Sensitive determination of triazines in underground waters using stir bar sorptive extraction directly coupled to automated thermal desorption and gas chromatography–mass spectrometry

Solvent-free automated thermal desorption-gas chromatography/mass spectrometry for direct screening of hazardous compounds in consumer textiles

The global production of textiles utilizes numerous large-volume chemicals that may remain to some extent in the finished garments. Arylamines, quinolines, and halogenated nitrobenzene compounds are possible mutagens, carcinogens and/or skin sensitizers. For prevention, control of clothing and other textiles must be improved, especially those imported from countries without regulations of textile chemicals. An automated analytical methodology with on-line extraction, separation, and detection would largely simplify screening surveys of hazardous chemicals in textiles. Automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) was developed and evaluated as a solvent-free, direct chemical analysis for screening of textiles. It requires a minimum of sample handling with a total run time of 38 min including sample desorption, chromatographic separation, and mass spectrometric detection. For most of the studied compounds, method quantification limit (MQL) was below 5 µg/g for 5 mg of textile sample, which is sufficiently low for screening and control of quinoline and arylamines regulated by EU. Several chemicals were detected and quantified when the ATD-GC/MS method was applied in a limited pilot screening of synthetic fiber garments. A number of arylamines were detected, where some of the halogenated dinitroanilines were found in concentrations up to 300 µg/g. This is ten times higher than the concentration limit for similar arylamines listed by the EU REACH regulation. Other chemicals detected in the investigated textiles were several quinolines, benzothiazole, naphthalene, and 3,5-dinitrobromobenzene. Based on the present results, we suggest ATD-GC/MS as a screening method for the control of harmful chemicals in clothing garments and other textiles.

Mechanochemically sulfidated zero-valent iron as persulfate activation catalyst in permeable reactive barriers for groundwater remediation - A feasibility study

The technology of permeable reactive barriers is reliable and economically effective to prevent the spread of pollutants in groundwaters. Yet, it is efficacious only with easily reducible chemicals such as heavy metals and halogenated organics. In the present study, sulfidated zero-valent iron solventless synthesized by ball-milling is proposed as a possible barrier filling for activation of persulfate to achieve sound removal of reduction-resistant organic pollutants (the herbicide atrazine was used as a model pollutant). Preliminary batch experiments demonstrated rapid degradation of atrazine. Continuous experiments executed in columns proved the superior efficiency of sulfidated iron as a persulfate activator, compared to zero-valent iron, in terms of removal of both atrazine and byproducts. Optimal atrazine removal in the column was achieved with 10% sulfidated iron packing, and 9 mM persulfate at a hydraulic residence time of 6.02 h. Under such conditions, the estimated bed length of the reactive barrier for 99% atrazine removal was 8.69 cm. The morphology and surface-active species in the column demonstrated that activation of persulfate mainly occurred at the inlet of the column until the complete usage of the active species. Batch experiments with coexisting ions suggested that they have a minor influence on atrazine removal percentage, while Mg2+, Ca2+, CO2- and HCO- had a significant impact on the kinetics of the process. However, analogous column experiments demonstrated that the coexisting ions have a negative influence on both atrazine and its byproducts. The results obtained in this study corroborate the potential application of persulfate-enhanced permeable reactive barriers for in situ removal of atrazine from underground water.

Recent advances in the extraction of triazine herbicides from water samples

Pesticides are excessively used in agriculture to improve the quality of crops by eliminating the negative effects of pests. Among the different groups of pesticides, triazine pesticides are a group of compounds that contain a substituted C₃ H₃ N₃ heterocyclic ring, and they are widely used. Triazine pesticides can be dangerous for humans as well as for the aquatic environment because of their high toxicity and endocrine disrupting effect. However, the concentration of these chemical compounds in water samples is low. Moreover, other compounds that may exist in the water samples can interfere with the determination of triazine pesticides. As a result, it is important to develop sample preparation methods that provide preconcentration of the target analyte and sufficient clean-up of the samples. Recently, a wide variety of novel microextraction and miniaturized extraction techniques (e.g., solid-phase microextraction and liquid-phase microextraction, stir bar sorptive extraction, fabric phase sorptive extraction, dispersive solid-phase extraction, and magnetic solid-phase extraction) have been developed. In this review, we aim to discuss the recent advances regarding the extraction of triazine pesticides from environmental water samples. Emphasis will be given to novel sample preparation methods and novel sorbents developed for sorbent-based extraction techniques.

Brominated Flame Retardants, Microplastics, and Biocides in the Marine Environment: Recent Updates of Occurrence, Analysis, and Impacts

Emerging contaminants (ECs) may pose adverse effects on the marine ecosystem and human health. Based on the analysis of publications filed in recent years, this paper provides a comprehensive overview on three prominent groups of ECs, i.e., brominated flame retardants, microplastics, and biocides. It includes detailed discussions on: (1) the occurrence of ECs in seawater, sediment, and biota; (2) analytical detection and monitoring approaches for these target ECs; and (3) the biological impacts of the ECs on humans and other trophic levels. This review provides a summary of recent advances in the field and remaining knowledge gaps to address, to enable the assessment of risk and support the development of regulations and mitigation technologies for the control of ECs in the marine environment.

Determination of Triazine Herbicides in Drinking Water by Dispersive Micro Solid Phase Extraction with Ultrahigh-Performance Liquid Chromatography-High-Resolution Mass Spectrometric Detection

A novel dispersive micro solid phase extraction (DMSPE) method based on a polymer cation exchange material (PCX) was applied to the simultaneous determination of the 30 triazine herbicides in drinking water with ultrahigh-performance liquid chromatography-high-resolution mass spectrometric detection. Drinking water samples were acidified with formic acid, and then triazines were adsorbed by the PCX sorbent. Subsequently, the analytes were eluted with ammonium hydroxide/acetonitrile. The chromatographic separation was performed on an HSS T3 column using water (4 mM ammonium formate and 0.1% formic acid) and acetonitrile (0.1% formic acid) as the mobile phase. The method achieved LODs of 0.2-30.0 ng/L for the 30 triazines, with recoveries in the range of 70.5-112.1%, and the precision of the method was better than 12.7%. These results indicated that the proposed method had the advantages of convenience and high efficiency when applied to the analysis of the 30 triazines in drinking water.

An environmentally friendly method for the determination of triazine herbicides in estuarine seawater samples by dispersive liquid-liquid microextraction

A fast, simple, sensitive and green chemistry method using dispersive liquid-liquid microextraction (DLLME) for the simultaneous determination of seven triazine herbicides (ametryn, atrazine, cyanazine, propazine, simazine, simetryn and terbuthylazine) in estuarine seawater samples has been developed. DLLME was carried out using a small volume of seawater (25 mL) and 300 μL of 1-octanol. Herbicide concentrations were determined by liquid chromatography-diode array detection, and results were confirmed by liquid chromatography-electrospray ionisation tandem spectrometry analysis. The analytical features of the proposed method were satisfactory with repeatability < ±5% and intermediate precision < ±10%, and recoveries ranged from 81-102% for all compounds. All the triazines exhibited linear matrix calibration curves with coefficients of determination >0.999 for all the analytes except for simazine (0.9975). Limits of quantification ranged between 0.19 and 1.12 μg L(-1). The method was applied to the analysis of seawater samples from ten points susceptible to contamination by triazines from estuary of A Coruña (Galicia, NW of Spain). The levels of the seven triazines were below the LODs in the analysed samples. Use of proposed method will allow for monitoring of triazines at levels below the regulatory limits set by the European Directive 2008/105/EC of 2 and 4 μg L(-1) for atrazine and simazine, respectively.

Application of a developed method for the extraction of triazines in surface waters and storage prior to analysis to seawaters of Galicia (northwest Spain)

A simple method based on solid-phase extraction combined with liquid chromatography for simultaneous determination of nine triazine herbicides (ametryn, atrazine, cyanazine, prometryn, propazine, simazine, simetryn, terbuthylazine, and terbutryn) in surface water samples was developed and validated. Under optimized conditions, 50 mL of water sample was pumped through the Oasis HLB cartridge, and triazines were eluted with 3 mL acetone. Finally the extract was concentrated to dryness, reconstituted with 1 mL methanol : water (1 : 1) and injected into the HPLC-DAD system. The stability of the herbicides on the cartridges at −18 and 4°C was also evaluated, and the recoveries obtained after three weeks of storage were satisfactory for all compounds. The analytical features of the proposed method were satisfactory: repeatability and intermediate precision were <10% and recoveries in spiked river water and seawater samples were higher than 93% for all compounds studied. Limits of quantification (varied from 0.46 to 0.98 µg L⁻¹) were adequately allowing the determination of these compounds at the levels requested by the 2008/105/EC Directive. Finally, this method was applied to the analysis of 50 seawater samples from Galicia (northwest Spain).

Sensitive determination of terazosin in pharmaceutical formulations and biological samples by ionic-liquid microextraction prior to spectrofluorimetry

An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF₆] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30% w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027 μg L⁻¹ and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future.

Current mass spectrometry strategies for the analysis of pesticides and their metabolites in food and water matrices

Analysis of pesticides and their metabolites in food and water matrices continues to be an active research area closely related to food safety and environmental issues. This review discusses the most widely applied mass spectrometric (MS) approaches to pesticide residues analysis over the last few years. The main techniques for sample preparation remain solvent extraction and solid-phase extraction. The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) approach is being increasingly used for the development of multi-class pesticide residues methods in various sample matrices. MS detectors-triple quadrupole (QqQ), ion-trap (IT), quadrupole linear ion trap (QqLIT), time-of-flight (TOF), and quadrupole time-of-flight (QqTOF)-have been established as powerful analytical tools sharing a primary role in the detection/quantification and/or identification/confirmation of pesticides and their metabolites. Recent developments in analytical instrumentation have enabled coupling of ultra-performance liquid chromatography (UPLC) and fast gas chromatography (GC) with MS detectors, and faster analysis for a greater number of pesticides. The newly developed "ambient-ionization" MS techniques (e.g., desorption electrospray ionization, DESI, and direct analysis in real time, DART) hyphenated with high-resolution MS platforms without liquid chromatography separation, and sometimes with minimum pre-treatment, have shown potential for pesticide residue screening. The recently introduced Orbitrap mass spectrometers can provide high resolving power and mass accuracy, to tackle complex analytical problems involved in pesticide residue analysis.

Chiral imprinted polymers as enantiospecific coatings of stir bar sorptive extraction devices

This paper reports the design of Molecularly Imprinted Polymers (MIP) with affinity towards (S)-citalopram using computational modeling for the selection of functional monomers and monomer:template ratio. Acrylamide was selected as functional monomer and the final complex functional monomer/template resulted in a 3:1 ratio. The polymer was synthesized by radical polymerization initiated by UV onto magnetic stir-bars in order to obtain a stir bar sorptive extraction (SBSE) device capable of selective enantiomeric recognition. After successful template removal, the parameters affecting the SBSE procedure (sample volume, ionic strength, extraction time and pH) were optimized for the effective rebinding of the target analyte. The resultant chirally imprinted polymer based stir-bar was able to selectively extract (S)-citalopram from a racemic mixture in an aqueous media with high specificity (specificity factor 4) between 25 and 500 μgL(-1). The MIP coated stir-bars can have significance for enantiospecific sample pre-concentration and subsequent analysis without the need for any chiral chromatographic separation.