Sylwia Kowalska

Stationary phase with specific surface properties for the separation of estradiol diastereoisomers

The aim of this study was to develop a procedure that enabled the separation of estradiol diastereoisomers. For this purpose a series of stationary phases with different surface properties has been utilized. Two of them contain various interaction sites, such as: cholesterol, n-acylamide, amine and silanols localised in the organic layer bonded to the surface of silica gel (SG-CHOL and SG-CHOL/AP). The other one contains mainly alkylamide ligands and also residual aminopropyl and silanol groups (SG-AP), as well as the last one consisting of hydrocarbonaceous material (SG-C(18)). In order to select the best type of stationary phase for this analysis, after chromatographic separation of 17-alpha-estradiol and 17-beta-estradiol, selectivity and resolution of the analytes were compared. The best separation of hormones was obtained for SG-CHOL packing, as a consequence of the structure and the properties of this stationary phase. To better understand the retention mechanism and the properties of the stationary phases, used in the separation of steroid compounds, the functional group contributions (tau) were compared with Hansch substituent constants (pi).

New generation of chromatographic packings and columns for determination of biologically active compounds

Analysis of biologically active substances is particularly important in the pharmaceutical and biomedical area. For separation of polar compounds or complex mixtures by normal (NP) or reversed phase liquid chromatography (RP-HPLC) and/or electromigration techniques, it is necessary to apply a new generation of packings and columns with strictly defined properties. It is connected to the definition of chromatographic behavior and determination of compounds that are described by its structure, as well as chemical and physical properties. One of the factors playing a predominant role in the separation process is the interaction between analyte and stationary phases. During recent years a large variety of stationary phases have become available and have been also applied in routine and research chromatographic separations. Bonded phases are in widespread use and popular because of the great number of available packing materials, allowing the solution of a scale of different separation problems. At the present time analytical methods cannot be restricted only to the so-called “black box.” To meet the requirements of modern analytical techniques, strong demands are put on further, deeper understanding of the essence of the separation process, among other things, on the basis of conclusions about interactions between solute and stationary phase surfaces. For surface characterization different physicochemical methods such as CP/MAS, NMR, FT IR, DCS, chromatography, etc., have been described. The resolution, as reflected by efficiency, selectivity, and retention patterns on these materials, has been demonstrated. The effect of structure of stationary phases on retention of a model series of test analytes has been proved and numerically expressed by means of the Quantitative Structure-Retention Relationship (QSSR). The main aim of this paper is to present possibilities of determining different biologically active compounds (e.g., vitamins, steroids, nucleosides, peptides) in complex chromatographic methods (sample preparation, final analysis, validation) using new generation of stationary phases, columns, and chips divides. Special attention is dedicated to the advantage of packing materials imitating natural membranes because of the possible examination of the interaction between drug membrane. They can permit to the design of new pharmaceuticals and observation of processes taking place on the border of phases without interfering in natural systems.

Studies of levels of biogenic amines in meat samples in relation to the content of additives

ABSTRACT The impact of meat additives on the concentration of biogenic amines and the quality of meat was studied. Fresh white and red meat samples were fortified with the following food additives: citric and lactic acids, disodium diphosphate, sodium nitrite, sodium metabisulphite, potassium sorbate, sodium chloride, ascorbic acid, α-tocopherol, propyl 3,4,5-trihydroxybenzoate (propyl gallate) and butylated hydroxyanisole. The content of spermine, spermidine, putrescine, cadaverine, histamine, tyramine, tryptamine and 2-phenylethylamine was determined by capillary isotachophoretic methods in meat samples (fresh and fortified) during four days of storage at 4°C. The results were applied to estimate the impact of the tested additives on the formation of biogenic amines in white and red meat. For all tested meats, sodium nitrite, sodium chloride and disodium diphosphate showed the best inhibition. However, cadaverine and putrescine were characterised by the biggest changes in concentration during the storage time of all the additives. Based on the presented data for the content of biogenic amines in meat samples analysed as a function of storage time and additives, we suggest that cadaverine and putrescine have a significant impact on meat quality. Graphical Abstract

Influence of pH on Benzoic Acid Derivatives' Retention and RP HPLC Column Classification

Abstract The pH role in benzoic acid derivatives chromatographic analysis were under the current study. The retention factor (k), as well as the peak asymmetry (f AS ), were determined and compared using five commercially available reversed phase columns. Utilization of statistical approaches of tested chromatographic columns were divided into several groups according to the obtained data (retention factor, asymmetry) due to the different mobile phases pH (pH=5.8 and 3.0). Although four studied columns (Purospher‐STAR, Alltima, Reprosil, Symmetry) were the octadecyl type, they showed significant differences in the benzoic acids derivatives. Obtained results allowed for distinctions in individual column chromatographic behavior explanation.