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An innovative analytical method has been developed to quantify the bioaccumulation in an amphipod crustacean ( Gammarus fossarum ) of three micropollutants regarded as anthropic-pollution markers: carbamazepine, oxazepam, and testosterone. A liquid-liquid extraction assisted by salts, known as QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) was miniaturised and optimised, so it could be adapted to the low mass samples (approximatively 5 mg dry weight). For this same reason and in order to obtain good sensitivity, ultra-trace analyses were carried out by means of nanoliquid chromatography. A preconcentration system by on-column trapping was optimised to increase the injection volume. In order to improve both sensitivity and selectivity, the multiple reaction monitoring cubed mode analyses (MRM 3 ) were carried out, validated and compared to the classic MRM. To the best of our knowledge, this is the first time that MRM 3 is coupled to nanoliquid chromatography for the analysis and detection of organic micropollutants <300 Da. The optimised extraction method exhibited recoveries superior to 80%. The limits of quantification of the target compounds were 0.3, 0.7 and 4.7 ng/g (wet weight) for oxazepam, carbamazepine and testosterone, respectively and the limits of detection were 0.1, 0.3 and 2.2 ng/g (wet weight), respectively. The intra- and inter-day precisions were inferior to 7.7% and 10.9%, respectively, for the three levels of concentration tested. The analytical strategy developed allowed to obtain limits of quantification lower than 1 ng/g (wet weight) and to establish the kinetic bioconcentration of contaminants within G. fossarum. [ABSTRACT FROM AUTHOR]

Abstract: Sample preparation procedures in use in many application areas are still tedious and manually intensive protocols. These characteristics mean that sample treatment is considered the most time-consuming and error-prone part of the analytical scheme. The increasing demand for faster, more cost-effective and environmental friendly analytical methods is a major incentive to improve these conventional procedures and has spurred research in this field during the last decades. This review provides an overview of the most relevant developments and successful approaches proposed in recent years concerning sample preparation. The current state-of-the-art is discussed on the basis of examples selected from representative application areas and involving conventional instrumental techniques for the final determination of the target compounds. Emphasis will be on those techniques and approaches that have already demonstrated their practicality by the analysis of real-life samples, and in particular on those dealing with the determination of minor organic components. The potential of the latest developments in this field for sample treatment simplification and complete hyphenation and integration of analytical process is discussed and the most pressing remaining limitations evaluated. [Copyright &y& Elsevier]

Abstract: Several procedures are available for simulating and optimising separations in ion chromatography (IC), based on the application of retention models to an extensive database of analyte retention times on a wide range of columns. These procedures are subject to errors arising from batch-to-batch variability in the synthesis of stationary phases, or when using a column having a different diameter to that used when the database was acquired originally. Approaches are described in which the retention database can be recalibrated to accommodate changes in the stationary phase (ion-exchange selectivity coefficient and ion-exchange capacity) or in the column diameter which lead to changes in phase ratio. The entire database can be recalibrated for all analytes on a particular column by performing three isocratic separations with two analyte ions. The retention data so obtained are then used to derive a “porting” equation which is employed to generate the required simulated separation. Accurate prediction of retention times is demonstrated for both anions and cations on 2mm and 0.4mm diameter columns under elution conditions which consist of up to five sequential isocratic or linear gradient elution steps. The proposed approach gives average errors in retention time prediction of less than 3% and the correlation coefficient was 0.9849 between predicted and observed retention times for 344 data points comprising 33 anionic or cationic analytes, 5 column internal diameters and 8 complex elution profiles. [Copyright &y& Elsevier]

Abstract: This study reports on a quantitative study of the influence of the most important geometrical design parameters for micro-machined flow distributors with uniform cross-section and filled with diamond-shaped pillars having their longest dimension oriented perpendicular to the axial flow direction. It was found that the shape of the bands eluting from the distributor improves with increasing aspect ratio (AR) of the pillars, both in terms of global warp and local axial dispersion. Increasing the AR from 5 to 25 reduces the distributor length needed to bring the maximal transversal velocity difference below 5% from 170μm to 15μm when using pillars with axial width of 5μm. To solve the problem that high AR pillar distributors only have a limited number of exit points, and therefore produce bands with a strong local warp, one can conceive mixed size distributors, wherein a zone filled with several rows of very high AR pillars is followed by one or more zones consisting of pillars with a smaller AR. With such a design, the variance of the eluting bands can be reduced to only 30% of the variance of a single size distributor. [ABSTRACT FROM AUTHOR]

Abstract: A new methodology is proposed for monitoring 16 priority polycyclic aromatic hydrocarbons, using tree leaves as passive samplers, by means of a mini-ultrasonic probe coupled with reversed-phase liquid chromatography (RP-LC) and fluorescence (FL) detection. Separation and detection of the 16 PAHs were completed in 19min, using a 3μm (particle size) C18 column RP-LC with acetonitrile–water gradient elution. The ultrasonic probe device used was equipped with a 2mm titanium tip, and sample and solvent amounts used were just 50mg and 1mL, respectively. Multivariate optimisation of the variables affecting extraction was conducted by means of full factorial analysis to determine which of the variables were significant. A central composite design was applied to define surface responses and to calculate optimal values for the variables. The accuracy of the method was determined by both analysis of a Certified Reference Material with a similar matrix (IAEA-140 OC, seaweed) and by comparison of the results obtained with those from a previously developed method. The proposed analytical method avoids some of the main problems encountered in the determination of PAH in complex matrices; no clean-up step is necessary, consequently sample preparation time and costs can be significantly reduced. The developed method was applied to determine PAH in leaf samples from medlar and red and white mangrove trees, situated near PAH pollution sources. [Copyright &y& Elsevier]

Abstract: A new method has been developed to allow the determination of the chlorate, chloride and perchlorate anions in inorganic explosive residues to be made using isotachophoresis (ITP). To enable a good separation of these species to be achieved the method involves the use of two complexing agents. Indium(III) is used to allow the determination of chloride whilst using nitrate as the leading ion and α-cyclodextrin is used to allow the separation of chlorate and perchlorate. Separations were carried out using a miniaturised poly(methyl methacrylate) (PMMA) separation device. The method was applied to analysing both model samples and actual inorganic explosive containing residue samples. Successful determinations of these samples were achieved with no interference from other anions typically found in inorganic explosive residues. Limits of detection (LOD) for the species of interest were calculated to be 0.80mgl−1 for chloride, 1.75mgl−1 for chlorate and 1.40mgl−1 for perchlorate. [Copyright &y& Elsevier]

Abstract: This paper presents the findings of a feasibility study investigating the behaviour of DNA under conditions of miniaturised isotachophoresis. An electrolyte system comprising a leading electrolyte of 5mM perchloric acid at pH 6.0 and a terminating electrolyte of 10mM gallic acid was devised and used to perform isotachophoresis of DNA containing samples on a miniaturised poly(methyl methacrylate) device. Under such conditions it was found that no separation of DNA fragments was observed with the substance migrating instead as a single isotachophoretic zone. Whilst such a result shows the method is unsuitable for analysis DNA it offers significant potential as a means of sample preparation for subsequent analysis using another method. This is because the single zone of DNA formed is preconcentrated to a constant concentration governed by the leading ion and is separated from all species with different effective electrophoretic mobilities. [Copyright &y& Elsevier]

Abstract: An injection moulded free flow isotachophoresis (FFITP) microdevice with integrated carbon fibre loaded electrodes with a separation chamber of 36.4mm wide, 28.7mm long and 100μm deep is presented. The microdevice was completely fabricated by injection moulding in carbon fibre loaded polystyrene for the electrodes and crystal polystyrene for the remainder of the chip and was bonded together using ultrasonic welding. Two injection moulded electrode designs were compared, one with the electrode surface level with the separation chamber and one with a recessed electrode. Separations of two anionic dyes, 0.2mM each of amaranth and acid green and separations of 0.2mM each of amaranth, bromophenol blue and glutamate were performed on the microdevice. Flow rates of 1.25mlmin−1 for the leading and terminating electrolytes were used and a flow rate of 0.63mlmin−1 for the sample. Electric fields of up to 370Vcm−1 were applied across the separation chamber. Joule heating was not found to be significant although out-gassing was observed at drive currents greater than 3mA. [Copyright &y& Elsevier]

Abstract: Enhanced sensitivity is a well known benefit of miniaturised LC–electrospray (ESI)–MS/MS methods. The suitability of miniaturised LC–MS/MS for quantification of small molecules in dialysates was investigated using the anti-epileptic drug oxcarbazepine, its active metabolite, 10,11-dihydro-10-hydroxycarbamazepine, and the internal standard for microdialysis probe calibration, 2-methyl-5H-dibenz(b,f)azepine-5-carboxamide, as test compounds. ESI–MS detection is sensitive to matrix effects. Therefore, dialysate matrix effects were investigated by comparing the responses of standards made in water, Ringer''s solution (salt solution used as perfusion fluid) and blank dialysate matrix. Due to the occurrence of ion suppression or enhancement, direct injection of dialysis samples onto the analytical column could not be applied for quantification of small molecules in dialysis samples. Column switching was necessary for desalting and preconcentration of the dialysates. However, this approach was not able to completely eliminate salt effects when the injection volume exceeded 1μL. No differences in response between Ringer''s solution and dialysate matrix were detected at capillary and nano-dimensions. Calibration standards should be prepared with Ringer''s solution instead of water for quantitative analysis of microdialysates. A microbore, capillary and nano-LC–ESI–MS/MS method were compared in terms of method feasibility, linearity, sensitivity, accuracy and precision. Downscaling to capillary and nano-dimensions resulted in a gain in detection sensitivity of 5 and 50, respectively. Miniaturised LC–MS/MS was found to be fit for quantification of small molecules in dialysates with acceptable accuracy and method precision. [Copyright &y& Elsevier]

Abstract: A new design of miniaturised separation device for performing isotachophoresis (ITP) has been produced. The device contains a simple arrangement of channels comprising a single separation channel with a ‘double T’ injection geometry. The device was produced in poly(methyl methacrylate) and incorporates an on-column conductivity detector. A new electrolyte system was developed to enable the rapid determination of chloride to be made. This electrolyte system uses a leading ion of 3.5mM nitrate at pH 3.0 with 0.5mM indium(III) added as a complexing agent. Use of this electrolyte system with the new separation device allowed chloride samples to be analysed in under 100s, with a limit of detection (LOD) calculated to be 2.2mgl−1. [Copyright &y& Elsevier]

A method allowing the miniaturised isotachophoretic analysis of amino acids has been developed. To overcome the problems of carbonate contamination which occur when performing separations at alkaline pH levels glycolate was used as the leading ion. Addition of magnesium to the leading electrolyte as a counter species was found to improve the separations. The method has been used on a poly(methyl methacrylate) microdevice with integrated on-column conductivity detectors. The behaviour of a range of common amino acids was investigated and successful separations of up to seven amino acids were made. Good linearity was observed with calibration curves for aspartic acid and phenylalanine over the range 0.063–1.0 mM. Limits of detection for these two species were calculated to be 0.060 and 0.018 mM, respectively. [Copyright &y& Elsevier]

An electrolyte system, using malic acid as a complexing agent, has been developed to allow the determination of transition metal cations using miniaturised isotachophoresis. The method allowed the simultaneous determination of Mn2+, Cr3+, Fe2+, Co2+, Zn2+ and Ni2+ to be made without interference from other common ions. Limits of detection were calculated to be in the range 0.5–1.0mgl-1 for Mn2+, Cr3+ Co2+and Zn2+ and 2.0mgl-1 for Fe2+ and 4.7mgl-1 for Ni2+. The successful analysis of five industrial samples, containing a range of these metal ions, obtained from metal processing plants were achieved in under 13min. The separations were performed on a poly(methyl methacrylate) chip with integrated platinum wire conductivity detection electrodes. [Copyright &y& Elsevier]

Separation and focusing of proteins is described in a miniaturised dynamic field gradient focusing device with a 2.5 cm × 0.1 cm channel filled with a porous polymer monolith. The separation channel is in contact with a parallel electric field channel with five individually addressable electrodes through a porous glass membrane so that a variable field can be generated that drives charged proteins electroosmotically against a constant hydrodynamic flow. Separated pre-stained proteins were detected by means of a digital camera and background subtraction. [Copyright &y& Elsevier]