Mimicking Daphnia magna bioassay performance by an electronic tongue for urban water quality control

Toxicity is one of the key parameters of water quality in environmental monitoring. However, being evaluated as a response of living beings (as their mobility, fertility, death rate, etc.) to water quality, toxicity can only be assessed with the help of these living beings. This imposes certain restrictions on toxicity bioassay as an analytical method: biotest organisms must be properly bred, fed and kept under strictly regulated conditions and duration of tests can be quite long (up to several days), thus making the whole procedure the prerogative of the limited number of highly specialized laboratories. This report describes an original application of potentiometric multisensor system (electronic tongue) when the set of electrochemical sensors was calibrated against Daphnia magna death rate in order to perform toxicity assessment of urban waters without immediate involvement of living creatures. PRM (partial robust M) and PLS (projections on latent structures) regression models based on the data from this multisensor system allowed for prediction of toxicity of unknown water samples in terms of biotests but in the fast and simple instrumental way. Typical errors of water toxicity predictions were below 20% in terms of Daphnia death rate which can be considered as a good result taking into account the complexity of the task.     

Recognition of adulteration of Italian wines by thin-film multisensor array and artificial neural networks

The paper reports the use of a chemoresistive multisensor array for recognition of some adulterated Italian wines (two white, four red, two rosè) added with methanol, ethanol or other same-colour wine. A multisensor array constituted by four thin-film semiconducting metal oxide sensors, surface-activated by Pt, Au, Pd, Bi metal catalysts, has been used to generate the chemical pattern of the volatile compounds present in the wine samples. The responses of the multisensor array towards wines tested by headspace sampling have been evaluated. Multivariate analysis including principal component analysis (PCA) as well as back-propagation method trained artificial neural networks (ANNs) have been applied to analytical data generated from the multisensor array to identify both the adulteration of wines and to determine the added content of adulterant agent of methanol or ethanol up to 10 vol.%. The cross-validated ANNs provide the highest achieved percentage of correct classification of 93% and the highest achieved correlation coefficient of 0.997 and 0.921 for predicted-versus-true concentration of methanol and ethanol adulterant agent, respectively.     

基于媒介体的电化学水体总毒性检测方法现状及展望

基于媒介体的电化学水体总毒性检测方法是一种灵敏、可靠的水体总毒性检测方法。 它以原位培养微生物为毒性检测受试体,能够更加准确的反映目标水体的水体总毒性变化,因此适合用于水体复合污染的评估及水质安全预警。 本文从检测原理、媒介体、微生物等方面详细阐述了该方法的研究现状,并对该方法今后的发展方向进行了展望。     

Analysis of tea samples with a multisensor system and capillary electrophoresis

Potential of an “electronic tongue” multisensor system in identification of various tea samples and in quantitative analysis of separate tea components was studied. As a reference method for quantitative analysis of antioxidants of the polyphenolic type served micellar electrokinetic chromatography with a UV detector. The contents of epicatechin gallate, epigallocatechin gallate, epicatechin, epigallocatechin, gallic acid, gallocatechin gallate, and caffeine alkaloid in various tea samples were quantitatively estimated.     

Profiling cells and body fluids--chromatography and two-dimensional electrophoresis as complementary techniques

Recent results on the use of gas chromatography-mass spectrometry, high-performance liquid chromatography with diode array detector, amino acid analysis and high-resolution two-dimensional (2-D) electrophoresis to study body fluids and cells in health and disease are surveyed. The chromatography profiling techniques are particularly suitable for the diagnosis of inborn errors of metabolism, with DNA technology as a complementary tool for prenatal diagnosis. Both chromatography and electrophoresis were utilized to study pre-diagnostic sera from the JANUS serum bank and to classify certain bacteria. Protein profiling by 2-D electrophoresis was employed to identify marker proteins associated with the metastatic properties of cloned cancer cells. The electrophoretic technique is also appropriate as a preparative tool for isolating sufficient amounts of marker proteins for microsequencing of amino acids. Chromatography and protein profiling were complementary tools for evaluating the toxicity and mutagenicity of environmental samples in a new test utilizing living human leukocytes and fibroblasts.     

Pesticide toxicity assessment using an electrochemical biosensor with <Emphasis Type="Italic">Pseudomonas putida</Emphasis> and a bioluminescence inhibition assay with <Emphasis Type="Italic">Vibrio fischeri</Emphasis>

Two different toxicity tests, an electrochemical biosensor Cellsense and a bioluminescence inhibition assay ToxAlert were performed in order to establish and compare the acute toxicity responses of different types of raw and spiked water for a selected group of pesticides. The selected compounds were endosulfan, chlorfenvinphos, dimethoate, fenamiphos, ametryn, deltamethrin and alpha-cypermethrin; all of them are used in large quantities for agricultural purposes. In the first step, the study of the toxicity responses for each individual pesticide with Milli-Q water was carried out. Next, the toxic responses of different mixtures of these pesticides in different water matrices, i.e., Milli-Q water, surface water, groundwater and wastewater were studied in order to evaluate (i) device advantages and limitations for the toxicity evaluation of real environmental samples, (ii) antagonistic or synergistic effects and (iii) the influence of the water matrices. The survey of pesticides in real samples was carried out using a combined method involving both chemical analysis and toxicity bioassays. Chemical analysis involved the use of solid-phase micro-extraction (SPME) followed by gas chromatography with electron capture detection (GC/ECD) or thermoionic specific detection (GC/TSD) with mass spectrometric confirmation (GC/MS).     

Identification of adulteration in milk by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The development is described of a rapid, simply and accurate analytical method aimed at evaluating both the presence of cow milk in either raw ewe and water buffalo milk samples employed in industrial processes and the addition of powdered milk to samples of fresh raw milk, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The presence of adulteration is defined by evaluating the protein patterns coming from the most abundant whey proteins, alpha-lactalbumin and beta-lactoglobulin, used as molecular markers. As no pretreatment of the milk samples is required and owing to the speed and ease of use of MALDI-MS the proposed analytical protocol can be used as a routine strategy for the identification of possible adulteration of the raw fresh milk samples that the dairy industry receives from producers every day.     

A Potentiometric Multisensor System of Anion-Selective Electrodes Based on Ionic Liquids

The possibility of using solid-state and liquid PVC-membrane electrodes based on ionic liquids to design a potentiometric multisensor system is assessed. Ionic liquids with 1,3-dihexadecylimidazolium cation and chloride, bromide, iodide, and nitrate anions are used. The sensitivity parameters of the sensors are determined. A multisensor array is applied to detect chloride and iodide anions in the multicomponent mixture. The designed system is used to discriminate between mineral waters of different compositions by applying the method of principal component analysis (PCA).     

Multivariate Calibration Transfer between two Potentiometric Multisensor Systems

A multivariate calibration of multisensor systems is a very important stage in their application. Construction of reliable calibration model requires significant investment of time and money. Once established, calibration model can be applied normally only together with that particular multisensor system, which was employed for its’ construction – this can be a serious limitation for a wide adoption of multisensor systems in common laboratory practice. In order to address this issue we have studied the applicability of several calibration transfer techniques, such as direct standardization, single wavelength standardization and standardization with regularization coefficient for the data obtained from two potentiometric multisensor systems in analysis of complex lanthanide mixtures. It was found that mathematical correction of sensor array response using standardization with regularization coefficient allows for using the regression model derived for one sensor array together with the data obtained from another sensor array. The value of root mean squared error of prediction for total lanthanide concentration increased insignificantly (0.10 instead of 0.07 in log scale) compared with that provided by the first multisensor system.     

Electronic tongue for quality assessment of ethanol, vodka and eau-de-vie

Rapid quality assessment of alcoholic beverages, including brand identification and detection of products of unacceptable quality or counterfeits is an important practical task. In the present work the multisensor electronic tongue system (ET), based on array of potentiometric chemical sensors was applied to recognition and classification of spirits such as vodka and ethanol used for vodka production and also for eau-de-vie in cognac production. The ET system was capable of detecting presence of contaminant substances in vodka in concentrations exceeding allowed levels as well as of distinguishing vodka complying and not complying with state quality standards. Ten brands of vodka produced at the same distillery using water and ethanol of different purity and various taste additives were discriminated using the instrument. The ET could distinguish synthetic and alimentary grain ethanol as well as alimentary ethanol of different grades (i.e. different degree of purification). A feasibility study was run on several eau-de-vie samples, which included fresh and aged eau-de-vie as well as samples produced using different distillation technology and samples kept in contact with different kinds of oak. The electronic tongue showed a promise as an analytical instrument for rapid quality assessment of spirits.     

Analytical method for authentication of Traditional Balsamic Vinegar of Modena

(13)C NMR spectroscopy was employed for evaluating glucose and fructose isoforms content in Traditional Balsamic Vinegar of Modena. With the use of reference spectra recorded in water for samples obtained with respect to set rules, a shift determination method for fructose carbon isoforms was introduced to determine the frauds present in unknown Traditional Balsamic Vinegar of Modena samples. No sample preparation yields this approach highly reliable and time saving. Following this approach, for the first time, an objective analytical technique can be used alternatively to the actual procedures for Traditional Balsamic Vinegar certification.     

A modified method for the analysis of organics in industrial wastewater as directed by their toxicity to Vibrio fischeri

A method for the identification of toxic compounds in industrial wastewater is presented, consisting of sequential solid phase extraction (SPE), fractionation by HPLC and GC-MS for compound identification. All analytical steps are accompanied by an automated detection of the aquatic toxicity by luminescence inhibition of Vibrio fischeri, which helps to reduce the large number of samples and subsamples that have to be processed by exluding those without toxic effects. The advantages of this procedure in comparison to previous methods of toxicity directed water analysis are discussed. The procedure was successfully applied to various samples of tannery wastewater, showing that benzothiazoles account for the major toxicity of tanyard wastewater. For very polar wastewater constituents, such as in beamhouse wastewaters, the use of LC-MS/MS for the final compound identification is suggested.     

Multianalyte imaging in one-shot format sensors for natural waters

A one-shot multisensor based on ionophore-chromoionophore chemistry for optical monitoring of potassium, magnesium and hardness in water is presented. The analytical procedure uses a black and white non-cooled CCD camera for image acquisition of the one-shot multisensor after reaction, followed by data treatment for quantitation using the grey value pixel average from a defined region of interest from each sensing area to build the analytical parameter 1 − α. In optimised experimental conditions, the procedure shows a large linear range, up to 6 orders using the linearised model and good detection limits: 9.92 × 10⁻⁵ mM, 1.86 × 10⁻³ mM and 1.30 × 10⁻² mg L⁻¹ of CaCO₃ for potassium, magnesium and hardness, respectively. This analysis system exhibits good precision in terms of relative standard deviation (RSD%) from 2.3 to 3.8 for potassium, from 5.0 to 6.8 for magnesium and from 5.4 to 5.9 for hardness. The trueness of this multisensor procedure was demonstrated comparing it with results obtained by a DAD spectrophotometer used as a reference. Finally, it was satisfactorily applied to the analysis of these analytes in miscellaneous samples, such as water and beverage samples from different origins, validating the results against atomic absorption spectrometry (AAS) as the reference procedure.     

Principle of nonlinear chemical fingerprint by using dissipative components in samples as well as calculation and evaluation of similarity

Under the conditions of constant temperature and pressure,different influences of samples with different chemical components on the mechanism of nonlinear chemical reaction will cause different changes of the potential-time relationship curve of the nonlinear chemical reaction system.Using it as the character,and using the B-Z nonlinear chemical system to use acetone and substrates in samples as main dissipative substances qua an example,the principle of nonlinear chemical fingerprint has been researched and discussed in detail.At the same time,the general method for calculating the system similarity about nonlinear chemical fingerprint was also put forward,and similarities of nonlinear chemistry fingerprints of different batches of Guhan Yangshengjing and 18 sorts of other samples were calculated by Euclidean distance,correlation coefficient,included angle cosine and system similarity,at the same time,the various similarities were analyzed.The results showed that,both of correlation coefficient and included angle cosine are unable to be used as the criterion for quantitatively evaluating the similarity of nonlinear chemistry fingerprint;as non-parametric similarity,Euclidean distance can accurately reflect the feature differences in the fingerprints,but as parametric similarity,sometimes,Euclidean distance can not accurately reflect the relative extent of characteristic difference in the nonlinear chemical fingerprints;system similarity can most truthfully reflect the characteristic difference in the nonlinear chemical fingerprints,and is the best evaluating method among the four ones.Therefore,system similarity can be used to quantitatively calculate the similar extent between the nonlinear chemical fingerprints.An economical,simple and convenient,easy pushing and effective method for identifying and evaluating complicated samples has successfully been put forward.     

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet method for the determination of diethofencarb and pyrimethanil in aqueous samples

A dispersive liquid-liquid microextraction method was developed for the determination of fungicides (diethofencarb and pyrimethanil) in aqueous samples. It is based on the use of solidified floating organic drops combined with high-performance liquid chromatography. Extraction solvent and dispersive solvent, extraction time and salt effect were optimized. Under optimized conditions, the enrichment factors for a 5?mL water sample are between 145 and 161. The limits of detection for diethofencarb and pyrimethanil are 0.24 and 0.09???g ? L^?1, respectively. The method offers good repeatability and high recovery. Compared with dispersive liquid-liquid microextraction, it has a higher enrichment factor, high precision due to the ease with which the solidified floating phase is transferred, thus avoiding the loss of analyte. Toxic solvents were replaced by 1-dodecanol with its much lower toxicity. The method has been successfully applied to the determination of the two fungicides in tap water, lake water, and river water.     

A modified method for the analysis of organics in industrial wastewater as directed by their toxicity to Vibrio fischeri

A method for the identification of toxic compounds in industrial wastewater is presented, consisting of sequential solid phase extraction (SPE), fractionation by HPLC and GC-MS for compound identification. All analytical steps are accompanied by an automated detection of the aquatic toxicity by luminescence inhibition of Vibrio fischeri, which helps to reduce the large number of samples and subsamples that have to be processed by exluding those without toxic effects. The advantages of this procedure in comparison to previous methods of toxicity directed water analysis are discussed. The procedure was successfully applied to various samples of tannery wastewater, showing that benzothiazoles account for the major toxicity of tanyard wastewater. For very polar wastewater constituents, such as in beamhouse wastewaters, the use of LC-MS/MS for the final compound identification is suggested. Received: 25 September 1998 / Revised: 20 November 1998 / Accepted: 26 November 1998     

Multivariate Observations of the Distribution of Polychlorinated Biphenyls in Environmental Compartments of Two Harbours

Abstract

The objectives of this study were to identify, classify and categorize polychlorinated biphenyl (PCB) residues in samples collected from the Hamilton and Wheatley Harbour environmental compartments. The study is built around the use of a principal components analysis method, namely the soft independent modelling of class analogy (SIMCA) technique. This multivariate method is widely used for evaluating differences and observing similarities among multiple objects. The results obtained from this work confirm that the gas chromatographic data sets obtained with the samples provide a good approximation of the pattern derived from a determination of the composition of commercial Aroclors in water, sediment and biota samples. The data analysis technique provides insight into the origin of PCB contamination in environmental samples and indicates pathways for the environmental degradation or bioaccumulation of PCBs. This investigation contributes some evidence that multivariate reduction techniques are suitable for the investigation of complex data sets in environmental studies.     

Rapid determination of anilines in water samples by dispersive liquid-liquid microextraction based on solidification of floating organic drop prior to gas chromatography-mass spectrometry

A rapid, sensitive and environmentally friendly method for the analysis of 14 anilines in water samples by dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME-SFO) prior to gas chromatography–mass spectrometry (GC-MS) was developed and optimized. In the proposed method, cyclohexane was used as the extraction solvent as its toxicity was much lower than that of the solvent usually used in dispersive liquid–liquid microextraction (DLLME). In the optimized conditions, the method exhibited good analytical performance. Based on a signal-to-noise ratio of 3, limits of detection for anilines were in the range of 0.07 to 0.29 μg L⁻¹, and the linear range was 0.5–200 μg L⁻¹ with regression coefficients (r ²) higher than 0.9977. It was efficient for qualitative and quantitative analysis of anilines in water samples. The relative standard deviations varied from 2.9 to 8.6 % depending on different compounds indicating good precision. Tap water and river water were selected for evaluating the application to real water samples. The relative recoveries of anilines for the two real samples spiked with 10 μg L⁻¹ anilines were in the scope of 78.2–114.6 % and 77.3–115.6 %, respectively.     

Improved solvent collection system for a dispersive liquid-liquid microextraction of organochlorine pesticides from water using low-density organic solvent

In this study, the organochlorine pesticides (OCPs) levels in lake and tap water samples were determined by a dispersive liquid-liquid microextraction method using a low-density organic solvent and an improved solvent collection system (DLLME-ISCS). This method used a very small volume of a solvent of low toxicity (11 μL of 1-nonanol and 400 μL of methanol) to extract OCPs from 10 mL water samples prior to the analysis by GC. After centrifugation in the dispersive liquid-liquid microextraction, there was a liquid organic drop floating between the water surface and the glass wall of the centrifuge tube. The liquid organic drop (with some water phase) was transferred into a microtube (3 mm×15 mm) with a syringe. The organic and aqueous phases were separated in the microtube immediately. Then, 1 μL of the organic solvent (which was in the upper portion of liquid in the microtube) was easily collected by a syringe and injected into the GC-ECD system for the analysis. Under optimum conditions, the linear range of this method was 5-5000 ng/L for most of the analytes. The correlation coefficient was higher than 0.997. Enrichment factors ranged from 1309 to 3629. The relative recoveries ranged from 73 to 119% for lake water samples. The LODs of the method ranged from 0.7 to 9.4 ng/L. The precision of the method ranged from 1.0 to 10.8% for lake water.