Ciecze jonowe jako medium sorpcyjne w mikroekstrakcji do pojedynczej kropli. Cz.II. Praktyka analityczna

Pomimo rosnącego zainteresowania metodami analitycznymi opartymi na użyciu cieczy jonowych ich sprzężenie wraz z techniką mikroekstrakcji do pojedynczej kropli nie osiągnęło zadowalającej popularności oraz akceptacji ze strony środowiska naukowego.

Comparison of GC–MS and MEKC methods for caffeine determination in preworkout supplements

E. Waraksa , A. Pokrywka, M. Konop, J. Namieśnik , E. Kłodzińska – ELECTROPHORESIS – 2019
In this study, GC–MS- and MEKC-based methods for determination of caffeine (CAF) in preworkout supplements were developed and validated. The proposed protocols utilized minimal sample preparation (simple dilution and syringe filtration). The developed methods achieved satisfactory validation parameters, i.e. good linearity (R2 0.9988 and R2 0.9985 for GC–MS- and MEKC-based method, respectively), satisfactory intraand interaccuracy (within 92.6–100.7% for method utilizing GC–MS and 92.1–110.3% for protocol based on MEKC) and precision (CV 15.9% and CV 6.3% for GC– MS- and MEKC-based method, respectively) and recovery (within 100.1–100.8% for method utilizing GC–MS and 101.5–106.2% for protocol based on MEKC). The LOD was 0.03 and 3 g/mL formethod utilizing GC–MS andMEKC, respectively. The CAF concentrations determined by GC–MS- and MEKC-based methods were found to be in the range of 8.53–11.23 and 8.20–11.61 g/mL, respectively. Taking into consideration information on the labels, the investigated supplements were found to contain from 110.0 to 167.3% of the declared CAF content, which confirmed the literature reports on incompatibility of the declared product compositions with real ones. Nevertheless, the consumption of examined supplements as recommended by producers did not lead to exceeding the CAF safe limit of 400 mg per day. Additionally, the MEKC-based method allowed for detection and identification of vitamin B3 and B6 in all of the investigated supplement samples, which demonstrated that MEKC-based protocols may be an appropriate assays for simultaneous determination of CAF and vitamins.

Comparison of Redox Properties of Flavonoid Aglycones and Corresponding Glycosides and Their Mixtures in the Cellular Model

Flavonoids are polyphenolic compounds commonly found in plants. As dietary components, they have been shown to exhibit numerous pro-health properties that are believed to be associated with their antioxidant effects. In this study, the antioxidant activity of four flavonoid compounds was determined by cellular antioxidant activity assay using HT29 cells as a model of the alimentary tract. The strongest impact on cellular redox status was observed for aglycones which acted as both antioxidants (quercetin) and prooxidants (naringenin). Interestingly, mixtures of tested compounds displayed only antioxidative properties.

Determination of Antioxidant Activity of Vitamin C by Voltammetric Methods

Voltammetric methods—cyclic (CV) and differential pulse voltammetry (DPV) are considered the most appropriate way to evaluate antioxidant activity of redox active compounds. They provide information about both mechanism and kinetics of electrochemical oxidation of antioxidants as well as their physical and chemical properties such as the redox potential or the number of electrons transferred. These methods are helpful for understanding the mechanisms of oxidation or reduction processes of antioxidant compounds. This work presents the electrochemical properties of vitamin C obtained by both CV and DPV methods.

Determination of free tyrosine in equestrian supplements by LC–MS/MS and comparison of its quantity with total free amino acids content in view of doping control

E. Waraksa , K. Kowalski , R. Rola, E. Kłodzińska, T. Bieńkowski, J. Namieśnik MICROCHEMICAL JOURNAL – 2019
The reports on the probable beneficial impact of tyrosine (TYR) supplementation on performance enhancement have contributed to the growth of interest in TYR in equestrian sports field and related industries, such as the manufacture of dietary and nutritional supplements. In this study, the first attempt to the assessment of horses exposure to TYR during nutritional supplementation was demonstrated by quantification of unbound TYR and a total free amino acids (AAs), and subsequent determination of the ratio of TYR to a total free AAs content in equestrian supplement samples. Within the scope of this study, a rapid and sensitive LC–MS/MS-based method for the determination of unbound TYR and a simple spectrophotometric protocol for the quantification of a total free AAs have been developed and validated according to the international guidelines for bioanalytical methods. For sample preparation, an ultrasound-assisted solid-liquid extraction (USLE; for solid samples) and ultrasound-assisted liquid-liquid extraction (ULLE; for liquid samples) have been optimized. The comprehensive approach on the simultaneous assessment of matrix effect, recovery, process efficiency, accuracy, precision, curve factor and internal standard association demonstrated satisfactory validation parameters for LC–MS/MS-based procedure, such as global matrix effect in the range of 89.9–91.9%, good linearity (R2 > 0.9929), limit of detection (0.6 ng/mL) and recovery within 89.2–108.0%. For spectrophotometric method, limit of detection was 1100 ng/mL, recovery ranged from 103.2 to 108.8%, both, intra- and inter-day accuracy was within 89.5–108.7%, and both, intra- and inter-assay precision was below 8.5%. In view of the satisfactory validation parameters obtained for both methods, the procedures can be utilized for routine analysis of dietary and nutritional supplements.

Dietary antioxidants as a source of hydrogen peroxide

M. Grzesik, G. Bartosz, I. Stefaniuk, M. Pichla, J. Namieśnik , I. Sadowska-Bartosz FOOD CHEMISTRY – 2019
Studies of 54 antioxidants revealed that 27 of them, mainly polyphenols, generated hydrogen peroxide (H2O2) when added to Dulbecco’s modified Eagle’s medium (DMEM), other media used for culture of mammalian and yeast cells and phosphate-buffered saline. The most active antioxidants were: propyl gallate (PG), (−)-epigallocatechin gallate (EGCG) and quercetin (Q). Chelex treatment and iron chelators decreased H2O2 generation suggesting that transition metal ions catalyze antioxidant autoxidation and H2O2 production. Green tea also generated H2O2; tea prepared on tap water generated significantly more H2O2 than tea prepared on deionized water. Ascorbic acid decreased H2O2 production although it generated H2O2 itself, in the absence of other additives. Lemon added to the tea significantly reduced generation of H2O2. Hydrogen peroxide generated in the medium contributed to the cytotoxicity of PG, EGCG and Q to human prostate carcinoma DU-145 cells, since catalase increased the survival of the cells subjected to these compounds in vitro.

Dispersive liquid-liquid microextraction combined with gas chromatography–mass spectrometry for in situ determination of biogenic amines in meat: Estimation of meat's freshness

A dispersive liquid-liquid microextraction (DLLME) gas chromatography–mass spectrometry (GC–MS) technique was developed for the determination of selected biogenic amines (BAs) in samples of poultry, pork and beef. Prior to the extraction process, an appropriate volume of sodium hydroxide solution was added to each of the portioned samples. Next, samples were homogenized, centrifuged and finally sonicated at an increased temperature. After another centrifugation, the supernatant was made up to 50 mL in a calibrated flask. Subsequently, 5 mL of supernatant was separately subjected to a derivatization and extraction procedure. A mixture of methanol (dispersive solvent; 210 μL), chloroform (extractive solvent; 300 μL), and isobutyl chloroformate (derivatizing reagent; 100 μL) was used in the extraction process together with an admixture of pyridine and HCl in order to eliminate the by-products. The application of the method enables fast derivatization and extraction of the BAs and a straightforward and rapid sample enrichment. It displayed good linearity, intra- and inter-day precision and good recoveries. The proposed methodology is characterized by low limits of detection and quantification (0.003–0.009 μg/g and 0.009–0.029 μg/g, respectively). The green character of the method was established based on the results of two tools, namely the Analytical Eco-Scale and GAPI. It was successfully used to analyse samples of poultry, porcine and bovine meat. Multivariate statistical data analysis was applied in order to evaluate the potential use of the determined BAs as spoilage markers of particular meat types.

Electronic Noses in Medical Diagnostics

Electronic nose technology is being developed in order to identify aromas in a way parallel to the biologic olfaction. When applied to the field of medicine, such device should be able to identify and discriminate between different diseases. In recent years this kind of approach finds application in medical diagnostics, and especially in disease screening. Despite the fact that devices utilizing chemical sensor arrays are not routinely used in everyday medical practice, their prospective use would solve some established issues in healthcare. It would also find application in prophylactics by facilitating a widespread deployment of screening tests. In this review the comprehensive summary of research in medical diagnostics using electronic noses is presented. A special attention has been paid to application of these devices and sensor technologies, in response to current trends in medicine.

Evaluation of Health Hazard Due to Emission of Volatile Organic Compounds from Various Processing Units of Wastewater Treatment Plant

The paper describes an attempt at health risk assessment and odour concentration determination in the most important units of a wastewater treatment plant. The cancer risk (CR) and hazard index (HI) parameters in selected measurement locations were calculated based on the results of chromatographic analyses (GCxGC-TOF-MS) and the United States Environmental Protection Agency (US EPA) guidelines. No exceedance of the CR and HI acceptable levels was observed for identified and quantitatively determined compounds from the VOCs group. The acceptable level was exceeded for the summary HI parameter. Following a classification of the International Agency for Research on Cancer (IARC), it was noticed that the highest hazard was connected to the presence of formaldehyde belonging to group 1—the compounds regarded as carcinogenic. Based on the olfactometric analyses, it was estimated that the highest odour concentration, 37.2 ou/m3, occurred at the solid waste composting piles. It was also revealed that an increase in odour concentration corresponded to a higher health risk for employees of the wastewater treatment plant, due to exposure to volatile odorous compounds. Accordingly, this method of odour measurement can be a fast indicator describing health risk level.

Evaluation of the influence of grapevine growing conditions on wine quality

Scientists are increasingly interested in the viticulture concept of terroir, which states that unique properties of wine are strictly related to the environmental conditions under which grapes are cultivated. The aim of the research was to compare the parameters characterizing wines produced in Poland, such as pH, conductivity, total organic carbon (TOC), and concentration of anions (F−, Cl−, NO2−, NO3−, PO43−, SO42−). It was shown that red wines were characterized by higher acidity and higher concentration of fluoride ions compared to white wines. All wine samples were characterized by a high concentration of phosphate ions which is associated with the process of soil fertilization with phosphorus compounds. A tentative chemometric analysis was performed in order to examine the correlations between the determined parameters. The results were compared in terms of the effect of soil type on the concentration of compounds contained in wine, and the pH and conductivity parameters. The analysis has shown that the soil in which the grapevines grow has a significant impact on the values of selected parameters and on the content of selected chemical compounds.