Deep eutectic solvent-based shaking-assisted extraction for determination of bioactive compounds from Norway spruce roots.

Polyphenolic compounds play an essential role in plant growth, reproduction, and defense mechanisms against pathogens and environmental stresses. Extracting these compounds is the initial step in assessing phytochemical changes, where the choice of extraction method significantly influences the extracted analytes. However, due to environmental factors, analyzing numerous samples is necessary for statistically significant results, often leading to the use of harmful organic solvents for extraction. Therefore, in this study, a novel DES-based shaking-assisted extraction procedure for the separation of polyphenolic compounds from plant samples followed by LC-ESI-QTOF-MS analysis was developed. The DES was prepared from choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and fructose (Fru) as the hydrogen bond donor (HBD) at various molar ratios with the addition of 30% water to reduce viscosity. Several experimental variables affecting extraction efficiency were studied and optimized using one-variable-at-a-time (OVAT) and confirmed by response surface design (RS). Nearly the same experimental conditions were obtained using both optimization methods and were set as follows: 30 mg of sample, 300 mg of ChCl:Fru 1:2 DES containing 30% w/w of water, 500 rpm shaking speed, 30 min extraction time, 10°C extraction temperature. The results were compared with those obtained using conventional solvents, such as ethanol, methanol and water, whereby the DES-based shaking-assisted extraction method showed a higher efficiency than the classical procedures. The greenness of the developed method was compared with the greenness of existing procedures for the extraction of polyphenolic substances from solid plant samples using the complementary green analytical procedure index (ComplexGAPI) approach, while the results for the developed method were better or comparable to the existing ones. In addition, the practicability of the developed procedure was evaluated by application of the blue applicability grade index (BAGI) metric. The developed procedure was applied to the determination of spruce root samples with satisfactory results and has the potential for use in the analysis of similar plant samples.

Application of liquid-phase microextraction to the analysis of plant and herbal samples.

INTRODUCTION: The analysis of plant and herbal samples is a challenging task for analytical chemists due to the complexity of the matrix combined with the low concentration of analytes. In recent years different liquid-phase microextraction (LPME) techniques coupled with a variety of analytical equipment have been developed for the determination of both organic and inorganic analytes. OBJECTIVE: Over the past few years, the number of research papers in this field has shown a markedly growing tendency. Therefore, the purpose of this review paper is to summarise and critically evaluate research articles focused on the application of LPME techniques for the analysis of plant and herbal samples. RESULTS: Due to the complex nature of the samples, the direct application of LPME techniques to the analysis of plants has not often been done. LPME techniques as well as their modalities have been commonly applied in combination with other pretreatment techniques, including a solid-liquid extraction technique supported by mechanical agitation or auxiliary energies for plant analysis. Applications and the most important parameters are summarised in the tables. CONCLUSION: This review summarises the application of the LPME procedure and shows the major benefits of LPME, such as the low volume of solvents used, high enrichment factor, simplicity of operation and wide selection of applicable detection techniques. We can expect further development of microextraction analytical methods that focus on direct sample analysis with the application of green extraction solvents while fully automating procedures for the analysis of plant materials.

Use of sequential injection analysis with lab-at-valve and an optical probe for simultaneous spectrophotometric determination of ascorbic acid and cysteine by mean centering of ratio kinetic profiles.

Two new, simple, relatively fast and robust methods for the simultaneous kinetic determination of binary mixtures of ascorbic acid (Asc) and cysteine (Cys) were developed using the mean centering of ratio kinetic profiles method. The methods are based on the difference in the reaction rates of Asc and Cys with 18-molybdodiphosphate at pH 5.1. An optical probe as well as the sequential injection analysis lab-at-valve (SIA-LAV) method were used to carry out simultaneous kinetic analysis. The benefits of the mean centering of ratio kinetic profiles method were shown in comparison with other spectrophotometric kinetic methods. Asc and Cys can be determined in the concentration ranges 20-200 and 8-90 µmol L-1 with the batch spectrophotometric method and 10-200 and 4-40 µmol L-1 with the SI-LAV method, respectively. The method was successfully used to determine Asc and Cys in dietary supplements.

Simultaneous determination of rutin and ascorbic acid in a sequential injection lab-at-valve system.

A green, simple, accurate and highly sensitive sequential injection lab-at-valve procedure has been developed for the simultaneous determination of ascorbic acid (Asc) and rutin using 18-molybdo-2-phosphate Wells-Dawson heteropoly anion (18-MPA). The method is based on the dependence of the reaction rate between 18-MPA and reducing agents on the solution pH. Only Asc is capable of interacting with 18-MPA at pH 4.7, while at pH 7.4 the reaction with both Asc and rutin proceeds simultaneously. In order to improve the precision and sensitivity of the analysis, to minimize reagent consumption and to remove the Schlieren effect, the manifold for the sequential injection analysis was supplemented with external reaction chamber, and the reaction mixture was segmented. By the reduction of 18-MPA with reducing agents one- and two-electron heteropoly blues are formed. The fraction of one-electron heteropoly blue increases at low concentrations of the reducer. Measurement of the absorbance at a wavelength corresponding to the isobestic point allows strictly linear calibration graphs to be obtained. The calibration curves were linear in the concentration ranges of 0.3-24mgL-1 and 0.2-14mgL-1 with detection limits of 0.13mgL-1 and 0.09mgL-1 for rutin and Asc, respectively. The determination of rutin was possible in the presence of up to a 20-fold molar excess of Asc. The method was applied to the determination of Asc and rutin in ascorutin tablets with acceptable accuracy and precision (1-2%).

Use of Innovative (Micro)Extraction Techniques to Characterise Harpagophytum procumbens Root and its Commercial Food Supplements.

INTRODUCTION: For the determination of harpagoside and the wide phenolic pattern in Harpagophytum procumbens root and its commercial food supplements, dispersive liquid-liquid microextraction (DLLME), ultrasound-assisted DLLME (UA-DLLME), and sugaring-out liquid-liquid extraction (SULLE) were tested and compared. OBJECTIVES: In order to optimise the extraction efficiency, DLLME and UA-DLLME were performed in different solvents (water and aqueous solutions of glucose, ß-cyclodextrin, (2-hydroxypropyl)-ß-cyclodextrin, sodium chloride, natural deep eutectic solvent, and ionic liquid). MATERIAL AND METHODS: The plant material was ground and sieved to obtain a uniform granulometry before extraction. Commercial food supplements, containing H. procumbens are commercially available in Italy. RESULTS: The most effective sodium chloride-aided-DLLME was then optimised and applied for analyses followed by HPLC-PDA. For comparison, microwave-assisted extraction was performed using the same solvents and the best results were obtained using 1% of ß-cyclodextrin or 15% of sodium chloride. CONCLUSION: All commercial samples respected the European Pharmacopoeia monograph for this plant material, showing a harpagoside content ≥ 1.2%. Copyright © 2017 John Wiley & Sons, Ltd.