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1
Content available remote Photocatalysis combined with chromatographic methods as a new promising tool in drug metabolism studies – a review
Gawlik M., Skibiński R., Trawiński J., Komsta Ł.
Acta Chromatographica
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2018
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Vol. 30, no. 1
1--8
EN
The number of new drugs launched to the market is constantly increasing; however, the metabolism of many of them is still not fully established. The knowledge of drug metabolism pathways is crucial for the efficacy and safety of therapies and, in classical approach, requires the use of animals as well as human volunteers, but this kind of research is expensive and time-consuming. Therefore, nowadays, more and more biological and chemical in vitro methods are developed for the drug metabolism study. This review is focused on the photocatalytic degradation of chemicals and the application of this process in chromatographic methods of drug metabolism research. A theoretical background of photocatalysis and all its applications in a drug metabolism study were reviewed, and other in vitro methods that are actually used were summarized and discussed. Other analytical methods used in this area were also discussed and compared.
2
Content available remote Chemometric analysis of chromatographic data in stability investigation of cephalosporins
Dąbrowska M., Komsta Ł., Opoka W., Starek M.
Acta Chromatographica
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2018
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Vol. 30, no. 4
255--263
EN
The specific aim of this investigation was to study the kinetics of the degradation of cefazolin, cefaclor, cefuroxime axetil, and cefepime in aqueous solution, in the presence (or absence) of various redox agents (iodine solution, potassium permanganate, hydrogen peroxide, sodium thiosulfate, and ascorbic acid) as a function of temperature. Various factors, such as concentration of the analyzed compounds and redox agents, storage time, and temperature, were analyzed. The degradation process of chosen antibiotics was observed chromatographically and fitted to the kinetic models, obtaining model parameters (k, t0.1, t0.5). Principal component analysis (PCA), parallel factor analysis (PARAFAC), and hierarchical cluster analysis (HCA) methods were carried out to interpret the dependencies between these factors on the drug stability.
3
Content available remote Comparison of ESI and APCI sources in Q-TOF mass spectrometer in photodegradation study of selected psychotropic drugs
Trawiński J., Skibiński R., Komsta Ł.
Acta Chromatographica
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2017
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Vol. 29, no. 2
161--172
EN
Ultra high-performance liquid chromatography (UHPLC) coupled with high-resolution quadrupole time-of-flight (Q-TOF) mass spectrometry was used for the preliminary photodegradation study of nine new generation psychotropic drugs. Based on the above method, two ionization sample modes — electrospray and atmospheric pressure chemical ionization were used for the registration of photodegradation profiles of the selected drugs. Multivariate chemometric analysis showed that electrospray ionization (ESI) method is more specific than atmospheric pressure chemical ionization (APCI) in high-resolution mass spectrometry (HR-MS) analysis of the analyzed psychotropic drugs. It was noticed that, with the use of ESI method, more potential photodegradation products can be identified and lower limits of its detection can be obtained.
4
Content available remote Revisiting thin-layer chromatography as a lipophilicity determination tool. Part IV — A closer look on extrapolation and averaging
Komsta Ł., Gowin E.
Acta Chromatographica
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2014
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Vol. 26, no. 1
1--12
EN
The paper compares linear, quadratic, and cubical regression together with several weighted and robust approaches in the context of lipophilicity determination. The comparison is done on 35 model compounds on data from different modifiers used on RP18, CN, and silica plates. It can be concluded that the use of weighted and moderately robust regression technique increases correlation between extrapolated retention and real lipophilicity, whereas polynomial and very robust techniques give visibly worse results due to their excessive flexibility and higher extrapolation uncertainty. Additionally, we have compared averaging retention from different modifiers by RF, k, and RM values. The results are similar; however, surprisingly, RF averaging performs slightly better to the other approaches.
5
Content available remote Determination of microelements in sprouts grown on metal-enriched solutions by ion chromatography
Blicharska E., Komsta Ł., Kocjan R., Gumieniczek A., Kloc A., Kaźmierczak J.
Acta Chromatographica
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2014
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Vol. 26, no. 4
739--747
EN
The paper discusses a possibility to grow seeds on solutions of microelements and application of sprouts enriched in such a way as an alternative to commercial dietary supplements. It contains a short review of the approaches reported till now and a systematic experimental study, carried on the most frequently used seeds (Lens culinaris, Helianthus annuus, Vigna radiata, Glycine max, and Lepidium sativum).Seven metals (Fe, Cu, Zn, Ni, Co, Cd, and Mn) were studied. Seeds were grown on cellulose in 20°C temperature using deionized water enriched with metals in concentrations: 100, 50, 25, 12.5, 6.25, and 3.125 mg/L in a period of 4 days. The reference samples were the seeds grown on pure deionized water. Sprouts were mineralized by microwave radiation, and the metal content was quantified by ion chromatography with on-line post-column derivatization and spectrophotometric detection.The conclusions can be treated as general recommendations, which seeds should be grown and what concentrations of metals in solutions should be applied to provide good enrichment and to avoid risk of microelement overdose.
6
Content available remote Densitometry, video-scanning and capillary electrophoresis for determination of valsartan and amlodipine in a combined dosage form: A comparative study
Inglot T. W., Gumieniczek A., Komsta Ł., Związek R.
Acta Chromatographica
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2013
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Vol. 25, no. 1
47-58
EN
Comparison of classical densitometry, video-scanning, and capillary electrophoresis was performed for determination of angiotensin II receptor antagonist, valsartan, and calcium channels blocker, amlodipine, in a combined dosage form. Thin layer chromatography was performed on RP8F254 TLC plates with a mobile phase consisting of acetonitrile-phosphate buffer at pH 9.0 (5:5, v/v) and temperature 20 °C. Densitometry was done in the reflectance mode at 217 nm for valsartan and in the absorbance mode at 370 nm for amlodipine. Video-scanning was elaborated at 254 and 366 nm for valsartan and amlodipine, respectively. For chromatographic analysis, calibration plots were constructed in the range of 0.4–2.8 μg per spot for valsartan and 0.02–0.14 μg per spot for amlodipine. Capillary electrophoresis (CE) was performed using a 75 μm × 94 cm fused silica capillary (72 cm effective length), 0.01 mol L-1 borate buffer at pH 8.0, 20 kV voltage, 30 °C temperature, hydrodynamic injection (10 mbar, 6 s) and UV detection at 237 nm. Calibration plots were constructed in the range of 0.1–0.6 mg mL-1 for valsartan and 0.005–0.03 mg mL-1 for amlodipine. All methods were validated in respect to robustness, specificity, stability, linearity, precision, and accuracy. Generally, statistical comparison between the methods did not show significant differences so all procedures are suitable for pharmaceutical analysis.
7
Content available remote Validation of specificity in quantitative thin layer chromatography—is spectral correlation a reliable measure of spot purity?
Kobyłka M., Komsta Ł.
Acta Chromatographica
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2012
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Vol. 24, no. 3
433--444
EN
The current guidelines of quantitative method development establish a requirement to validate a set of method parameters and the selectivity is one of the most important parameters to be proven. Currently, one of the most frequently used approaches is to measure the spectrum of a spot together with some reference spots and to correlate them. Additionally, several places of the spot (start, middle, end) can be measured and also correlated. In the current paper we perform a simulation done on 170 real spectra with different levels of contamination and noise, establishing the distribution of correlation coefficient. It can be concluded that contamination up to 10% almost cannot be detected by simple correlation measurement, regardless of the noise level. Moreover, at a high noise level there is a very low margin between correlation of different compounds and the correlation of the same (but noisy) spectra. These observations suggest that the spectral correlation cannot be a reliable measure of method specificity and some another chemometric methods need to be searched in further research.
8
Content available remote Salting-out chromatography : a practical review
Komsta Ł., Skibiński R., Bojarczuk A, Radoń M.
Acta Chromatographica
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2011
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Vol. 23, no. 2
191--203
EN
This review focuses on the salting-out effect and its use in chromatographic analysis, mainly thin-layer chromatography. First, a theoretical background is given, focusing on the general salting-out theory and a comparison with chaotropic salt addition, practised recently in reversed-phase chromatography. All the salting-out chromatographic applications in literature (from the 1960s to the present moment) are then reviewed.
9
Content available remote Multi-way analysis of retention of model compounds in thin-layer chromatography
Komsta Ł., Skibiński R., Gumieniczek A., Wojnar A.
Acta Chromatographica
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2010
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Vol. 22, no. 1
27--36
EN
The thin-layer chromatographic (TLC) retention of 35 model compounds has been investigated with ten screening mobile phases on six normal-phase and seven reversed-phase adsorbents. The retention factors formed two cubes with dimensions 35 × 10 × 6 and 35 × 10 × 7, respectively, which enabled three-way analysis by PARAFAC. A one-component PARAFAC model was optimum in both cases and two-component models performed worse. The one-component model explained 78.8% of the variance in normal-phase chromatography and 94.2% of the variance in reversed-phase chromatography. These results showed that the major variability of the retention factor ( R F ) can be modelled as the product of three factors related to the substance itself, the mobile phase, and the adsorbent. R F modelling was substantially better than using k or R M (rate mobility) values.
10
Content available remote A new general equation for retention modeling from the organic modifier content of the mobile phase
Komsta Ł.
Acta Chromatographica
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2010
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Vol. 22, no. 2
267--279
EN
A general equation is presented for modeling retention, using the organic modifier content of the mobile phase. The equation is based on the Box-Cox transform of modifier concentration. Both the semilogarithmic relationship (Soczewiński-Wachtmeister equation) and logarithmic relationship (Snyder-Soczewiński equation) are special cases of the proposed equation. The equation can be fitted easily with free software and an additional coefficient can be interpreted as closeness to the previous models. Even with strong closeness to log-log dependence, the equation still enables extrapolation to zero modifier content. A case study on nine drug-like substances is also discussed, with comparison of 14 previously proposed retention equations found in the literature.
11
Chemometryczne techniki kalibracyjne w spektrofotometrii. Cz. I - techniki liniowe
Komsta Ł., Paryło M.
Analityka : nauka i praktyka
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2009
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nr 3
9-15
PL
Techniki chemometryczne stosowane są szeroko w spektroskopii. Ich cechą odróżniającą od klasycznych technik jest użycie kompletnego widma jako zmiennej zawierającej szukaną informację.
12
Chemometryczne techniki kalibracyjne w spektrofotometrii. Cz. II - sztuczne sieci neuronowe
Komsta Ł., Dudek K.
Analityka : nauka i praktyka
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2009
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nr 4
4-7
PL
Chociaż pierwsze sztuczne sieci neuronowe konstruowano na podstawie analogowych układów elektronicznych, prawdziwy rozkwit tej dziedziny nastąpił w latach dziewięćdziesiątych w związku ze znacznym poszerzeniem możliwości obliczeniowych komputerów.
13
Content available remote The kernel density estimate as a measure of the performance of one and two-dimensional TLC systems with large retention datasets in the context of their use in fingerprinting
Komsta Ł., Szewczyk K.
Acta Chromatographica
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2009
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Vol. 21, no. 1
13-27
EN
A new objective chromatographic response function, R K , based on the kernel density estimate, is introduced for estimation of the fingerprinting performance of a particular TLC system (uniformity of retention) for which a large set of experimental R F values of possible components of the mixture is available. The R K criterion is insensitive to large numbers (hundreds or thousands) of R F values, when the previously proposed criteria cease. It can be applied to one and two-dimensional TLC and is easily computed. As an example of its application, the performance of twelve general screening systems was evaluated in the context of herbal extract fingerprinting (88 phytochemical standards) by both one and two-dimensional TLC.
14
Content available remote Dealing with charged-coupled device noise in thin-layer videodensitometry. Optimization of several image-denoising techniques
Komsta Ł.
Acta Chromatographica
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2009
|
Vol. 21, no. 3
355--367
EN
Charged-coupled device (CCD) noise can be a serious problem during videoscanning, especially when scanning dark plates with weakly fluorescent spots. The proper denoising of videoscans inside mathematical environments is a critical part of any advanced chemometric processing. The paper reports comparison and optimization of representative videoscan denoising by different techniques. Several kind of filters (averaging, circular, Gaussian, Savitzky-Golay, median, Wiener, FIR) and wavelet shrinkage (twelve mother wavelets from the Daubechies, Symmlet, and Coiflet family, five decomposition levels, and soft/hard thresholding) were optimized against noise autocorrelation or mean-squared error to the reference image. The reference image was obtained by grabbing and averaging 256 CCD frames. The median filter is the winner of the competition; other filters except Gaussian and wavelet shrinkage at high decomposition level are also sufficient and good ways of videoscan denoising. The Gaussian filter and wavelet shrinkage at low decomposition level performed worst and could not be recommended.
15
Content available remote Extending equal-spreading criteria to two-dimensional thin layer chromatography - the points in a unit square problem revisited
Komsta Ł.
Acta Chromatographica
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2008
|
Vol. 20, no. 3
309-327
EN
Optimization of two-dimensional thin-layer chromatographic separation often relies on selection of the two most orthogonal chromatographic systems which best co-operate in the separation. This is mainly achieved by investigating the correlation between R F values or scoring the distances between the spots. This paper presents and discusses another approach, based on the distances to the closest spot and to the top or bottom of the plate. The theory arises from a well-known geometrical problem about equal-spreading of the points inside a unit square. Two coefficients are proposed - sensitive and insensitive to complete separation, which are the two-dimensional version of previously proposed R U and R D criteria (retention uniformity and retention distance, describing the equal-spreading of the spots in one-dimensional chromatography). They are included in the range 0-1 and their distribution as a random variable is well defined and not affected by the number of separated compounds.
16
Content available remote Comparative validation of densitometric and videodensitometric determination of lovastatin and simvastatin in pharmaceuticals
Komsta Ł., Skibiński R., Hopkała H., Winiarczyk-Serwacka M.
Chemia Analityczna
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2007
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Vol. 52, No. 5
771-779
EN
Densitometric and videodensitometric methods for determination of lovastatin and simva-statin in commercially available pharmaceutical have been described. Analysis was performed using HPTLC Si F254 plates and hexane-methylethylketone (55:45 v/v) mobile phase. Densitometric detection was performed at 230 nm, and videoscanning at 254 nm. Calibration plots were constructed in the range 4-16 &mi; g per spot for both drugs. Calibration data were subjected to statistical analysis using AIC criterion. Quadratic regression was finally chosen. Active substances were extracted from tablets with methanol. Densitometric method was much more precise than videodensitometric one. However, no significant differences in the accuracy between both procedures were observed. The proposed methods can be used in routine drug analysis due to their precision, accuracy, and relatively low consumption of materials and reagents.
PL
W pracy opisano densytometryczną i wideodcnsylometryczną metodę oznaczania lowasta-tyny i simwastatyny w dostępnych na rynku polskim preparatach farmaceutycznych. Analizę przeprowadzono na płytkach HPTLC pokrytych żelem krzemionkowym z użyciem fazy ruchomej o składzie heksan-metyletylketon (55:45 v/v). Detekcję densytometryczną przeprowadzono przy długości fali 230 nm, a wideoskanowanie przy 254 nm. Krzywe kalibracyjne skonstruowano w zakresie stężeń 4-16 &mi; g na plamkę. Dane kalibracyjne zostały poddane analizie statystycznej i na podstawie kryterium AIC wybrano regresję kwadratową. Ekstrakcję z tabletek przeprowadzono metanolem. Pomiędzy obiema metodami nie stwierdzono różnic w dokładności, natomiast densy tometria odznaczała się wyraźnie lepszą precyzją. Proponowana metoda jest dokładna i precyzyjna, może być użyta w rutynowej analizie produktów leczniczych.
17
Ocena statystyczna kalibracji metod analitycznych
Komsta Ł., Misztal G.
Analityka : nauka i praktyka
|
2007
|
nr 1
26-30
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