Capillary electrophoretic analysis of ionic content in exhaled breath condensate and pH monitoring as a non-invasive method in gastroesophageal reflux disease diagnostics.

In this study, the ionic profile and pH of exhaled breath condensate (EBC) in a group of patients with acid and weakly acid reflux and no-reflux controls were compared. A portable sampler was used for non-invasive EBC collection from five exhalations. The ionic profile (anions, cations, organic acids) and pH of the collected EBC samples were measured by capillary electrophoresis with contactless conductivity detection and a pH microelectrode, respectively. Several ions were elevated in the patient groups. Sodium cation was elevated in weakly acid reflux (significance level p < 0.01) and acid reflux (p < 0.05) compared to no-reflux controls. Butyrate and propionate were elevated in both acid reflux and weakly acid reflux compared to no-reflux controls (butyrate: p < 0.01, propionate: p < 0.05). The median values of pH (after de-aeration with N2) were also significantly higher (p < 0.01) in groups with acid reflux and weakly acid reflux than in the control group with no reflux. The ionic analysis and simultaneous pH measurement offer a simple, cheap, fast, and non-invasive approach in gastroesophageal reflux disease diagnostics.

Optimization of background electrolyte composition for simultaneous contactless conductivity and fluorescence detection in capillary electrophoresis of biological samples.

In this article, optimization of BGE for simultaneous separation of inorganic ions, organic acids, and glutathione using dual C4 D-LIF detection in capillary electrophoresis is presented. The optimized BGE consisted of 30 mM 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid, 15 mM 2-amino-2-hydroxymethyl-propane-1,3-diol, and 2 mM 18-crown-6 at pH 7.2 and allowed simultaneous separation of ten inorganic anions and cations, three organic acids and glutathione in 20 min. The samples were injected hydrodynamically from both capillary ends using the double-opposite end injection principle. Sensitive detection of anions, cations, and organic acids with micromolar LODs using C4 D and simultaneously glutathione with nanomolar LODs using LIF was achieved in a single run. The developed BGE may be useful in analyses of biological samples containing analytes with differing concentrations of several orders of magnitude that is not possible with single detection mode.

Evaluation of Important Analytical Parameters of the Peptest Immunoassay that Limit its Use in Diagnosing Gastroesophageal Reflux Disease.

GOAL: To evaluate the analytical parameters of a lateral flow (LF) pepsin immunoassay (Peptest) and assess its suitability in the diagnostics of gastroesophageal reflux disease (GERD). BACKGROUND: Peptest is a noninvasive assay to analyze pepsin in saliva, intended for use in GERD diagnostics. Although commercialized, fundamental studies on its performance are missing. The assay therefore requires basic analytical parameter evaluation to assess its suitability in clinical practice. STUDY: Assay reaction's time dependence, reader device repeatability, and individual LF devices and longitudinal pepsin concentration reproducibility in individual subjects was evaluated. Salivary pepsin was analyzed in 32 GERD patients with extraesophageal reflux symptoms and 13 healthy individuals. RESULTS: The assay's signal increase is not completed at the recommend readout time and continues to increase for another 25 minutes. The relative standard deviation of measurement was good when using the same LF device, ranging from 2.3% to 12.9%, but the reproducibility of 10 different individual LF devices was poor. The random error when analyzing the same saliva sample on 10 LF devices was as high as 36 ng/mL and this value is thus suggested as the positivity cut-off. Pepsin concentration in individual subjects during a 10-day period varied significantly. The sensitivity of the Peptest was 36.8% in the group with acid reflux and 23.1% in the group with weakly acid reflux. The specificity was 61.5%. CONCLUSIONS: The Peptest assay's sensitivity and specificity is low, the results are highly variable and it should not be used as a near-patient diagnostic method in primary care.

Sensitive determination of malondialdehyde in exhaled breath condensate and biological fluids by capillary electrophoresis with laser induced fluorescence detection.

In this work, a sensitive capillary electrophoresis method with laser induced fluorescence detection for determination of malondialdehyde in various biological fluids was developed. Malondialdehyde reacts with thiobarbituric acid under optimized conditions of pH=2, reaction time of 60min and temperature of 90°C, yielding an adduct that can be separated in a 50mM sodium borate background electrolyte at pH 9. The separation of the formed adduct was accomplished in less than 6min with limit of detection of 1.1nM due to the use of 532nm laser module, exactly matching the maximum excitation wavelength of the formed adduct. The developed method offers unprecedented sensitivity and was for the first time used for analysis of malondialdehyde in exhaled breath condensate. The method proved to be also applicable to other samples of biological fluids, such as blood plasma and saliva.

Capillary electrophoresis in the analysis of biologically important thiols.

In this review article, CE methods for analysis of biologically important thiols are overviewed. The article covers the period from the previously published comprehensive review in 2004 until mid-2016, with emphasis on various detection modes, novel approaches for sample preconcentration, and applications in clinical practice. The most commonly used detection methods, such as conductometry or absorbance detection, although universally applicable and available in most commercial instruments have low sensitivity and have only limited use in thiol analysis. Amperometric and MS detection are more sensitive and have their steady place in thiol analysis, although the mainstay remains CE with LIF detection, reaching nanomolar concentration sensitivities for most of the thiols. Novel probes for CE-LIF have been developed and tested. The preconcentration approaches using modified gold nanoparticles reaching excellent sensitivities in the picomolar range and various sample stacking methods are also reviewed. Finally, significant clinical applications of the developed methods are discussed with critical insights into the future of CE analysis of thiols.