Search

OBJECTIVE To evaluate the effects of using ropivacaine combined with dexmedetomidine for sciatic and saphenous nerve blocks in dogs. ANIMALS 7 healthy adult Beagles. PROCEDURES In phase 1, dogs received each of the following 3 treatments in random order: perineural sciatic and saphenous nerve injections of 0.5% ropivacaine (0.4 mL/kg) mixed with saline (0.9% NaCl) solution (0.04 mL/kg; DEX0PN), 0.5% ropivacaine mixed with dexmedetomidine (1 µg/kg; DEX1PN), and 0.5% ropivacaine mixed with dexmedetomidine (2 µg/kg; DEX2PN). In phase 2, dogs received perineural sciatic and saphenous nerve injections of 0.5% ropivacaine and an IV injection of diluted dexmedetomidine (1 µg/kg; DEX1IV). For perineural injections, the dose was divided equally between the 2 sites. Duration of sensory blockade was evaluated, and plasma dexmedetomidine concentrations were measured. RESULTS Duration of sensory blockade was significantly longer with DEX1PN and DEX2PN, compared with DEX0PN; DEX1IV did not prolong duration of sensory blockade, compared with DEX0PN. Peak plasma dexmedetomidine concentrations were reached after 15 minutes with DEX1PN (mean ± SD, 348 ± 200 pg/mL) and after 30 minutes DEX2PN (816 ± 607 pg/mL), and bioavailability was 54 ± 40% and 73 ± 43%, respectively. The highest plasma dexmedetomidine concentration was measured with DEX1IV (1,032 ± 415 pg/mL) 5 minutes after injection. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that perineural injection of 0.5% ropivacaine in combination with dexmedetomidine (1 µg/kg) for locoregional anesthesia in dogs seemed to balance the benefit of prolonging sensory nerve blockade while minimizing adverse effects.

Bladder cancer (BC) is a common malignancy of the urinary system and a leading cause of death worldwide. In this work, untargeted metabolomic profiling of biological fluids is presented as a non-invasive tool for bladder cancer biomarker discovery as a first step towards developing superior methods for detection, treatment, and prevention well as to further our current understanding of this disease. In this study, urine samples from 24 healthy volunteers and 24 BC patients were subjected to metabolomic profiling using high throughput solid-phase microextraction (SPME) in thin-film format and reversed-phase high-performance liquid chromatography coupled with a Q Exactive Focus Orbitrap mass spectrometer. The chemometric analysis enabled the selection of metabolites contributing to the observed separation of BC patients from the control group. Relevant differences were demonstrated for phenylalanine metabolism compounds, i.e., benzoic acid, hippuric acid, and 4-hydroxycinnamic acid. Furthermore, compounds involved in the metabolism of histidine, beta-alanine, and glycerophospholipids were also identified. Thin-film SPME can be efficiently used as an alternative approach to other traditional urine sample preparation methods, demonstrating the SPME technique as a simple and efficient tool for urinary metabolomics research. Moreover, this study’s results may support a better understanding of bladder cancer development and progression mechanisms.

Chronic rhinosinusitis (CRS) is an inflammatory disease of the paranasal sinuses. It is defined as the presence of a minimum of two out of four main symptoms such as hyposmia, facial pain, nasal blockage, and discharge, which last for 8–12 weeks. CRS significantly impairs a patient’s quality of life. It needs special treatment mainly focusing on preventing local infection/inflammation with corticosteroid sprays or improving sinus drainage using nasal saline irrigation. When other treatments fail, endoscopic sinus surgery is considered an effective option. According to the state-of-the-art knowledge of CRS, there is more evidence suggesting that it is more of an inflammatory disease than an infectious one. This condition is also treated as a multifactorial inflammatory disorder as it may be triggered by various factors, such as bacterial or fungal infections, airborne irritants, defects in innate immunity, or the presence of concomitant diseases. Due to the incomplete understanding of the pathological processes of CRS, there is a continuous search for new indicators that are directly related to the pathogenesis of this disease—e.g., in the field of systems biology. The studies adopting systems biology search for possible factors responsible for the disease at genetic, transcriptomic, proteomic, and metabolomic levels. The analyses of the changes in the genome, transcriptome, proteome, and metabolome may reveal the dysfunctional pathways of inflammatory regulation and provide a clear insight into the pathogenesis of this disease. Therefore, in the present paper, we have summarized the state-of-the-art knowledge of the application of systems biology in the pathology and development of CRS.

Prostate cancer (CaP) is a common cancer in men. Its late detection and inefficient diagnosis are a challenge for researchers who are currently searching for new cancer-related indicators that would facilitate better detectability of CaP and explain its pathogenesis. In the present preliminary study, endogenous volatile metabolites were detected in plasma and urine samples by using the metabolic fingerprinting approach. The analyses were performed using the GC-QqQ/MS technique in the scan mode. The detected and putatively identified metabolites were statistically analyzed using advanced univariate and multivariate statistical methods. Eleven urinary and three plasma metabolites were selected as statistically significant in patients with CaP as compared to those in healthy controls. Supervised methods such as logistic regression and quadratic support vector machine were applied to obtain the classification models. The accuracy, sensitivity, and specificity of the models were above 83%, 85%, and 81%, respectively. The putatively identified metabolites were associated with biochemical pathways such as tricarboxylic acid cycle, glycolysis, carbohydrate conversion, and steroidal lipid metabolism that are mainly involved in energy production for cell growth and proliferation.

The investigation of innovative label-free &alpha, amino acids detection methods represents a crucial step for the early diagnosis of several diseases. While 1,8-diazafluoren-9-one (DFO) is known in forensic application because of the fluorescent products by reacting with the amino acids present in the papillary exudate, its application for diagnostic purposes has not been fully investigated. The stabilization of DFO over a transparent substrate allows its complexation with biomolecules for the detection of &alpha, amino acids. In this study, DFO was immobilized into a titanium dioxide (TiO2) matrix for the fluorescence detection of glycine, as a target &alpha, amino acid (a potential marker of the urogenital tract cancers). The DFO/TiO2 composite was characterized by atomic force microscopy, spectroscopic ellipsometry, fluorescence spectroscopy and fluorescence microscopy. The performed fluorescent studies indicate spectacular formation of aggregates at higher concentration. The measurements performed using various fluorescence and microscopic techniques together with the suitable analysis show that the aggregates are able to emit short-lived fluorescence.

The discovery of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, has opened a new frontier in the study of signal transduction and understanding cell-to-cell communication. EVs play a key role regulating various biological processes such as tissue regeneration, blood coagulation, immunomodulation or carcinogenesis. Therefore, they gain much attention as potentially therapeutic and non-invasive diagnostic targets. In this aspect, a comprehensive characterization of the EVs molecular content and understanding EVs functions are especially relevant. However, routine isolation of a usually small amount of high purity EVs is challenging, and analysis requires highly sensitive advanced analytical solutions. The utility of EVs in clinical settings is still limited due to the lack of standardization in existing protocols. This review focuses on the implication of the state-of-the-art mass-spectrometry based untargeted metabolomics approach for the molecular profiling of EVs, with the emphasis on the analytical methodologies, highlighting potential challenges and limitations.

Aim: The purpose of this work was to develop and validate a rapid and robust LC–MS/MS method for the determination of dexmedetomidine (DEX) in plasma, suitable for analysis of a large number of samples. Method: Systematic approach, Design of Experiments, was applied to optimize ESI source parameters and to evaluate method robustness, therefore, a rapid, stable and cost-effective assay was developed. The method was validated according to US FDA guidelines. LLOQ was determined at 5 pg/ml. The assay was linear over the examined concentration range (5–2500 pg/ml), Results: Experimental design approach was applied for optimization of ESI source parameters and evaluation of method robustness. The method was validated according to the US FDA guidelines. LLOQ was determined at 5 pg/ml. The assay was linear over the examined concentration range (R2 > 0.98). The accuracies, intra- and interday precisions were less than 15%. The stability data confirmed reliable behavior of DEX under tested conditions. Conclusion: Application of Design of Experiments approach allowed for fast and efficient analytical method development and validation as well as for reduced usage of chemicals necessary for regular method optimization. The proposed technique was applied to determination of DEX pharmacokinetics in pediatric patients undergoing long-term sedation in the intensive care unit.

Modified nucleosides and deoxynucleosides are investigated as potential markers of pathological disorders. Due to different molecular properties, their concurrent extraction from biological matrices is challenging. The aim of the present work was the development of sample preparation procedure allowing for simultaneous extraction of 12 selected modified nucleosides and deoxynucleosides with the use of solid phase extraction (SPE) technique. Commercially available mixed-mode SPE cartridges based on phenylboronic acid and cation-exchange sorbents were utilized. In order to decrease the number of experiments and, consequently the volume of applied solvents, the developed method was optimized with the use of Design of Experiments approach. Optimization of SPE method was carried out by employing Fractional Factorial Design with selected input variables such as composition of conditioning, washing and elution solvents. Next, Full Factorial Design with conditioning, extraction and elution duration time as factors was employed. Evaluated responses in these two experimental sets were peak areas of selected analytes. Levels of assessed factors were determined. Developed and optimized SPE procedure allowed for simultaneous extraction of modified nucleosides and deoxynucleosides with mean recovery of 76.0%. Procedure was applied on the exemplary urine samples with the use of high performance liquid chromatography hyphenated with triple quadrupole mass spectrometry (HPLC-QqQ/MS).

The chromatographic properties of eight steroids: trans-andros-terone, methyltestosterone, testosterone, progesterone, cortisone, hydrocortisone, estrone, and β-estradiol were studied by planar chromatography by use of aluminum oxide plates as well as of four different binary mobile phases (acetonitrile-water, acetonitrile-DMSO, acetone-petroleum ether, and acetone-water). Correlations between chromatographic data and physicochemical parameters were presented as results of established quantitative structure-retention relationships (QSRRs). Principal component analysis (PCA) and multiple linear regression (MLR) showed the possible relationships between the retentions and the physicochemical parameters of the studied compounds. The evaluation of thin-layer chromatographic (TLC) separation power, based on ΔhRF, was also discussed. Finally, two chromatographic systems for the effective separation of glucocorticoids and other analyzed steroid hormones were recommended.

An increase in cocaine consumption has been observed in Europe during the last decade. Benzoylecgonine, as a main urinary metabolite of cocaine in human, is so far the most reliable marker of cocaine consumption. Determination of cocaine and its metabolite in complex biological samples as urine or blood, requires efficient and selective sample pretreatment. In this preliminary study, the newly synthesized sorbent materials were proposed for selective extraction of cocaine and benzoylecgonine from urine samples. Application of these sorbent media allowed to determine cocaine and benzoylecgonine in urine samples at the concentration level of 100ng/ml with good recovery values as 81.7%±6.6 and 73.8%±4.2, respectively. The newly synthesized materials provided efficient, inexpensive and selective extraction of both cocaine and benzoylecgonine from urine samples, which can consequently lead to an increase of the sensitivity of the current available screening diagnostic tests.

Sewage epidemiology, as compared to crime statistics, health, medical reports or population surveys, is becoming the most objective and realistic approach to estimate drug consumption and trends in local communities. In this study we proposed newly synthesized sorbent materials for selective extraction of cocaine and benzoylecgonine from wastewater samples. The molecular modeling calculations were conducted to provide the choice of proper template and functional monomer for synthesis of extraction materials. The physicochemical properties of synthesized sorbents were studied using various techniques. The newly developed sorbent materials were applied for selective extraction of cocaine and benzoylecgonine from wastewater samples collected from different wastewater treatment plants in Poland. The obtained recoveries values in wastewater samples were 83.6(±7.1)% and 72.1(±4.8)%, for cocaine and benzoylecgonine, respectively. The newly developed sorbents comprise an alternative to conventional ones, which are not entirely suitable for highly efficient purification of environmental samples due to the presence of contaminants.

Fast and reliable methods for the determination of hydrophobicity and acidity are desired in pre-clinical drug development phases to eliminate compounds with poor pharmacokinetic properties. Reversed-phase high-performance liquid chromatography (RP HPLC) coupled with time-of-flight mass spectrometry (RP HPLC-ESI-TOF-MS) is a convenient technique for that purpose. In this work we determined the chromatographic measure of hydrophobicity (logkw) and dissociation constant (pKa) simultaneously for a large and diverse group of 161 drugs. Retention times were determined by means of RP HPLC-ESI-TOF-MS for a series of pH and organic modifier gradients. We were able to measure retention times for 140 out of 161 (87%) compounds. For those analytes logkw and pKa parameters were calculated and compared with literature and ACD Labs-calculated data. The determined chromatographic measure of hydrophobicity and dissociation constant was closely related to literature and theoretically calculated values. Applied methodology achieved the medium-throughput screening rate of 100 compounds per day and proved to be a simple, fast and reliable approach of assessing important physicochemical properties of drugs. This technique has certain limitations as it is not applicable for very hydrophilic analytes (logP

Metabolomics is an emerging approach in a systems biology field. Due to continuous development in advanced analytical techniques and in bioinformatics, metabolomics has been extensively applied as a novel, holistic diagnostic tool in clinical and biomedical studies. Metabolome's measurement, as a chemical reflection of a current phenotype of a particular biological system, is nowadays frequently implemented to understand pathophysiological processes involved in disease progression as well as to search for new diagnostic or prognostic biomarkers of various organism's disorders. In this review, we discussed the research strategies and analytical platforms commonly applied in the metabolomics studies. The applications of the metabolomics in laboratory diagnostics in the last 5 years were also reviewed according to the type of biological sample used in the metabolome's analysis. We also discussed some limitations and further improvements which should be considered taking in mind potential applications of metabolomic research and practice.

The phenanthrene skeleton is an important moiety in medical chemistry as it is present in steroidal drugs used as anti-inflammatory and anti-asthmatic agents as well as synthetic hormones or potassium sparing diuretics. Chromatographic properties of 14 derivatives containing the phenanthrene skeleton in their structure with known lipophilicityhave been studied. NP, RP, and cyano-bonded silica stationary phaseswith three binary mobile phases (acetonitrile–water, acetone–water, and acetone–petroleum ether) were tested. Obtained chromatographic data were correlated with the lipophilicity expressed as values of log partition coefficient (P). The presented study was undertaken to find the best TLC system and chromatographic data processing method in order to predict log P values. Correlations between chromatographic data and measurements of lipophilicity of compounds were presented as results of established quantitative structure-retention relationships. Principal component analysis and cluster analysis were used to investigate the similarities among chromatographic systems.

Urinary nucleosides and deoxynucleosides are mainly known as metabolites of RNA turnover and oxidative damage of DNA. For several decades these metabolites have been examined for their potential use in disease states including cancer and oxidative stress. Subsequent improvements in analytical sensitivity and specificity have provided a reliable means to measure these unique molecules to better assess their relationship to physiologic and pathophysiologic conditions. In fact, some are currently used as antiviral and antitumor agents. In this review we provide insight into their molecular characteristics, highlight current separation techniques and detection methods, and explore potential clinical usefulness.

Urinary nucleosides and deoxynucleosides are mainly known as metabolites of RNA turnover and oxidative damage of DNA. For several decades these metabolites have been examined for their potential use in disease states including cancer and oxidative stress. Subsequent improvements in analytical sensitivity and specificity have provided a reliable means to measure these unique molecules to better assess their relationship to physiologic and pathophysiologic conditions. In fact, some are currently used as antiviral and antitumor agents. In this review we provide insight into their molecular characteristics, highlight current separation techniques and detection methods, and explore potential clinical usefulness.

Wound healing is still a serious medical problem due to process complexity and lack of effective medicaments. This is particularly true in the treatment of wounds arising in the course of such diseases as AIDS or diabetes. Therefore, scientific efforts are focused on the search for new compounds of natural origin, which could be used as medicines or evaluated for subsequent drug design. In folk medicine, grasshopper (Chorthippus spp.) abdominal secretion has been used to accelerate the wound healing process. In this context, the knowledge of the composition of grasshopper abdominal secretion is crucial. The aim of this study was to determine the main water-soluble components of grasshopper abdominal secretion with the use of GC/MS/MS. Liquid–liquid extraction was used as a pretreatment method to clean up, concentrate and fractionate compounds from the complex insect matrix. To obtain more stable and volatile compounds, necessary for GC/MS/MS analysis, a double-step derivatization process was carried out with the use of methoxyamine hydrochloride and a mixture of bis-N,O-trimethylsilyl trifluoroacetamide and chlorotrimethylsilane. As a result, 2,108 compounds were identified, mainly as amino acids, carbohydrates and organic acids. Some of the identified compounds are emphasized due to antimicrobial, antifungal or antioxidant activities reported in the literature. Moreover, a set of compounds characteristic for Chorthippus spp. samples has been selected. In the last part of the study, a statistical analysis was performed to demonstrate differences in composition of aqueous fractions of abdominal secretions from grasshoppers collected at two distant locations: Starogard Gdanski and Łubianka meadows.

In recent years biologically active compounds isolated from insects call special interest of drug researchers. According to some Polish etnopharmacological observations, secretion from the grasshopper's abdomen ( Orthoptera family) is believed to speed up the process of wound healing. In the present work we focused on determination of main components of the lipid fraction of material from grasshopper abdomen using GC–MS/MS. Samples were qualitatively analyzed using gas chromatography coupled with mass spectrometry. Both liquid–liquid extraction and solid-phase extraction pretreatment methods were used to concentrate and fractionate the compounds from the insect. In the derivatized fractions ca. 350 compounds were identified, including substances of known biological activity. The potential agents affecting wound healing have been indicated. A set of compounds characteristic for all the studied Chorthippus spp., have been identified. Data analysis revealed different lipidomic profiles of grasshoppers depending on the insects origin and collection area.

Chamomile has been used as an herbal medication since ancient times and is still popular because it contains various bioactive phytochemicals that could provide therapeutic effects. In this study, a simple and reliable HPLC method was developed to evaluate the quality consistency of nineteen chamomile samples through establishing a chromatographic fingerprint, quantification of phenolic compounds and determination of antioxidant activity. For fingerprint analysis, 12 peaks were selected as the common peaks to evaluate the similarities of commercial samples of chamomile obtained from different manufacturers. A similarity analysis was performed to assess the similarity/dissimilarity of chamomile samples where values varied from 0.868 to 0.990 what indicating that samples from different manufacturers were consistent. Additionally, simultaneous quantification of five phenolic acids (gallic, caffeic, syringic, p-coumaric, ferulic) and four flavonoids (rutin, myricetin, quercetin and keampferol) was performed to interpret the quality consistency. In quantitative analysis, the nine individual phenolic compounds showed good regression (r > 0.9975). Inter- and intra-day precisions for all analysed compounds expressed as relative standard deviation (CV) ranged from 0.05% to 3.12%. Since flavonoids and other polyphenols are commonly recognised as natural antioxidants, the antioxidant activity of chamomile samples was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/antioxidant power (FRAP) assay. Correlation analysis was used to assess the relationship between antioxidant activity and phenolic composition, and multivariate analysis (PCA and HCA) were applied to distinguish chamomile samples. Results shown in the study indicate high similarity of chamomile samples among them, widely spread in the market and commonly used by people as infusions or teas, as well as that there were no statistically significant differences among them, which in turn is a proof of high quality of commercially available samples of chamomile. The study indicated that the combination of chromatographic fingerprint and quantitative analysis can be readily utilised as a quality consistency method for chamomile and related medicinal preparations. Moreover, the applied strategy seems to be the most promising for the assessment of the investigated plant material.

The beginning of the twenty-first century has brought a flourishing of new technologies and innovative diagnostic and analytical tools to face the challenges of current medicine. To cope with these challenges and to understand disease processes there has been development of such studies as genomics, transcriptomics, proteomics, and metabolomics. These and others, the “-omics,” create a new type of biology called “systeomics.” Moreover, elucidation of the genetic code at the turn of the millennium initiated the development of genomics. However, many questions are still unanswered, especially regarding the relationship between gene expression and pathogenic processes.

The goal of the present paper was to develop a quantitative structure-activity relationship (QSAR) method using a simple statistical approach, such as multiple linear regression (MLR) for predicting the blood-brain barrier (BBB) permeability of chemical compounds. The "best" MLR models, comprised logP and either molecular mass (M) or isolated atomic energy (E(isol)), tested on a structurally diverse set of 66 compounds, is characterized the by correlation coefficients (R) around 0.8. The obtained models were validated using leave-one-out (LOO) cross-validation technique and the correlation coefficient of leave-one-out- R(LOO)(2) (Q(2)) was at least 0.6. Analysis of a case from legal medicine demonstrated informative value of our QSAR model. To best authors' knowledge the present study is a first application of the developed QSAR models of BBB permeability to case from the legal medicine. Our data indicate that molecular energy-related descriptors, in combination with the well-known descriptors of lipophilicity may have a supportive value in predicting blood-brain distribution, which is of utmost importance in drug development and toxicological studies.

Prostate cancer (CaP) is a leading cause of cancer deaths in men worldwide. The alarming statistics, the currently applied biomarkers are still not enough specific and selective. In addition, pathogenesis of CaP development is not totally understood. Therefore, in the present work, metabolomics study related to urinary metabolic fingerprinting analyses has been performed in order to scrutinize potential biomarkers that could help in explaining the pathomechanism of the disease and be potentially useful in its diagnosis and prognosis. Urine samples from CaP patients and healthy volunteers were analyzed with the use of high performance liquid chromatography coupled with time of flight mass spectrometry detection (HPLC-TOF/MS) in positive and negative polarity as well as gas chromatography hyphenated with triple quadruple mass spectrometry detection (GC-QqQ/MS) in a scan mode. The obtained data sets were statistically analyzed using univariate and multivariate statistical analyses. The Principal Component Analysis (PCA) was used to check systems' stability and possible outliers, whereas Partial Least Squares Discriminant Analysis (PLS-DA) was performed for evaluation of quality of the model as well as its predictive ability using statistically significant metabolites. The subsequent identification of selected metabolites using NIST library and commonly available databases allows for creation of a list of putative biomarkers and related biochemical pathways they are involved in. The selected pathways, like urea and tricarboxylic acid cycle, amino acid and purine metabolism, can play crucial role in pathogenesis of prostate cancer disease.

The aim of the study was to develop and validate a simple and rapid method for the determination of cyclosporine A (CsA) in ocular rabbit tissues using reversed-phase ultra-high-performance liquid chromatography (UHPLC) with UV detection. Previous publications on chromatographic methods of CsA determination in ocular tissues involved only reversed-phase HPLC separation, usually in combination with such detection techniques as radio-immunoassay and mass spectrometry. The application of the UHPLC technique allowed us to significantly decrease the analysis time. Cyclosporine D (CsD) was applied as the internal standard. Satisfactory separation was achieved on an XB-C18 Kinetex column at 60°C with the use of gradient elution mode. The retention times of CsA and CsD were found to be 4.5 and 5.1 min, respectively. The developed assay is specific, sensitive (limit of detection = 6 ng/mL and limit of quantitation = 18 ng/mL) and linear within the analyte concentration range of 0.018-5 µg/mL, with a correlation coefficient of 0.999. High sensitivity, low injection volume (10 μL), short time of analysis (6.5 min) and simplicity make this method useful for the fast analysis of CsA in rabbit ocular tissues and fluids: lacrimal fluid, aqueous humor, cornea, conjunctiva and eye globe.

Nucleosides, the RNA metabolites, are well known as potential markers in various types of cancer. They are mainly detected in urine wherein their concentrations were found elevated in cancer patients. In order to determine the nucleosides' profile in urine with satisfactory sensitivity and accuracy, advanced analytical techniques should be applied involving mass spectrometry detection. In this work we overviewed actual possibilities in targeted and untargeted metabolomics studies of nucleosides and their analogues (cis-diol metabolites) using high performance liquid chromatography hyphenated with mass spectrometry detection. We focused on challenges and drawbacks using different types of ion sources and analyzers. The nucleosides' fragmentation patterns were also compared for the sake of their identification in biological samples. As applied analytical techniques allow for the metabolites' determination, statistical approach essential for evaluation of nucleosides as cancer markers was also reviewed.

Convenient methods for testing drug candidates’ lipophilicity and acidity are highly requested in modern pharmaceutical research and drug development strategies. Reversed-phase high-performance liquid chromatography (RP HPLC) might be particularly useful for the determination of both dissociation constant and the (pH-dependent) partition coefficient related parameters, applicable in high-throughput analysis of multi-component mixtures. The general theory of combined pH/organic modifier gradient has recently provided equations relating gradient retention time and pH of the mobile phase. The purpose of this work was to facilitate the identification of analytes in this technique by its transfer to RP HPLC coupled with time-of-flight mass spectrometry with electrospray ionization source (ESI-TOF-MS). The accuracy of the proposed methodology was assessed by analyzing a set of known drugs. The ammonium formate, ammonium acetate or ammonium bicarbonate buffers were used to control pH during chromatographic analysis. In result, the p K a and hydrophobicity parameters were determined and the accuracy of the estimated values was assessed by comparing them with literature data. The gradient RP HPLC coupled with ESI-TOF-MS methods allowed for the rapid determination of dissociation constant and hydrophobicity and was shown to be especially applicable for complex mixtures. The use of ESI-TOF-MS detection allowed to achieve the medium-throughput screening rate (100 compounds/day) and provided a simple approach to assess pharmacokinetically important physicochemical properties of drugs.