Use Of Internal Standard Research Articles

Capillary isoelectric focusing of individual mitochondria.

Mitochondria are highly heterogeneous organelles that likely have unique isoelectric points (pI), which are related to their surface compositions and could be exploited in their purification and isolation. Previous methods to determine pI of mitochondria report an average pI. This article is the first report of the determination of the isoelectric points of individual mitochondria by capillary isoelectric focusing (cIEF). In this method, mitochondria labeled with the mitochondrial-specific probe 10-N-nonyl acridine orange (NAO) are injected into a fused-silica capillary in a solution of carrier ampholytes at physiological pH and osmolarity, where they are focused then chemically mobilized and detected by laser-induced fluorescence (LIF). Fluorescein-derived pI markers are used as internal standards to assign a pI value to each individually detected mitochondrial event, and a mitochondrial pI distribution is determined. This method provides reproducible distributions of individual mitochondrial pI, accurate determination of the pI of individual mitochondria by the use of internal standards, and resolution of 0.03 pH units between individual mitochondria. This method could also be applied to investigate or design separations of organelle subtypes (e.g., subsarcolemmal and interfibrillar skeletal muscle mitochondria) and to determine the pIs of other biological or nonbiological particles.

Internal standards: A source of analytical bias for volatile organic analyte determinations

The use of internal standards in the determination of volatile organic compounds as described in SW-846 Method 8260C introduces a potential for bias in results once the internal standards (ISTDs) are added to a sample for analysis. The bias is relative to the dissimilarity between the analyte and internal standard physical properties that influence how easily analytes are separated from a matrix and concentrated during analysis.Method 5032 is a vacuum distillation procedure for extracting analytes from a sample for use with Method 8260C. Vacuum distillation is also incorporated within another GC/MS analytical procedure, Method 8261A. Method 8260C/5032 and Method 8261A are experimentally identical, however, Method 8261A uses internal standards differently by relating the recovery of each compound to its boiling point and relative volatility. By processing each analysis (water, soil, and biota) using both Method 8260C and Method 8261A, the two approaches are compared on the basis of analyte bias and the failure rate of the quality controls.Analytes were grouped by how similar their boiling points and natural log of their relative volatilities (lnRVs) were to their Method 8260C recommended ISTDs. For the most similar analytes, the Method 8260C determinations yielded an average bias less than 10% and a failure to meet calibration criteria less than 7%. However, as the difference between analyte and ISTD became greater the bias increased to over 40% (matrix dependent) and its calibration failure rate approached 70%. In comparison, when the Method 8260C data were reprocessed as Method 8261A determinations, this trend for groupings was minimized with biases increasing from 6% to only 20% and the calibration failure rate went from 0% to 15%.

Simultaneous determination of potassium guaiacolsulfonate, guaifenesin, diphenhydramine HCl and carbetapentane citrate in syrups by using HPLC-DAD coupled with partial least squares multivariate calibration

A simple and rapid analytical procedure was proposed for the determination of chromatographic peaks by means of partial least squares multivariate calibration (PLS) of high-performance liquid chromatography with diode array detection (HPLC-DAD). The method is exemplified with analysis of quaternary mixtures of potassium guaiacolsulfonate (PG), guaifenesin (GU), diphenhydramine HCI (DP) and carbetapentane citrate (CP) in syrup preparations. In this method, the area does not need to be directly measured and predictions are more accurate. Though the chromatographic and spectral peaks of the analytes were heavily overlapped and interferents coeluted with the compounds studied, good recoveries of analytes could be obtained with HPLC-DAD coupled with PLS calibration. This method was tested by analyzing the synthetic mixture of PG, GU, DP and CP. As a comparison method, a classsical HPLC method was used. The proposed methods were applied to syrups samples containing four drugs and the obtained results were statistically compared with each other. Finally, the main advantage of HPLC-PLS method over the classical HPLC method tried to emphasized as the using of simple mobile phase, shorter analysis time and no use of internal standard and gradient elution.

A combined application of thermal desorber and gas chromatography to the analysis of gaseous carbonyls with the aid of two internal standards

In this study, a series of GC calibration experiments were conducted to examine the feasibility of the thermal desorption approach for the quantification of five carbonyl compounds (acetaldehyde, propionaldehyde, butyraldehyde, isovaleraldehyde, and valeraldehyde) in conjunction with two internal standard compounds. The gaseous working standards of carbonyls were calibrated with the aid of thermal desorption as a function of standard concentration and of loading volume. The detection properties were then compared against two types of external calibration data sets derived by fixed standard volume and fixed standard concentration approach. According to this comparison, the fixed standard volume-based calibration of carbonyls should be more sensitive and reliable than its fixed standard concentration counterpart. Moreover, the use of internal standard can improve the analytical reliability of aromatics and some carbonyls to a considerable extent. Our preliminary test on real samples, however, indicates that the performance of internal calibration, when tested using samples of varying dilution ranges, can be moderately different from that derivable from standard gases. It thus suggests that the reliability of calibration approaches should be examined carefully with the considerations on the interactive relationships between the compound-specific properties and the operation conditions of the instrumental setups.

Cleanup strategies and advantages in the determination of several therapeutic classes of pharmaceuticals in wastewater samples by SPE–LC–MS/MS

This work describes the development and validation of an offline solid-phase extraction with simultaneous cleanup capability, followed by liquid chromatography-(electrospray ionisation)-ion trap mass spectrometry, enabling the concurrent determination of 23 pharmaceuticals of diverse chemical nature, among the most consumed in Portugal, in wastewater samples. Several cleanup strategies, exploiting the physical and chemical properties of the analytes vs. interferences, alongside with the use of internal standards, were assayed in order to minimise the influence of matrix components in the ionisation efficiency of target analytes. After testing all combinations of adsorbents (normal-phase, ion exchange and mixed composition) and elution solvents, the best results were achieved with the mixed-anion exchange Oasis MAX cartridges. They provided recovery rates generally higher than 60%. The precision of the method ranged from 2% to 18% and 4% to 19% (except for diclofenac (22%) and simvastatin (26%)) for intra- and inter-day analysis, respectively. Method detection limits varied between 1 and 20ngL(-1), while method quantification limits were <85ngL(-1) (both excluding ibuprofen). This analytical method was applied to gather preliminary results on influents and effluents of two wastewater treatment plants (WWTPs) located in the urban region of Porto (Portugal). Typically, paracetamol, hydrochlorothiazide, furosemide, naproxen, ibuprofen, diclofenac and bezafibrate were detected in concentrations ranging from 1 to 20μgL(-1), while gemfibrozil, simvastatin, ketoprofen, azithromycin, bisoprolol, lorazepam and paroxetine were quantified in levels below 1μgL(-1). These WWTPs were given particular attention since they discharge their effluents into the Douro river, where water is extracted for the production of drinking water. Some sampling spots in this river were also analysed.

Impacts of Inter- and Intralaboratory Variations on the Reproducibility of Microbial Community Analyses

With the advent of molecular biological techniques, especially next-generation sequencing and metagenomics, the number of microbial biogeography studies is rapidly increasing. However, these studies involve the synthesis of data generated by different laboratories using different protocols, chemicals, etc., all with inherent biases. The aim of this study was to assess inter- as well as intralaboratory variations in microbial community composition when standardized protocols are applied to a single soil sample. Aliquots from a homogenized soil sample from a rice field in Italy were sent to five participating laboratories. DNA was extracted by two investigators per laboratory using an identical protocol. All DNA samples were sent to one laboratory to perform DNA quantification, quantitative PCR (QPCR), and microarray and denaturing gradient gel electrophoresis (DGGE) analyses of methanotrophic communities. Yields, as well as purity of DNA, were significantly different between laboratories but in some cases also between investigators within the same laboratory. The differences in yield and quality of the extracted DNA were reflected in QPCR, microarray, and DGGE analysis results. Diversity indices (Shannon-Wiener, evenness, and richness) differed significantly between laboratories. The observed differences have implications for every project in which microbial communities are compared in different habitats, even if assessed within the same laboratory. To be able to make sensible comparisons leading to valid conclusions, intralaboratory variation should be assessed. Standardization of DNA extraction protocols and possible use of internal standards in interlaboratory comparisons may help in rendering a "quantifiable" bias.

Analysis of perfluorinated compounds in sludge by liquid extraction and high performance liquid chromatography-tandem mass spectrometry

Perfluorinated compounds are emerging persistent organic pollutants. Wastewater treatment plants are reported to be one of their primary sources. However, a standard analytical method for sludge samples has not been set up. A novel and rapid analytical method based on the liquid extraction, followed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was set up for 7 perfluorocarboxylic acids (PFCAs) and their precursors, 6:2 and 8:2 unsaturated flourotelomer carboxylic acids (FTUCAs), and 2 perfluoroalkyl sulfonates (PFASs) and their precursors, 5 derivates of sulfonamide in sludge. The parameters of methanol extraction, including pH, sonication temperature and time, and eluent volume were optimized. The extraction method was optimized as neutral extraction under sonication at 40 degrees C for 10 min, and it was successfully used for the analysis of perfluorinated compounds in the sludge samples. The linear calibration curves were obtained in the ranges of 0.1-20 microg/L for PFCAs and 6: 2/8: 2 FTUCA and 0.25-50 microg/L for PFASs and their precusors with linear correlation coefficients larger than 0.99. The recoveries of the target compounds ranged from 74% to 141% (except for FTUCAs) and the limits of quantification ranged from 0.6 to 30 microg/kg (dry weight). The use of internal standards can well correct the ion suppression (or enhancement) induced by co-eluting components present in the sample extracts, and improve the quantitative accuracy.

Stability, preservation, and quantification of hormones and estrogenic and androgenic activities in surface water runoff

Degradation of hormones that may occur during storage of surface water samples can lead to underestimations in estrogenic and androgenic activities and inaccuracies in hormone concentrations. The current study investigated the use of sodium azide, hydrochloric acid (HCl), and sulfuric acid (H₂SO₄) to inhibit the degradation of hormones and estrogenic and androgenic activities in samples of surface water runoff from cattle manure-amended fields during storage at 4°C. Hormones and hormone metabolites were extracted using solid-phase extraction and analyzed using high-performance liquid chromatography (HPLC) with tandem MS. Estrogenic and androgenic activities were assessed by E-screen and A-screen, respectively. Results of the current study indicate significant degradation of estrogenic, androgenic, and progestogenic hormones and activities, which is likely attributable to microbial activity, within hours of sample collection. The inclusion of internal standards provides a means to account for hormone losses caused by extraction inefficiency and to some extent degradation. However, internal standards are unable to adequately account for significant losses and are not available for E-screen and A-screen. Sodium azide did not adequately inhibit androgen degradation at the concentration used (1 g/L). Acid preservation (HCl or H₂SO₄, pH 2) stabilized the estrogenic and androgenic activities, and coupling acid preservation with the use of internal standards resulted in reliable and accurate recovery of a suite of androgens, estrogens, and progestogens for up to 14 d of storage at 4°C.

Electroosmotic sampling. Application to determination of ectopeptidase activity in organotypic hippocampal slice cultures.

We hypothesize that peptide-containing solutions pulled through tissue should reveal the presence and activity of peptidases in the tissue. Using the natural zeta-potential in the organotypic hippocampal slice culture (OHSC), physiological fluids can be pulled through the tissue with an electric field. The hydrolysis of the peptides present in the fluid drawn through the tissue can be determined using capillary HPLC with electrochemical detection of the biuret complexes of the peptides following a postcolumn reaction. We have characterized this new sampling method by measuring the flow rate, examining the use of internal standards, and examining cell death caused by sampling. The sampling flow rate ranges from 60 to 150 nL/min with a 150 microm (ID) sampling capillary with an electric field (at the tip of the capillary) from 30 to 60 V/cm. Cell death can be negligible with controlled sampling conditions. Using this sampling approach, we have electroosmotically pulled Leu-enkephalin through OHSCs to identify ectopeptidase activity in the CA3 region. These studies show that a bestatin-sensitive aminopeptidase may be critical for the hydrolysis of exogenous Leu-enkephalin, a neuropeptide present in the CA3 region of OHSCs.

LIFESTYLE AND SOCIOECONOMIC DETERMINANTS OF BLOOD PRESSURE IN SCHOOL-AGED CHILDREN AND ADOLESCENTS: PP.37.506

Objective: To examine the associations between childhood and adolescence lifestyle/socioeconomic status (SES) and blood pressure (BP). Design and Methods: We performed a cross-sectional, nation-wide survey of BP and SES in Poland. Study participants (children and adolescents 6.5–18.5 years of age) were randomly selected using two-stage sampling; schools were primary sampling units. Medical history, lifestyle and socioeconomic data were collected by a questionnaire obtained during the BP measurement. Systolic and diastolic BP (SBP, DBP) and mean arterial pressure (MAP) were measured in triplicate using oscillometric device Datascope Accutor Plus. BP (average of second and third measurement) was adjusted for age and sex by converting it into Z-scores with the use of internal standard. Crude BP Z-scores were adjusted for confounders: weight and BMI using multiple linear regression. Differences of mean Z-scores by categories of explanatory lifestyle/SES variables were analyzed using Student's t-test (in case of variable with two categories) or analysis of variance (ANOVA, in case of variable with more than two categories). Differences in SBP, DBP and MAP were tested separately. Results: There were 16 976 children and adolescents (8133 boys), aged 7–18 years, free of chronic diseases and medication, enrolled in the study from November 2007 to November 2009. Table 1 shows difference in BP according to SES characteristics.Ordinal lifestyle/SES explanatory variables having more than two categories: PA, mother/father education, income per capita showed dose-response type of association with BP: BP decreasing with improved socioeconomic status or increasing physical activity. Conclusions: A low family socioeconomic status and sedentary lifestyle are associated with higher BP in children and adolescents. There were no significant differences in BP in relation to family size, exposure to TV or computer in room, in which the child sleeps.

Development of 2D Chiral Chromatography with Accelerator Mass Spectrometry for Quantification of 14 C-Labeled R - and S -Verapamil in Plasma

A microdose study was performed where 50 µg R/S-(14)C-verapamil was dosed intravenously to human volunteers. In order to quantify the individual R- and S-enantiomers in human plasma a 2D chiral HPLC method with subsequent analysis by accelerator mass spectrometry was verified. R/S-verapamil was separated on a C18 column and the isolated fraction was applied to a chiral column where the verapamil enantiomers were separated. Experimental recovery (∼73% [coefficient of variation {CV} = 16%] and 66% [CV = 21%] for R- and S-verapamil, respectively) was accounted for by the use of internal standardization from the fluorescence response of nonlabeled R- and S-verapamil. The precision of the assay ranged from 4.1 to 15.9% CV and the limit of quantitation was 1.95-4.81 pg/ml for R-verapamil and 1.76-3.34 pg/ml for S-verapamil. This method was successfully applied to the analysis of R- and S-verapamil in human plasma.

Improved method for the quantification of lysophospholipids including enol ether species by liquid chromatography-tandem mass spectrometry

LC/ESI-MS/MS has been previously demonstrated to be a powerful method to detect and quantify molecular species of glycerophospholipids including lysophospholipids. In this study, we provide an improved pre-mass spectrometry lipid extraction procedure that avoids the acid-catalyzed decomposition of plasmenyl phospholipids that is problematic with previously reported methods. We show that the use of lysophospholipid internal standards with perdeuterated fatty acyl chains avoids isobar problems associated with the use of internal standards containing odd carbon number fatty acyl chains. We also show that LC prior to MS is required to avoid numerous problems associated with isobars and with MS in-source decomposition of lysophosphatidylserine. The reported method of using normal phase chromatography/ESI-MS is used to quantify lysophospholipids in serum and to quantify lysophospholipids produced in mammalian cells by human group X secreted phospholipase A(2). The latter shows that group X phospholipase A(2) added exogenously to cells generates a different set of lysophospholipids compared with enzyme produced endogenously in cells, which supports earlier studies showing that this phospholipase A(2) can act on cell membranes prior to externalization from cells.

Quantitative MALDI-MS n Analysis of Cocaine in the Autopsied Brain of a Human Cocaine User Employing a Wide Isolation Window and Internal Standards

Detection of drugs in tissue typically requires extensive sample preparation in which the tissue is first homogenized, followed by drug extraction, before the extracts are finally analyzed by LC/MS. Directly analyzing drugs in intact tissue would eliminate any complications introduced by sample pretreatment. A matrix-assisted laser desorption/ionization tandem mass spectrometry (MALDI-MS(n)) method as been developed for the quantification of cocaine present in postmortem brain tissue of a chronic human cocaine user. It is shown that tandem mass spectrometry (MS(2) and MS(3) increase selectivity, which is critical for differentiating analyte ions from background ions such as matrix clusters and endogenous compounds found in brain tissue. It is also shown that the use of internal standards corrects for signal variability during quantitative MALDI, which can be caused by inhomogeneous crystal formation, inconsistent sample preparation, and laser shot-to-shot variability. The MALDI-MS(n) method developed allows for a single MS(3) experiment that uses a wide isolation window to isolate both analyte and internal standard target ions. This method is shown to provide improved precision [approximately 10-20 times reduction in percent relative standard deviation (%RSD)] for quantitative analysis compared to using two alternating MS(3) experiments that separately isolate the target analyte and internal standard ions.

Urine 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a specific marker of oxidative stress, using direct, isocratic LC–MS/MS: Method evaluation and application in study of biological variation in healthy adults

Background Urine 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) is a specific biomarker of oxidative stress. We evaluated a modified LC–MS/MS assay for urine 8-oxodG and determined biological variation in healthy adults. Method Untreated urine was injected into an isocratic LC–MS/MS system (positive-ion MRM mode). Urine 8-oxodG in 51 healthy volunteers was measured; within- and between-day variations in 23 healthy volunteers were investigated. Results Dose–response was linear to 452 nmol/l; limit of detection = 2.3 nmol/l; within-run and between-run CVs were < 3.0% and < 4.7%, respectively; recovery = 97%–101%; accuracy = 97.7–103.5%. Urine 8-oxodG (median, mean [SD]): 1.70, 1.70[0.60]nmol/mmol creatinine ( n = 51). Men had higher ( p = 0.027) concentrations than women matched for age and body mass index: mean [SD]: 1.90[1.60]; n = 26 vs. 1.50[0.55]; n = 25. Within- and between-day variations were wide but random. No significant differences were seen overall across time-points within 1 day or at the same time-point across 5 consecutive days. Conclusions The method has advantages of speed and relative simplicity as it does not require sample pre-treatment for 8-oxodG extraction, the use of internal standard or gradient LC elution and has high linearity, specificity, precision and recovery. Biological variation in urine 8-oxodG is wide, but no within- or between-day differences at the group concentration were seen in healthy adults.

Halogenated Peptides as Internal Standards (H-PINS): INTRODUCTION OF AN MS-BASED INTERNAL STANDARD SET FOR LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

As the application for quantitative proteomics in the life sciences has grown in recent years, so has the need for more robust and generally applicable methods for quality control and calibration. The reliability of quantitative proteomics is tightly linked to the reproducibility and stability of the analytical platforms, which are typically multicomponent (e.g. sample preparation, multistep separations, and mass spectrometry) with individual components contributing unequally to the overall system reproducibility. Variations in quantitative accuracy are thus inevitable, and quality control and calibration become essential for the assessment of the quality of the analyses themselves. Toward this end, the use of internal standards cannot only assist in the detection and removal of outlier data acquired by an irreproducible system (quality control) but can also be used for detection of changes in instruments for their subsequent performance and calibration. Here we introduce a set of halogenated peptides as internal standards. The peptides are custom designed to have properties suitable for various quality control assessments, data calibration, and normalization processes. The unique isotope distribution of halogenated peptides makes their mass spectral detection easy and unambiguous when spiked into complex peptide mixtures. In addition, they were designed to elute sequentially over an entire aqueous to organic LC gradient and to have m/z values within the commonly scanned mass range (300-1800 Da). In a series of experiments in which these peptides were spiked into an enriched N-glycosite peptide fraction (i.e. from formerly N-glycosylated intact proteins in their deglycosylated form) isolated from human plasma, we show the utility and performance of these halogenated peptides for sample preparation and LC injection quality control as well as for retention time and mass calibration. Further use of the peptides for signal intensity normalization and retention time synchronization for selected reaction monitoring experiments is also demonstrated.

Determination of the antifungal agent posaconazole in human serum by HPLC with parallel column-switching technique

Posaconazole is a new broad-spectrum antifungal agent that is currently only available as an oral suspension and shows high intra- and inter-individual differences in oral bioavailibility. Pre-existing methods for the determination of the substance involve the use of internal standards or require a quite complicated and time-consuming sample pre-treatment. Our HPLC method is fast and fully-automated and there is no need for any manual sample pre-treatment. On-line transfer of posaconazole from the extraction column was followed by chromatographic separation on a C18 column and fluorescence detection ( λ ex: 261 nm, λ em: 357 nm). Retention time of posaconazole was about 11.7 min, the lower limit of quantification was found to be 0.1 mg/l. A linear calibration curve was obtained over the concentration range of 0.1–5 mg/l using a 50 μl sample ( r 2 = 0.999). The relative standard deviations of intra-day variations ranged from 2.3% to 9.4%, intra-day accuracy from 88.8% to 114.8%.

The relative influence of phosphorylation and methylation on responsiveness of peptides to MALDI and ESI mass spectrometry

Qualitative and quantitative analysis of post-translational protein modifications by mass spectrometry is often hampered by changes in the ionization/detection efficiencies caused by amino acid modifications. This paper reports a comprehensive study of the influence of phosphorylation and methylation on the responsiveness of peptides to matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry. Using well-characterized synthetic peptide mixtures consisting of modified peptides and their unmodified analogs, relative ionization/detection efficiencies of phosphorylated, monomethylated, and dimethylated peptides were determined. Our results clearly confirm that the ion yields are generally lower and the signal intensities are reduced with phosphopeptides than with their nonphosphorylated analogs and that this has to be taken into account in MALDI and ESI mass spectrometry. However, the average reduction of ion yield caused by phosphorylation is more pronounced with MALDI than with ESI. The unpredictable impact of phosphorylation does not depend on the hydrophobicity and net charge of the peptide, indicating that reliable quantification of phosphorylation by mass spectrometry requires the use of internal standards. In contrast to phosphorylation, mono- and dimethylated peptides frequently exhibit increased signal intensities in MALDI mass spectrometry (MALDI-MS). Despite minor matrix-dependent variability, MALDI methods are well suited for the sensitive detection of dimethylated arginine and lysine peptides. Mono- and dimethylation of the arginine guanidino group did not significantly influence the ionization efficiency of peptides in ESI-MS.

Linear and accurate quantitation of proenkephalin-derived peptides by isotopic labeling with internal standards and mass spectrometry

Proenkephalin (PE) represents the precursor protein of the active peptide neurotransmitter enkephalin. Quantitative analysis of peptides and proteins is an objective of mass spectrometry-based studies of biological systems and will be important for studying the proteolytic conversion of proproteins to active enkephalin and neuropeptides. The goal of this study was to define and optimize quantitation of different amounts of tryptic peptides derived from PE using light (H4, 4 hydrogens) and heavy (D4, 4 deuteriums) succinic anhydride for isotopic labeling of peptides analyzed by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Comparisons were made between PE-derived peptides with and without internal standards. Importantly, incorporation of internal standards of known amounts of heavy isotope-labeled tryptic peptides of PE provided linear calibration plots with accurate quantitation. In contrast, comparison of light and heavy isotope-labeled peptides without internal standards produced variable and inaccurate nonlinear isotopic ratio comparisons of PE-derived peptides. These results demonstrate that use of internal standards composed of a defined amount(s) of standard peptides (PE-derived tryptic peptides) is necessary for high-quality linear quantitation of peptides by isotopic labeling and MS/MS.

Use of NMR and NMR Prediction Software To Identify Components in Red Bull Energy Drinks

A laboratory experiment designed as part of an upper-level undergraduate analytical chemistry course is described. Students investigate two popular soft drinks (Red Bull Energy Drink and sugar-free Red Bull Energy Drink) by NMR spectroscopy. With assistance of modern NMR prediction software they identify and quantify major components in each drink. Students are introduced to solvent suppression, use of internal standards, hands-on collection of simple 1D and 2D NMR spectra, spectral interpretation of mixtures, component quantification, and spectral simulation and prediction.

A portable capillary electropherograph equipped with a cross‐sampler and a contactless‐conductivity detector for the detection of the degradation products of chemical warfare agents in soil extracts

A fully portable CE device equipped with a capacitively coupled contactless-conductivity detector and a cross-injection device is put to the test in laboratory conditions. The portable device is capable of working on batteries for at least 4 h. After that, its performance is strongly affected by the drop in the high-voltage output and analysis may be interrupted if its length exceeds a reasonable time. The concentration of the BGE affects both ionic strength and conductivity. Choosing an optimal concentration of BGE is therefore about finding a good compromise between selectivity and sensitivity. All experiments were performed using a mixture of histidine and MES with a concentration of 15 mM as BGE. The performance of the cross-injection device is optimized by the use of internal standards. Satisfactory reproducibility is gained as the RSD of peak areas is reduced to 8% or less. LODs for different phosphonic acids are in the range of 2.5-9.7 microM. For the analysis of adsorption of phosphonic acids in sand and loamy soil samples, calibration curves are constructed. Linearity in a measured concentration range of 10-100 microM is excellent, as the squares of correlation constants are approximately 1. The concentration analysis of phosphonic acids in soil extracts demonstrates that their adsorption curves in sand and loamy soil follow different adsorption isotherms.