbecued foods and the nitro-PAHs were detected in some barbecued food samples. The mechanism of mass spectrometric decomposition of nitro-PAHs was investigated as well.

Assessment of nitro-polycyclic aromatic hydrocarbons in PM₁ near an area of heavy-duty traffic

The objective of this research was to evaluate nitro-polycyclic aromatic hydrocarbons (NPAHs) associated with ultrafine airborne particles (PM1) in areas affected by vehicles in the metropolitan area of Porto Alegre (MAPA), RS, Brazil. Extraction, isolation/derivatization, and subsequently gas chromatography with electron capture detection (GC/ECD) were the techniques used to extract and determine NPAHs (1-nitronaphthalene, 2-nitrofluorene,3-nitrofluoranthene,1-nitropyrene, and 6-nitrochrysene) associated with PM1 Airborne particles (PM1) were collected using PTFE filters in a PM162M automatic sampler. The analytical method was validated by the Standard Reference Material - SRM 1649 b - from the National Institute of Standards and Technology (NIST, USA). The results were consistent with the certified values. 3-NFlt and 6-NChr reached highest concentrations of 0.047 ng·m(-3) and 0.0284 ng·m(-3), respectively, in Sapucaia do Sul and Canoas. Seasonal variation showed higher NPAH concentrations in cold days. The NPAHs associated with PM1 were correlated with the pollutants nitrogen oxides and NPAHs with meteorological variables: temperature and wind speed. The results indicated that vehicles with diesel engines were influential. This was confirmed by the study of the ratios NPAHs/PAHs, 1-NPyr/Pyr, and 6-NChr/Chr.

Analysis of carcinogenic polycyclic aromatic hydrocarbons in complex environmental mixtures by LC-APPI-MS/MS

Here we developed a highly sensitive, fast and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the detection and analysis of 16 different polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs that have been identified as carcinogens and classified according to their biological potency. Comparison to standard analysis procedures based on gas chromatography-mass spectrometry (GC-MS) instrumentation demonstrated an improved easiness of sample preparation and sensitivity of detection achieved with the new LC-MS/MS method employing an atmospheric pressure photoionization (APPI) source attached to an API 4000 mass spectrometer (LC-APPI-MS/MS). The favorable outcome could be confirmed by analyzing complex mixtures such as certain Standard Reference Materials (SRMs) obtained from the National Institute of Standards & Technology (NIST), i.e., SRM 1975 and SRM 2975, and several diesel exhaust soots provided by the German automobile industry. Certified concentrations of individual analytes provided by NIST not only could be confirmed, but additional extremely potent carcinogens such as several isomeric hexacyclic dibenzopyrenes (DBPs), 5-methylchrysene (5-MC), and others have been detected in these crude samples in a concentration range down to below 1 ng g(-1) raw material.