Łukasz Komsta

• PhD, DSc, Prof.
• Professor at Medical University of Lublin

The Directional Median Analysis is a new proposal of robust data exploration. It can be treated as a multivariate extension of the idea similar to Theil-Sen estimator, where one finds a direction which minimizes the sum of angles to all observations. Theoretical analysis of this problem reveals that this analysis can be perceived as a special case...

The lipophilicity of a compound is a fundamental property related to pharmaceutical and biomedical activity. As many approaches are mixed together in every-day published studies, the subject needs some standardization. The paper presents a comparative study on several approaches of TLC lipophilicity determination: a single TLC run, extrapolation of...

A novel, easy, and cheap technique for preliminary quantitative evaluation of antiradical activity, based on HPTLC, has been proposed. This method combines chromatographic separation of polar compounds, present in plant extracts, with data analysis by means of image processing software. Bleaching of the purple DPPH• color, caused by substances with...

The article is intended to introduce and discuss a new quantile regression method for baseline detrending of chromatographic signals. It is compared with current methods based on polynomial fitting, spline fitting, LOESS, and Whittaker smoother, each with thresholding and reweighting approach. For curve flexibility selection in existing algorithms,...

The purpose of the research was to recommend a unified procedure of image preprocessing of 2D thin layer videoscans for further supervised or unsupervised chemometric analysis. All work was done with open source software. The videoscans saved as JPG files underwent the following procedures: denoising using a median filter, baseline removal with the...

The 5-heterocyclic 2-(2,4-dihydroxyphenyl)-1,3,4-thiadiazoles were obtained as potential biologically active compounds. Lipophilicity is one of the most important physicochemical properties of compounds and was already taken into account during the drug candidates design and development. The lipophilicity of compounds was determined using the compu...

Considerable evidence suggests that glucocorticoids (GCs) play an important role in neurodegeneration. Chronic elevated levels of GCs can result in neuronal degeneration of the hippocampal piramidal neurons, which are paralleled by cognitive deficits. Moreover, GCs potentiate stress or ischemia-induced accumulation of excitatory amino acids (EAA) i...

Many forms of drugs are designed to undergo dissolution upon oral administration. The kinetics and efficiency of this process are critical parameters to be controlled. The methods of its evaluation are described in official guidelines issued by the Food and Drug Administration (FDA), European Medicines Agency (EMA) and World Health Organization (WH...

The advantages of hyperspectral imaging in videodensitometry are presented and discussed with the example of extracts from 70 Polish grasses. An inexpensive microscope camera was modified to cover the infrared spectrum range, and then 11 combinations of illumination (254 nm, 366 nm, white light), together with various filters (no filter, IRCut, UV,...

A set of Gentiana L. species was successfully grown in vitro under the same conditions , and 72 samples from various cultures of these species (root, shoot, cotyledon callus, hypocotyl callus, and root callus) were obtained. e investigated species e obtained samples were extracted with a methanol-acetone-water (3:1:1) mixture, evaporated to dryne...

The advantages of high dynamic range (HDR) imaging in videodensitometry are presented and discussed on the example of Gentiana extract thin-layer fingerprints visualized under 254 nm. An inexpensive microscope camera, together with security surveillance lens, mounted instead of original camera on videodensitometry chamber, allows to grab HDR images...

In this study, nine forced degradation products of maraviroc were found using chemometric analysis. This antiretroviral drug was subjected to photolytic, oxidative, as well as neutral, basic and acidic hydrolysis stress conditions. Additionally, its electrochemical transformation on platinum, gold and glassy carbon screen-printed electrodes was exa...

70 species of grasses family (Poaceae), coming from genera: Agrostis, Alopecurus, Anthoxanthum, Apera, Arrhenatherum, Avena, Brachypodium, Briza, Bromus, Calamagrostis, Corynephorus, Cynosurus, Dactylis, Danthonia, Deschampsia, Digitaria, Echinochloa, Elymus, Eragrostis, Festuca, Glyceria, Helictotrichon, Hierochloe, Holcus, Hordeum, Koeleria, Leym...

The experimental design methodology based on central composite design of experiments was applied to compare the retention mechanisms in supercritical fluid chromatography (SFC) and non-aqueous hydrophilic interaction liquid chromatography (NA-HILIC). The selected set consists of 26 compounds that belong to imidazoline and serotonin receptor ligands...

Twenty-one species of Gentiana L. were successfully grown in vitro in the same conditions and 72 samples of various cultures of these species (root, shoots, cotyledon callus, hypocotyl callus, and root callus) were obtained. The investigated species were as follows: G. affinis, G. andrewsii, G. bhutanica, G. burseri, G. cachemirica, G. capitata, G....

70 Species of grasses family (Poaceae), coming from genera: Agrostis, Alopecurus, Anthoxanthum, Apera, Arrhenatherum, Avena, Brachypodium, Briza, Bromus, Calamagrostis, Corynephorus, Cynosurus, Dactylis, Danthonia, Deschampsia, Digitaria, Echinochloa, Elymus, Eragrostis, Festuca, Glyceria, Helictotrichon, Hierochloe, Holcus, Hordeum, Koeleria, Leym...

Adverse early life experiences are associated with an enhanced risk for mental and physical health problems, including substance abuse. Despite clinical evidence, the mechanisms underlying these relationships are not fully understood. Maternal separation (MS) is a commonly used animal model of early neglect. The aim of the current study is to deter...

The ethanol extracts of five Origanum species: O. majorana L., O. onites L., O. syriacum L., O. vulgare subsp. hirtum (Link) Ietsw., and O. vulgare subsp. viride (Boiss.) Hayek, collected annually (each month), were investigated for their cholinesterase inhibition and antioxidant effects. The phytochemical composition of a total of 60 extracts was...

This is an introductory tutorial and review about the uncertainty problem in chromatographic calibration. It emphasizes some unobvious, but important details influencing errors in the calibration curve estimation, uncertainty in prediction, as well as the connections and dependences between them, all from various perspectives of uncertainty measure...

Lipophilicity is one of the principal QSAR parameters which influences among others the pharmacodynamics and pharmacokinetic properties of a drug candidates. In this paper, the lipophilicity of 14 amide derivatives of 1,3-dimethyl-2,6-dioxopurin-7-yl-alkylcarboxylic acids as multifunctional TRPA1 channel antagonists and phosphodiesterase 4/7 inhibi...

Fetal alcohol spectrum disorders (FASDs) are one of the most common consequences of ethanol exposure during pregnancy. In adulthood, these disorders can be manifested by learning and memory deficits and depressive-like behavior. Ethanol-induced oxidative stress may be one of the factors that induces FASD development. The mammalian target of the Rap...

This paper is a continuation of lipophilicity research on 14 compounds (tryptophan, kynurenine pathway products, auxin pathway products, serotonin pathway products, tryptamine, as well as two synthetic auxin analogs): indole-2-acetic acid sodium salt (IAA), serotonin, 5-hydroxy-L-tryptophan, tryptamine, L-tryptophan, L-kynurenine (KYN), kynurenic a...

The aim of this study was to evaluate the ability of multivariate techniques to predict antioxidant and cytotoxic activity of the selected lichens from the chromatographic data. A simple and reproducible HPLC-DAD technique has been used to obtain the chromatographic fingerprint profiles. Reversed phase high performance liquid chromatography (RP-HPL...

This paper presents an optimization of conditions for microshoot cultures of Nasturtium officinale R. Br. (watercress). Variants of the Murashige and Skoog (MS) medium containing different plant growth regulators (PGRs): cytokinins—BA (6-benzyladenine), 2iP (6-γ,γ-dimethylallylaminopurine), KIN (kinetin), Zea (zeatin), and auxins—IAA (3-indoleaceti...

Hemerocallis plants are important vegetables with nutritional and health value, especially in eastern Asia, where they have been used as medicines to cure disease such as depression and inflammation for thousands of years. The present study concerns the determination of flavonoids and phenolic acids, as well as antioxidant, anti-collagenase, anti-e...

Agitated shoot cultures of two aronias, Aronia melanocarpa (Michx.) Elliott and Aronia arbutifolia (L.) Pers., were maintained on Murashige & Skoog medium (1 mg/l BA and 1 mg/l NAA), both with and without the addition of various biosynthetic precursors of phenolic acids and depsides (phenylalanine, cinnamic acid, benzoic acid and caffeic acid). Eac...

Abdominal artery aneurysm (AAA) refers to abdominal aortic dilatation of 3 cm or greater. AAA is frequently underdiagnosed due to often asymptomatic character of the disease, leading to elevated mortality due to aneurysm rupture. MiRNA constitute a pool of small RNAs controlling gene expression and is involved in many pathologic conditions in human...

Objectives: Data on the elemental status, redistribution of the elements, role of occupational exposure and dietary assessment in preeclampsia (PE) are scarce. There are many disparities in the findings of essential and non-essential elements' role in PE. In this article we overview the changes in the content of selected elements in pregnancy comp...

Chronic venous disease (CVD) is a vascular disease of lower limbs with high prevalence worldwide. Pathologic features include varicose veins, venous valves dysfunction and skin ulceration resulting from dysfunction of cell proliferation, apoptosis and angiogenesis. These processes are partly regulated by microRNA (miRNA)-dependent modulation of gen...

Fourteen compounds, including tryptophan and its metabolites: kynurenine pathway products (kynurenine, kynurenic acid, 3-hydroxykynurenine), auxin pathway products (indoleacetic acid, indolepropionic acid, indolebutyric acid, indolepyruvic acid), serotonin pathway products (5-hydroxytryptophan, serotonin, melatonin), tryptamine, as well as two synt...

The mixed-mode chromatographic behavior was estimated for imidazoline and serotonin receptor ligands, and their related compounds on dual hydrophilic/reversed phase stationary phase. The Box-Cox transformation was used to obtain the most suitable mathematical equations which describe the mixed-mode retention. Optimal equations were found for the op...

Military training areas, where ecosystems are shaped under a complex disturbance regime, are recognized to be favourable pieces of land for maintaining high biological diversity. Our study focused on explosion craters – a small-scale disturbance type of high severity, and their effect on species diversity including vascular plants, bryophytes and l...

In vitro callus cultures of Verbena officinalis L. were maintained on solid Murashige and Skoog medium, enriched with 1 mg dm-3 BA and 1 mg dm-3 IBA under LED lights (red, blue, red/blue 70%/30%), in darkness and under control fluorescent lamps. The measurements of 2 phenylpropanoid glycosides (verbascoside and isoverbascoside) and 23 phenolic acid...

Atherosclerosis and its comorbidities are the major contributors to the global burden of death worldwide. Lower extremities arterial disease (LEAD) is a common manifestation of atherosclerotic disease of arteries of lower extremities. MicroRNAs belong to epigenetic factors that regulate gene expression and have not yet been extensively studied in L...

Isoquinoline alkaloids belong to the toxic secondary metabolites occurring in plants of many families. The high biological activity makes these compounds promising agents for use in medicine, particularly as anticancer drugs. The aim of our study was to evaluate the cytotoxicity and proapoptotic activity of sanguinarine, berberine, and extracts of...

Already learned at school, planar chromatography summarizes sample results as illustrative image (fingerprints) understood intuitively. The list of globally urgent analyses is long to check the quality of especially food, dietary supplements, nutraceuticals, pharmaceuticals, environmental samples etc. An analytical public domain open source tool co...

In this study, the in vitro phase I metabolism of lacosamide was characterized with the use of ultra-high-performance liquid chromatography combined with high-resolution mass spectrometry (quadrupole time-of-flight). The use of two metabolism simulation techniques (photocatalysis and human liver microsomes) allowed the characterization of a polar m...

W związku z akceptacją matematycznej definicji siatki ATPOL przez jej twórców z końcem 2017 r. (Komsta 2016; Verey 2017), zaistniała teoretyczna możliwość swobodnego za-gęszczania "oczek" tej siatki do bardzo niewielkich pól ("kwadratów") 1 z dowolnie dużą dokładnością (w praktyce ograniczoną jedynie dokładnością wyznaczania położenia geo-graficzne...

Seven chromatographic grade solvents miscible with water (acetone, acetonitrile, dioxane, ethanol, isopropanol, methanol, tetrahydrofuran), as well as water itself were investigated in the context of their eluotropic strength in reversed-phase chromatography on four medium-polar adsorbents (cellulose, CN, NH2 and DIOL). The test set for this resear...

In the present study, the phenolic compounds in 70% (v/v) methanol extracts from the inflorescences of Carduus carlinoides Gouan, Carduus nigrescens Vill, Carduus defloratus L., Carduus nutans L., and Carduus crispus Gouan were identified. The extracts were tested by the RP-HPLC and HPLC/ESI-QTOF/MS methods. Flavonoids and phenolic acids were extra...

The eluotropic strength on RP2 and RP8 plates was investigated for 7 chromatographic grade solvents miscible with water as a diluent (acetone, acetonitrile, dioxane, ethanol, isopropanol, methanol, and tetrahydrofuran) as well as for water itself. Thirty-five model compounds were used as a test set in the investigation. The use of a modern chemomet...

The authors wish to make the following corrections to their paper [...]

Green tea infusions are one of the most popular beverages consumed across the world, especially is Asian countries. Green tea quality is primarily based on catechin content, however, the concentration of elements could also significantly influence its biological properties and thus quality and safety. The main purpose of the present study was the e...

This paper deals with some important (but often neglected) details about the uncertainty of retention measurement in thin layer chromatography, the propagation of uncertainty during computing simple and more complex values from the retention data, ending in influence of the retention uncertainty onto the regression estimates during extrapolation an...

It is well known that drugs can directly react with excipients. In addition, excipients can be a source of impurities that either directly react with drugs or catalyze their degradation. Thus, binary mixtures of three diuretics, torasemide, furosemide and amiloride with different excipients, Between the excipients examined, lactose and starch did n...

A comprehensive study on the composition and antioxidant properties of black tea samples with a chemometric approach was performed via LC-ESI-Q-TOF-MS, DPPH radical scavenging assay, and Folin–Ciocalteu assay (TPC). Marked differences between the teas from seven different countries (China, India, Iran, Japan, Kenya, Nepal, Sri Lanka) were shown. Th...

Forced degradation of toloxatone in solutions under basic, acidic, neutral, photo UV-VIS, photo UVC and oxidative stress conditions was investigated and structural elucidation of its degradation products was performed with the use of UHPLC system coupled ESI-Q-TOF mass spectrometer. Eight degradation products were found and their masses and formula...

The authors propose an unambiguous and consistent way of recording typical (decimal) and non-typical ATPOL grid divisions for botanical and other scientific studies. The proposed method of marking grid fields is compatible with the decimal convention adopted earlier (ZAJąC 1978; ZAJąC & ZAJąC 2001). It is shown that the proposed method of notation...

The presence of multidrug resistance (MDR) in tumor cells is considered as the major cause of failure of cancer chemotherapy. The mechanism responsible for the phenomenon of multidrug resistance is explained, among others, as overexpression of membrane transporters primarily from the ABC family which actively remove cytostatics from the tumor cell....

Preclinical data indicated that the metabotropic glutamate receptors 5 (mGlu5) and glutamate receptors 2/3 (mGlu2/3) are involved in modulating morphine antinociception. However, little is known about the role of metabotropic glutamate receptors 7 (mGlu7) in this phenomenon. We compared the effects of AMN082 (0.1, 1 or 5mg/kg, ip), a selective mGlu...

The creation of the SBI system has no serious aim. It is a result of a long spare time mental entertainment. SBI can be used by programmers for fun (yes, it is binary!) or studied together with the SI system in comparative way (to enhance the understanding and knowledge about the physical relationships). Last, but not least, it is a good candidate...

During our previous studies, we discovered that reversed-phase thin-layer chromatography (RP-TLC) plates can behave in typical normal-phase manner, which is not widely known nor used in the literature. Therefore, we decided to investigate this behavior more comprehensively on RP-8 plates. We used 35 model compounds, and performed chemometric screen...

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. Variou...

This review focuses on four unusual thin-layer chromatography (TLC) approaches for the determination of lipophilicity: (1) the use of medium-polar stationary phases: CN, NH2, and DIOL instead of RP plates, together with water-based mobile phase; (2) the use of silica gel in a typical normal-phase manner and treating extrapolated retention indices a...

The aim of this study was to determine if altered levels of selected trace elements manifest themselves during chronic depression. To identify elements strongly associated with chronic depression, relationships between the elemental contents of hair and nails and the interelement correlations were checked. Inductively coupled plasma mass spectromet...

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...

The retention behaviors were investigated for a series of eight cephalosporins in thin-layer chromatography (TLC) using stationary phases of RP-2, RP-8, RP-18, NH2, DIOL, and CN chemically bonded silica gel. Additionally, various binary mobile phases (water/methanol and water/acetone) were used in different volume proportions. The retention behavio...

The eluotropic strength on thin-layer silica plates was investigated for 20 chromatographic grade solvents available in current market. 35 model compounds were used as test subjects in the investigation. The use of modern mixture screening design allowed to estimate each solvent as a separate elution coefficient with an acceptable error of estimati...

The present paper describes the chemical composition of the essential oils obtained by hydrodistillation from four Impatiens species, Impatiens glandulifera Royle, I. parviflora DC., I. balsamina L. and I. noli-tangere L. The GC and GC-MS methods resulted in identification of 226 volatile compounds comprising from 61.7%–88.2% of the total amount. T...

The RF value dataset of 35 model compounds, chromatographed with 20 pure solvents as the mobile phase each on 9 adsorbents: RP2, RP8, RP18, alumina, cellulose, CN, DIOL, NH2, and silica, was subjected to trilinear analysis with parallel factor analysis. The two-factor optimal model explained 87% of total information in this complex dataset. The fir...

Forced degradation of clozapine in solutions under acidic, basic, neutral, photo UV-vis, photo UVC and oxidative stress conditions was investigated and structural elucidation of its degradation products was performed with the use of the UHPLC-DAD system coupled with accurate hybrid ESI-Q-TOF mass spectrometer. The developed method allows to collect...

The aim of present study was to determine and to compare the chemical composition of six Impatiens species. For this purpose, UHPLC-DAD-MS3 analyses and spectrophotometric assays were used. The results revealed the presence of nineteen constituents comprising phenolic acids and flavonoids. The total phenolic content in the samples ranged from 8.8 t...

Ultra high-performance liquid chromatography (UHPLC) coupled with highresolution 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 us...

Artykuł przedstawia aktualnie sygnalizowane wątpliwości dotyczące korzystania z siatki geobotanicznej ATPOL, w szczególności brak jasno zdefiniowanego algorytmu przeliczania współrzędnych geograficznych na pole siatki. Zaprezentowano wyniki analiz matematycznych oryginalnej tabeli współrzędnych. Z analiz wynika, że siatka ATPOL zbudowana jest z kwa...

Ultra high performance liquid chromatography (UHPLC), coupled with accurate quadrupole-time-of-flight (Q-TOF) mass spectrometry, was used for the stability study of acetylsalicylic acid within a variety of different organic solutions: methanol, ethanol, propan-2-ol, acetonitrile, tetrahydrofuran and 1,4-dioxane. With the use of gradient elution chr...

The multivariate analysis of retention data in TLC allows the chromatographer to visualize the multidimensional retention data and explore hidden properties and dependences. The most often used techniques are hierarchical cluster analysis (HCA) and principal component analysis (PCA), however some other techniques are also reported. This review pres...

ATPOL is a geobotanical grid system used in Poland in geobotanical studies since the 1970s. The present article summarizes and explains some inconsistencies raised by botanists, connected mainly with unknown geodetic principles of this grid. The original grid was analyzed mathematically and a solution was found to convert coordinates – ATPOL grid i...

10 homeopathic remedies commercially available (each in 3 dilutions) as sugar granules, where half of them were of organic (and half inorganic) origin were subjected to solid-state infrared spectroscopy, both in middle infrared (ATR-FTIR) and near infrared (NIR) range. Measurements were repeated six times (six days, each sample was measured once in...

Four commercially available formulations containing iron, zinc and manganese were subjected to dissolution profile testing during 60 minutes and the dissolution was analyzed by ion chromatography. The obtained curves were analyzed directly by principal component analysis (PCA). The main trend (87.1% of variance) was connected with average dissoluti...

A new HPLC method was introduced and validated for simultaneous determination of perindopril and indapamide. Validation procedure included specificity, sensitivity, robustness, stability, linearity, precision and accuracy. The method was used for the dissolution test of perindopril and indapamide in three fixed-dose formulations. The dissolution pr...

The photodegradation of paliperidone in aqueous and methanol media under UVA and UVC irradiation was investigated. The identification and structural elucidation of its photodegradation products were performed by the use of the reversed phase liquid chromatography coupled with accurate mass hybrid Q-TOF mass spectrometer and atmospheric pressure che...

The lipophilicity (RM0 ) and specific hydrophobic surface area for the representatives of four generation cephalosporins have been determined by reversed-phase thin-layer chromatography, and the effect of different mobile-phase modifiers (such as methanol, acetonitrile, acetone, 1,4-dioxane and 2-propanol) on the retention has been studied. The com...

Thin-layer chromatography (TLC) on two adsorbents (RP18 and CN) and with six modifiers (acetonitrile, acetone, dioxane, propan-2-ol, methanol, and tetrahydrofurane), followed by classical RM value extrapolation (previous results), was chemometrically compared with new one-run gradient high-performance liquid chromatography (HPLC) (C18, C18e, CN, an...

The lipophilicity of fifteen fluoroquinolones has been investigated. Reversed-phase thin layer chromatography with densitometric detection was applied to determine RM0 factor. The RP-TLC investigations were performed in mixtures of organic modifier-water. The partition coefficients of examined fluoroquinolones were also calculated with computationa...

The cytotoxic and antioxidant properties of lipophilic compounds extracted from different parts of four Chenopodium L. (C.album, C. hybridum, C. rubrum and C. urbicum) species were evaluated. The highest phenolics content was found in herb and seeds of all examined plants. The large amounts of free polyphenols was observed in herb extracts of C. al...

Nowadays, chromatographic methods coupled with mass spectrometry are the most commonly used tools in metabolomics studies. These methods are currently being developed and various techniques and strategies are proposed for the profiling analysis of biological samples. However, the most important thing used to maximize the number of entities in the r...

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...

Previous studies have indicated that metabotropic glutamate receptors 7 (mGluR7s) are involved in drug addiction. However, the role of these receptors in drug-induced behavioral sensitization is unknown. The aim of the present study was to determine whether systemic injection of AMN082, a selective mGluR7 allosteric agonist, reduces the cocaine- an...

A novel stability-indicating TLC method for determination of propafenone hydrochloride (PRO) in bulk drug and POLFENON tablets. Normal-phase high performance thin layer chromatographic separation was achieved by use of silica gel 60 F254 plates and mixture of chloroform–methanol–acetic acid 99.5% (7.9:2:0.1, v/v/v) as the mobile phase. Linear calib...

The retention (RM) values of nine one-point adsorption model compounds: diphenylamine, indol, 2-naphtol, 1-naphtol, 1-naphtylamine, 4-toluidine, carbazole, 4-chloraniline, and thymol were investigated on silica gel using six modifiers: acetone, dioxane, hexane, isopropanol, methylethylketone, ethyl acetate, and tetrahydrofurane (in hexane). These c...

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 regress...

We present chemometric analysis of the retention of 35 simple model compounds in nonmicellar and micellar TLC systems. Nonmicellar systems were investigated on silica gel, RP18, and CN plates, by use of several modifiers in hexane or water as the mobile phase. Micellar systems were processed on silica and RP8 plates with three surfactants (cetyltri...

The chromatographic behavior of a series of coxibs and oxicams, drugs from a group of non-steroidal anti-inflammatory drugs, was studied by reversed-phase thin-layer chromatography with binary mobile phases containing water and the organic modifiers: methanol, acetone, 1,4-dioxane, acetonitrile and 2-propanol. Linear relationships were obtained bet...

The paper discusses the usefulness of self modelling multivariate curve resolution (nonnegative matrix factorization) as a chemometric tool for the analysis of inhomogeneous spots captured by densitometer in multivariate way. The discussion is based on two examples: a spot of decomposed aspirin with comparative spot of pure salicylic acid, and spot...

A recent study showed that spectral correlation cannot be considered as a reliable method for spot purity of thin-layer chromatography (TLC). The current paper discusses limitations of possible chemometric techniques performed on diode-array detection or multiwavelength densitograms of spots. The primary difference between high-performance liquid c...