|
|
Application of capillary electrophoresis for dried blood spots analysis
Ryšavá, Lenka ; Tůma,, Petr (referee) ; Petr,, Jan (referee) ; Kubáň, Pavel (advisor)
Blood samples are normally analyzed in the form of plasma or serum. As an alternative for blood sampling and storage, dry blood spots (DBS) have been increasingly used in recent years. In the actual dissertation thesis, DBS are processed and analyzed by capillary electrophoresis (CE), which has been very rarely used for DBS analysis in the past. However, CE offers several features, given by the recent development of this technique, not available for standard analytical methods. Direct coupling of microextraction techniques to CE and simultaneous determination of analytes present in complex matrices leads to minimization or elimination of deficiencies in DBS analysis, for example the effect of sample matrix, hematocrit effect, and inhomogeneous distribution of analytes in DBS. In the simplest possible arrangement, sample treatment, injection, and analysis of DBS samples are achieved exclusively by a single commercial CE instrument. Application of newly developed fully soluble materials for DBS sampling offers better extraction efficiency and more accurate quantitation. The developed concepts include new methods for efficient treatment of DBS samples and their direct analysis without the need for operator intervention and they provide sufficient selectivity and sensitivity for the determination of important analytes not only in DBSs but also in other complex samples.
|
|
|
Rapid fabrication of microextraction devices for direct determination of basic drugs in dried blood spots
Ryšavá, Lenka ; Přikryl, Jan ; Dvořák, Miloš ; Malá, Zdeňka ; Kubáň, Pavel
A 3D-printed cutter was designed for rapid fabrication of supported liquid membrane (SLM) extraction devices compatible with injection system of commercial capillary electrophoresis (CE) instrument. Low cost and single use microextraction devices were fabricated from polypropylene micropipette tips with high precision (dimension variances ≤ 3% RSD). Practical applicability of the microextraction devices was examined by in-line coupling of SLM extractions to CE for direct analysis of four model basic drugs in dried blood spot extracts. Excellent repeatability of the hyphenated technique was achieved (RSD ≤ 7.6%), transfer of analytes across the SLM ranged from 23 to 73% and limits of detection were as low as 0.07 μg/mL.
|
|
|
Hollow fibre-liquid phase microextraction of basic drugs from dried dried blood spots
Dvořák, Miloš ; Miková, B. ; Šlampová, Andrea ; Kubáň, Pavel
Hollow fibre-liquid phase microextraction (HF-LPME) was applied for rapid and efficient extraction of basic drugs from dried blood spots (DBS). Basic drugs from DBS were first extracted into 10 mM NaOH solution, which acted as the HF-LPME donor solution, and simultaneously the neutralized drugs were transferred across the HF and preconcentrated in 10 mM HCl acceptor solution inside the HF lumen. Mixture (1:1, v:v) of 1-ethyl-2-nitrobenzene and dihexyl ether was used for impregnation of the porous HF membrane. Analytes in the acceptor solution were injected directly from the HF into capillary electrophoresis instrument for further separation, detection and quantification. Repeatability of the hyphenated analytical system ranged from 9.8 to 13.8 % (RSD) and enrichment factors of 52 – 78 were obtained for model basic drugs spiked to DBS extracts at a concentration level of 0.1 mg/L.
|
|
|
Micro-electromembrane extraction across multiple aqueous and organic phases for selective pretreatment of raw biological samples
Kubáň, Pavel ; Boček, Petr ; Seip, K. F. ; Gjelstad, A. ; Pedersen-Bjergaard, S.
Micro-electromembrane extraction (μ-EME) across multiple aqueous and organic\nsolutions was developed for selective extractions of various analytes from untreated\nbiological samples. The novel approach requires μL volumes of samples and organic\nsolvents, which form consecutive immiscible plugs in a transparent polymeric capillary\nand the extraction process is accelerated by application of d.c. voltage. Number of the\nplugs, their composition, volume and sequence in the extraction capillary can be chosen\nspecifically for each particular application and high variability and selectivity of the\nextraction process can be achieved. In this contribution, we demonstrate suitability of\na five-phase μ-EME system for simultaneous extractions of cations and anions from\nurine and for selective extractions of basic analytes based on their acid-base strength\nfrom plasma.
|
|
|
Capillary electrophoresis with contactless conductivity detection for rapid determination of meldonium in urine
Šlampová, Andrea ; Kubáň, Pavel
A simple, rapid and cheap capillary electrophoresis-capacitively coupled contactless\nconductivity detection (CE-C4D) method for determination of meldonium (MEL) in\nurine samples was developed. Sample pretreatment was minimized to dilution of urine\nsamples with DI water and MEL was determined by CE-C4D in background electrolyte\nconsisting of 2 M acetic acid (pH 2.3) in ng mL−1 to mg mL−1 concentration range.\nSample-to-sample analysis time was less than 4 min, limit of detection and\nquantification was 0.015 and 0.05 μg mL−1, respectively, and the method showed\nexcellent linearity (r2 ≥ 0.9998), recovery (97.6–99.9%) and intraday as well as interday\nrepeatability (RSD ≤ 4.7%).
|
|
| |
|
|
Polymer inclusion membranes open new way in practical use of in-line coupling of microextraction to CZE
Pantůčková, Pavla ; Kubáň, Pavel ; Boček, Petr
Polymer inclusion membranes (PIMs) have several important features, i.e., PIMs are dry and non-porous membranes, which can be prepared ahead of use and stored without noticeable deterioration in extraction performance. In-line coupling of microextractions across PIMs to commercial capillary zone electrophoresis (CZE) instrument has been demonstrated in this contribution. Purpose-made microextraction devices with PIMs were applied, which ensured complete automation of the entire analytical procedure. Practical 169 applicability of the hyphenated analytical method was demonstrated on direct extraction, injection, CZE separation and quantification of formate (the major metabolite in methanol poisoning) in clinical samples.
|
|
|
Considerations on electrolysis in electromembrane extraction of basic drugs
Šlampová, Andrea ; Kubáň, Pavel ; Boček, Petr
Electrolysis may significantly affect composition and pH values of non-optimized acceptor solutions and have fatal consequences on quantitative EME results for weak and medium strong analytes. Acceptor solutions consisting of high concentrations of weak acids have therefore been proposed as suitable operational solutions for electromembrane extraction (EME) of selected basic drugs. 500 mM formic acid efficiently eliminated the electrolytically produced OH– ions, offered constant pH and thus long-term EME performance and was easily compatible with subsequent analytical methods. Maximum EME recoveries ranged from 66 to 89% and were constant between 40 and 80 min of EME and no back-extraction of the analytes into donor solutions was observed.
|
|
|
Electrolysis in electromembrane extractions. Effects on extraction performance for substituted phenols
Šlampová, Andrea ; Kubáň, Pavel ; Boček, Petr
Electrolysis was shown to play a significant role in electromembrane extraction (EME) performance. Alkaline acceptors, prepared as 1 – 10 mM CsOH solutions, suffered from electrolytic reactions during EMEs of substituted phenols and their pH values decreased by more than 8 units after 40 min of EMEs at 50 V. As a consequence, serious deterioration of EME performance was observed for weak and medium-strong acidic phenols due to their compromised ionization and their subsequent back-extraction into organic phase and donor solution. Application of acceptor solutions consisting of high concentrations of weak bases (e.g. 500 mM ethanolamine) ensured similar initial pH conditions as for the alkali-metal hydroxide based solutions, moreover, significantly better tolerance to electrolysis-induced effects was obtained. Stable pH of acceptor solutions was achieved as well as an improved EME performance for all analytes over the entire extraction period.
|
|
| |
guest ::
RSS feed.