Renata Gadzała-Kopciuch

Polyfunctional chemically bonded stationary phase for reversed phase high-performance liquid chromatography

SummaryPreparation of a chemically-bonded-silica stationary phase (SG-MIX), with different polar and nonpolar functional groups such as hydroxyl (-OH), amino (-NH2), cyano (-CN), phenyl (-Ph), octyl (-C8) and octadecyl (-C18), is described. The characteristics of the prepared packing was done by physicochemical methods such as elemental analysis, FTIR spectroscopy, solid-state nuclear magnetic resonance (NMR), chromatography (GC and HPLC) as well as by analysis of quantitative structure-retention relationships (QSRR). The polyfunctional SG-MIX phase possesses properties of a reversed-phase material modified by specific inputs to retention due to interactions of analytes with polar functionalities on the surface of adsorbent. The new type of packing was successfully used for both analytical and preparative separation of finasteride from its metabolite, N-methylfinasteride.

Isolation, purification and determination of 4-n-nonylphenol and 4-tert-octylphenol in aqueous and biological samples

The aim of the present study was to attempt to describe the procedure of isolation, purification, enrichment and determination of 4-n-nonylphenol (4-n-NP) and 4-tert-octylphenol (4-t-OP) in water and biological samples (fish tissue). There were five procedures of solid phase extraction (SPE) tested using different sorbents for the isolation of analytes from water samples. Moreover, we isolated these chemicals from biological matrices with the aid of various extraction methods. The purpose of it was to perform an optimisation of ultrasonic bath, accelerated solvent extraction (ASE) and solid phase extraction process of alkylphenols from biological samples, through the choice of selective sorbents (octadecyl, octadecyl end-capped and amine) and search solvents (methylene chloride, methanol, hexane). Reversed-phase HPLC with diode array detection was used for the determination of 4-n-NP and 4-t-OP in water and fish tissue samples. Sensitivity was evaluated by determining the limit of detection (LOD=0.06 and 0.04ng microL(-1)) and limit of quantification (LOQ=0.18 and 0.16ng microL(-1)) of 4-NP and 4-t-OP, respectively. A series of standard solutions for 4-n-NP and 4-t-OP provided the basis for plotting an analytical curve and obtaining a linear dependence in the range of approximately 1-25ng microL(-1). The best efficiencies obtained for 4-n-NP and 4-t-OP in water samples were 76.65% (+/-1.49) and 83.08% (+/-3.73), respectively. In the case of fish tissue, different situation was observed because the obtained values were considerably lower, being 68.32% for 4-t-OP using hexane (program 1) as solvent and 72.35% (program 2) for 4-n-NP using acetonitrile.

Supramolecular recognition of estrogens via molecularly imprinted polymers

The isolation and preconcentration of estrogens from new types of biological samples (acellular and protein-free simulated body fluid) by molecularly imprinted solid-phase extraction has been described. In this technique, supramolecular receptors, namely molecularly imprinted polymers (MIPs) are used as a sorbent material. The recognition sites of MIPs were prepared by non-covalent multiple interactions and formed with the target 17β-estradiol as a template molecule. High-performance liquid chromatography with spectroscopic UV, selective, and a sensitive electrochemical CoulArray detector was used for the determination of 17β-estradiol, estrone, and estriol in simulated body fluid which mimicked human plasma.

Removal of zearalenone toxin from synthetics gastric and body fluids using talc and diatomite: a batch kinetic study.

Adsorption kinetics of zearalenone (ZEA) toxin from synthetic gastric fluid (SGF) and synthetic body fluid (SBF) by talc and diatomite was studied in the batch experiments. Chemical composition, morphology and structure of the used adsorbents were examined by scanning electron microscopy, FTIR spectroscopy and low-temperature nitrogen adsorption/desorption method. High performance liquid chromatography (HPLC) method was used for ZEA determining. The study results showed that ZEA is more effectively adsorbed on the talc (73% and 54% from SGF and SBF respectively). The efficiency on the diatomite was lower (53% and 42% from SGF and SBF respectively). The first order kinetics model was applied to describe the adsorption process. Rate of the ZEA adsorption from SGF is very rapid initially with about 95% of amount of the toxin adsorbed during first 5 min, while ZEA is adsorbed from SBF in two steps. The values of determined Gibbs free energy of adsorption (from -13 to -17 kJ/mol) indicated that adsorption of ZEA toxin by the both adsorbents are spontaneous and exothermic.

Determination of zearalenone and its metabolites in endometrial cancer by coupled separation techniques

This study presents a selective method of isolation of zearalenone (ZON) and its metabolite, α-zearalenol (α-ZOL), in neoplastically changed human tissue by accelerated solvent and ultrasonic extractions using a mixture of acetonitrile/water (84/16% v/v) as the extraction solvent. Extraction effectiveness was determined through the selection of parameters (composition of the solvent mixture, temperature, pressure, number of cycles) with tissue contamination at the level of nanograms per gram. The produced acetonitrile/water extracts were purified, and analytes were enriched in columns packed with homemade molecularly imprinted polymers. Purified extracts were determined by liquid chromatography (LC) coupled with different detection systems (diode array detection - DAD and mass spectrometry - MS) involving the Ascentis RP-Amide as a stationary phase and gradient elution. The combination of UE-MISPE-LC (ultrasonic extraction - molecularly imprinted solid-phase extraction - liquid chromatography) produced high (R ≈ 95–98%) and repeatable (RSD < 3%) recovery values for ZON and α-ZOL.

Isolation and determination of estrogens in water samples by solid‐phase extraction using molecularly imprinted polymers and HPLC

Advanced SPE with molecularly imprinted polymers (MIP) was used in this study. A noncovalent imprinting approach was applied to separate 17β-estradiol, estriol, and estrone from water samples. Polymer material was prepared by bulk polymerization with methacrylic acid as a functional monomer, divinylbenzene and ethyleneglycol dimethacrylate as crosslinkers, and acetonitrile, acetonitrile/toluene (3:1, v/v) or isooctane/toluene (1:99, v/v) as a porogen. We also prepared an MIP film on a silica gel surface with methacrylic acid and ethyleneglycol dimethacrylate as monomers and acetonitrile as a solvent. Qualitative and quantitative hormone analyses were carried out by HPLC with various detection techniques, including UV/visible spectroscopic detection (diode array detection) and electrochemical detection (CoulArray). The results of the study indicate that MIP technology is an excellent method for the quality control of estrogens in environmental analyses with a low quantification limit for 17β-estradiol of around 26 (diode array detection) and 0.25 ng/mL (electrochemical detection). The proposed method was found to be suitable for routine determinations of the analyzed compound in environmental laboratories.

Analytical procedure for the determination of zearalenone in environmental and biological samples.

The metabolism of zearalenone (ZEA) and analytical methods for determining the presence of ZEA and its metabolites are discussed in this study. Similar to phytoestrogens, solid metaloestrogens, pharmaceuticals, and selected pesticides, ZEA is a substance that displays endocrine activity. ZEA is accumulated in living organisms, and it is capable of contaminating all trophic levels of the food chain, from grain, maize, and other crop plants to human consumers. Zearalenone has a structure similar to that of estrogen (the presence of a macrocyclic lactone ring), it has an affinity for estrogen receptors, and it competes with 17β-estradiol for binding the estrogen receptor in natural pathways. As endocrine disruptors, zearalenone and its metabolites can also contribute to carcinogenic mutations associated with female secondary sex characteristics. The determination of zearalenone and its metabolites in various matrices, first of all biological and environmental samples, poses significant problems. A variety ways of extracting and purifying zearalenone, including liquid-liquid extraction and solid-phase extraction, are described. Furthermore, it describes the possibility of applying a plurality of sensitive and specific instrumental methods, chromatographic techniques (TLC, HPLC, GC) as well as other methods (immunoaffinity chromatography).

Comparison of Several Extraction Methods for the Isolation of Benzoic Acid Derivatives from Melissa officinalis

Abstract Several extraction techniques, such as Soxhlet extraction, solid phase extraction using molecularly imprinted polymer, matrix solid phase dispersion, and supercritical fluid extraction were evaluated for the isolation and purification of phenolic compounds, e.g., benzoic acids from natural samples of Melissa officinalis. The extracts of benzoic acids were analyzed by high performance liquid chromatography (HPLC) in reversed phase modus (C18 column) and under gradient elution (acetonitrile/0.074 mol/L formic acid). The results showed that the recovery rates of gallic acid, p‐hydroxybenzoic acid, protocatechuic acid, gentisic acid, vanillic acid, and syringic acid from biological materials by MSPD was equivalent with and, in fact, higher than that of conventional extraction methods.

Estrogens and Their Analytics by Hyphenated Separation Techniques

Estrogens as biologically active compounds belong to a group of steroids hormones. The definition of these substances is a very important factor in humans. These compounds play an essential role because regulate many physiological processes, including normal cell growth, development and tissue-specific gene regulation in the reproductive tract and in the central nervous and skeleton systems. The much higher concentration of these matters is key in growth of sexual organs and development of secondary sexual features in women. Synthetic compounds which initiate or enhance the effect of estrogens are called xenobiotics. Xenobiotics are found in the human body in much higher concentrations than are usual. They can modify the functions of the endocrine, reproductive, nervous and immune system. For this reason it is significant to determine these compounds. Their physico-chemical properties and complex structure cause many analytical problems. Chromatography, especially liquid chromatography (LC), is used in an extremely large range of analytical methods. Successful analysis of estrogens requires a rapid, reliable, precise method for sample preparation and cleanup to remove potential interfering components. An applicable procedure is the use of solid-phase extraction (SPE), especially with molecularly imprinted polymer (MIP), therefore SPE-MIP. MIPs are taylor-made synthetic materials capable of selectivity rebinding a target analyte based on a combination of recognition mechanisms including size, shape and functionality. Combination SPE-MIP and LC with various detection techniques present an excellent method in quality control of estrogens.

Determination of Biotin in Pharmaceutical Preparation by Means of HPLC and/or MEKC

Abstract This work describes the development of HPLC and micellar electrokinetic capillary chromatography (MEKC) methods, towards the selectivity for biotin analysis and its use for the analysis of pharmaceutical preparation (gel as a filling of a capsule). The isolation of biotin from this matrix was possible after dissolution of the gel from the capsules in hexane, and extraction of fat‐soluble vitamins. The separation of the biotin extract by HPLC did not give good results. Therefore, separation of biotin from interfering substances was performed with high resolution by MEKC with diode‐array detector (DAD). The optimization of composition of the buffer in MEKC was obtained for six different concentration of sodium dodecyl sulfate (SDS). The relative standard deviation (RSD) for migration time was 0.91% and for peak area the RSD was better than 2.5%. The detection limit ranged from 5 to 200 µg/mL. The limit of detection level for biotin was 0.15 µg/mL.