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Vitamin K is one of the many health-promoting substances whose impact on the human body has been underestimated until recently. However, recently published research results have changed this situation, prompting some researchers to consider it a new panacea for diseases of old age. The result is a significant increase in interest in the accurate analysis of vitamin K in various types of samples, ranging from food, through dietary supplements, to biological matrices and clinical trials, both observational and interventional. This review summarizes the current state of knowledge about the proven and speculated biological activity of vitamin K and its importance for the world's aging societies, including the methods used for its isolation and analysis in various matrices types. Of all the analytical methods, the currently preferred methods of choice for the direct analysis of vitamin K are chromatographic methods, in particular liquid chromatography-tandem mass spectrometry. This technique, despite its sensitivity and selectivity, requires an appropriate stage of sample preparation. As there is still room for improvement in the efficiency of these methods, especially at the sample preparation stage, this review shows the directions that need to be taken to make these methods faster, more efficient and more environmentally friendly. [ABSTRACT FROM AUTHOR]

Vitamin K, as a natural protector of our blood, bones, kidneys, and brain, is essential for human health. It is also considered an effective anti-aging agent with comprehensive biological effects, including antifungal, antibacterial, anti-inflammatory, analgesic, and even antioxidant properties. Of these, the least is known about the antioxidant properties of natural vitamin K. To fill this gap, this study compared the antioxidant properties of extracts obtained from commonly consumed green plants with different vitamin K contents with the activity of vitamin K standard solutions at concentrations corresponding to the vitamin K contents in the extracts. Various measurement methods were used in the research (i.e., DPPH, FRAP, CUPRAC, and the β-carotene bleaching test). Among the tested methods, the β-carotene bleaching test is the most sensitive in the assessment of this unusual compound. In light of the data presented, the antioxidant response of vitamin K alone is dose-dependent. However, in extracts, the activity of this compound is modulated by other constituents present in them. As a result, the activity does not always correlate with vitamin K content. The presented data supplement the knowledge about the antioxidant properties with the contribution resulting from the presence of vitamin K in green plant extracts. [ABSTRACT FROM AUTHOR]

The extensive use of rodenticides poses a severe threat to non-target species, particularly birds of prey and scavengers. In this study, a GC-MS/MS-based method was used to unlock the cause of bird deaths in Poland. Organs (liver, heart, kidney, and lungs) collected during autopsies of two rooks (Corvus frugilegus) and one carrion crow (Corvus corone corone), as well as fecal samples, were analyzed for the presence of anticoagulant coumarin derivatives, i.e., warfarin and bromadiolone. As for warfarin, the highest concentration was found in crow samples overall, with concentrations in the feces and lungs at 5.812 ± 0.368 µg/g and 4.840 ± 0.256 µg/g, respectively. The heart showed the lowest concentration of this compound (0.128 ± 0.01 µg/g). In the case of bromadiolone, the highest concentration was recorded in the liver of a rook (16.659 ± 1.499 µg/g) and this concentration significantly exceeded the levels in the other samples. By revealing the reality of the threat, these discoveries emphasize the need to regulate and monitor the trade in rodenticides. [ABSTRACT FROM AUTHOR]

Concern for the future of the next generation leads to the search for alternative solutions for the proper management of materials considered as useless waste. This study fits into this research trend. Its aim is to demonstrate the potential of walnut husks as a source of compounds with antioxidant properties that can be used in non-food industries. Pressurized liquid extraction, i.e., one of the modern green extraction techniques used on an industrial scale, as well as conventional extraction in Soxhlet and maceration were applied to prepare the extracts. In order to assess in depth their antioxidant activity in relation to the content of characteristic components, various activity assessment methods were used in this research. The results proved that the husk components have such antioxidant properties that they can be of interest to the cosmetics and pharmaceutical industries regarding the management of this waste. The results confirmed the usefulness of assisted extraction in increasing the ecological and economic values of the proposed waste disposal. Moreover, they showed that juglonehas very weak antioxidant properties, and the antioxidant effect of the mixture containing husk extract and juglone solution is mainly additive. [ABSTRACT FROM AUTHOR]

Featured Application: The obtained results not only extend knowledge about the antioxidant properties of mixtures but can be helpful in the effective design of functional foods. This is a particularly important aspect from the point of view of both the manufacturer and the consumer, whose consciousness regarding the promotion and propagation of a healthy lifestyle has recently increased. The issue of the increase in the average age of many communities is also important. Taking into account the increasing tendency of the incidence of age-related diseases, more and more attention is paid to supplementing the body with natural products with high antioxidant activity. Plants are a rich source of substances with antioxidant properties, including high amounts of polyphenolic compounds, as well as other substances that do not necessarily have antioxidant properties. The presented paper concerns the evaluation of the antioxidant properties of polyphenolics and their binary mixtures in the presence of other components of the system that do not exhibit antioxidant properties. Model systems containing chlorogenic acid and kaempferol were used in the experiments, differing not only in the volume of the alcoholic antioxidant solution in the measurement system, but also in temperature, content of water, metal ions and hydrogen ions. The ability to neutralize free radicals in the systems was estimated using the ABTS method. In light of the presented data, the dominant resultant antioxidant effect in the mixture is antagonism. Its value depends not only on the mutual relations of individual compounds, but also on the presence of other components in the tested system, not only antioxidants. The greatest effect on the antioxidant properties was observed for systems containing iron ions, ethanol and in the presence of hydrogen ions. The obtained results indicate an extremely complex nature of the assessment of antioxidant properties, even in seemingly simple measurement systems. [ABSTRACT FROM AUTHOR]

Biological properties of menaquinone-7, one of the vitamin K2 vitamers (K2MK-7), both those proven and those that remain to be investigated, arouse extensive interest that goes beyond the strictly scientific framework. The most important of them is the prevention of age-related diseases, considering that we live in the times identified as the era of aging societies and many people are exposed to the vitamin K2MK-7 deficiency. Therefore, an effective analytical protocol that can be adopted as a diagnostic and preventive analytics tool is needed. Herein, a simple sample preparation method followed by the liquid chromatography-tandem mass spectrometry-based method (LC-MS/MS), was used for the selective and sensitive determination of K2MK-7 in serum samples. Under the optimized conditions, using 500 µL of serum and the same amount of n-hexane, the reproducibility and the accuracy were obtained in the ranges of 89–97% and 86–110%, respectively, and the limit of detection value was 0.01 ng/mL. This method was used for the routine analysis. Statistical interpretation of the data from 518 samples obtained during 2 years of practice allowed for obtaining information on the content and distribution of K2MK-7 in the Polish population, broken down by the sex and age groups. [ABSTRACT FROM AUTHOR]

Flavonoids, secondary plant metabolites with many health-promoting properties, including antioxidant, are a valuable component of food products, especially functional foods. In the latter, plant extracts are commonly used, the properties of which are attributed to the characteristic main ingredients. However, in a mixture the antioxidant properties of the individual ingredients do not always show an additive effect. This paper presents and discusses the antioxidant properties of naturally occurring flavonoid aglycones and their binary mixtures. In the experiments, model systems were used that differed in the volume of the alcoholic antioxidant solution in the measuring system and its concentration in the range in which it occurs in nature. Antioxidant properties were determined by ABTS and DPPH methods. The presented data proved that the dominant resultant effect in the mixtures is antioxidant antagonism. The magnitude of the observed antagonism depends on the mutual relations of individual components, their concentrations and the method used to assess antioxidant properties. It was shown that the observed non-additive antioxidant effect of the mixture results from the formation of intramolecular hydrogen bonds between phenolic groups of the antioxidant molecule. The presented results may be useful in the context of proper design of functional foods. [ABSTRACT FROM AUTHOR]

Nature is a valuable source of anti-oxidants that have a health-promoting effect by inhibiting various undesirable changes leading to cell degradation and, consequently, potential disease ailments. One of them is gallic acid which has been used as a healing agent since ancient times. Currently, due to various beneficial properties, this compound is considered to be one of the main phenolic acids of great importance in numerous industries. It is commonly used as a substance protecting against the harmful effects of UV radiation, an astringent in cosmetic preparations, and a preservative in food products. Therefore, gallic acid is now deemed essential for both human health and industry. Increasingly better methods of its isolation and analysis are being developed, and new solutions are being sought to increase its production. This review, presenting a concise characterization of gallic acid, updates the knowledge about its various biological activities and methods used for its isolation and determination, including chromatographic and non-chromatographic methods. [ABSTRACT FROM AUTHOR]

In this study it was shown that the fungistatic and antioxidant activities of onion extracts are related to the type of liquid used as the extractant and the technique of its preparation. A change in the antioxidant properties of white and red onion extracts was demonstrated with the change of the temperature of the pressurized hot water extraction process, which can be easily related to the changes accompanying the process of thermal processing of vegetables and fruits during cooking. Owing to the experimental and mathematical approaches concerning both the main and characteristic components of onions, i.e., quercetin and phenols, respectively, with the biological activity of the extracts, it was possible to demonstrate the significant share of these compounds in the antifungal and antioxidant properties of the extracts. Considering that the research was carried out, inter alia, on onion husks, demonstrating a very high potential of biological properties of this waste material from agricultural production, the research results presented in the paper should encourage the popularization of the use of this so far underestimated raw material for the production of various functional materials. [ABSTRACT FROM AUTHOR]

In this article, we have presented the development and validation of a rapid and sensitive reversed-phase liquid chromatography with tandem mass spectrometry (LC-MS/MS) method for the determination of vincristine (VCR) in patient serum samples. Chromatographic separation was achieved on a Kinetex® (Singapore) column using a mobile phase consisting of 25 mM acetic acid and 0.3% formic acid (A) and methanol (B) in a gradient elution mode at a flow rate of 0.3 mL/min. The VCR and internal standard (vinblastine) were monitored using the multiple reaction monitoring mode under positive electrospray ionization. The lower limit of quantification (LLOQ) was 0.67 ng/mL, and the upper limit of quantification (ULOQ) was 250 ng/mL for VCR. The calculated values of LOD and LOQ for VCR were 0.075 and 0.228 ng/mL, respectively. The calibration curve was linear over the VCR concentration range of 1.0–250 ng/mL in serum. The intra- and inter-day precision and precision were within the generally accepted criteria for the bioanalytical method (<15%). The method was successfully applied to the analysis of serum samples in clinical practice. [ABSTRACT FROM AUTHOR]

Chlorogenic acid (CQA) is one of phenolics commonly found in higher plants, possessing numerous health-promoting effects on humans. Unfortunately, it is easily degraded/transformed into other substances during extraction. Therefore, its reliable analysis requires a special approach that does not involve high temperatures. This paper presents a very simple method of CQA isolation using the sea sand disruption method with subsequent purification of the extract using the ion-pair solid-phase extraction process, followed by HPLC–DAD detection. It was found that control of the ion pairing reagent concentration and sample pH is crucial to improve purification, and that the best results, with recovery exceeding 98%, were obtained for 0.05 M tetrabutylammonium bisulfate at pH 7 when the ion pairs were formed directly in the extract and eluted from the C18 sorbent using an acidified methanol–water mixture. The practical potential of the developed procedure was verified by using it for CQA isolation from different plants. The approach represents one of the contemporary analytical trends and current advances in the solid phase extraction, in which several sorption extraction techniques are combined to ensure high-quality analytical results. [ABSTRACT FROM AUTHOR]

One of the most important issues considered in ecotoxicology is the elevated accumulation of different elements in soil as a consequence of anthropogenic activities. In this paper, determination of nine elements in soil obtained from three different forest complexes (sycamore, beech, and spruce) in urbanized and non-urbanized regions of Tatra National Park is presented. Additionally, a comprehensive presentation of detailed results of correlation analyses between individual elements in accordance to each valley, as well as to selected species of trees, is shown. Speciation studies included chemical forms of the following elements: Fe, Mn, Zn, Cu, Pb, Cd, Ni, Cr, Co. Soil extracts were obtained in accordance with Rudd’s methodology and all species were determined using atomic absorption spectrophotometry (AAS). The study compares the content of selected chemical forms (exchangeable and adsorbed, organic solutions and carbonates) of chosen metals in soil of four valleys of Tatra National Park: Chochołowska, Strążyska, Mała Łąka, and Kościeliska. The first three (group A) are considered as non-urbanized areas, whereas the last four (group B), on the account of many home fireplaces located there, as urbanized areas. [ABSTRACT FROM AUTHOR]

Sulthiame is an old antiepileptic medicine with controversial history, whose effectiveness and safety in use have been stated in some current studies. However, there is still a need for further clinical examinations for confirmation of its usefulness and tolerability in monotherapy and add‐on therapy for epilepsy of various etiologies. A fully validated RP HPLC–UV method for determination of sulthiame in serum/plasma samples using desethylatrazine as the internal standard was developed. The biological fluid was prepared for analysis by a simple precipitation method with acetonitrile. The following validation parameters of the method were determined: selectivity/specificity, linearity range (0.2–50.0 μl/ml, R2 > 0.9999), limits of detection (0.19 μl/ml) and quantification (0.58 μl/ml), precision (intra‐day CV 1.06% and inter‐day CV 1.25%), extraction recovery (~100%), accuracy (bias, −4.61–0.80%), carryover and ruggedness. Moreover, the stability of the medicine in plasma samples under different storage conditions was also tested. The usability of the method for clinical examinations was checked by analysis of serum samples originating from 19 patients treated with sulthiame. The proposed method is appropriate for determination of sulthiame in serum/plasma samples for drug monitoring purposes, as well as for pharmacokinetic studies. [ABSTRACT FROM AUTHOR]

Introduction: Effective diagnosis of cardiovascular diseases requires the right tools to be used enabling selective and sensitive analysis of their biomarkers. One of them is homocysteine (Hcy), nowadays determined by immunoassays and chromatographic methods. This study aims to compare the results obtained by direct chemiluminescence immunoassay (CLIA) and high performance liquid chromatography with fluorescent detection (HPLC-FD) using commercial kits. Materials and methods: Homocysteine concentration was determined in serum samples obtained from 101 individuals, using Atellica IM HCY (Siemens Healthineers, Erlangen, Germany) and HCY in plasma/serum - HPLC-FD (Chromsystems Instruments & Chemicals GmbH, Gräfelfing, Germany) tests validated for routine analysis. The latter was applied as a reference method. The comparability and agreement between the tested methods were evaluated using the Passing-Bablok (PB) regression analysis and the Bland-Altman (BA) method of the differences analysis. Results: Studies showed that CLIA gives higher Hcy concentrations (15.7 ± 4.14 µmol/L). Passing-Bablok regression analysis of the results obtained with CLIA (y) compared with HPLC-FD (x) yielded an intercept of 0.22 (95%CI: - 2.16 to 2.46) and slope of 1.58 (95%CI: 1.33 to 1.87). Bland-Altman analysis demonstrated a systematic positive bias for CLIA of 5.85 ± 2.77 µmol/L. Conclusions: Methods disagreement precludes their interchangeability. Lower Hcy values by HPLC-FD result from its greater selectivity. High performance liquid chromatography with fluorescent detection should be considered as preferential method for analysing Hcy in blood serum as well as the recommended reference method for routine clinical analysis. This fact, however, imposes the need to establish new reference ranges. [ABSTRACT FROM AUTHOR]

The green husk is one of the major wastes produced during the walnut (Juglans regia L.) cultivation. However, the results presented in this article may contribute to extension of their usefulness as new and safe plant protection products. The results confirmed the activity of the walnut green husk extracts against plant (Alternaria alternata, Rhizoctonia solani, Botrytis cinerea, Fusarium culmorum, Phytophthora cactorum) and bee (Ascosphaera apis) pathogenic fungi, and showed that the extraction conditions differentiate the properties of the obtained isolates. The increase in the isolation temperature leads to a significant reduction in the antifungal activity of the extracts. The change of the extractant type modifies the resistance of individual fungi. The observed variations in the properties are consistent with the change of juglone content in these extracts. However, considering the juglone concentration provided 50% inhibition of the growth of individual mycelia, the observed differentiation of the antifungal properties of extracts should not be associated only with the juglone content. This observation, supported by the results obtained using gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography coupled to mass spectrometry (LC-MS), suggests a synergistic effect of the other components on the antifungal activity of walnut green husk extracts. [ABSTRACT FROM AUTHOR]

The aim of this paper is to present in the most comprehensive way the facts about the application of PLE in the analysis of secondary metabolites in plants. It is true that due to its specific extraction conditions, PLE is one of the most effective and versatile techniques of plant constituents isolation. It is also true that it has popularized the use of aqueous organic mixtures, and even water alone, for the extraction of nonpolar compounds. Yet, the same specific extraction conditions can lead to erroneous results of plant constituent content analysis. Disclosure of new facts about the application of PLE in the analysis of secondary plant metabolites provides an insight into an often overlooked aspect of extraction of active compounds from plants. • This review updates knowledge about the applicability of PLE. • It discusses the effectiveness and usefulness of PLE in the context of its achievements. • It discloses the limitations of PLE in the plant constituents content analysis. • Knowing all these facts can lead to the creation of a perfect method with a good method. [ABSTRACT FROM AUTHOR]

Abstract The aim of this paper was to present the diversity of analytical challenges in which the MSPD technique is useful and the variety of sorbents that are currently applied to meet these challenges with particular emphasis on new research areas in which the MSPD process started to be applied. In addition, the paper presents new tools to improve both the MSPD yields using the MSPD processes supported by centrifugation, ultrasound, microwave and magnetism and its selectivity combining MSPD with other extraction techniques in particular, with microextraction ones, such as liquid-liquid microextraction dispersion or homogeneous liquid-liquid microextraction. Facing the problem of the increased urgency for further reduction of sample preparation costs and organic solvent usage, alternative MSPD approaches such as the solventless MSPD mode and MSPD with sand used as a dispersing material in the so-called sea sand dispersion method were discussed. Highlights • This review updates knowledge about the applicability of MSPD. • It discuss the versatility and flexibility of MSPD in the context of its achievements and limitations. • Indicates new research areas in which MSPD began to be applied. • In addition, indicates those that in the near future should use this simple process. [ABSTRACT FROM AUTHOR]

Chlorogenic acids (CQAs), the esters of caffeic acid and quinic acid, are biologically important phenolic compounds present in many plant species. Nowadays much is known from their prohealth properties, including anti-cancer activity. Yet, the supposition that they may be helpful in fighting obesity and modify glucose-6-phosphatase involved in glucose metabolism have led to a revival of research on CQAs properties and their natural occurrence. Much attention is also paid to the proper analysis of CQAs content in plants and plant products due to the fact that the main CQAs representative in nature i.e. 5-O-caffeoylquinic acid (5-CQA) is commonly employed as a quality marker in the control of various natural products. The common procedures used so far for CQAs determination in plants involve conventional long lasting solvent extraction realized at higher temperatures prior to chromatographic analysis. The drawbacks associated to the conventional extraction techniques have led to the search for new alternative extraction processes that additionally could improve extracts quality. The latter is particularly important as regards CQAs applications, and the fact that these compounds easily transform/degrade to others. According to reports, the conventional heating of 5-CQA in the presence of water causes its isomerization and transformation. The reports prove that 5-CQA not only isomerizes to 3- and 4-O-caffeoylquinic acid, but also undergoes other transformations such as esterification and reactions with water. Hence, in the attempt to improve the process of chlorogenic acids extraction and to make it more effective and environmentally friendly, innovative so-called "enhanced" techniques of extraction have been recently developed and applied. To guarantee the proper analysis of compounds with very similar properties forming the chlorogenic acids family and their numerous transformation/degradation products, hyphenated techniques, in particular LC-MS, are currently being used. The purpose of this review is to summary and overview of the sources, properties, and methods which have been developed to improve the extraction and analysis of chlorogenic acids in plants and plant products, with particular reference to 5-CQA and 1,3-di- CQA as these compounds of the CQAs family with many beneficial effects on human health. [ABSTRACT FROM AUTHOR]

Pressurized liquid extraction (PLE) is considered as an effective and quick sample preparation method, especially in plant analysis. This quick extraction process favors the isolation of compounds for which long exposure time in high temperatures is undesirable. However, despite this advantage, the application of PLE for plant compounds extraction involves certain problems, such as instability of the compounds. The obtained data proved that even in short-lasting PLE, quercetin 4'-glucoside undergoing the hydrolytical degradation process produces the corresponding aglycon quercetin when water is a component of the applied extractant. The increase of water content in methanol-water extractant mixture heightens the transformation degree of quercetin 4'-glucoside into quercetin and increases its concentration in the PLE extracts. The degradation is accelerated by increased extraction temperature and time. In plant samples, the degradation of quercetin 4'-glucoside is much higher because of the plant matrix effects. The presented results explain why extraction of quercetin from plants by pure methanol is less efficient than by water containing alcohol solutions. More importantly, they prove that the application of water-alcohol extractant during sample preparation leads to the hydrolytical degradation of glycosides to aglycones, and, as a consequence, to false conclusions in plant analysis. [ABSTRACT FROM AUTHOR]

This study deals with the sea sand disruption method (SSDM) in sample preparation for chromatographic analysis of quercetin in different plants. Several SSDM variables were tested in relation to quercetin recovery: sample to sand mass ratio, type of dispersing liquid, volume of the solvent applied for analyte elution, and the time of grinding. The optimized procedure has been applied for the extraction of quercetin from the edible and inedible parts of different varieties of onion, apples, and tea. The SSDM results are comparable with those obtained by pressurized liquid extraction, regarded as one of the most effective sample preparation techniques. The presented results show that the hydrolysis of quercetin glycoside form in SSDM conditions does not occur or is negligible. Hence, the method is especially useful when the estimation of the real amount of aglycones in plants is required. [ABSTRACT FROM AUTHOR]

Chlorogenic acids (CQAs) are phenolic compounds naturally occurring in all higher plants. They are potentially useful in pharmaceuticals, foodstuffs, food additives, and cosmetics due to their recently suggested biomedical activity. Hence, research interest in CQA properties, their isomers, and natural occurrence has been growing. Pressurized liquid extraction (PLE) is regarded as an effective and quick sample preparation method in plant analysis. The short time of PLE decreases the risk of chemical degradation of extracted compounds, thus increasing the attractiveness of its application. However, PLE applied for plant sample preparation is not free from limitations. We found that fr-ans-5-O-caffeoylquinic acid (trans-5-CQA), the main CQA isomer, isomerizes to 3- and 4-O-caffeoylquinic acids and undergoes transesterification, hydrolysis, and reaction with water even in rapid PLE. Moreover, the number and concentration of trans-5-CQA derivatives formed in PLE strongly depends on extractant composition, its pH, and extraction time and temperature. It was not possible to find the PLE conditions in which the transformation process of trans-5-CQA would be eliminated. [ABSTRACT FROM AUTHOR]

Silymarin, a mixture of flavonolignans exhibiting many pharmacological activities, is obtained from the fruits of milk thistle (Silybum marianum L. Gaertner). Due to the high lipid content in thistle fruits, the European Pharmacopoeia recommends a two-step process of its extraction. First, the fruits are defatted for 6 h, using n-hexane; second, silymarin is extracted with methanol for 5 more hours. The presented data show that this extremely long traditional Soxhlet extraction process can be shortened to a few minutes using pressurized liquid extraction (PLE). PLE also allows to eliminate the defatting stage required in the traditional procedure, thus simplifying the silymarin extraction procedure and preventing silymarin loss caused by defatting. The PLE recoveries obtained under the optimized extraction conditions are clearly better than the ones obtained by the Pharmacopoeia-recommended Soxhlet extraction procedure. The PLE yields of silychristin, silydianin, silybin A, silybin B, isosilybin A and isosilybin B in acetone are 3.3, 6.9, 3.3, 5.1, 2.6 and 1.5 mg/g of the non-defatted fruits, respectively. The 5-h Soxhlet extraction with methanol on defatted fruits gives only ∼72% of the silymarin amount obtained in 10 min PLE at 125°C. [ABSTRACT FROM AUTHOR]

The influence of different purge times on the yield of the main essential oil constituents of rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and chamomile (Chamomilla recutita L.) was investigated. The pressurized liquid extraction process was performed by applying different extraction temperatures and solvents. The results presented in the paper show that the estimated yield of essential oil components extracted from the plants in the pressurized liquid extraction process is purge time-dependent. The differences in the estimated yields are mainly connected with the evaporation of individual essential oil components and the applied solvent during the purge; the more volatile an essential oil constituent is, the greater is its loss during purge time, and the faster the evaporation of the solvent during the purge process is, the higher the concentration of less volatile essential oil components in the pressurized liquid extraction receptacle. The effect of purge time on the estimated yield of individual essential oil constituents is additionally differentiated by the extraction temperature and the extraction ability of the applied solvent. [ABSTRACT FROM AUTHOR]

Abstract: 2,2′-Diphenyl-1-picrylhydrazyl (DPPH ) method is commonly applied for the estimation of antioxidant activity of single compounds and their mixtures. The method is based on the spectrophotometric measurement of DPPH concentration changes resulting from the DPPH reaction with an antioxidant. The amount of remaining DPPH in the examined system is a measure of the antioxidative activity of compounds. The study shows that the type and amount of solvent used for the antioxidant dissolution, water content, and hydrogen or metal ion concentration in the measuring system significantly influence the differences in the amount of unreacted DPPH . The presence of ethyl acetate or dioxane or metal ions in the system decreases the kinetics of the reaction between DPPH and butylohydroxytoluene in relation to its kinetics in the system containing only methanolic solutions. The opposite effect is observed for water, low concentration of chloroform or hydrogen ions. The presented relationships confirm the necessity of standardising the DPPH method and show the complexity of the problem, even in very simple DPPH /antioxidant systems. [Copyright &y& Elsevier]

Introduction - Matrix solid-phase dispersion (MSPD) is a very simple, cheap and relatively quick sample preparation procedure which involves simultaneous disruption and extraction of various solid and semi-solid samples due to the direct mechanical blending of the sample with a SPE sorbent, mainly C18. Little is known about MSPD application as a sample preparation method for the analysis of essential oil components in herbs. Objective - To evaluate if C18 sorbent, commonly used in MSPD process, can be substituted with sand in the procedure of essential oil analysis. Methodology - Essential oil extracts were obtained from mint, sage, chamomile, marjoram, savory and oregano using MSPD with C18 sorbent or sand, pressurised liquid extraction and steam distillation. Their qualitative and quantitative compositions ware established by GC-MS and GC-FID. Results - The results prove that C18 sorbent can be substituted with sand in the procedure of essential oil analysis in herbs. The recoveries of essential oil components estimated using MSPD/sand are almost equal to those using pressurised liquid extraction. Conclusion - The results presented in the paper reveal that MSPD with sand is suitable for the isolation of essential oil components from herbs. Its extraction efficiency is equivalent to pressurised liquid extraction, recognised as one of the most efficient extraction methods. The cost of MSPD procedure for essential oil analysis can be significantly diminished by substituting C18 with sand. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]