Improvements in the determination of eight polycyclic aromatic hydrocarbons through a stepwise interlaboratory study approach

A summarising account of a systematic stepwise approach based on interlaboratory studies carried out by a number of laboratories from European Union and EFTA countries is given. This approach has been designed to improve the analytical state of the art in the determination of selected polycyclic aromatic hydrocarbons in different environmental matrices. The approach resulted in a certification exercise to produce a sewage sludge as Certified Reference Material (CRM). The results of the programme showed that HPLC and GC are equally reliable for PAH analysis at submicrogram to microgram per gram levels in various environmental matrices. Major improvements were achieved during the programme, resulting in reduced coefficients of variation and between-laboratory differences. Several recommendations emerging from the programme experience are presented.     

Evaluation of a multiresidue method for measuring fourteen chemical groups of pesticides in water by use of LC-MS-MS

European Council Directive 98/83/EC on the quality of water intended for human consumption brought a new challenge for water-quality control routine laboratories, mainly on pesticides analysis. Under the guidelines of ISO/IEC 17025:2005, a multiresidue method was developed, validated, implemented in routine, and studied with real samples during a one-year period. The proposed method enables routine laboratories to handle a large number of samples, since 28 pesticides of 14 different chemical groups can be quantitated in a single procedure. The method comprises a solid-phase extraction step and subsequent analysis by liquid chromatography-mass spectrometry (LC-MS-MS). The accuracy was established on the basis of participation in interlaboratory proficiency tests, with encouraging results (majority |z-score| <2), and the precision was consistently analysed over one year. The limits of quantitation (below 0.050 μg L⁻¹) are in agreement with the enforced threshold value for pesticides of 0.10 μg L⁻¹. Overall method performance is suitable for routine use according to accreditation rules, taking into account the data collected over one year. Figure Simultaneous SPE extraction system for high thoughput analysis Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Notes: IAREN is an accredited laboratory under the ISO/IEC 17025:2005 for 165 analytical determinations and part of the NORMAN Network of Reference laboratories for monitoring of emerging environmental pollutants in the European Union. This work was presented (podium presentation) at the 12th Symposium on Sampling and Handling of the International Association of Environmental Analytical Chemistry (IAEAC), Zaragoza, 2006.     

Interlaboratory Study to Improve the Quality Control of Methylmercury Determination in Sediment

The results are presented of an interlaboratory study on methylmercury (MeHg) in sediment carried out by a group of European laboratories within the framework of a project managed by the EC Standards, Measurements and Testing Programme (formerly BCR). The aim of this exercise was to evaluate the performance of current methods used for MeHg determination in sediment in order to improve the state-of-the-art prior to the certification of a candidate reference material. The paper describes the organization of the interlaboratory study, the preparation of the sediment material used, the techniques evaluated and the results obtained by the participating laboratories. The outcome of the collaborative project showed that certification could be contemplated, providing that certain analytical techniques were optimized, especially with regard to extraction methods.     

Liquid chromatography-electrospray ionization isotope dilution mass spectrometry analysis of paraquat and diquat using conventional and multilayer solid-phase extraction cartridges

The performance of alkyl-silica sorbent packed solid-phase extraction (SPE) cartridges and a mixed-mode, polymeric sorbent packed SPE cartridge (resin SPE cartridge) were evaluated for the sample preparation of paraquat and diquat in environmental water and vegetation matrices. Also the recoveries of the native and 2H-labeled paraquat and diquat were correlated to validate that the 2H-labeled species can be used for the isotopic dilution mass spectrometry (IDMS) analysis of paraquat and diquat. The results show that the extraction efficiency of alkyl-silica SPE is dependent on the carbon loading of the sorbent and deteriorates with an increasing sample pH. The resin SPE cartridge required no pH adjustment and showed excellent correlation between the native and 2H-labeled species, therefore, allowing us to develop the first liquid chromatography-electrospray ionization IDMS analytical method for the analysis of paraquat and diquat in environmental water and vegetation matrices. Method detection limits derived using standard EPA protocol were 0.2 and 0.1 microg/l for paraquat and diquat in water matrices, and 0.02 and 0.01 microg/g in vegetation matrices, respectively.     

Laboratory intercomparison study on the analysis of short-chain chlorinated paraffins in an extract of industrial soil

Short-chain chlorinated paraffins (SCCPs) comprise a class of organic pollutants used in many industrial applications and released into the environment. The analytical determination of SCCPs is very challenging. Although there is at present no fully validated measurement procedure that might be applied in routine monitoring, the European Union Water Framework Directive (WFD) has required regular monitoring of this class of compounds at river-basin scale since 2007.To assess the status quo of the analysis of SCCPs in relation to the requirements of the WFD, we organized an interlaboratory comparison on the quantification of SCCPs in an extract of an industrial soil. Six laboratories participated in the exercise using three different techniques [i.e. gas chromatography (GC) coupled to mass spectrometry (MS) in electron-capture negative ionization mode, GC with atomic emission detection, and carbon-skeleton GC-MS]. The results reported were in the range 8.5–3200 mg/L. This confirms that reliable quantification of SCCPs is still very difficult to achieve and that the comparability of SCCP data reported to the European Commission is at least questionable.     

Inter-laboratory comparison of liquid chromatographic techniques and enzyme-linked immunosorbent assay for the determination of surfactants in wastewaters

Seven laboratories participated in an inter-laboratory comparison exercise within the framework of the PRISTINE, SANDRINE and INEXsPORT European Union Projects. Solid-phase extraction (SPE) methodologies were used for the extraction of target analytes from wastewaters. The analytical strategies were based on liquid chromatography (LC) coupled to mass spectrometric (MS) or to fluorescent (FL) detection in all cases with the exception of one laboratory using a test-tube enzyme-linked immunosorbent assay kit. Samples were spiked with the surfactants nonylphenolpolyglycol ether, coconut diethanolamide, linear alkylbenzene sulfonate, nonylphenolpolyglycol ether sulfate, alkylpolyglycol ether and secondary alkane sulfonate. After enrichment on previously conditioned SPE cartridges, the SPE cartridges were distributed among the participating laboratories without the information about the amount of spiked surfactants. In addition, SPE cartridges loaded with a real-world environmental sample containing a tannery wastewater were also analyzed. The results of the programme showed that SPE followed by LC-MS techniques are reliable for the surfactants determination at submicrogram to microgram per liter levels in wastewaters. Inter-laboratory precision values were calculated as the reproducibility relative standard deviation (RSD(R)) which was determined from the reproducibility standard deviation (sR) and the average concentration at a particular concentration level. When data from all laboratories were pooled, the RSD(R) values ranged from 5.1 to 28.3% for the determination of target analytes. The most accurate result corresponded to that given for linear alkylbenzene sulfonates. Taking into account that different methodologies were used (including non-chromatographic techniques) and the complexity of the samples analyzed, it can be considered that acceptable reproducibility values were obtained in this inter-laboratory study.     

Improvements in the determination of chlorobenzenes and chlorophenols through a stepwise interlaboratory study approach

A systematic quality control programme carried out by a number of laboratories from the European Union and from EFTA countries is described. The programme was designated to improve the analytical state of the art in the determination of selected chlorinated benzenes and chlorinated phenols in different environmental matrices. To that end a stepwise interlaboratory study approach was chosen, analysing, in consecutive order, a clean extract of soil, a raw extract and the soil itself. Eight analytes were selected for the study, i.e. three chlorobenzenes and five chlorophenols. During the programme significant improvements in analytical performance were achieved, as shown by a decrease in within-laboratory coeffficients of variation as well as by acceptable coefficients of variation in the mean value of laboratory means of all analytes in the final matrix analysed, i.e. a natural soil. The results of the programme prompted the European Union to embark upon a pentachlorophenol interlaboratory certification study to produce an industrial soil candidate Certified Reference Material (CRM) [1].     

Reference materials for PAHs in foodstuffs: Results of the certification exercise of two coconut oil reference materials

This certification exercise was the final stage of a stepwise interlaboratory study approach, organized within the SMT-program of the EC, for the development of certified reference materials (CRMs) for the determination of PAHs in foodstuffs. The certification exercise was carried out by thirteen European laboratories using a variety of extraction and clean-up procedures and different analytical procedures. Two different coconut oil materials were certified for their mass fractions of six selected PAHs.     

Improvements in the determination of chlorobenzenes and chlorophenols through a stepwise interlaboratory study approach

A systematic quality control programme carried out by a number of laboratories from the European Union and from EFTA countries is described. The programme was designated to improve the analytical state of the art in the determination of selected chlorinated benzenes and chlorinated phenols in different environmental matrices. To that end a stepwise interlaboratory study approach was chosen, analysing, in consecutive order, a clean extract of soil, a raw extract and the soil itself. Eight analytes were selected for the study, i.e. three chlorobenzenes and five chlorophenols. During the programme significant improvements in analytical performance were achieved, as shown by a decrease in within-laboratory coeffficients of variation as well as by acceptable coefficients of variation in the mean value of laboratory means of all analytes in the final matrix analysed, i.e. a natural soil. The results of the programme prompted the European Union to embark upon a pentachlorophenol interlaboratory certification study to produce an industrial soil candidate Certified Reference Material (CRM) [1]. Received: 28 August 1997 / Revised: 15 October 1997 / Accepted: 21 October 1997     

First European interlaboratory study of the analysis of benzoxazinone derivatives in plants by liquid chromatography

Six laboratories from four different countries participated in the first European interlaboratory comparison exercise within the framework of the "Fate and toxicity of allelochemicals (natural plant toxins) in relation to environment and consumer" (FATEALLCHEM) European Union Project. The study, organized between November 2002 and March 2003, involved the analyses of seven benzoxazinone derivatives in two standard solutions and one purified extract of root material. Results are reported from the first phase of the study that examined the variability associated with different detection methods and different laboratories. The analytical strategies were based on liquid chromatography (LC) with diode array detection, LC coupled to mass spectrometry (MS) and LC coupled to tandem MS. When data from all laboratories were pooled, the relative standard deviation values ranged from 2 to 14% for the determination of target compounds in standard solutions, and between 19 and 47% for the analysis in root material. Comparison of the three detection techniques leads to the conclusion that MS approaches are the most accurate and precise techniques for the determination of benzoxazinone derivatives at ng/microL level in plant material.     

Catching the elusive persistent and mobile organic compounds: Novel sample preparation and advanced analytical techniques

Persistent and Mobile Organic Compounds (PMOCs) are emerging pollutants in the environment that have only been rarely detected in previous years due to the lack of analytical techniques available for their analysis. These compounds, being very polar, are able to spread through the surface waters, and reach groundwaters and drinking water sources. The challenges in the analysis of these compounds in water include their poor extraction efficiencies from environmental matrices and weak retention in conventional chromatographic columns. As a result, the toxicity and environmental fate of PMOCs are largely unknown. This review will examine recent developments in sorbent and chromatographic column technologies, and other sample preparation strategies that will enable analysis of PMOCs and advance our knowledge on their fate and transport in the environment. In addition, analysis of these compounds in water via liquid chromatography with tandem mass spectrometry (LC–MS/MS) are discussed in this review.     

Reference materials for PAHs in foodstuffs: Results of the certification exercise of two coconut oil reference materials

This certification exercise was the final stage of a stepwise interlaboratory study approach, organized within the SMT-program of the EC, for the development of certified reference materials (CRMs) for the determination of PAHs in foodstuffs. The certification exercise was carried out by thirteen European laboratories using a variety of extraction and clean-up procedures and different analytical procedures. Two different coconut oil materials were certified for their mass fractions of six selected PAHs. Received: 25 May 1997 / Revised: 5 September 1997 / Accepted: 28 September 1997     

Optimization and validation of HPLC-UV-DAD and HPLC-APCI-MS methodologies for the determination of selected PAHs in water samples

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants resulting from emissions of a variety of sources including industrial combustion, discharge of fossil fuels, and residential heating. Because of their mutagenic and carcinogenic properties, the study of PAHs in environmental matrices is of great importance. In this work, the extraction of 9 out of the 16 PAH priority pollutants according to the U.S. Environmental Protection Agency is carried out through liquid-liquid extraction (LLE) and solid-phase extraction (SPE). The determination of PAHs is made by high-performance liquid chromatography with diode-array detection and liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. Between the extraction techniques used, LLE is revealed to be efficient in the extraction of the higher molecular weight PAHs, though SPE is adequate for the extraction of all PAHs. In the real water samples analyzed, no PAH is detected under the analysis conditions used.     

A programme to improve the quality of butyltin determinations in environmental matrices

One of the major prerequisites for the certification of various analytes in different Certified Reference Materials (CRMs) is that the analytical methods used are of verified performance and, hence, that no systematic errors have been left undetected. In the case of difficult measurements, research and feasibility studies are often necessary to ensure that the methods are operating under good quality control. The EC Standards Measurements and Testing Programme (SMT, formerly BCR) usually follows a step-by-step approach which consists in series of interlaboratory studies to assess and improve the quality of measurements prior to certification by comparing different analytical techniques. A programme following such stepwise approach has started in 1987 with the aim of improving the quality of butyltin determinations in environmental matrices. The project involved ca. 20 laboratories from different Member States of the European Union. The first interlaboratory study dealt with simple solutions containing mixtures of organotin compounds and a second exercise focused on the analysis of a tributyltin-spiked sediment. These exercises were continued by two certifications on butyltins in sediment, the first of which could not be successfully concluded owing to the high spread of results observed between the results of different techniques. The second certification allowed a CRM certified for its contents of di- and tributyltin (CRM 462) to be produced. This programme on Sn speciation is now focusing on the certification of butyltin and phenyltin compounds in candidate CRMs of mussel and sediment. This paper gives an account of the step-by-step approach followed and presents the results of the two certification exercises carried out so far. The preparation of the mussel candidate CRM is also described.     

Role of molecularly imprinted polymers for selective determination of environmental pollutants--a review

The molecularly imprinted polymers (MIPs) are synthetic polymers possessing specific cavities designed for a target molecule. By a mechanism of molecular recognition, the MIPs are used as selective tools for the development of various analytical techniques such as liquid chromatography, capillary electrochromatography, solid-phase extraction (SPE), binding assays and biosensors. This review describes the application of MIPs to the determination of environmental pollutants in these different analytical approaches with a special emphasis on their potential as selective SPE sorbent for the selective extraction of target analytes from complex matrices.     

Trace analysis of environmental matrices by large-volume injection and liquid chromatography–mass spectrometry

The time-honored convention of concentrating aqueous samples by solid-phase extraction (SPE) is being challenged by the increasingly widespread use of large-volume injection (LVI) liquid chromatography–mass spectrometry (LC–MS) for the determination of traces of polar organic contaminants in environmental samples. Although different LVI approaches have been proposed over the last 40 years, the simplest and most popular way of performing LVI is known as single-column LVI (SC-LVI), in which a large-volume of an aqueous sample is directly injected into an analytical column. For the purposes of this critical review, LVI is defined as an injected sample volume that is ≥10% of the void volume of the analytical column. Compared with other techniques, SC-LVI is easier to set up, because it requires only small hardware modifications to existing autosamplers and, thus, it will be the main focus of this review. Although not new, SC-LVI is gaining acceptance and the approach is emerging as a technique that will render SPE nearly obsolete for many environmental applications. In this review, we discuss: the history and development of various forms of LVI; the critical factors that must be considered when creating and optimizing SC-LVI methods; and typical applications that demonstrate the range of environmental matrices to which LVI is applicable, for example drinking water, groundwater, and surface water including seawater and wastewater. Furthermore, we indicate direction and areas that must be addressed to fully delineate the limits of SC-LVI.     

On-line solid phase extraction LC-MS/MS analysis of pharmaceutical indicators in water: A green alternative to conventional methods

A method using automated on-line solid phase extraction (SPE) directly coupled to liquid chromatography/tandem mass spectrometry (LC-MS/MS) has been developed for the analysis of six pharmaceuticals by isotope dilution. These selected pharmaceuticals were chosen as representative indicator compounds and were used to evaluate the performance of the on-line SPE method in four distinct water matrices. Method reporting limits (MRLs) ranged from 10 to 25 ng/L, based on a 1 mL extraction volume. Matrix spike recoveries ranged from 88 to 118% for all matrices investigated, including finished drinking water, surface water, wastewater effluent and septic tank influent. Precision tests were performed at 50 and 1000 ng/L with relative standard deviations (RSDs) between 1.3 and 5.7%. A variety of samples were also extracted using a traditional off-line automated SPE method for comparison. Results for both extraction methods were in good agreement; however, on-line SPE used approximately 98% less solvent and less time. On-line SPE coupled to LC-MS/MS analysis for selected indicators offers an alternative, more environmentally friendly, method for pharmaceutical analysis in water by saving time and costs while reducing hazardous waste and potential environmental pollution as compared with off-line SPE methods.     

EAL interlaboratory comparison Wa1 – Testing of potable water

 The accreditation of laboratories has emphasized the use of interlaboratory comparisons as a tool to monitor the comparability and accuracy of results laboratories produce. An interlaboratory comparison for water laboratories was organized among European Cooperation for Accreditation (EA) member countries; 30 laboratories, 7 of which were not accredited, from 14 European countries participated in this intercomparison. All the laboratories were chosen by the appropriate national accreditation bodies, with the instruction to select as participants those laboratories which act as national reference laboratories in this field. About 90% of the data collected was considered satisfactory after statistical treatment. Non-accredited laboratories performed as well as accredited laboratories. The laboratories were asked to take corrective action and report the corrections to the accreditation bodies. A great variation in the reported uncertainties of the results was observed. There seems to be a need to organize EA interlaboratory comparisons for national reference laboratories analysing water. It is obvious that even reference laboratories need training in how to estimate the uncertainty of results. Received: 22 July 1998 · Accepted: 21 September 1998     

Recently developed GC/MS and LC/MS methods for determining NSAIDs in water samples

Pharmaceuticals have become major targets in environmental chemistry due to their presence in aquatic environments (following incomplete removal in wastewater treatment or point-source contaminations), threat to drinking water sources and concern about their possible effects to wildlife and humans. Recently several methods have been developed for the determination of drugs and their metabolites in the lower nanogram per litre range, most of them using solid-phase extraction (SPE) or solid-phase microextraction (SPME), derivatisation and finally gas chromatography mass spectrometry (GC-MS), gas chromatography tandem mass spectrometry (GC-MS/MS) and liquid chromatography electrospray tandem mass spectrometry (LC-ES/MS/MS). Due to the elevated polarity of non-steroidal anti-inflamatory drugs (NSAIDs), analytical techniques based on either liquid chromatography coupled to mass spectrometry (LC-MS) and gas chromatography coupled to mass spectrometry (GC-MS) after a previous derivatisation step are essential. The most advanced aspects of current GC-MS, GC-MS/MS and LC-MS/MS methodologies for NSAID analysis are presented.     

Multi-residue analytical method for the determination of emerging pollutants in water by solid-phase extraction and liquid chromatography-tandem mass spectrometry

This paper describes the development and validation of a method for the simultaneous determination of 53 multi-class emerging organic pollutants in water samples using solid-phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), using electrospray ionisation (ESI) in both positive and negative modes. Target compounds include acidic herbicides, UV filters, insect repellents, organophosphorous flame retardants, a bactericide, pharmaceuticals and metabolites. A single SPE consisting on the loading of 200-500 mL of sample adjusted to pH 7 on Oasis HLB 200mg cartridges and elution with methanol, permitted obtaining good recoveries: higher than 60% for tap, surface and wastewater in most cases. The 7 isotopically labelled internal standards effectively compensated losses during sample preparation and matrix effects at LC-MS/MS determination. The precision of the method, calculated as relative standard deviation (RSD) was below 15% for all compounds and all tested matrices. Detection limits (LODs) based on the confirmation, less intense, MRM (multiple reaction monitoring) transition and considering blanks varied between 0.3 and 30 ngL(-1). Finally, the developed method was applied to the determination of target analytes in various samples, including tap, surface and waste water. Among the tested emerging pollutants, 31 were found in wastewater in concentrations reaching up to 10 microgL(-1) in the case of ibuprofen. Also, 13 species were detected in tap water with concentrations up to 0.13 microgL(-1) for tri(chloropropyl) phosphate (TCPP).