Direct Solvent Extraction Research Articles

Gas Chromatography-Mass Spectrometry-Based Analyses of Fecal Short-Chain Fatty Acids (SCFAs): A Summary Review and Own Experience.

The gut microbiome, crucial to human health, changes with age and disease, and influences metabolic profiles. Gut bacteria produce short-chain fatty acids (SCFAs), essential for maintaining homeostasis and modulating inflammation. Dysbiosis, commonly due to poor diet or lifestyle, disrupts the integrity of the intestinal barrier and may contribute to conditions such as obesity, diabetes, and non-alcoholic fatty liver disease (NAFLD). Analytical methods such as gas chromatography-mass spectrometry (GC/MS) are vital for SCFA analysis, with various preparation and storage techniques improving the accuracy. Advances in these methods have improved the reliability and sensitivity of SCFA quantification, which is crucial for the identification of disease biomarkers. Evidence from GC/MS-based studies has revealed that accurate SCFA quantification requires meticulous sample preparation and handling. The process begins with the extraction of SCFAs from biological samples using methods such as direct solvent extraction or solid-phase microextraction (SPME), both of which require optimization for maximum recovery. Derivatization, which chemically modifies SCFAs to enhance volatility and detectability, is a crucial step, typically involving esterification or silylation. Following this, the cleanup process removes impurities that might interfere with the analysis. Although recent advances in GC/MS technology have significantly improved SCFA-detection sensitivity and specificity, proper sample storage, with acid preservatives and the avoidance of repeated thawing, is essential for maintaining SCFA integrity.

Development of a conceptual direct solvent extraction (DSX) route and a flowsheet to produce purified concentrated cobalt and nickel solutions representing sulfuric acid leach liquor of laterite

Direct solvent extraction (DSX) was applied to produce purified concentrated Ni and Co solutions from a synthetic sulfuric liquor containing Ca, Cu, Mg, Mn, and Zn as impurities, which simulates the solution obtained by the sulfation-roasting-leaching process after precipitation of Fe, Al, and Cr. The commercial extractants Versatic 10, Cyanex 272, D2EHPA, TBP were used in 3 solvent extraction circuits. In the first circuit, operated at 40 °C, Versatic 10 (0.5 M) fully extracted Cu, Zn, Ni, and Co in 3 stages at O/A = 2:1, and pH 6.5, leaving remaining Mn (54% was extracted) and most of the Ca and Mg in the raffinate. The co-extracted Ca and Mg were fully scrubbed off the loaded Versatic 10 in 2 stages at O/A = 5:1, and pH 6.5. The other metals were stripped out of the Versatic 10 extract using a synthetic Ni spent electrolyte (60 g/L Ni, 2 M H2SO4) in 2 stages at O/A = 9:1. This loaded strip liquor was subjected to a second circuit with Cyanex 272 (0.64 M) operated at 50 °C. Three stages were required to fully extract Co, Cu, Mn, and Zn (O/A = 2:1, pH 4), whereas the raffinate containing 82 g/L Ni was deemed suitable for electrowinning. The co-extracted Ni(II) was fully scrubbed off the loaded Cyanex 272 in only 1 stage at O/A = 5:1, and pH 4. All Co, Cu, Mn, and Zn were stripped out from the scrubbed loaded Cyanex 272 in 2 stages at O/A = 10:1 using a synthetic Co spent electrolyte (45 g/L Co, 1 M H2SO4). The raffinate containing 58.4 g/L Co was submitted to a third circuit using a D2EHPA (0.6 M) + TBP (0.73 M) synergistic system operated at 50 °C. Zinc(II) was fully extracted by the D2EHPA + TBP system in 2 stages at pH 2 and O/A = 1:3, while Mn(II) and Cu(II) were fully extracted from the Zn-depleted raffinate in 2 stages at pH 3.5 and O/A = 2:1. The raffinate containing 58.3 g/L Co was deemed suitable for electrowinning. Copper(II), Mn(II), and Zn(II) were stripped out from the loaded D2EHPA + TBP in 3 stages at O/A = 2.5:1 using 1 M H2SO4. The real number of moles of extractants involved in the extractions and apparent equilibrium constants were estimated for all circuits. A flowsheet of the purification conceptual route is presented.

Single Cell Analysis of Proteoforms.

We introduce single cell Proteoform imaging Mass Spectrometry (scPiMS), which realizes the benefit of direct solvent extraction and MS detection of intact proteins from single cells dropcast onto glass slides. Sampling and detection of whole proteoforms by individual ion mass spectrometry enable a scalable approach to single cell proteomics. This new scPiMS platform addresses the throughput bottleneck in single cell proteomics and boosts the cell processing rate by several fold while accessing protein composition with higher coverage.

Degradation of cathode in air and its influences on direct recycling

Delamination has been widely used in direct recycling of spent lithium-ion batteries (LIBs) as the first step to harvest cathode materials from cathodes. The variations of the recycling performance have been documented in many studies. The main mechanism of delamination is the inactivation of bonding forces provided by the polyvinylidene fluoride (PVDF) binder. It is believed that the storage environment (air exposure time) will affect the performances of delamination to some extent. Three representative methods (direct calcination, pressure washing, and NMP solvent extraction) for delamination were studied to elucidate the effect of air exposure time on delamination efficiency. The peel-off efficiency (98–99%) of the direct calcination method was barely influenced by air exposure time. The pressure washing system or NMP solvent extraction method also exhibited high peel-off efficiency using samples after a long air exposure time (1 month), however these methods may have problems regarding Al contamination, i.e., 11.5 mg/g of pressure washing system and 134.4 mg/g of NMP solvent extraction. Results suggest that enhanced adhesion (0.11 MPa/month) could be a potential reason why air contact time affects delamination, with O2 and/or H2O acting as contributors. This finding may help to maximum performance of delamination, as it highlights the importance of storage conditions of the spent LIBs prior to direct recycling.

Characterization of the key odorants in fresh Amomum tsao-ko Crevost et Lemaire fruit by gas chromatography-olfactometry, quantitative analysis and aroma reconstitution

To decode key odorants (KOs) in fresh Amomum tsao-ko Crevost et Lemaire fruit (FAF) and investigate the effect of isolation methods on KOs and enantiomer ratios, volatiles were isolated using both direct solvent extraction combined with solvent-assisted flavor evaporation (DSE-SAFE) and hydrodistillation (HD) and analyzed by gas chromatography‒mass spectrometry/olfactometry. In total, 55 odor-active compounds with flavor dilution factors between 1 and 8192 were identified, of which 36 and 39 odorants were detected in the SAFE and HD isolates, respectively. By quantitative analysis and odor activity value calculation, 22 odorants in the SAFE isolate and 25 odorants in the HD isolate were determined to be FAF KOs. The differences in the concentrations and the number of KOs caused the two isolates to have different odor characteristics. The recombination experiment further confirmed the results. Among the three studied chiral odorants, including linalool, 4-terpenol, and α-terpineol, the (S)-(−)-enantiomer was dominant, and the (S)-(−)-enantiomer inverted into the (R)-(−)-enantiomer during HD.

МИРОВЫЕ ТЕНДЕНЦИИ РАЗВИТИЯ ТЕХНОЛОГИЙ ГИДРОМЕТАЛЛУРГИЧЕСКОЙ ПЕРЕРАБОТКИ НИКЕЛЕВЫХ РУД НА ДЕЙСТВУЮЩИХ ПРЕДПРИЯТИЯХ

The paper provides a critical analysis of sources, a generalization of factual and theoretical material on the main hydromet-allurgical technologies for processing nickel ores. It has been established that the use of autoclave leaching of ores is the most common method of processing. This process takes place mainly in capacitive reactors with a stirrer. It was found that, depending on the type of ore, there are two main ways to carry out autoclave leaching: acid leaching under high pressure and the Caron process (ammonia leaching during roasting). The review shows that sulfuric acid leaching is predominantly used in Cuba and Western Australia, as well as in Finland, South Africa and Canada. Nitric acid leaching is being used in pilot plants in Australia at the CSIRO facility. Chlorine leaching is used in Japan, Norway, France and Canada. Ammonia processes have been implemented in Cuba, the Czech Republic and Australia, as well as in Brazil, Canada and the Philippines, India and Gag Island in Indonesia. The article presents the latest achievements in the field of extraction of nickel and cobalt from productive solutions, as well as the advantages and disadvantages of existing schemes at operating enterprises in the world. Having analyzed the main technologies for processing nickel ore, we can say that traditionally Ni and Co are extracted from productive solutions after leaching in one of three ways: 1. Precipitation of mixed nickel and cobalt sulfide; 2. Precipitation of mixed nickel and cobalt hydroxide; 3. Direct solvent extraction. The analysis showed that the most optimal and least time-consuming process, providing a relatively high degree of extraction of target metals, is extraction. Impurity removal is most expediently carried out by precipitation, however, the loss of nickel and cobalt should be taken into account.

A Rapid Procedure for the Simultaneous Determination of Eugenol, Linalool and Fatty Acid Composition in Basil Leaves.

Eugenol and linalool are often the most abundant volatile compounds found in basil (Ocimum basilicum L., Lamiaceae) leaves, and they are interesting for the aroma they provide and for their numerous beneficial bioactivities. Their determination is thus needed for several purposes. In the present study, to avoid the previous isolation of essential oil, the direct solvent extraction is proposed coupled with a transmethylation to convert acyl lipids into fatty acids methyl esters (FAMEs), thus assessing the possible simultaneous analysis of eugenol and linalool with FAMEs by gas chromatography coupled to flame ionization detector (GC-FID). The method has been validated and applied to ten basil leaves samples in which eugenol and linalool were found in mean concentrations of 2.80 ± 0.15 and 1.01 ± 0.04 g kg-1 (dry weight), respectively. FAMEs composition was dominated by linolenic acid (52.1-56.1%) followed by palmitic acid (19.3-22.4%) and linoleic acid (9.6-11.3%). The ratio of n6-polyunsaturated fatty acids (PUFAs)/n3-PUFAs was in the range of 0.17-0.20 in the investigated samples. The proposed method exploits a rapid procedure requiring 40 min, making use of a small amount of solvent and allowing the simultaneous determination of molecules contributing to assess the quality of this worldwide appreciated herb.

A simple method for analysis of vitamin A palmitate in fortified cereal products using direct solvent extraction followed by reversed-phase HPLC with UV detection

Vitamin A is generally analysed using a time-consuming and possibly detrimental saponification step, followed by extraction and HPLC analysis. We here developed a new method to analyse retinyl palmitate (RP) (also known as vitamin A palmitate) without the need for saponification and validated it in model systems consisting of RP, soy oil and wheat bran, and in RP-fortified cereal products. Two direct solvent extraction protocols using acetone/methanol (7/3, v/v) or chloroform/methanol (1/1, v/v) were tested. After extraction, RP was quantified by reversed-phase HPLC with UV detection. The HPLC method had low limits of detection (0.01 µg/mL) and quantification (0.03 µg/mL). Both extraction protocols showed a good recovery (88–105 %) and intra-and inter-day precision (<5%) for RP extraction from the model systems. The obtained results corresponded to results obtained using a golden standard approach. For complex food matrices like bread and cookies, the chloroform/methanol extraction protocol showed the best performance characteristics.

Determination of three oryzanols in rice by mixed-mode solid-phase extraction coupled with high performance liquid chromatography-tandem mass spectrometry

建立了利用高效液相色谱-串联质谱结合混合型阴离子交换固相萃取柱测定稻米中3种谷维素(环木菠萝烯醇阿魏酸酯(CA-FA)、24-亚甲基环木菠萝烯醇阿魏酸酯(24MCA-FA)和菜油甾醇阿魏酸酯(Camp-FA))含量的分析方法。实验通过优化3种谷维素的多反应监测(MRM)质谱参数,比较了在不同流动相中的分离度以及响应强度,同时考察了不同提取条件、净化条件对3种谷维素提取率和净化效果的影响,再结合外标法定量,实现了对稻米中3种谷维素的定量分析。实验结果表明,采用5 mmol/L乙酸铵水溶液为流动相A,甲醇∶乙腈=1∶1(v/v)为流动相B,梯度洗脱,3种谷维素在Agilent Eclipse XDB-C8色谱柱(150 mm×2.1 mm, 3.5 μm)上基本分离且响应强度和峰形最佳;提取条件经正交实验优化后可得:料液比为1∶20(g/mL)、提取溶剂为甲醇、浸泡时间为12 h、超声温度为40 ℃以及超声时间为20 min时,3种谷维素提取率最高;对混合型阴离子交换固相萃取柱的上样溶剂以及洗脱溶剂优化后,样品基质效应为1.6%~10.8%。在各优化条件下,3种谷维素在各自的线性范围内线性良好,相关系数(r2)均≥0.9983,检出限(LOD)为0.5~1.0 μg/L,定量限(LOQ)为2.0~3.5 μg/L。在稻米样品本底浓度2、5和10倍的加标水平下3种谷维素的平均回收率为86.1%~110.6%,相对标准偏差(RSD)为0.9%~3.2%。该方法可快速准确测定稻米中3种谷维素的含量,为后续稻米中谷维素类化合物测定及鉴定奠定基础。

Effect of pre-concentration on membrane solvent extraction process for the recovery of rare earth elements from dilute acidic leachate

Pre-concentration and separation processes of Rare Earth Elements (REEs) were investigated in terms of several factors. Nitric acid leachate of e-waste was first pre-treated by increasing pH and filtering through microfiltration. For pre-concentration, pre-treated leachate was concentrated by nanofiltration. While a 70% permeate recovery ratio was kept constant, the rare earth elements concentrations were triplicated under optimum conditions. A flat sheet supported liquid membrane process with a polyvinylidene fluoride (PVDF) support membrane was successfully used to extract REEs from the pre-treated leachate. Of the two extractants evaluated, bis-2-ethylhexyl phosphoric acid (D2EHPA) displayed a higher REE separation efficiency than did di-2,4,4,-trimethylpentyl phosphinic acid (Cyanex 272). However, Cyanex 272 separated Sc more selectively. For direct membrane solvent extraction (MSX) and MSX with pre-concentration, pre-treatment pH and D2EHPA concentrations were optimized at values of 1.5% and 15%, respectively. When comparing the results of MSX for direct and pre-concentrated configurations, it was seen that REEs and HREEs recoveries were increased 10% and 30% in MSX with pre-concentration at the end of single-stage MSX. Pre-concentration not only increased the MSX process efficiency but also enabled acid recovery from nanofiltration permeate. A more environmentally friendly and economical process scheme was proposed, including acid recovery from both NF filtrate and post-MSX leaching residue by two different membrane distillation configurations.

Effect of optimal-water boiling cooking on the volatile compounds in 26 Japonica rice varieties from China

The aim of this study was to scientifically investigate the impact of optimal-water boiling cooking on the volatile profile of 26 japonica rice varieties. A modified direct solvent extraction combined with gas chromatography-mass spectrometry was applied to analyze the volatiles in raw and cooked samples. 2-Acetyl-1-pyrroline (2AP) was only detected in aromatic varieties and decreased after cooking (-81.94% – −43.97%). Great losses of esters and long-chain ketones were exhibited after cooking. Cooking accelerated lipid oxidation and degradation of phenolic acids, thus volatiles originate from lipid oxidation and several benzenoid compounds showed increase trends in majority of the samples. Increases of 3 saturated aldehydes including hexanal (48.01% – 306.02%), octanal and nonanal (67.03% – 544.15%) could be observed in all samples. Acetophenone, 2-methoxy-4-vinylphenol (11.95% – 297.61%) and vanillin (14.29% – 319.25%) were also enhanced upon cooking. Correlations existed in volatiles with common precursors or involved in same pathways. According to multivariate and univariate statistical analysis, 18 volatiles most greatly influenced by cooking were selected. This study will facilitate the aroma improvement of cooked rice in the future.

Quantitation of propionic acid in emmental cheese products by direct solvent extraction.

Propionic acid (PA) is commonly present in Emmental cheese (EM) with relatively high concentration. Even though PA is allowed as GRAS in the USA, it may cause neurological disorders if it is consumed excessively. The maximum level of the preservative PA in cheese is set at 3.0g/kg by the Korean Food Code. Also, the minimum level of PA in EM (150mg / 100g) was set by Codex in 1967. Therefore, PA monitoring in EM, with relatively high level of intrinsic PA, is necessary to recommend the sound use of the PA in the EM ripened. The current official PA analysis method consisting of steam distillation and solvent extraction / evaporation, is too cumbersome to be handled in sample preparation process. In this study, acidic acetone-based direct extraction method was successfully applied to 12 EM samples for the determination of PA level.

Optimization of solvent extraction and HPLC-DAD method parameters for determination of phenolic compounds in various Brazilian propolis

Propolis is an organotherapeutic product collected by honey bees that contains a large number of phytoconstituents, possessing excellent pharmacological properties. In this study, phenolic composition and antioxidant capacity were evaluated in different types of Brown, Green and mixture of Red, Green I and Brown II (RGB) Brazilian propolis. Ultrasonic-assisted extraction was performed by direct solvent extraction (DSE) and successive solvent extraction (SSE) methods. The ethanolic extract of Green I propolis by SSE was higher in total phenolics (403.88 mg GAE/g extract), flavonoids (311.57 mg QE/g extract), and DPPH· scavenging activity (82.33 µMol TE/g extract) compared to other Brazilian propolis samples. Moreover, different solvent phases were used in the HPLC-DAD analysis and the results were validated by linearity and sensitivity. The optimized method was proven to be precise revealing good separation of standard phenolic compounds. Thermal stability of the compounds was accessed by using different column oven temperatures (40, 50 and 60 °C), and the results showed that lower temperature (40° C) retains the maximum contents of total phenolics in the 80% ethanolic extract of Green I propolis (253.71 mg/g extract) by DSE compared to other propolis samples. This extract (109.35 mg/g extract) also obtained a higher amount of total phenolic compounds in the SSE compared to ethyl acetate and acetone extracts. Among the phenolic compounds, artepillin C (60.10 mg/g extract) was higher in the SSE of Green I propolis 80% ethanolic extract. Thus, this study optimized the extraction and HPLC analytical conditions for the determination of phenolic composition and antioxidant capacity in different samples of Brazilian propolis.

Hydrogel patch from liquid smoke and vitamin K Collard Greens extract for wound healing applications

Wound care by using wound dressing has been evolved available in various physical forms including hydrogels with the highest global use reaching 43%. Nowadays, hydrogels are available at high cost because produced from synthetic materials, so natural materials are needed to obtain antibacterial wound dressing. This study aims to analyze the hydrogel patch PVA/chitosan/starch infused liquid smoke and vitamin K collard greens extract which are antibacterial effects and accelerates wound healing. This study was a laboratory experiment. Collard greens were extracted by using the Direct Solvent Extraction II method. The membrane characteristic tested using SEM test. The parallel streak method (AATCC 147-2004) was used for antibacterial testing. The hydrogel patch application was carried out on 28 male Rattus norvegicus strain wistar rats. They were given incisions wound and treated by a control group and 3 treatment groups and conducted wound healing analysis on the 4th,7th,11th and 14th day observation. The antibacterial test showed the hydrogel patch infused liquid smoke with a concentration of 12% was the optimum concentration inhibiting S. aureus. In conclusion, the hydrogel patch has a smooth and porous surface, can be inhibited the growth of S. aureus, and proven to completely heal the animal wound.

Antioxidant Activity of Vitamin E Concentrate from Magnesium Salts of Palm Fatty Acid Distillate (Mg-PFAD)

Vitamin E concentrate was produced through saponification of palm fatty acid distillates (PFAD) and magnesium oxide to form Mg-PFAD, followed by three-stages vitamin E extraction with isopropanol, hexane, or ethanol. The vitamin E-rich extracts were evaporated to remove solvent and produced vitamin E concentrate. The objectives of this research were to investigate the effect of organic solvent’s types and solvent to Mg-PFAD mass ratios on vitamin E concentration, solvent selectivity, and antioxidant activity of the vitamin E concentrate. Vitamin E concentrates obtained after isopropanol extraction had vitamin E concentration of 784 ppm with vitamin E recovery of 16 mg tocopherol/100 mg tocopherol in Mg-PFAD, while vitamin E concentrates obtained after hexane extraction had vitamin E concentration of 574 ppm with vitamin E recovery of 35 mg tocopherol/100 mg tocopherol in Mg-PFAD. Isopropanol extraction produced vitamin E concentrate with the highest selectivity for vitamin E and the highest antioxidant activity of 79% IC. It was found that vitamin E concentration was not proportional to the antioxidant activity of the vitamin E concentrate.Keywords: Direct solvent extraction, palm fatty acid distillate, saponification, vitamin E, unsaponifiable matter

Recovery of lithium from leach solutions of battery waste using direct solvent extraction with TBP and FeCl3

Although societal interest in lithium has grown due to its increased demand for manufacturing of lithium ion batteries (LIBs), recent research studies about LIB recycling with solvent extraction did not focus on Li recovery and Li remained in the raffinate contaminated with impurities. In this research presented direct Li recovery from LIB waste leachate prior to Ni and Co is a novel and promising approach.The applied SX system (tributyl phosphate (TBP) as extractant and iron(III) chloride (FeCl3) as co-extractant in kerosene) is known from Li separation from natural brines. Batch equilibrium experiments at room temperature were conducted with preloaded organic phase (NaCl and FeCl3, TBP (80% (v/v)) and kerosene (20% (v/v)) and synthetic aqueous LIB waste leachate solution (1.3–1.5 g L−1 Al, 14.2–17.8 g L−1 Co, 1.9–2.2 g L−1 Cu, 0.7–0.8 g L−1 Fe, 2.4–2.7 g L−1 Li, 1.9–2.1 g L−1 Mn, 1.8–2.0 g L−1 Ni, E = 603 mV Ag/AgCl). Loading with emphasis on the competitive extraction between Li and H+, substitution of MgCl2 as chloride source and variation of the phase ratios as well as scrubbing and stripping are investigated in this research.Lithium was selectively separated over divalent LIB metals (Mn, Cu, Co, Ni) and Al(III) from a multicomponent mixture, and the extraction ability of the system is H+ > Li+ > > LIB metals. Aiming for maximum Li extraction initial concentration of H+ was chosen to be 0.1 M. Substitution of MgCl2, used in the brine systems, by AlCl3 as chloride source promoted Li extraction (E(Li) = 87.7% for R(O/A) = 1) due to its strong salting out effect. This resulted in enhanced separation factors (β(Ni) = 2825 and β(Co) = 854 for R(O/A) = 1). Loaded organic phase was purified using 1 M LiCl +2 M AlCl3 scrubbing solution prior stripping. Stripping with 6 M HCl in single-stage at R(O/A) = 5 resulted in stripping liquor containing 12.26 g L−1, 0.02 g L−1, 0.04 g L−1, and 0.04 g L−1 of Li, Mn, Co and Cu, respectively.

An Insight by Molecular Sensory Science Approaches to Contributions and Variations of the Key Odorants in Shiitake Mushrooms

An insight using molecular sensory science approaches to the contributions and variations of the key odorants in shiitake mushrooms is revealed in this study. Odorants were extracted by headspace solid phase microextraction (HS-SPME) and direct solvent extraction combined with solvent-assisted flavor evaporation (DSE-SAFE) in fresh and hot-air-dried shiitake mushrooms. Among them, 18 and 22 predominant odorants were determined by detection frequency analysis (DFA) and aroma extract dilution analysis (AEDA) combined with gas chromatography-olfactometry (GC-O) in the fresh and dried samples, respectively. The contributions of these predominant odorants in the food matrix were determined by quantification and odor activity values (OAVs) with aroma recombination verification. There were 13 and 14 odorants identified as key contributing odorants to overall aroma, respectively. 1-Octen-3-ol and 1-octen-3-one were the most key contributing odorants in the fresh samples in contributing mushroom-like odor. After hot-air-drying, the OAV and concentrations on dry basis of the key contributing odorants changed, due to oxidation, degradation, caramelization and Maillard reactions of fatty acids, polysaccharides and amino acids. 1-Octen-3-ol was reduced most significantly and degraded to 1-hydroxy-3-octanone, while phenylethyl alcohol increased the most and was formed by phenylalanine. In hot-air-dried samples, lenthionine became the most important contributor and samples were characterized by a sulfury odor. Overall contributions and variations of odorants to the aroma of shiitake mushrooms were revealed at the molecular level.

Effects of Ultrasound-Assisted and Direct Solvent Extraction Methods on the Antioxidant and Antibacterial Properties of Saffron (Crocus sativus L.) Corm Extract

In this study, the response surface methodology (RSM) based on a central composite face-centered design (CCD) was used to optimize the extraction of bioactive constituents from Crocus sativus corms. The ultrasound-assisted extraction (UAE) was compared with the conventional direct solvent extraction (DSE) procedure. The optimum conditions of ethanol (80%), 48 °C and 60 min in DSE, and ethanol (80%), 37 °C, 45 min, and 37 kHz in UAE, were determined to receive extracts with maximum antioxidant activity and total phenolic content (TPC). The results showed TPC values of 89.28 and 100.39 (mg gallic acid equivalents in 100 g dry saffron corm) and total flavonoid contents (TFC) of 0.912 and 1.558 (mg quercetin equivalents in100 g dried saffron corm) for the optimized DSE and UAE extracts, respectively. The GC-MS analysis showed n-hexadecanoic acid as one of the main non-polar constituents in the saffron corm extract (39.315% and 19.015% in DSE and UAE extracts, respectively). The disc diffusion tests revealed a degree of activity of saffron corm extracts against Staphylococcus aureus at a minimum concentration of 300 mg/mL.

Ultrasound-microwave assisted extraction of flavonoid compounds from Eucommia ulmoides leaves and an evaluation of their antioxidant and antibacterial activities

Ultrasound/microwave assisted extraction (UMAE) of flavonoid compounds from Eucommia ulmoides leaves was studied and the extraction conditions were optimized by the Plackett-Burman design (PBD) method combined with the Box-Behnken design (BBD). The antioxidant and antibacterial activities of the flavonoid extract were investigated. The results show that the optimal conditions were an ethanol concentration of 41%, microwave power of 178 W and an ultrasound extraction time of 26 min. Under these conditions, the yield of the flavonoid compounds was 2.454%?0.230%, which was higher than that after direct solvent extraction, ultrasound extraction and microwave extraction. The results of in vitro antioxidant assays showed that the flavonoid extract had scavenging capacity for DPPH, ABTS and hydroxyl radicals, with corresponding IC50 values of 30.76 mg/L, 21.09 mg/L, 248.4 mg/L, respectively. In addition, this extract exhibited strong antibacterial activity on Escherichia coli, Staphylococcus aureus and Salmonella typhimurium.

Extraction and quantitative analysis of water, sediment, soil and biosolids for trace-level trimethylsilanol

ABSTRACTMethylsilanols such as trimethylsilanol (TMS) are considered as the major hydrolytic degradation products of methylsiloxanes, a class of anthropogenic organometallic substances with a wide range of applications. The distribution of these silanols in various environmental compartments, therefore, could provide direct information on silanols’ chemical fate and environmental exposure. Existing methods for the quantification of the silanols are not sensitive and robust enough for analyzing environmental media where trace- and ultra-trace-level concentrations may be expected. In the present study, solid-phase extraction (SPE) and solvent extraction in combination with gas chromatography-mass spectrometry (GC/MS) were tested for analyzing water, sediment, soil and biosolids samples for TMS. ISOLUTE® ENV+ solid-phase sorbent was found to be most suitable for extraction of water samples for ultra-trace TMS, while direct solvent extraction worked for solids samples such as soil, sediment and biosolids. Coupling with an isotopic internal standard and SPE extraction, direct GC/MS analysis without derivatization can reach a method detection limit for TMS as low as 0.10 µg L−1 in water. The detection limits for solid samples varied from 0.21 ng g−1 ww (wet weights) to 10 ng g−1 ww, mostly limited by background concentrations of TMS in extraction solvents. It was also observed that prolonged sample storage may lead to a reduction in TMS concentrations, regardless of the concentrations of coexisting methylsiloxanes.