Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sampling”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,207 records · Page 67Linked to original sources
PubMed1992

Polycyclic aromatic hydrocarbons in air samples of meat smokehouses.

In a screening programme nine Danish meat smokehouses were randomly selected for measurements on concentration of airborne polycyclic aromatic hydrocarbons (PAH). A total of 23 stationary air samples were collected during the entire working period of the kiln either above the kiln doors or approximately 2 m in front of the kiln doors (i.e. total exposure on the day of sampling). Three of these samples had a PAH content below the detection limit of the highly sensitive assay employed. Furthermore, eight personal air samples were collected during the periods of tending the kiln (i.e. peak exposure measurement). Three of these samples were below the detection limit. Total airborne PAH concentration of the stationary air samples calculated as the sum of the concentration of 16 selected PAH compounds, was in general far lower than the total airborne PAH concentration measured in the same manner in smokehouses curing fish (Nordholm et al., 1986). In contrast to the study on PAH exposure in smokehouses curing fish, the present study revealed no significant difference between total PAH content in air samples collected above the kilns compared with samples collected approximately 2 m in front of the kiln doors. Calculation of the relative content of the individual PAH compounds in the stationary air samples collected in meat smokehouses showed naphthalene to be the major compound in (70% +/- 26% of total PAH), whereas the relative content of carcinogenic PAH compounds in average represented 4.0% of the total PAH content. However, only approximately 15% of the stationary air samples with detectable content of total PAH contained detectable amounts of carcinogenic PAH compounds. Hence it was concluded that PAH exposure during cold meat curing might be considered a limited health hazard compared with PAH exposure during hot fish curing.

Air Pollutants, Occupational↗
PubMed1995

Effects of sample handling temperatures on bovine skim milk progesterone concentrations.

The effects of incubation of whole milk at various temperatures and times on the concentration of progesterone in the skim milk fraction was determined. For the study, milk samples were collected from 10 pregnant Holstein cows. The milk from each cow was transferred to culture tubes to provide 32 replicates of 3 ml volume. To begin the incubation study, all samples were placed in a 37 degrees C water bath for 4 h. The end of this incubation was designated as time 0 and a sample from each cow was centrifuged to harvest skim milk. At time 0, samples from each cow were divided among incubation temperatures of 0 degrees, 4 degrees, 20 degrees and 37 degrees C. Samples were removed from each incubation group at 30, 60, 90 and 120 min. After 120 min, all remaining samples were returned to the 37 degrees C incubation and skim milk was collected at 30, 60 and 90 min. Progesterone was measured in skim milk by radioimmunoassay. The mean +/- SE concentration of progesterone in skim milk at time 0 was 10.9 +/- 1.1 nmol/L. The mean concentration of progesterone in skim milk was higher (P < 0.05) in all samples incubated at 0 degrees and 4 degrees C, with incremental increases ranging from 34% to 67% above time 0. Progesterone in skim milk returned to time 0 concentrations in milk samples transferred from 0 degrees or 4 degrees C to 37 degrees C. There was no change in skim milk progesterone in whole milk samples incubated at 20 degrees or 37 degrees C. From this study, it can be concluded that the concentration of progesterone in skim milk is temperature dependent. Inconsistency in handling whole milk samples can have a profound effect in the concentration of progesterone on skim milk. The temperature-dependent effect was reversible and may be related to solubility of progesterone in milk fat.

Journal Article↗
PubMedDate not supplied

Storage and preservation of whole blood samples for use in detection of human immunodeficiency virus type-1 by the polymerase chain reaction.

Methods used in the diagnosis of human immunodeficiency virus type-1 (HIV-1) infection by the polymerase chain reaction (PCR) usually require the separation of lymphocytes from a whole-blood sample within 24 hours of patient sampling. A method is described in which blood samples are mixed with a cryopreservative ('Glycigel'), stored frozen, and DNA suitable for use in an HIV PCR recovered. Samples can be stored at -20 degrees C for up to 3 months and still give positive results with all samples from infected patients; storage at -80 degrees C for at least 3 months shows no loss of titre. The method shows no loss of sensitivity compared to previously described sample preparation methods. Deglycerolised Glycigel supernatants were found to be suitable for conventional anti-HIV-1 serological studies and loss of sensitivity only represented the dilution effect due to sample preparation. Application of the method as a means of storing samples frozen at the point of sampling and transporting them to a central laboratory for processing is demonstrated using samples taken from HIV-1-infected mothers and their babies.

Adult↗
PubMed1991

Assessment of mean oocyst count in groups of kids: litter, individual randomized and non-randomized fecal samplings.

A trial was conducted in six pens of kids visited five times monthly to compare different regimes of fecal sampling in order to assess average coccidial infection at a group level. In addition to individual fecal samplings of all the kids in the pen, giving the actual mean oocyst count, three sampling methods were performed: (i) individual sampling of three, five, seven, ten, 15, 20 or more animals according to the numbers of animals in the pen; (ii) sampling of feces in the litter; (iii) individual sampling of six kids, three with the poorest and three with the highest daily weight gain. Results indicated that drawing a random sample of ten kids was necessary to obtain a good estimation, with an accuracy of 25% in more than 90% of pens. Sampling of feces in the litter and individual sampling of six kids selected on daily weight gain considerations gave accurate estimation of the actual mean oocyst counts except in the case of high levels of infection. Further investigations would be needed to assess the diagnostic value of such sampling techniques whatever the coccidial infection level.

Age Factors↗
PubMed2005

Comparison of a novel passive sampler to standard water-column sampling for organic contaminants associated with wastewater effluents entering a New Jersey stream.

Four water samples collected using standard depth and width water-column sampling methodology were compared to an innovative passive, in situ, sampler (the polar organic chemical integrative sampler or POCIS) for the detection of 96 organic wastewater-related contaminants (OWCs) in a stream that receives agricultural, municipal, and industrial wastewaters. Thirty-two OWCs were identified in POCIS extracts whereas 9-24 were identified in individual water-column samples demonstrating the utility of POCIS for identifying contaminants whose occurrence are transient or whose concentrations are below routine analytical detection limits. Overall, 10 OWCs were identified exclusively in the POCIS extracts and only six solely identified in the water-column samples, however, repetitive water samples taken using the standard method during the POCIS deployment period required multiple trips to the sampling site and an increased number of samples to store, process, and analyze. Due to the greater number of OWCs detected in the POCIS extracts as compared to individual water-column samples, the ease of performing a single deployment as compared to collecting and processing multiple water samples, the greater mass of chemical residues sequestered, and the ability to detect chemicals which dissipate quickly, the passive sampling technique offers an efficient and effective alternative for detecting OWCs in our waterways for wastewater contaminants.

Chromatography, Liquid↗
PubMed2006

A comparison of river water quality sampling methodologies under highly variable load conditions.

When river water quality fluctuates over relatively short periods of time with respect to the sampling frequency, the collection of grab samples may be inappropriate for characterising average water quality. This paper presents the results of a water quality monitoring study carried out on a stretch of the river Lambro (northern Italy) dominated by a periodically overloaded sewage treatment works (STW) located near its upstream end. Water quality was strongly influenced by a pronounced diurnal cycle in pollutant loads caused by the regular emission of untreated waste water during periods of high domestic flow (daytime). Two different sampling techniques were employed: grab sampling and 24-h composite sampling using automatic samplers. Samples were collected at the plant overflow and at several sites along the river and analysed for two common ingredients of household detergents, linear alkylbenzene sulphonate (LAS) and boron (B) and for routine water quality variables. The results obtained show that: (1) The diurnal variability of point-source-derived chemical concentrations in the river downstream of the undersized STW increased with increasing removal efficiency in sewage treatment. (2) The shape of the diurnal concentration signal remained relatively intact for a considerable distance downstream of the STW for several water quality variables, suggesting that hydrodynamic dispersion plays a relatively minor role in controlling concentration patterns in this river. (3) In-stream degradation of LAS was consistent with first order kinetics with a rate constant of 0.05-0.06 h(-1). (4) Grab sampling is a relatively inefficient methodology for capturing mean concentrations for rivers subjected to highly variable loads, especially when it is restricted to office hours. The inefficiency of grab sampling is more marked for substances (e.g. LAS) which are effectively removed during sewage treatment than for substances which are not. (5) For LAS, diurnal variability in the concentration signal decreases with distance downstream, making grab sampling an increasingly reliable methodology for estimating mean concentrations. (6) 24-h composite sampling is an efficient way of eliminating the effect of diurnal variations in load strength.

Environmental Monitoring↗
PubMed2003

Quantitation of estrogens in ground water and swine lagoon samples using solid-phase extraction, pentafluorobenzyl/trimethylsilyl derivatizations and gas chromatography-negative ion chemical ionization tandem mass spectrometry.

A method was developed for the confirmed identification and quantitation of 17beta-estradiol, estrone, 17alpha-ethynylestradiol and 16alpha-hydroxy-17beta-estradiol (estriol) in ground water and swine lagoon samples. Centrifuged and filtered samples were extracted using solid-phase extraction (SPE), and extracts were derivatized using pentafluorobenzy] bromide (PFBBR) and N-trimethylsilylimidazole (TMSI). Analysis was done using negative ion chemical ionization (NICI) gas chromatography-mass spectrometry-mass spectrometry (GC-MS-MS). Deuterated analogs of each of the estrogens were used as isotope dilution standards (IDS) and were added to the samples before extraction. A limit of quantitation of 1 ng/l in ground water was obtained using 500 ml of ground water sample, 1.0 ml of extract volume and the lowest calibration standard of 0.5 pg/microl. For a 25 ml swine lagoon sample, the limit of quantitation was 40 ng/l. The average recovery of the four estrogens spiked into 500 ml of distilled water and ground water samples (n = 16) at 2 ng/l was 103% (S.D. 14%). For 25 ml of swine lagoon samples spiked at 500, 1000 and 10,000 ng/l, the average recovery for the four estrogens was 103% (S.D. 15%). The method detection limits (MDLs) of the four estrogens spiked at 2 ng/l in a 500 ml of ground water sample ranged from 0.2 to 0.6 ng/l. In swine lagoon samples from three different types of swine operations, estrone was found at levels up to 25,000 ng/l, followed by estriol and estradiol up to levels at 10,000 and 3000 ng/l, respectively. It was found that pretreatment of swine lagoon samples with formaldehyde was necessary to prevent conversion of estradiol to estrone.

Animals↗
PubMed2005

Validated sampling strategy for assessing contaminants in soil stockpiles.

Dutch legislation on the reuse of soil requires a sampling strategy to determine the degree of contamination. This sampling strategy was developed in three stages. Its main aim is to obtain a single analytical result, representative of the true mean concentration of the soil stockpile. The development process started with an investigation into how sample pre-treatment could be used to obtain representative results from composite samples of heterogeneous soil stockpiles. Combining a large number of random increments allows stockpile heterogeneity to be fully represented in the sample. The resulting pre-treatment method was then combined with a theoretical approach to determine the necessary number of increments per composite sample. At the second stage, the sampling strategy was evaluated using computerised models of contaminant heterogeneity in soil stockpiles. The now theoretically based sampling strategy was implemented by the Netherlands Centre for Soil Treatment in 1995. It was applied to all types of soil stockpiles, ranging from clean to heavily contaminated, over a period of four years. This resulted in a database containing the analytical results of 2570 soil stockpiles. At the final stage these results were used for a thorough validation of the sampling strategy. It was concluded that the model approach has indeed resulted in a sampling strategy that achieves analytical results representative of the mean concentration of soil stockpiles.

Environmental Monitoring↗
PubMed2006

Factor structure and internal consistency of the Young Schema Questionnaire (Short Form) in Korean and Australian samples.

We investigated cross-cultural differences in the factor structure and psychometric properties of the 75-item Young Schema Questionnaire-Short Form (YSQ-SF). Participants were 833 South Korean and 271 Australian undergraduate students. The South Korean sample was randomly divided into two sub-samples. Sample A was used for Exploratory Factor Analysis (EFA) and sample B was used for Confirmatory Factor Analysis (CFA). EFA for the South Korean sample revealed a 13-factor solution to be the best fit for the data, and CFA on the data from sample B confirmed this result. CFA on the data from the Australian sample also revealed a 13-factor solution. The overall scale of the YSQ-SF demonstrated a high level of internal consistency in the South Korean and Australian groups. Furthermore, adequate internal consistencies for all subscales in the South Korean and Australian samples were demonstrated. In conclusion, the results showed that YSQ-SF with 13 factors has good psychometric properties and reliability for South Korean and Australian University students. Korean samples had significantly higher YSD scores on most of the 13 subscales than the Australian sample. However, limitations of the current study preclude the generalisability of the findings to beyond undergraduate student populations.

Adolescent↗
PubMed2006

Analysis of human breath samples with a multi-bed sorption trap and comprehensive two-dimensional gas chromatography (GCxGC).

A multi-bed sorption trap designed to quantitatively collect volatile organic compounds from large-volume vapor samples and inject them into a gas chromatograph is combined with a comprehensive two-dimensional gas chromatograph (GCxGC) for the analysis of organic compounds in human breath samples. The first-column effluent of the GCxGC is modulated by a single-stage, resistively-heated and air-cooled segment of 0.18-mm i.d. stainless steel column using the same stationary phase as the first column. Cooling gas is provided by a two-stage conventional refrigeration system, and thus no consumables other than carrier gas and electric power are required. The sorption trap uses four discreet beds, three containing different grades of graphitized carbon and one containing a carbon molecular sieve. The ordering of the beds in the trap tube is from the weakest to strongest adsorbent during sample collection. Breath samples are collected in gas sampling bags, and samples are passed through the trap at a flow rate of about 50 cm3/min. After sample collection, hydrogen carrier gas flow is initiated in the direction opposite to the sample collection flow, and the metal trap tube is resistively heated to inject a sample plug into the GCxGC. Performance data for the combined GCxGC/sorption-trap instrument is described, and human breath-sample chromatograms are presented.

Breath Tests↗
PubMed2006

Evaluation of methods used to concentrate and detect hepatitis A virus in water samples.

Two adsorption-elution concentration methods, both involving negatively charged membranes, were evaluated in order to monitor hepatitis A virus (HAV) contamination in tap, river, mineral and coastal water samples: elution with urea-arginine phosphate buffer/reconcentration with magnesium chloride (method 1); and sodium hydroxide elution/reconcentration with a commercial concentrator (method 2). Nested (qualitative) reverse transcriptase PCR (RT-PCR) and real-time (quantitative) RT-PCR were used to detect and quantify HAV RNA in concentrated water samples. For concentrating HAV, method 1 was found to be the most suitable for tap water and method 2 most suitable for mineral water. HAV inoculated experimentally was detected in river water samples by both methods and in coastal water samples by neither method. The detection limits were 6 x 10(9) g equiv./ml for qualitative PCR and 60 g equiv./ml for quantitative PCR. In a field application study, HAV was detected in 20% of river and tap water samples but not in coastal or mineral water samples. River water samples contained subgenotype IA, and tap water samples contained subgenotype IB. It is concluded that, although influencing qualitative PCR, the concentration method does not affect quantitative PCR, which could therefore be used for all types of water samples. Both techniques are recommended for detecting HAV in environmental water samples.

Fresh Water↗
PubMed2004

Airborne viable, non-viable, and allergenic fungi in a rural agricultural area of India: a 2-year study at five outdoor sampling stations.

The information on airborne allergenic fungal flora in rural agricultural areas is largely lacking. Adequate information is not available to the bioaerosol researchers regarding the choice of single versus multiple sampling stations for the monitoring of both viable and non-viable airborne fungi. There is no long-term study estimating the ratios of viable and non-viable fungi in the air and earlier studies did not focus on the fractions of airborne allergenic fungi with respect to the total airborne fungal load. To fill these knowledge gaps, volumetric paired assessments of airborne viable and non-viable fungi were performed in five outdoor sampling stations during two consecutive years in a rural agricultural area of India. Samples were collected at 10-day intervals by the Burkard Personal Slide Sampler and the Andersen Two-Stage Viable Sampler. The data on the concentrations of total and individual fungal types from five stations and 2 different years were analyzed and compared by statistical methods. The allergenicity of the prevalent airborne viable fungi was estimated by the skin-prick tests of >100 rural allergy patients using the antigenic fungal extracts from isolates collected with the Andersen sampler. The ranges of total fungal spore concentration were 82-2365 spores per cubic meter of air (spores/m3) in the first sampling year and 156-2022 spores/m3 in the second sampling year. The concentration ranges of viable fungi were 72-1796 colony-forming units per cubic meter of air (CFU/m3) in the first sampling year and 155-1256 CFU/m3 in the second sampling year. No statistically significant difference was observed between the total spore data of the 2 years, however, the data between five stations showed a significant difference (P<0.0001). No statistically significant difference existed between stations and years with respect to the concentration of viable fungi. When the data of individual allergenic fungal concentrations were compared between stations and years, no statistically significant difference was observed in all cases except for Aspergillus japonicus and Rhizopus nigricans, which showed significant difference in case of stations and years, respectively. The ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler from all sampling stations ranged between 0.29 and 7.61. The antigenic extracts of eight prevalent viable airborne fungi (A. flavus, A. japonicus, A. fumigatus, Alternaria alternata, Cladosporium cladosporioides, Curvularia pallescens, Fusarium roseum, and R. nigricans) demonstrated >60% positive reactions in the skin prick test. These selected allergenic fungi collectively represented 31.7-63.2% of the total airborne viable fungi in different stations. The study concluded that: (i) a rich fungal airspora existed in the rural study area, (ii) to achieve representative information on the total airborne fungal spores of an area, the monitoring in multiple sampling stations is preferable over a single sampling station; for viable fungi, however, one station can be considered, (iii) the percentage of airborne fungal viability is higher in rural agricultural areas, and (iv) approximately 52% of the viable airborne fungi in the rural study area were allergenic.

Agriculture↗
PubMed2005

The effect of sampling design on extensive bryomonitoring surveys of air pollution.

In this study, we investigated if the different sampling designs normally used in extensive bryomonitoring surveys of air pollution allow compliance with the objectives proposed in the 'Heavy Metals in European Moss' project. For this, we have used data on concentrations of As, Cu, Se and Zn from five moss sampling surveys carried out in Galicia (NW Spain), using three types of sampling design: regular grid, sampling sites inside squares and the strategy recommended in the guidelines for European surveys. To study the effect of the interaction between the sampling design and the spatial pattern of the presence of contaminants, we have used a simulated and a real pattern onto which we superimposed the three sampling designs considered. We found that only random sampling and grid sampling allow compliance with the proposed objectives, and we discuss the advantages of the latter over the former. The data corresponding to studies using different sampling designs are not comparable, and in future large-scale surveys, the same design must be used if the results are to be compared and if valid conclusions are to be reached. The scale of the grid determines the scale to which the objectives are complied with, so that for correct standardization of the technique, and taking into account the most commonly used grid sizes, we recommend a grid size of 30 x 30 or 32 x 32 km. When additional samplings are required, the size of the grid size should be 30/2(n) or 32/2(n) km.

Air Pollution↗
PubMed2004

Influence of sampling time on bacteriological diagnosis of goat intramammary infection.

Intramammary infection in seven commercial goat herds was studied using premilking and postmilking samples for purposes as bacteriological diagnosis. Using a positive result on both premilking and postmilking samples as the definitive diagnosis, we compared the efficacy of single samples collected either premilking or postmilking. With this aim, 2268 bacteriological culture results were compared. The kappa values (0.60) showed moderate agreement between the two samples. Specificity and positive predictive value were higher for postmilking samples than for premilking samples. Specificity of postmilking samples was 99.4% for coagulase-negative staphylococci, 99.9% for Gram-negative bacilli, 100% for streptococci, 99.9% for corynebacteria and 100% for mixed cultures. Premilking samples specificity was 96.6, 99.5, 99.7, 99.8 and 99.8%, respectively. False positive diagnoses were more frequent for premilking samples. The results suggest that postmilking samples should be used to diagnosis of goat intramammary infection.

Animals↗
PubMed2004

Gene expression profiling in human endometrial cancer tissue samples: utility and diagnostic value.

OBJECTIVE: Recently, gene expression profiling techniques have been used on several human cancers to classify tumor subgroups with a specific biological behavior, which were previously undetected by the conventional histopathologic staging systems. In the current study, the clinical usefulness and prognostic value of gene expression profiling in human endometrial carcinomas were studied. METHODS: A macro cDNA array, containing cDNAs of 588 genes selected from different areas of cancer research, was used to generate gene expression profiles of tumor tissue samples. The gene expression profiles of 12 endometrial cancers, 3 benign (e.g. noncancer) endometrial tissue samples and 3 myometrial tissue samples, taken from human surgical specimen, were compared. RESULTS: The efficacy to generate a gene expression profile of these tissue samples was 77%. The RNA samples could be randomly taken from the tissue samples and were highly reproducible. Cluster analysis of gene expression profiles of the different samples showed that the benign endometrial and the myometrial samples clustered separately from the tumor samples, indicating that the gene expression profiles were tissue specific and not patient specific. Cluster analysis of the tumor samples revealed two distinct tumor clusters. Ranking of the tumors in the two clusters showed high similarity with the histopathologic classification [International Federation of Gynecology and Obstetrics (FIGO) grading]. CONCLUSION: Classification of endometrial tumors on basis of their gene expression profiles showed similarity with the FIGO grading system.

Adult↗
PubMed2000

Time-weighted average sampling of volatile and semi-volatile airborne organic compounds by the solid-phase microextraction device.

The ultimate goal of the chemist is to perform sample preparation, and analysis, if possible at the place where a sample is located rather than moving the sample to laboratory, as is common practice in many cases at the present time. This approach eliminates errors and time associated with sample transport and storage and therefore it would result in more accurate, precise and faster analytical data. In addition to portability, two other important features of ideal field sample preparation technique are elimination of solvent use and integration with a sampling step. A method is developed which addresses these requirements for the determination of time-weighted average concentration of gas phase compounds using a solid-phase microextraction device. Quantification of target analytes in air using this method can be carried out without external calibration. The volatile and semi-volatile organic compounds in air diffuse into the fiber coating which is retracted a known distance into its needle housing during the sampling period. The coatings used are poly(dimethylsiloxane) and poly(dimethylsiloxane)-divinylbenzene. The sampling rate at which gas phase analytes load onto the fiber is determined for a wide range of hydrocarbons. There is a good agreement between the theoretical and experimental sampling rates. Sampling time ranges from 1 min to 24 h depending on the coating used and its retraction distance. Effect of the flow-rate on the uptake rate by the fiber is studied. The method is tested in the field and compared with National Institute of Occupational Health and Safety Method 1550. Good agreement between the results is obtained.

Chromatography↗
PubMed2001

Capillary zone electrophoresis of orotic acid in urine with on-line isotachophoresis sample pretreatment and diode array detection.

Potentialities of capillary zone electrophoresis with on-line isotachophoresis sample pretreatment and diode array detection (ITP-CZE-DAD) to the separation, detection and identification of trace analytes present in biological matrices were investigated. Urine represented a multicomponent, variable and high ionic strength matrix while orotic acid was chosen as a model analyte of a practical clinical relevance in this investigation. Using the ITP-CZE combination in the column-coupling configuration of the separation system ITP provided an enhanced sample load capacity to the separation system (a 30 microl sample injection volume), concentrated the analyte and served as an on-line sample clean up technique. On the other hand, CZE performed a final separation of the analyte from matrix constituents present in the ITP pretreated sample and provided favorable conditions for its detection and identification by DAD. Using current correction and smoothing procedures analytically relevant DAD spectra of orotic acid could be obtained also in instances when this was injected in a model sample at a 2 x 10(-7) mol/l concentration (an estimated limit of determination of orotic acid at a 218 nm detection wavelength). ITP-CZE separations of urine samples (based on differences in acid-base properties and host-guest complexations of the analyte and matrix anionic constituents) led to significant sample clean ups. Consequently, DAD spectra of orotic acid matching its reference spectrum, could be acquired also in instances when the acid was present in urine matrices (loaded in 30 microl injection volumes of 20-fold diluted urine samples) at 4-6 x 10(-7) mol/l concentrations. Here, residual trace matrix interferents prevented a closer approach to the above value attainable for model samples. Although this work was focused only on one analyte and urine matrix it implies very promising potentialities of the ITP-CZE-DAD combination in the identification and quantitation of trace analytes present in biological matrices, in general.

Adult↗
PubMed2001

Isotachophoresis and isotachophoresis--zone electrophoresis separations of inorganic anions present in water samples on a planar chip with column-coupling separation channels and conductivity detection.

The use of a poly(methylmethacrylate) chip, provided with two separation channels in the column-coupling (CC) arrangement and on-column conductivity detection sensors, to electrophoretic separations of a group of inorganic anions (chloride, nitrate, sulfate, nitrite, fluoride and phosphate) that need to be monitored in various environmental matrices was studied. The electrophoretic methods employed in this study included isotachophoresis (ITP) and capillary zone electrophoresis (CZE) with on-line coupled ITP sample pretreatment (ITP-CZE). Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the CC chip were suppressed and electrophoresis was a dominant transport process in the separations performed by these methods. ITP separations on the chip provided rapid resolutions of sub-nmol amounts of the complete group of the studied anions and made possible rapid separations and reproducible quantitations of macroconstituents currently present in water samples (chloride, nitrate and sulfate). However, concentration limits of detection attainable under the employed ITP separating conditions (2-3 x 10(-5) mol/l) were not sufficient for the detection of typical anionic microconstituents in water samples (nitrite, fluoride and phosphate). On the other hand, these anions could be detected at 5-7 x 10(-7) mol/l concentrations by the conductivity detector in the CZE stage of the ITP-CZE combination on the CC chip. A sample clean-up performed in the ITP stage of the combination effectively complemented such a detection sensitivity and nitrite, fluoride and phosphate could be reproducibly quantified also in samples containing the macroconstituents at 10(4) higher concentrations. ITP-CZE analyses of tap, mineral and river water samples showed that the CC chip offers means for rapid and reproducible procedures to the determination of these anions in water (4-6 min analysis times under our working conditions). Here, the ITP sample pretreatment concentrated the analytes and removed nanomol amounts of the macroconstituents from the separation compartment of the chip within 3-4 min. Both the ITP and ITP-CZE procedures required no or only minimum manipulations with water samples before their analyses on the chip. For example, tap water samples were analyzed directly while a short degassing of mineral water (to prevent bubble formation during the separation) and filtration of river water samples (to remove particulates and colloids) were the only operations needed in this respect.

Electrochemistry↗