Ion-pair in-tube solid phase microextraction for the simultaneous determination of phthalates and their degradation products in atmospheric particulate matter.

An in-tube solid phase microextraction, coupled with high-performance liquid chromatography with diode array detection (IT-SPME-HPLC-DAD) method, has been developed for the simultaneous determination of 13 diesters (from dimethyl to dioctylphthalate plus diisobutyl, benzylbutyl, di-2-ethylhexyl, diisononyl and diisodecylphthalate) and 2 monoesters of phthalic acid (mono-butyl and mono-(2-ethylhexyl) phthalate) in particulate matter (PM10). Triethylamine at pH=3 was used as an ion-pair reagent with a double function, of regulating the chromatographic retention of the monoesters and the most hydrophilic diesters on a monolithic silica column, and of improving their extraction on a porous polymer with divinylbenzene-4-vinylpyridine capillary. The chromatographic separation was achieved in 13min. A previous ultrasound-assisted extraction from PM10filters was also optimized using methanol as solvent. The method detection limits were 0.09-0.52ngm-3, the inter-day precision at concentration of 20ngmL-1 was between 4.2% and 12.7% (n=15), and the average recovery was 87.3%. The average absolute IT-SPME recovery was 26.2% and the linear range reached up to 109ngm-3 for most analytes. The method was applied to PM10 samples from different environments collected in Galicia (Spain). DiBP was the major phthalate, followed by its isomer DnBP in urban sites and by DEP in the suburban area. In all samples, DEHP quantified correlates with the isomers of dibutylphthalate. Total PAE concentration was between 14.5 and 245.5ngm-3. To the best of our knowledge, this is the first time that a method allows the simultaneous determination of 13 phthalates and their degradation products in particulate matter.

Trends in analytical methodologies for the determination of alkylphenols and bisphenol A in water samples.

In the last decade, the impact of alkylphenols and bisphenol A in the aquatic environment has been widely evaluated because of their high use in industrial and household applications as well as their toxicological effects. These compounds are well-known endocrine disrupting compounds (EDCs) which can affect the hormonal system of humans and wildlife, even at low concentrations. Due to the fact that these pollutants enter into the environment through waters, and it is the most affected compartment, analytical methods which allow the determination of these compounds in aqueous samples at low levels are mandatory. In this review, an overview of the most significant advances in the analytical methodologies for the determination of alkylphenols and bisphenol A in waters is considered (from 2002 to the present). Sample handling and instrumental detection strategies are critically discussed, including analytical parameters related to quality assurance and quality control (QA/QC). Special attention is paid to miniaturized sample preparation methodologies and approaches proposed to reduce time- and reagents consumption according to Green Chemistry principles, which have increased in the last five years. Finally, relevant applications of these methods to the analysis of water samples are examined, being wastewater and surface water the most investigated.

A comparative study of extractant and chromatographic phases for the rapid and sensitive determination of six phthalates in rainwater samples.

Six phthalic acid esters were determined in rainwater samples, from which a very low sample volume was collected. This method combines on-line in-tube solid-phase microextraction coupled to high-performance liquid chromatography with a diode-array detector. In order to obtain a short analysis time and to reduce the consumption of organic solvents, two chromatographic phases (C18 monolithic and cyanopropyl silica) are compared. Although three critical pairs are found, faster separation, good resolution and lower pressures are achieved using C18 monolithic column. In order to achieve a simple and sensitive method, two commercial capillaries (a porous polymer with divinylbenzene-4-vinylpyridine and a liquid-phase capillary with 95% poly(dimethylsiloxane)-5% poly(diphenylsiloxane)) are tested for the extraction process. Due to great differences of hydrophobicity among the six phthalates, the selection of a modifier is necessary for a good extraction. The best conditions are achieved using 5 mL of sample containing 40% methanol in a 70 cm-long porous polymer capillary. The procedural blanks are controlled and taken into account in the calculation of the detection limits. Except for dimethylphthalate, the method detection limits are in the range from 0.2 to 0.9 ng mL-1 and the inter-day precision is between 5.3% and 12.5%. The recoveries were within the range of 71%-101%. Rainwater samples are analyzed in order to examine the dilution effect and washout of phthalates in the atmosphere. Dibutyl phthalate is the predominant phthalate found and di-(2-ethylhexyl) phthalate is detected in all analyzed samples.

Reliable, rapid and simple method for the analysis of phthalates in sediments by ultrasonic solvent extraction followed by head space-solid phase microextraction gas chromatography mass spectrometry determination.

In this work, a new reliable, simple and fast method for the determination of six PAEs in sediments, based on ultrasonic solvent extraction (USE) followed by head space solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry determination (GC-MS), is proposed. The extraction parameters were studied, and the most favourable conditions were selected. The analytical features of the method were calculated: matrix effect, accuracy (ranged from 90% to 111%), repeatability and intermediate precision (RSD <10%), detection and quantification limits of the method (ranged from 0.001µgg-1 (DOP) to 0.142µgg-1 (DEP)), and satisfactory results were obtained. Major advantages of this approach are low consumption of reagents and solvents, no clean-up or evaporation steps were required and minimum sample manipulation. In addition, cross contamination from glassware, solvents and samples is minimized, thus procedural blanks are keeping to a minimum.. The applicability of the proposed method was demonstrated analysing sediment samples from Galician coast (NW Spain). The proposed method allows the application in routine laboratory conditions and its implementation in environmental monitoring studies under the European Water Framework Directive (WFD) and Marine Strategy Framework Directive (MSFD).

A novel and cost-effective method for the determination of fifteen polycyclic aromatic hydrocarbons in low volume rainwater samples.

A novel single-step method was developed for the determination of 15 polycyclic aromatic hydrocarbons (PAHs) at ultratrace levels in rainwater by on-line in-tube solid-phase microextraction (IT-SPME) coupled to high-performance liquid chromatography-photodiode array-fluorescence detection. This paper is focused on a study of the IT-SPME coupling and optimization, its application to rainwater and other environmental waters and the stability of PAH rainwater solutions. In order to solve the different extractive behavior of PAHs, several IT-SPME parameters were optimized, with the type and percentage of organic modifier playing a decisive role. In the kinetic study on stability of PAH solutions, the organic modifier has proven to be effective as a preservative, avoiding the loss of the higher-molecular weight PAHs. The proposed method presents a wide interval of linearity (10-1500ngL(-1)) and a good relative standard deviation between 3.4% and 14.6% for the PAHs analyzed. Detection and quantification limits between 2.3 and 28ngL(-1) and 5.7 and 65ngL(-1) were obtained respectively, taking into account the values of the procedure blanks. Recoveries for different kinds of real water samples were within the range of 72-110%. Low and medium-molecular weight PAHs predominate in daily and monthly rainwater samples analyzed. In comparison with other methods reported, the proposed method achieves a significant reduction of the sample volume, the organic solvent consumption and time of sample treatment, allowing a cost-effective analysis of environmental waters. The method is especially suitable for samples from the precipitation events of low intensity or short duration for which sample volume is limiting.

PAH detection in Quercus robur leaves and Pinus pinaster needles: A fast method for biomonitoring purpose.

Due to the complexity and heterogeneity of plant matrices, new procedure should be standardized for each single biomonitor. Thus, here is described a matrix solid-phase dispersion extraction method, previously used for moss samples, improved and modified for the analyses of PAHs in Quercus robur leaves and Pinus pinaster needles, species widely used in biomonitoring studies across Europe. The improvements compared to the previous procedure are the use of Florisil added with further clean-up sorbents, 10% deactivated silica for pine needles and PSA for oak leaves, being these matrices rich in interfering compounds, as shown by the gas chromatography-mass spectrometry analyses acquired in full scan mode. Good trueness, with values in the range 90-120% for the most of compounds, high precision (intermediate precision between 2% and 12%) and good sensitivity using only 250mg of samples (limits of quantification lower than 3 and 1.5ngg(-1), respectively for pine and oak) were achieved by the selected procedures. These methods proved to be reliable for PAH analyses and, having advantage of fastness, can be used in biomonitoring studies of PAH air contamination.

Occurrence of alkylphenols and bisphenol A in wild mussel samples from the Spanish Atlantic coast and Bay of Biscay.

Wild mussels (Mytilus galloprovincialis) were selected as bioindicators of chemical pollution to evaluate the occurrence and spatial distribution of five endocrine disrupting compounds in the Spanish Atlantic coast and Bay of Biscay. A total of 24 samples were collected in May, 2011 and analysed by selective pressurized liquid extraction followed by liquid chromatography tandem mass spectrometry determination. Branched alkylphenols (4-tert-octylphenol and nonylphenol) were determined in more than 90% of the analysed samples whereas the presence of linear alkylphenols (4-n-octylphenol and 4-n-nonylphenol) was scarcely detected (<12% of the samples). Wastewater treatment plants discharges and nautical, fishing and shipping activities were considered the primary sources of contamination by alkylphenols. Bisphenol A was found in 16% of the analysed samples associated to punctual industrial discharges. A total endocrine disrupting compound (alkylphenols and bisphenol A) average concentration of 604ngg(-1) dw was calculated and nonylphenol was the main contributor in almost all sampling points.

Strengths and weaknesses of in-tube solid-phase microextraction: A scoping review.

In-tube solid-phase microextraction (in-tube SPME or IT-SPME) is a sample preparation technique which has demonstrated over time its ability to couple with liquid chromatography (LC), as well as its advantages as a miniaturized technique. However, the in-tube SPME perspectives in the forthcoming years depend on solutions that can be brought to the environmental, industrial, food and biomedical analysis. The purpose of this scoping review is to examine the strengths and weaknesses of this technique during the period 2009 to 2015 in order to identify research gaps that should be addressed in the future, as well as the tendencies that are meant to strengthen the technique. In terms of methodological aspects, this scoping review shows the in-tube SPME strengths in the coupling with LC (LC-mass spectrometry, capillary LC, ultra-high-pressure LC), in the new performances (magnetic IT-SPME and electrochemically controlled in-tube SPME) and in the wide range of development of coatings and capillaries. Concerning the applicability, most in-tube SPME studies (around 80%) carry out environmental and biomedical analyses, a lower number food analyses and few industrial analyses. Some promising studies in proteomics have been performed. The review makes a critical description of parameters used in the optimization of in-tube SPME methods, highlighting the importance of some of them (i.e. type of capillary coatings). Commercial capillaries in environmental analysis and laboratory-prepared capillaries in biomedical analysis have been employed with good results. The most consolidated configuration is in-valve mode, however the cycle mode configuration is frequently chosen for biomedical analysis. This scoping review revealed that some aspects such as the combination of in-tube SPME with other sample treatment techniques for the analysis of solid samples should be developed in depth in the near future.

Occurrence, distribution and bioaccumulation of endocrine disrupting compounds in water, sediment and biota samples from a European river basin.

The occurrence, distribution and bioaccumulation of five endocrine disrupting compounds (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol and bisphenol A) in water, sediment and biota (Corbicula fluminea) collected along the Minho River estuary (NW Iberian Peninsula) were examined. Samples were collected in two campaigns (May and November, 2012) and analyzed by different extraction procedures followed by liquid chromatography tandem mass spectrometry determination. The presence of linear isomers (4-n-octylphenol and 4-n-nonylphenol) was scarcely observed whereas branched isomers (4-tert-octylphenol and nonylphenol) were measured in almost all samples. Wastewater treatment plant effluents and nautical, fishing and agricultural activities are considered the primary source of pollution of the river by alkylphenols. The presence of bisphenol A in the river could be mainly associated to punctual sources of contamination from industrial discharges. A decrease in the total concentration of phenolic compounds in water was observed from spring to autumn (from 0.888 µg L(-1) in May to 0.05 µg L(-1) in November), while similar values were shown in C. fluminea samples from the two campaigns (1388 and 1228 ng g(-1) dw in spring and autumn, respectively). In sediments, the total concentration of the target compounds varied between 13 and 4536 ng g(-1) dw (average of 1041 ng g(-1) dw). Sediment-water partition coefficient (Kd), bioaccumulation factor (BAF) and biota-sediment accumulation factor (BSAF) were estimated and highest values were obtained for nonylphenol. Calculated risk quotients showed low and moderate risk for the aquatic environment from the presence of the target compounds at all sampling points. The estimation of the daily intake of the studied compounds via water and biota ingestion indicated no risk for human health.

Pressurized hot water extraction followed by miniaturized membrane assisted solvent extraction for the green analysis of alkylphenols in sediments.

A novel and Green analytical methodology for the determination of alkylphenols (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol) in sediments was developed and validated. The method was based on pressurized hot water extraction (PHWE) followed by miniaturized membrane assisted solvent extraction (MASE) and liquid chromatography-electrospray ionization tandem mass spectrometry detection (LC-ESI-MS/MS). The extraction conditions were optimized by a Plackett-Burman design in order to minimize the number of assays according to Green principles. Matrix effect was studied and compensated using deuterated labeled standards as surrogate standards for the quantitation of the target compounds. The analytical features of the method were satisfactory: relative recoveries varied between 92 and 103% and repeatability and intermediate precision were <9% for all compounds. Quantitation limits of the method (MQL) ranged from 0.061 (4-n-nonylphenol) to 1.7ngg(-1) dry weight (nonylphenol). Sensitivity, selectivity, automaticity and fastness are the main advantages of the exposed methodology. Reagent consumption, analysis time and waste generation were minimized. The "greenness" of the proposed method was evaluated using an analytical Eco-Scale approach and satisfactory results were obtained. The applicability of the proposed method was demonstrated analysing sediment samples of Galicia coast (NW of Spain) and the ubiquity of alkylphenols in the environment was demonstrated.

Determination of organotin compounds in waters by headspace solid phase microextraction gas chromatography triple quadrupole tandem mass spectrometry under the European Water Framework Directive.

The European Union Water Framework Directive (2013/39/EU) sets very restrictive environmental quality standards for 45 priority substances and other pollutants, including organotin compounds (OTCs). Therefore, it is necessary to develop analytical methods in compliance with the environmental quality standard (EQSs) proposed to protect the aquatic environment and humans. The proposed method (HS-SPME-GC-QqQ-MS/MS) allows the determination of OTCs, i.e. monobutyltin (MBT), dibutyltin (DBT) and TBT in water in the range of few ng L(-1). The method is nearly full automated, sensitive and simple; it involves less reagents, reduces waste, and is less-time consuming than traditional methods for OTCs. As such, the procedure connects with the principles of green analytical chemistry. Additionally, good precision (RSD<20%), a very low method quantification limit (MQL) (0.76 ng L(-1) for TBT by using only 10 mL of sample) and excellent linearity (range MQL-20 ng L(-1)) are achieved. Under these conditions, the very restrictive limits for the environmental quality standards (EQS) fixed by the 2013/39/EU Directive are achieved.

Occurrence of endocrine disrupting compounds in five estuaries of the northwest coast of Spain: Ecological and human health impact.

The occurrence and spatial distribution of alkylphenols (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol) and bisphenol A were examined in five estuaries along the Northwest coastal area of Spain. As far as we know, no previous works about this topic could be found in the literature. A total of 98 seawater samples were collected during May 2011-July 2012 and analyzed by a highly sensitive DLLME-LC-MS/MS methodology recently developed. Results indicated nonylphenol was the most ubiquitous compound with maximal concentration of 0.337 µg L(-1) (Ría de Vigo). The environmental quality standards (EQS) established in Directive 2013/39/EU for 4-tert-octylphenol were slightly exceeded in some sampling points. Fishing harbours, water treatment plant and industrial discharges were supposed as the main sources of contamination. Low and medium ecological risk was determined in all estuaries. Possible endocrine effects on biota and population were estimated in terms of estrogenic activity and daily intake respectively, and no risk was found in any case.

Impact of medium-distance pollution sources in a Galician suburban site (NW Iberian peninsula).

This work studies airborne quality in a geographical area that has not been investigated broadly: a suburban site nearby A Coruña (Galicia, NW Iberian Peninsula). In contrast to major Spanish cities, the site has Atlantic characteristics: rainy, scarce calm weather and infrequent prolonged sunny periods. The relationships between several gaseous pollutants (NO, NO2, NOx, CO, O3, PM10, PM2.5 and PM1) and their temporal trends (daily, monthly and seasonal) were evaluated. The aim was to unravel whether medium- and long-distance sources were impacting upon the site. Univariate studies focused on factorizing the pollutants according to a codifying factor (wind direction, hour of the day, season and month). Multivariate studies (Varimax-rotated factorial analysis) were done separately on both weekdays and weekends. The intensity of the daily maxima for NO, NO2, NOx and CO was lower during the weekends, with O3 behaving opposite. PM average values agreed with previous historical reports for a rural background station relatively close to the site and they decreased daily between 11:00 and 19:00 h, likely because of the marine breeze. With moderate wind speeds the pollutants were associated to medium-distance pollution sources, mainly the city of A Coruña and a combination of industrial pollution sources (a power plant, a solid waste incinerator and a regional airport).

Analysis of endocrine disruptor compounds in marine sediments by in cell clean up-pressurized liquid extraction-liquid chromatography tandem mass spectrometry determination.

A less time-, solvent- and sorbent-consuming analytical methodology for the determination of bisphenol A and alkylphenols (4-tert-octylphenol, 4-octylphenol, 4-n-nonylphenol, nonylphenol) in marine sediment was developed and validated. The method was based on selective pressurized liquid extraction (SPLE) with a simultaneous in cell clean up combined with liquid chromatography-electrospray ionization tandem mass spectrometry in negative mode (LC-ESI-MS/MS). The SPLE extraction conditions were optimized by a Plackett-Burman design followed by a central composite design. Quantitation was performed by standard addition curves in order to correct matrix effects. The analytical features of the method were satisfactory: relative recoveries varied between 94 and 100% and repeatability and intermediate precision were <6% for all compounds. Uncertainty assessment of measurement was estimated on the basis of an in-house validation according to EURACHEM/CITAC guide. Quantitation limits of the method (MQL) ranged between 0.17 (4-n-nonylphenol) and 4.01 ng g(-1) dry weight (nonylphenol). Sensitivity, selectivity, automaticity and fastness are the main advantages of this green methodology. As an application, marine sediment samples from Galicia coast (NW of Spain) were analysed. Nonylphenol and 4-tert-octylphenol were measured in all samples at concentrations between 20.1 and 1409 ng g(-1) dry weight, respectively. Sediment toxicity was estimated and no risk to aquatic biota was found.

Determination of triazine herbicides in seaweeds: development of a sample preparation method based on Matrix Solid Phase Dispersion and Solid Phase Extraction Clean-up.

A method using dual process columns of Matrix Solid Phase Dispersion (MSPD) and Solid Phase Extraction (SPE) has been developed for extracting and cleaning-up of nine triazine herbicides (ametryn, atrazine, cyanazine, prometryn, propazine, simazine, simetryn, terbuthylazine and terbutryn) in seaweed samples. Under optimized conditions, samples were blended with 2g of octasilyl-derivatized silica (C8) and transferred into an SPE cartridge containing ENVI-Carb II/PSA (0.5/0.5 g) as a clean up co-sorbent. Then the dispersed sample was washed with 10 mL of n-hexane and triazines were eluted with 20 mL ethyl acetate and 5 mL acetonitrile. Finally the extract was concentrated to dryness, re-constituted with 1 mL methanol:water (1:1) and injected into the HPLC-DAD system. The linearity of the calibration curves was excellent in matrix matched standards, and yielded the coefficients of determination>0.995 for all the target analytes. The recoveries ranged from 75% to 100% with relative standard deviations lower than 7%. The achieved LOQs (<10 µg kg(-1)) for all triazines under study permits to ensure proper determination at the maximum allowed residue levels set in the European Union Legislation. Samples of three seaweeds were subjected to the procedure proving the suitability of MSPD method for the analysis of triazines in different seaweeds samples.

Determination of 13 estrogenic endocrine disrupting compounds in atmospheric particulate matter by pressurised liquid extraction and liquid chromatography-tandem mass spectrometry.

This paper describes the optimisation of an analytical method for the simultaneous determination of up to 13 estrogenic endocrine disrupting compounds (EDCs), including natural and synthetic estrogens, alkylphenols, bisphenol A and phthalate esters, in atmospheric particulate matter. This methodology is based on pressurised liquid extraction and liquid chromatography-tandem mass spectrometry and is the first method described for analysis of estrogens in air. Samples were collected with high-volume samplers equipped with quartz microfiber filters. Two selected reaction monitoring transitions were chosen for identification and confirmation of the target compounds. Quantitation was performed by the internal standard method with the use of deuterated surrogate standards. The analytical features of the method were satisfactory: absolute recoveries were around 45 % for all compounds, except estrogens (∼29 %), because of matrix effects. Repeatability was in all cases below 15 %. Quantitation limits of the method ranged from 5 pg/m(3) (for diethylphthalate) to 83 pg/m(3) (for 17-α-ethynylestradiol). As a part of the validation procedure, the developed method was applied to the analysis of eight air particulate samples (fine grain-size particles, PM2.5) collected in industrial, urban and non-polluted suburban areas of A Coruña (NW of Spain). Results evidenced the presence of dibutylphthalate, diethylhexylphthalate and nonylphenol in all samples. The highest concentration corresponded to dibutylphthalate (54.7 ng/m(3)) in an industrial area. Daily exposure to these EDCs in terms of estradiol equivalents (3 pg/day for toddlers and 5 pg/day for adults) is not expected to pose a risk to human health.

Membrane assisted solvent extraction coupled with liquid chromatography tandem mass spectrometry applied to the analysis of alkylphenols in water samples.

This work describes the development and validation of a novel, simple, sensitive and environmental friendly analytical method for the determination of alkylphenols in different types of water samples. The methodology was based on a membrane assisted solvent extraction of only 15 mL of water sample with 500 µL of hexane in combination with liquid chromatography-electrospray ionization tandem mass spectrometry in negative mode (LC-ESI-MS/MS). Acquisition was performed in the multiple reaction monitoring (MRM) mode recording two transitions for the identification of the target compounds. Quantitation is based on the use of deuterated labelled standards as surrogate standards. The figures of merit were satisfactory in all cases: absolute recoveries were close to 50% for most investigated compounds and relative recoveries varied between 81 and 108%. Repeatability and intermediate precision were <20% for all compounds. Uncertainty assessment of measurement was estimated on the basis of an in-house validation according to EURACHEM/CITAC guide. Quantitation limits of the method (MQL) were lower than 0.04 µg L(-1) in all cases, which allow the achievement of the limits established by the Directive 2008/105/EC for surface and seawater samples and by the new proposal COM (2011) 876 final. The feasibility of the proposed method was demonstrated analyzing seawater, surface water and drinking water samples from different areas of A Coruña (Northwest of Spain). The analyses evidenced the presence of nonylphenol in seawater (MQL-0.13 µg L(-1)) and surface water samples (0.12-0.19 µg L(-1)). The highest concentration was observed in drinking water (0.25 µg L(-1)).

Fast and selective pressurized liquid extraction with simultaneous in cell clean up for the analysis of alkylphenols and bisphenol A in bivalve molluscs.

A novel and green analytical methodology for the determination of alkylphenols (4-tert-octylphenol, 4-n-octylphenol, 4-n-nonylphenol, nonylphenol technical mixture) and bisphenol A in bivalve mollusc samples was developed and validated. The method was based on selective pressurized liquid extraction (SPLE) with a simultaneous in cell clean up combined with liquid chromatography­electrospray ionization tandem mass spectrometry in negative mode (LC­ESI-MS/MS). Quantitation was performed by standard addition curves in order to correct matrix effects. The analytical features of the method were satisfactory: relative recoveries varied between 80 and 107% and repeatability and intermediate precision were <20% for all compounds. Uncertainty assessment of measurement was estimated on the basis of an in-house validation according to EURACHEM/CITAC guide. Quantitation limits of the method (MQL) ranged between 0.34 (4-n-octylphenol) and 3.6 ng g(−1) dry weight (nonylphenol). The main advantages of the method are sensitivity, selectivity, automaticity, low volumes of solvents required and low sample analysis time (according with the principles of Green Chemistry). The method was applied to the analysis of mussel samples of Galicia coast (NW of Spain). Nonylphenol and 4-tert-octylphenol were measured in all samples at concentrations between 9.3 and 372 ng g(−1) dw. As an approach, the human daily intake of these compounds was estimated and no risk for human health was found.

Blank and sample handling troubleshooting in ultratrace analysis of alkylphenols and bisphenol A by liquid chromatography tandem mass spectrometry.

Blank contamination is a notorious problem in the ultratrace analysis of alkylphenols and bisphenol A. The achievement of low detection limits is complicated due to the high background signals. Furthermore, overestimations and underestimations in the analytical results can occur when blank levels are not stable. Thus, a review of sources of blank contamination in this type of analysis was carried out. Several sources of contamination were identified and useful guidelines are proposed for the determination of these compounds in water samples by liquid chromatography coupled with mass spectrometry. The system contamination was maintained below 0.09 ng (reagent blank) for all compounds and below 0.003 µg L(-1) (procedure blank). The main improvement was obtained by using LC-MS grade solvent in the mobile phase and PTFE syringe filters for the filtration of the sample extracts. Sample handling aspects such as filtration and storage of the water samples were also considered. The filtration of the samples should be avoided because both contamination and adsorption problems were observed when different kinds of filters were assayed. The refrigerated storage of water samples should be limited to 5 days (without addition of methanol) or 8 days (with 5% methanol).

Improving methodological aspects of the analysis of five regulated haloacetic acids in water samples by solid-phase extraction, ion-pair liquid chromatography and electrospray tandem mass spectrometry.

Haloacetic acids (HAAs) are organic pollutants originated from the drinking water disinfection process, which ought to be controlled and minimized. In this work a method for monitoring haloacetic acids (HAAs) in water samples is proposed, which can be used in quality control laboratories using the techniques most frequently available. Among its main advantages we may highlight its automated character, including minimal steps of sample preparation, and above all, its improved selectivity and sensitivity in the analysis of real samples. Five haloacetic acids (HAA5) were analyzed using solid-phase extraction (SPE) combined with ion-pair liquid chromatography and tandem mass spectrometry. For the optimization of the chromatographic separation, two amines (triethylamine, TEA and dibutylamine, DBA) as ion pair reagents were compared, and a better selectivity and sensitivity was obtained using DBA, especially for monohaloacetic acids. SPE conditions were optimized using different polymeric adsorbents. The electrospray source parameters were studied for maximum precursor ion accumulation, while the collision cell energy of the triple quadrupole mass spectrometer was adjusted for optimum fragmentation. Precursor ions detected were deprotonated, dimeric and decarboxylated ions. The major product ions formed were: ionized halogen atom (chloride and bromide) and decarboxylated ions. After enrichment of the HAAs in Lichrolut EN adsorbent, the limits of detection obtained by LC-MS/MS analysis (between 0.04 and 0.3 ng mL(-1)) were comparable to those obtained by GC-MS after derivatization. Linearity with good correlation coefficients was obtained over two orders of magnitude irrespective of the compound. Adequate recoveries were achieved (60-102%), and the repeatability and intermediate precision were in the range of 2.4-6.6% and 3.8-14.8%, respectively. In order to demonstrate the usefulness of the method for routine HAAs monitoring, different types of water samples were analyzed. In swimming pool water samples the ∑HAAs were determined between 76 and 154 ng mL(-1).