Atmospheric pressure chemical ionization in gas chromatography-mass spectrometry for the analysis of persistent organic pollutants

Atmospheric pressure chemical ionization (APCI) was primarily applied as the ion source for liquid chromatography-mass spectrometry (LC–MS). While APCI started to be used in gas chromatography-mass spectrometry (GC–MS) in 1970s, GC-APCI-MS was not widely used until recently. As a soft ionization technique, APCI provides highly diagnostic molecular ions, which is favored for the wide-scope screening. With the capability of tandem mass spectrometry (MS/MS), GC-APCI-MS methods with high sensitivity and selectivity have been developed and applied in the analysis of persistent organic pollutants (POPs) in environment and biological samples at trace levels. The present review introduces the history of the APCI source, with emphasis on mechanisms of ionization processes under the positive and negative ionization modes. Comparison between GC-APCI-MS and GC–MS with traditional electron ionization (EI) and chemical ionization (CI) are provided and discussed for selectivity, sensitivity and stability for the analyses of POPs. Previous studies found that the GC-APCI-MS methods provided limits of detection (LODs) around 10–100 times lower than other methods. An overview of GC-APCI-MS applications is given with the discussions on the advantages and drawbacks of various analytical methods applied for the analyses of POPs.     

Determination of organic priority pollutants in sewage treatment plant effluents by gas chromatography high-resolution mass spectrometry

In this work, we report the development and validation of an analytical method for the trace level determination of 14 selected (EU-directive) priority organic pollutants (namely, 1,2,3-trichlorobenzene (1,2,3-TCB), 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, hexachloro-1,3-butadiene, pentachlorobenzene, hexachlorobenzene, alachlor, α-hexachloro-cyclohexane (α-HCH), β-HCH, γ-HCH (lindane), δ-HCH, tetra-brominated diphenyl ether (tetra-BDE), penta-brominated diphenyl ether and hepta-brominated diphenyl ether) in wastewater samples from 5 different sewage treatment plants (STPs) located in Spain. The proposed methodology is based on liquid-liquid extraction with n-hexane followed by identification and confirmation of the selected pollutants by gas chromatography high-resolution mass spectrometry in selected ion recording acquisition mode. Recovery studies performed with spiked wastewater samples at two different concentration levels (0.1 and 1 μg L⁻¹) gave mean recoveries in the range 80-120% (except for trichlorobenzenes, ca. with 50%) with RSD values below 10% in most cases, thus confirming the usefulness of the proposed methodology for the analyses of this kind of complex samples. The obtained detection limits in effluent wastewater matrices were in the low nanogram per liter range, with values as low as 0.09 ng L⁻¹ for tetra-BDE and 0.3 ng L⁻¹ for hexachlorobenzene. Finally, the proposed methodology was successfully applied to a monitoring study intended to characterize wastewater effluents of 5 different sewage treatment plants with different major activities (Industrial, Coastal, Urban). Most of the compounds targeted were detected in the ng L⁻¹ range at concentrations ranging from 0.19 ng L⁻¹ to 135 ng L⁻¹ (hexachlorobenzene).     

Sampling and analysis of volatile organic compounds in air using a dualsorbent trap

Summary A dualsorbent trap containing graphitized carbon blacks was used for the collection of volatile and semi-volatile organic pollutants from the atmosphere of different workplaces and from an above-ground parking lot. The method proved to be sensitive, simple and reliable. Thermal desorption and solvent extraction methods followed by GC-MS analysis were employed.     

Analysis of 51 persistent organic pollutants in soil by means of ultrasonic solvent extraction and stir bar sorptive extraction GC-MS

A novel method based on ultrasonic solvent extraction and stir bar sorptive extraction (SBSE) for the analysis of 51 persistent organic pollutants including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenylethers (PBDEs) in soil samples was developed. The different parameters that affect both the extraction of analytes from the soil samples, such as solvent selection, solvent volume, mass of soil, and extraction time, and the partitioning from the solvent/water mixture to the PDMS were studied. The final selected conditions consisted of the extraction of 1 g of soil with 15 mL methanol by sonication for 30 min. The methanol extract was mixed with 85 mL of Milli-Q water and extracted by means of SBSE for 14 h at 900 rpm. The stir bars were analyzed by thermal desorption-GC-mass spectometry (TD-GC-MS). The effects of the matrix on the recovery of the various pollutants under the developed method were studied using two soils with very different physicochemical properties. Method sensitivity, linearity, repeatability, and reproducibility were also studied. Validation and accuracy of the method were conducted by analyzing two commercial certified reference materials (CRMs). The main advantage of this method resides in the fact that a small amount of a nontoxic solvent (methanol) is needed for the extraction of only 1 g of solid sample allowing LODs ranging from 0.01 to 2.0 microg/kg. Repeatability and reproducibility variations were lower than 20% for all investigated compounds. Results of the CRMs verify the high accuracy of this method.     

Odour-causing organic compounds in wastewater treatment plants: evaluation of headspace solid-phase microextraction as a concentration technique

Odorous emissions from wastewater collection systems and treatment facilities affecting quality of life have given local populations reasons to complain for decades. In order to characterise the composition of such malodorous emissions, a method based on headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC-MS) has been developed to determine a list of compounds belonging to different chemical families, which have been previously described as potentially responsible for odour complaints, in wastewater matrices. Some parameters affecting the chromatographic behaviour of the target compounds were studied (e.g. splitless time). Experimental conditions affecting the extraction process (temperature, time and salt content) were evaluated by applying a factorial design at two levels. Using a DVB/CAR/PDMS fibre and the optimised HS-SPME conditions, calibration curves were constructed with detection limits in the range of 0.003-0.6 μg L(-1). Recovery values higher than 70% and relative standard deviation values between 5 and 16% (n=5) were obtained for all compounds and found to be satisfactory. In wastewater samples, a decrease in the concentration of the analysed compounds through the different treatments was observed. Most of the target analytes were found in influent samples while only octanal and carvone were detected in samples from the plant effluent.     

Application of BaTiO3-based catalysts for piezocatalytic,photocatalytic and piezo-photocatalytic degradation of organic pollutants and bacterial disinfection in wastewater: A comprehensive review

The coupling of piezocatalysis and photocatalysis known as piezo-photocatalysis has attracted a lot of attention as one of the most effective advanced oxidation process (AOPs) for wastewater treatment, especially for the degradation of organic pollutants and disinfection of microbes. To advance this technology, there’s a need to develop lead free piezoelectric materials to drive both piezocatalytic and photocatalytic process to prevent secondary pollution due to lead toxicity. Hence, barium titanate (BaTiO₃) has been widely used as lead free piezoelectric material for several applications including water splitting, bacterial disinfection, and wastewater treatment due to its exceptional optical and piezoelectric properties. This work presents a comprehensive review on the application of BaTiO₃ as a promising lead-free piezo-photocatalyst for the catalytic degradation of organic pollutants and bacterial disinfection from aqueous solution. This review article details the optical and piezoelectric properties, modification strategies, and synthetic methods of BaTiO₃. Furthermore, the application of BaTiO₃ as a preferred piezo-photocatalyst for wastewater treatment and a future perspective is presented.     

基于色谱-质谱联用的新型有机污染物分析方法与技术

新型有机污染物是目前国内外关注的热点。在发现和分析新型有机污染物方面色谱-质谱联用技术发挥着至关重要的作用。本文对5类新型有机污染物(全氟化合物、药物、饮用水消毒副产物、农药转化产物和新农药、溴化阻燃剂)的主要色谱-质谱联用技术进行了介绍和评价,并对色谱-质谱联用的发展趋势进行了展望。     

Separation and preconcentration of persistent organic pollutants by cloud point extraction

Persistent organic pollutants (POPs) are recognized as a class of poisonous compounds which pose risks of causing adverse effects to human health and the environment. Thus, it is very important to detect POPs in environmental and biological samples. The identification and determination of very low levels of POPs in complex matrices is extremely difficult. Recently a promising environmentally benign extraction and preconcentration methodology based on cloud point extraction (CPE) has emerged as an efficient sample pretreatment technique for the determination of trace/ultra-trace POPs in complex matrices. The purpose of this paper is to review the past and latest use of CPE for preconcentrating POPs and its coupling to different contemporary instrumental methods of analysis. First, the comparison of various extraction techniques for POPs is described. Next, the general concept, influence factors and other methods associated with CPE technique are outlined and described. Last, the hyphenations of CPE to various instrumental methods for their determination are summarized and discussed.     

Analysis of volatile organic compounds in wastewater during various stages of treatment for high-tech industries

Summary A protocol combining purge-and-trap (P&T) and solid-phase microextraction (SPME) was established for the analysis of volatile organic compounds (VOCs) in the wastewater plant of high-tech industries. Over 60 VOCs could be analyzed by P&T coupled to gas chromatography/mass spectrometry (P&T-GC-MS). Four polar VOCs commonly used in the high-tech industries were determined by SPME coupled to gas chromatography/flame ionization detection (SPME-GC-FID). The limits of detection for the analytes were less than 1.1 μg L⁻¹ with P&T-GC-MS, and between 1.5 and 12.5 μg L⁻¹ with SPME-GC-FID. Satisfactory recoveries (83% to 130%) were obtained. Real samples were analyzed from a wastewater treatment plant during various stages of treatment. The major pollutant in the wastewater influent was found to be acetone (>4 ppm).     

Semiquantitative determination of residues of amphetamine in sewage sludge samples

A procedure based on HPLC and mass spectrometric detection has been developed for screening of residues of the illicit drug amphetamine in sewage sludge. Sample pretreatment consisted in extraction by 50 mM formic acid and methanol (80:20 v/v), followed by adjustment of the pH to 10 and preconcentration by SPE at poly(di-vinylbenzene)-N-vinylpyrrolidone. HPLC separation of the extract was done on a C18 RP with a mixture of 50 mM formic acid and methanol (80:20 v/v) as mobile phase. The mass spectrometer was operated in the MS2 and MS3 mode using the transition from m/z 136 to 119 and from m/z 119 to 91. Due to the complex matrix, ionization suppression effects as well as shifts in the sensitivity of the detector within a series of runs could not be fully excluded. Therefore, quantitation was done by standard addition together with external standards, so that semiquantitative results could be obtained down to concentrations of 2 microg/kg sewage sludge. Samples taken from various municipal sewage treatment plants indicate that amphetamine residues are ubiquitous in urban areas.     

A review of the determination of persistent organic pollutants for environmental forensics investigations

The field of environmental forensics emerged in the 1980s as a consequence of legislative frameworks enacted to enable parties, either states or individuals, to seek compensation with regard to contamination or injury due to damage to the environment. This legal environment requires stringent record keeping and defendable data therefore analysis can sometimes be confined to data to be obtained from certified laboratories using a standard accredited analytical method. Many of these methods were developed to target specific compounds for risk assessment purposes and not for environmental forensics applications such as source identification or age dating which often require larger data sets. The determination of persistent organic pollutants (POPs) for environmental forensic applications requires methods that are selective but also cover a wide range of target analytes which can be identified and quantified without bias. POPs are used in a wide variety of applications such as flame retardants, fire suppressants, heat transfer agents, surfactants and pesticides mainly because of their chemical inertness and stability. They also include compounds such as dioxins that can be unintentionally produced from industrial activities. POPs are persistent in the environment, bioaccumulative and/or toxic and therefore require analytical methods that are sensitive enough to meet the low detection limits needed for the protection of the environment and human health. A variety of techniques, procedures and instruments can be used which are well suited for different scenarios. Optimised methods are important to ensure that analytes are quantitatively extracted, matrix coextractables and interferences are removed and instruments are used most effectively and efficiently. This can require deviation from standard methods which can open the data up to further scrutiny in the courtroom. However, when argued effectively and strict QA/QC procedures are followed the development and optimization of methods based on investigation specific scenarios has the potential to generate better quality and more useful data.     

Application of dispersive liquid–liquid microextraction and gas chromatography with mass spectrometry for the determination of oxygenated volatile organic compounds in effluents from the production of petroleum bitumen

We present a new procedure for the determination of oxygenated volatile organic compounds in samples of postoxidative effluents from the production of petroleum bitumens using dispersive liquid–liquid microextraction and gas chromatography with mass spectrometry. The eight extraction parameters were optimized for 43 oxygenated volatile organic compounds. The detection limits obtained ranged from 0.07 to 0.82 μg/mL for most of the analytes, the precision was good (relative standard deviation below 2.91% at the 5 μg/mL level and 4.75% at the limit of quantification), the recoveries for the majority of compounds varied from 70.6 to 118.9%, and the linear range was wide, which demonstrates the usefulness of the procedure. The developed procedure was used for the determination of oxygenated volatile organic compounds in samples of raw postoxidative effluents and in effluents after chemical treatment. In total, 23 compounds at concentration levels from 0.37 to 32.95 μg/mL were identified in real samples. The same samples were also analyzed in the SCAN mode, which resulted in four more phenol derivatives being identified and tentatively determined. The studies demonstrated the need for monitoring volatile organic compounds content in effluents following various treatments due to the formation of secondary oxygenated volatile organic compounds.     

Low-temperature plasma ionization source for the online detection of indoor volatile organic compounds

A simple-structure, low-power, and low-cost low temperature plasma (LTP) ionization source, coupled with mass spectrometry, for the online detection of indoor volatile organic compounds (VOCs) has been constructed in this work. Air, instead of noble gases, was employed as the discharging and carrier gas. And a custom-built AC high-voltage power supply with a total power consumption of 5 W, frequency of 2-4 kHz, and amplitude around 1-5 kV_p-p was used. This LTP source is a soft ionization source. The initial performance of the ionization source has been evaluated by ionizing samples including alcohols, ketones, aldehydes and aromatics. These compounds cover most of the common air pollutants concerning people's health. It is well known that those plasmas generated by dielectric barrier discharge (DBD) produce significant amount of metastable species and electrons with mean energies greater than several electronvolt, but minimal fragmentation was observed in our work. Protonated ions are the dominant product for the VOCs detected after the ionization process. Further work has been conducted to confirm the detection feature of this source. The results are promising enough to ensure the novel LTP ionization source as an effective tool for the online detection of indoor VOCs.     

Persistent organic pollutants in edible fish: a human and environmental health problem

Many persistent organic pollutants (POPs) pose serious health hazards to both the environment and human. Among these, polychlorobiphenyls (PCBs) are probable human carcinogens and can also pose non-cancer health hazards to intellectual functions and the nervous, immune and reproductive systems. The risks and hazards associated with POP residues in tissues are a function of the dioxin-like compound toxicity and an individual's exposure. Fish consumption might become a serious problem because of bioaccumulation as revealed in many studies worldwide.We report data concerning the accumulation and pattern of hexachlorobenzene (HCB), p,p′-DDE and PCBs in edible tissues of commercial fish species (bluefin tuna Thunnus thynnus, swordfish Xiphias gladius, Atlantic mackerel Scomber scombrus) from Italian Seas and of the Antarctic toothfish Dissostichus mawsoni from the Ross Sea (Antarctica). The species analyzed are part of the human diet. 2,3,7,8-TCDD toxic equivalents (TEQs) and tolerable weekly intake (TWI) were also calculated to evaluate the toxic hazard for the population that include them in their diet.Gaschromatography revealed 0.16±0.24 and 0.4±0.2 ng/g wet wt of HCB in Antarctic toothfish and bluefin tuna, respectively. p,p′-DDE concentrations were 38±29 and 31±38 ng/g wet wt in swordfish and bluefin tuna muscle, respectively, and 0.66±0.57 ng/g wet wt in the Antarctic toothfish. PCBs showed higher concentrations and they were 89±82, 80±86 and 5.2±4.0 ng/g wet wt in the muscle of swordfish, bluefin tuna and Antarctic toothfish, respectively. In Mediterranean fish, the most abundant congeners were the most persistent PCB numbers 153, 138, 180, 118 and 170, which accounted for 51% and 47% of the total PCB residue in tuna fish and swordfish, respectively, and 18% in the Antarctic toothfish. TEQs were 1.97 and 4.65 pg/g wet wt in bluefin tuna muscle and gonads, respectively, and 0.11 pg/g wet wt in Antarctic toothfish. The TEQ weekly intake was calculated and values ranged 197–465 pg_TEQ/week when consuming 100 g of Mediterranean fish and therefore lower than the recommended TWI. Those values were higher (788–1860 pg_TEQ/week) than the recommended TWI, if 400 g of fish/week was consumed (with the exception of Antarctic fish).     

Analytical methods for the determination of selected steroid sex hormones and corticosteriods in wastewater

An analytical method for the determination of 12 selected estrogens, progestagens and corticosteroids is presented. The optimization of the method, including liquid chromatography separation, extraction on a solid phase, purification on a silica gel cartridge and detection by mass spectrometry, is described. Both the repeatability, with relative standard deviation ranging from 1.4 to 2.7%, and the accuracy, with recoveries ranging from 92.7 to 102.4%, were very satisfactory for ten of the target analytes. The limits of detection were lower than 1 ng/L for progestagens, androgens and corticosteroids, and ranged between 0.9 and 4.3 ng/L for estrogens. The results of the analysis of two sewage treatment plants in the area of Lyon (France) by this method reveal that all the compounds investigated are present in the effluents. The estrogen most frequently detected was estrone, with a median of 26.1 ng/L. The target progestagens were detected with concentrations ranging between 5 and 41 ng/L. Androgens were also present in most of the samples in the range 1–30 ng/L, while the corticosteroids were present only in one plant, with a median of 31.9 ng/L.     

An overview on the accumulation, distribution, transformations, toxicity and analytical methods for the monitoring of persistent organic pollutants

Recent years have seen an upsurge of interest in developing low cost and reliable methods for the detection and precise determination of ultra-trace concentrations of persistent organic pollutants (POPs), because of their bioaccumulation, transformation and toxicity. Therefore, a comprehensive review with 108 references referring to the distribution, source, accumulation, transformation, types and toxicity of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) is presented. The review also aims to highlight on the current best practices for the analysis of PCBs and OCPs. Moreover, with the signing of the Stockholm convention on POPs and the development of global monitoring programs, there is an increased need for laboratories in developing countries to determine such class of chemicals. A major focus revealed the need for low cost methods that can be implemented easily in developing countries such as electrochemical techniques.     

Calibration of mass selective detector in non-target analysis of volatile organic compounds in the air

Volatile organic compounds (VOCs) play an important role in the chemistry of the atmosphere and in biogeochemistry. They contribute to the oxidative capacity of the atmosphere, particle and air pollutants, as well as to the production of greenhouse gases (for instance ozone). Among analytical techniques for their determination in the atmosphere gas chromatography coupled with mass spectrometry (GC-MS) offers several advantages. However, for an accurate quantification calibration with standard substances is necessary. A quantitative structure-property relationship (QSPR) model for the prediction of MS response factors was developed on basis of our experimental measurements for the quantification of ozone precursors present in the atmosphere. A linear correlation between chemical structures and response factors was established by using a 7-parameter MLR model. The average error in the prediction of response factors was calculated by cross-validation procedure and was below 20%, which is sufficient for the determination of VOCs in the air. The proposed procedure is time consuming so it is more suited for the quantification of tentatively identified organic compounds during the reprocessing of MS chromatograms in cases when the original sample is no longer available.     

Analysis of persistent organic pollutants in marine sediments using a novel microwave assisted solvent extraction and liquid-phase microextraction technique

A simple and novel analytical method for quantifying persistent organic pollutants (POPs) in marine sediments has been developed using microwave assisted solvent extraction (MASE) and liquid-phase microextraction (LPME) using hollow fibre membrane (HFM). POPs studied included twelve organochlorine pesticides (OCP) and eight polychlorinated biphenyl (PCB) congeners. MASE was used for the extraction of POPs from 1 g of sediment using 10 ml of ultrapure water at 600 W for 20 min at 80 degrees C. The extract was subsequently subjected to a single step LPME-HFM cleanup and enrichment procedure. Recovery varied between 73 and 111% for OCPs; and 86-110% for PCBs, and exceeded levels achieved for conventional multi-step Soxhlet extraction coupled with solid-phase extraction. The method detection limit for each POP analyte ranged from 0.07 to 0.70 ng g(-1), and peak areas were proportional to analyte concentrations in the range of 5-500 ng g(-1). Relative standard deviations of less than 20% was obtained, based on triplicate sample analysis. The optimized technique was successfully applied to POP analysis of marine sediments collected from the northeastern and southwestern areas of Singapore's coastal environment.