Determination of metallic nanoparticles in soils by means spICP-MS after a microwave-assisted extraction treatment

Current sample preparation strategies for nanomaterials (NMs) analysis in soils by means single particle inductively coupled plasma mass spectrometry have significant constrains in terms of accuracy, sample throughput and applicability (i.e., type of NMs and soils). In this work, strengths and weakness of microwave assisted extraction (MAE) for NMs characterization in soils were systematically investigated. To this end, different extractants were tested (ultrapure water; NaOH, NH4OH, sodium citrate and tetrasodium pyrophosphate) and MAE operating conditions were optimized by means of design of experiments. Next, the developed method was applied to different type of metallic(oid) nanoparticles (Se-, Ag-, Pt- and AuNPs) and soils (alkaline, acid, sandy, clayey, SL36, loam ERMCC141; sludge amended ERM483). Results show that Pt- and AuNPs are preserved and quantitatively extracted from soils in 6 min (12 cycles of 30 s each) inside an 800 W oven by using 20 mL of 0.1 M NaOH solution. This methodology is applicable to soils showing a wide range of physicochemical properties except for clay rich samples. If clay soil fraction is significant (>15%), NMs are efficiently retained in the soil thus giving rise to poor recoveries (<10%). The analysis of labile NMs such as Se- and AgNPs is not feasible by means this approach since extraction conditions favors dissolution. Finally, when compared to current extraction methodologies (e.g., ultrasound, cloud point extraction, etc.), MAE affords better or equivalent accuracies and precision as well as higher sample throughput due to treatment speed and the possibility to work with several samples simultaneously.

LC-ESI-MS/MS analysis of phenolic compounds and in vitro cytotoxicity and apoptosis-inducing effects of Nonea pulmonarioides extracts

The chemical composition of Nonea pulmonarioides extracts were investigated for the first time. The phytoconstituents of the methanol extracts were screened by using LC/MS-MS technique. The anticancer activity of the acetone and methanol extracts were measured against four cancer cell lines; MCF-7, PC3, HT-29, and U-87 MG. Thirty phenolic compounds were identified, rosmarinic (90.06 mg analyte/g extract) and fumaric acids (39.737 mg analyte/g extract) were major compounds of the studied species. Moreover, both methanol and acetone extracts were found to have strong anticancer activities. The acetone extract HT-29 (with IC50 of 10.17 ± 0.25 µg/mL) compared with standard cis-platin (with IC50 of 22.20 ± 0.72 µg/mL) with apoptotic mediated programmed cell death. These findings identified N. pulmonarioides as a potential species exhibiting anticancer properties. In conclusion, the compelling results show that the methanol extract contains possible bioactive compounds with anticancer properties that require isolation and further characterisation.

Process optimisation of defatted wheat germ protein extraction in a novel alkaline-based deep eutectic solvent (DES) via Box-Behnken experimental design (BBD)

This is the first study to provide a preliminary investigation into the recovery of protein from wheat germ and the prediction of their extraction conditions in microwave cavity using a novel DES solvent. The response surface methodology was used to predict the microwaved protein extraction conditions of the DWG. The effects of DES buffer-concentration (X₁: 0.01-1.00 g/mL), microwave power (X₂: 50-250 W), irradiation time (X₃: 1-5 min) and sample-to-buffer ratio (X₄: 1:10-1:50) were tested using a single factor and Box-Behnken experimental design. Under the optimized conditions (X₁ = 0.52 g/mL, X₂ = 186 W, X₃ = 3.28 min, and X₄ = 1:39) protein yield and absorbed microwave were obtained at the optimal value of 33.00 % and 677 J/min, respectively with no denaturation of the protein as validated from the SDS-PAGE gel electrophoresis profile. Consequently, this investigation provides a practical approach for the extraction of bioactive protein from DWG using a novel deep eutectic solvent.

Environmentally friendly dyeing of wool and silk fabrics with natural colorant of turnsole (Chrozophora tinctoria L.)

With the increasing demand for environmentally friendly dyes, natural dye has become an attractive option replacing toxic synthetic dyes. Within the framework of this research, the natural dye of Chrozophora tinctoria L. was extracted using the microwave-assisted extraction method under different operating conditions. The influence of different factors influencing the extraction process (such as pH, extraction time, and microwave power) on the extraction efficiency was investigated by means of a multilevel three-factor design. The suggested model has a high coefficient of determination, indicating high predictability and good approximation. Optimal microwave extraction process conditions were obtained at a value of microwave power equal to 650 W, at a pH of 5 during a period of 3 min. Dyed wool and silk fabrics showed very good washing and light fastness properties.

Development of a microwave-based extraction for forensic biological samples

In this study, a quick microwave-based treatment was developed as a front end for DNA analysis of forensic samples. The effect of microwave treatment is to cause cell disruption which can improve the release of DNA during direct PCR as well as with extraction methods. Exposure to microwave preprocessing improved the quality of rapid genotyping, particularly when used with low level samples. Optimal results were obtained when samples were microwaved at 300W for 40 s, resulting in improved allele detection. Overall, the addition of this simple preprocessing step improves sensitivity and allele recovery for low level DNA samples when combined with expedited DNA analysis workflows. Its main advantages include speed, low cost, compatibility with downstream DNA methods and application to a wide variety of samples.

Water-induced release of recalcitrant polycyclic aromatic hydrocarbons from soil organic matter during microwave-assisted solvent extraction

Polycyclic aromatic hydrocarbons (PAHs) in soil can be recalcitrant to solvent extraction after aging. We showed in this study that mixing a small amount of water in the extracting solvent during microwave-assisted extraction (MAE) can release recalcitrant PAHs, resulting in significant improvement in the analyzed concentrations. The improvement factor (F) for the total of 16 priority PAHs (∑PAH16) listed by the United States Environmental Protection Agency was 1.44-1.55 for field soils. By comparing the F values for different soil organic components, we demonstrated that the recalcitrant PAHs were primarily associated with biochar, humic acid (HA), and humin (HM), with the F values for ∑PAH16 of 1.94, 6.62, and 4.59, respectively. The results showed that the recalcitrant PAHs comprised a sequestered fraction and a desorption-limited fraction. NMR spectra showed that water worked alone at elevated temperature to promote hydrolysis of biochar and destroy the macromolecular structure, thus causing the release of the otherwise sequestered PAHs during MAE. The substantial reduction in F values for HA and HM after demineralization indicated sequestration of PAHs in organic-mineral complexes, which can be destroyed by hot water treatment. The release of the sequestered fraction was nonselective and independent of compound hydrophobicity. In comparison, the release of the desorption-limited fraction was positively affected by the hydrophobicity of PAHs and was facilitated by the presence of water in the extracting solvent. The results of this study provide important insights into the sequestration and release of recalcitrant PAHs in soil.

Novel extraction of polyphenols from sour cherry pomace using natural deep eutectic solvents - Ultrafast microwave-assisted NADES preparation and extraction

In this work, new approaches for the green extraction of polyphenols from sour cherry pomace were explored. Three Natural Deep Eutectic Solvents (NADES) systems based on choline chloride (ChCl) as a hydrogen bond acceptor (HBA) and malic acid, urea, and fructose (MalA, Ur, and Fru) as hydrogen bond donors (HBD) were used. NADES systems were prepared by heating and stirring (H&S), ultrasound (US), and microwave (MW) methods. It was found that MW-assisted preparation was the fastest requiring less than 30 s. Polyphenol extraction from cherry pomace was performed also by three mentioned methods, and compared with conventional methods. MW extraction was the most rapid with less than 5 min necessary for the extract preparation. All three NADES systems were highly efficient for anthocyanin extraction, but the most efficient was ChCl:MalA system. Extract based on ChCl:MalA system was for 62.33% more efficient for anthocyanin extraction comparing with the conventional solvent.

Optimized microwave-assisted extraction of bioflavonoids from Albizia myriophylla bark using response surface methodology

Bioflavonoids are of great interest due to their health-benefitting properties and possible protection against certain types of diseases. A microwave-assisted extraction (MAE) method was investigated for maximum retention of total bioflavonoids from Albizia myriophylla bark (AMB). Response surface methodology (RSM) using central composite design were employed for obtaining the best possible combination of MAE process parameters including microwave power (400-900 W), liquid/solid ratio (20-40 ml/g), extraction time (20-40 min) and ethanol concentration (60-100%). Optimum conditions of extraction under which predicted maximum bioflavonoids yield of 152.74 mg QE/g DW and antioxidant activity of 75.33% in close proximity with the experimental values were: microwave power 728 W, liquid/solid ratio 24.70 ml/g, extraction time 39.86 min and ethanol concentration 70.36%. Satisfactory statistical parameters (R²), ANOVA for the model and lack-of-fit testing provided an adequate mathematical description of the MAE of bioflavonoids with high antioxidant activity. Therefore, MAE of AMB using RSM could be termed as a time-saving and an efficient method resulting to high yield with increased antioxidant activity. Also, HPLC analysis of AMB revealed the presence of bioflavonoids viz., naringin, quercetin and apigenin; which may be further extensively studied for use as therapeutics against various health issues.

Microwave assisted biocidal extraction is an alternative method to measure microbial biomass of carbon from cultivated and non-cultivated soils

Developing simple and cost-effective methods for soil microbial biomass carbon (MBC) measurement eases routine laboratory analysis and enables large numbers of soil samples to be measured in a relatively short period of time. Thus, the objective of this study was to develop a microwave-assisted biocidal-extraction (MWE) method which does not employ CHCl₃ as biocide and K₂SO₄ as C-extractor, to estimate MBC. First, the microorganisms of soil samples are killed using microwave (MW) irradiation at energy level of 800 J g^-1 soil as biocide followed by microwave irradiation extraction (MWE) at 562 W (120 J g^-1 soil for 1 min), using deionized water as solvent. Microbial biomass of carbon from two contrasting soils microwaved with 80, 100, and 140 J g^-1 soil did not differ from those obtained by using the chloroform fumigation-extraction (CFE) method with 0.5 mol L^-1 K₂SO₄ as extractant. To evaluate the robustness of the MWE method, twenty-six soil samples, from cultivated and non-cultivated areas, with clay contents from 70-690 g kg^-1, organic carbon from 5.52 to 50.82 g C kg^-1 and pH values from 3.9 to 6.8 were analyzed for MBC using MWE and CFE methods. There was a linear regression (MW = - 17.87 + 0.92*K₂SO₄; R² = 0.705; p < 0.001) between MWE and CFE. The biocidal microwave-assisted extraction method using 120 J g^-1 soil for 1 min is a cleaner method for evaluating MBC, because it does not require chloroform, potassium sulfate salt and takes a shorter time to extract a set of soil samples.

Data set of green extraction of valuable chemicals from lignocellulosic biomass using microwave method

Lignocellulosic biomass is a promising alternative for the replacement of limited fossil resources to produce various chemical compounds, such as 5-hydroxymethylfurfural, furfural, vanillin, vanillic acid, ferulic acid, syringaldehyde, and 4-aminobenzoic acid. However, the complex biomass structure is a limitation to making effective use of this naturally found feedstock. This research presents a data set of different compounds obtained directly from forest residues, with special emphasis on achieving effective utilization of the biomass. The extraction method and the catalyst are considered as the two main factors in this valorization process.

Concentration and reduction of antibiotic residues in selected wastewater treatment plants and receiving waterbodies in Durban, South Africa

In the province of KwaZulu-Natal, South Africa the incidence of resistant tuberculosis, upper respiratory tract diseases as well as diarrhoeal and parasitic infections is high. Treatment of these diseases with antibiotics is partly reflected by the excretion of the respective antibiotics and their subsequent occurrence in wastewater. Their quantitative reduction in wastewater treatment reflects their potential environmental as well as human impact, the latter due to the use of the recipient water for domestic purposes and for irrigation. Information of the occurrence and reduction of different classes of antibiotics in wastewater treatment is sparse, especially the particle bound fraction of these. Due to this, analyses of aqueous and particle bound antibiotics in untreated wastewater of four selected wastewater treatment plants (WWTPs) and their receiving water bodies was carried out in Durban, South Africa. The treatment step especially considered was the biological one, represented by activated sludge and trickling filters. The treatment further included secondary clarifiers and final chlorine disinfection. Composite samples were collected during the period February 2017 to May 2017 and analysed with online solid phase extraction - high performance liquid chromatography mass spectrometry (SPE-HPLC-MS). For the 13 assessed antibiotics, the limit of detection (LOD) and the limit of quantification (LOQ) ranged from 0.07 to 0.33 ng L^-1 and 0.23 to 1.09 ng L^-1 respectively, while the total percentage recovery was in the range of 51 to 111%. The percentage of individual antibiotics bound to the particulate fraction normally lost by sample (influent) filtration, if not analysed in parallel, was in the range of 2.6%-97.3% (n = 32). In this fraction (sludge from centrifuge sample), the concentration of bound antibiotics of all the target antibiotics were detected in the influent of all WWTP in concentration ranges between 1.3 ng L^-1 (Azithromycin; AZI) to 81,748 ng L^-1 (Ciprofloxacin; CIP). The antibiotics with the highest median concentrations in receiving water bodies of the respective WWTP were; Sulfamethoxazole; SUL (239 ng L^-1) WWTP "K", Ciprofloxacin; CIP (708 ng L^-1) WWTP "S" and Albendazole; ALB (325 ng L^-1 and 683 ng L^-1) WWTP "P" and "I" respectively. The overall percentage removal efficiency for the four WWTPs ranged from 21% to 100%. The biological treatment steps, activated sludge and trickling filters, were effective in removing antibiotics especially with the trickling filter and the impact of the sedimentation stage after activated sludge treatment.

Evaluation of Thymus vulgaris and Thymbra spicata essential oils and plant extracts for chemical composition, antioxidant, and antimicrobial properties

The objectives of this study were (a) to obtain the essential oils (by hydrodistillation [HD] and microwave-assisted extraction [MAE] methods) to determine the effect of the oil extraction method on the chemical composition, oil yield (%), free radical scavenging activity (IC50), ferric reducing antioxidant power (FRAP) value, and antimicrobial properties of Thymus vulgaris (thyme) and Thymbra spicata (zahter); and (b) to determine the effect of different solvents (methanol [80%] and ethanol [80%]) on extraction by means of the phenolic acid composition, total phenolic content, total flavonoid content, IC50, and FRAP value of thyme and zahter. Gas chromatography-mass spectrometry analysis showed that the amount of thymol (55.35%; 50.53%) and p-cymene (11.2%; 11.79%) was found to be highest in thyme, when using HD and MAE, respectively. However, the highest amounts of carvacrol (68.20%; 66.91%) and γ-terpinene (13.25%; 13.94%) were found in zahter, when using HD and MAE, respectively. Thyme essential oil had higher antioxidant capacity for both HD and MAE in comparison with zahter essential oil. Methanol extracts of both thyme and zahter had higher phenolic composition in comparison with their ethanol extracts. Extracts of both plants did not show any antimicrobial properties. However, essential oils of both thyme and zahter showed antimicrobial activity against chosen bacteria. Highest inhibition zone (radius) was shown against Staphylococcus aureus ATCC 9144 by the essential oils.

Liquid chromatography quadrupole time-of-flight mass spectrometry determination of six pharmaceuticals in vegetal biota. Uptake study in Lavandula dentata

A procedure based on microwave assisted extraction for the determination of 6 pharmaceuticals in samples of Lavandula dentata, Salicornia ramosissima and Juncus sp. by liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF/MS) was optimized and validated. Best results were obtained using microwave assisted extraction of 1.0g of homogeneous lyophilized samples and 5mL of a mixture ACN:H₂O (1:1 v/v) as extracting solvent. Analytical recoveries ranged from 60 to 107% with relative standard deviation (RSD) lower than 15%. Limits of quantitation (LOQ) for the 6 pharmaceuticals flumequine (FLM), carbamazepine (CBZ), ciprofloxacin (CPR), enrofloxacin (ENR), diclofenac (DCL), and ibuprofen (IBU) were in the range 20.8-125ngg^-1. The method was satisfactory applied for an uptake study in Lavandula dentata samples finding quantifying concentrations of FLM and CBZ in roots, leaf and stem.

Volatile Constituents from Different Parts of Three Lamiacea Herbs from Iran

The essential oils obtained by hydrodistillation from the stem, leaf and flower of Phlomis aucheri Boiss., which is endemic to Iran, stem, leaf and root of Teucrium polium L. and solvent free microwave extraction oil from leaf of Ajuga chamaecistus Ging. Subsp chamaecistus were analyzed by GC and GC/MS. Germacrene D (11.10%, 28.31% and 21. 06%) was the main constituent in the stem, leaf, and flower oils of P. aucheri, respectively. The other main component in the stem oil of the plant was (E) - anethole (24.58%) and in the flower oil was β- caryophyllene (15.93%). All three oils were rich in regard to sesquiterpenes. The main components in the stem, leaf and root of T. polium were α- muurolol (25.02%, 20.03% and 19.53%), α- cadinol (15.72%, 8.11% and 13.01%) and β-cayophyllene (10.86%, 10.11% and 10.64%) respectively. All three oils were rich in regard to sesquiterpenes. The major components in the leaf oil of A.chamaecistus were (z)-β-ocimene (12.11%) and germacrene D (10.11%). The oil of the plant was rich in regard to both monoterpens and sesquiter penes.

Optimization of microwave-assisted extraction of Sargassum thunbergii polysaccharides and its antioxidant and hypoglycemic activities

In the present work, optimization of microwave-assisted extraction of polysaccharides from Sargassum thunbergii was investigated. The physicochemical properties, structural characteristics, and in vitro antioxidant and hypoglycemic activities were determined. The optimal extraction conditions with a yield of 2.84±0.09% for extraction of polysaccharides (STP-1) were extraction time 23min, microwave power 547W, extraction temperature 80°C, and the ratio of raw material to water 1:27g/mL. STP-1 contained 32.7% of total carbohydrate, 1.86% of protein, and 15.2% of sulfates. STP-1 had a major molecular weight of 190.4kDa, and comprised of arabinose, galactose, glucose, xylose, mannose, galacturonic acid, and glucuronic acid with molar percentages of 1.94, 30.7, 4.54, 23.2, 17.6, 8.11, and 13.9%, respectively. In addition, STP-1 showed strong antioxidant and α-glucosidase inhibitory activities, and could improve the glucose uptake in insulin-resistant HepG2 cells, suggesting that STP-1 can be exploited as a promising natural antioxidant and hypoglycemic agent.

Optimization of microwave-assisted extraction of zerumbone from Zingiber zerumbet L. rhizome and evaluation of antiproliferative activity of optimized extracts

Background

The extraction of bioactive compounds from herbal materials requires optimization in order to recover the highest active dose. Response surface methodology was used to optimize variables affecting the microwave extraction of zerumbone from Zingiber zerumbet using the Box–Behnken design. The influence of variables, such as ethanol concentration (X₁), microwave power (X₂), irradiation time (X₃), and liquid-to-solid ratio (X₄), on the extraction of zerumbone was modeled using a second-order regression equation. The antiproliferative activity of optimized and non-optimized extracts was evaluated against the HeLa cancer cell line using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay.

Results

Two linear parameters, X₁ and X₄, and their quadratic parameters were highly significant at the P < 0.01 level. Two interaction parameters, X₁X₄ and X₂X₃ were significant, whereas interactions of X₁X₂, X₁X₃, X₂X₄ and X₃X₄ were insignificant (P > 0.05). The optimum microwave extraction conditions were as follows: ethanol concentration, 44%; microwave power, 518 W; irradiation time, 38.5 s; and liquid-to-solid ratio, 38 mL/g. Under these conditions, the maximum zerumbone yield was 5.88 mg/g DM, which was similar to the predicted value (5.946 mg/g DM). Optimized and non-optimized Z. zerumbet rhizome extracts exhibited significant antiproliferative activity against HeLa cancer cells, with half-maximal inhibitory concentration (IC₅₀) values of 4.3 and 7.8 μg/mL, respectively, compared with 1.68 μg/mL for the anticancer drug cisplatin. When the extract concentration increased from 4.3 to 16.0 μg/mL, the inhibition of cancer cell growth increased from 50.0 to 79.5%.

Conclusions

In this study, the optimized microwave protocol developed for extracting zerumbone from Z. zerumbet was faster and consumed less solvent than previous methods, while improving and enhancing the antiproliferative activity.

Antibacterial Activityand Comparison of the Volatile Oils of Tanacetum tenuisectum (Boiss.) Podl. Obtained by Three Different Methods of Extraction

The essential oils obtained by hydrodistillation (HD), steam distillation (SD) and solvent free microwave extraction (SFME) from the stems and flowers of Tanacetumtenuisectum (Boiss.) Podl., which is endemic to Iran, were analyzed by combination of GC and GC/MS. Camphor (26.91 %, 27.23% and 25.52%), borneol (12.61%,11.48% and 7.62%) and 1,8-cineole (7.93%, 13.23% and 11.26%) were the main constituents of the HD,SD and SFME oils of Tanacetumtenuisectum respectively. All three oils were rich in regard to monoterpenes and small percentage of sesquiterpenes and non terpenoid compounds. Antibacterial activity of the essential oil of the plant was determined against six Gram positive and Gram negative bacteria. The results showed that this oil was active against all of the tested bacteria.

Rapid extraction and determination of 25 bioactive constituents in Alpinia oxyphylla using microwave extraction with ultra high performance liquid chromatography with tandem mass spectrometry

A novel and rapid microwave extraction and ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of 25 bioactive constituents (including two new constituents) in Fructus Alpinia oxyphylla. The optimized conditions of the microwave extraction was a microwave power of 300 W, extraction temperature of 80°C, solvent-to-solid ratio of 30 mL/g and extraction time of 8 min. Separation was achieved on a Waters ACQUITY UPLC(®) HSS C18 column (2.1 mm× 50 mm, 1.8 μm) using gradient elution with a mobile phase consisting of acetonitrile and 1 mM ammonium acetate at a flow rate of 0.2 mL/min. This is the first report of the simultaneous determination of 25 bioactive constituents in Fructus Alpinia oxyphylla by ultra high performance liquid chromatography with tandem mass spectrometry. The method was validated with good linearity, acceptable precision and accuracy. The validated method was successfully applied to determine the contents of 25 bioactive constituents in Fructus Alpinia oxyphylla from different sources and the analysis results were classified by hierarchical cluster analysis, which indicated the effect of different cultivation regions on the contents of constituents. This study provides powerful and practical guidance in the quality control of Alpinia oxyphylla and lays the foundation for further research of Alpinia oxyphylla.

Sample preparation for an optimized extraction of localized metabolites in lichens: Application to Pseudevernia furfuracea

Lichens are symbiotic organisms known for producing unique secondary metabolites with attractive cosmetic and pharmacological properties. In this paper, we investigated three standard methods of preparation of Pseudevernia furfuracea (blender grinding, ball milling, pestle and mortar). The materials obtained were characterized by electronic microscopy, nitrogen adsorption and compared from the point of view of extraction. Their microscopic structure is related to extraction efficiency. In addition, it is shown using thalline reactions and mass spectrometry mapping (TOF-SIMS) that these metabolites are not evenly distributed throughout the organism. Particularly, atranorin (a secondary metabolite of interest) is mainly present in the cortex of P. furfuracea. Finally, using microwave assisted extraction (MAE) we obtained evidence that an appropriate preparation can increase the extraction efficiency of atranorin by a factor of five.

Comparison of microwave, ultrasound and accelerated-assisted solvent extraction for recovery of polyphenols from Citrus sinensis peels

Peel of Citrus sinensis contains significant amounts of bioactive polyphenols that could be used as ingredients for a number of value-added products with health benefits. Extraction of polyphenols from the peels was performed using a microwave-assisted extraction (MAE) technique. The effects of aqueous acetone concentration, microwave power, extraction time and solvent-to-solid ratio on the total phenolic content (TPC), total antioxidant activity (TAA) (using DPPH and ORAC-values) and individual phenolic acids (IPA) were investigated using a response surface method. The TPC, TAA and IPA of peel extracts using MAE was compared with conventional, ultrasound-assisted and accelerated solvent extraction. The maximum predicted TPC under the optimal MAE conditions (51% acetone concentration in water (v/v), 500 W microwave power, 122 s extraction time and 25 mL g(-1) solvent to solid ratio), was 12.20 mg GAE g(-1) DW. The TPC and TAA in MAE extracts were higher than the other three extracts.

Evaluation of microscopic structure of Justicia wynaadensis and the stability of its color extracted by using conventional and microwave extraction method

Justicia wynaadensis locally known as Moddu Soppu belongs to the family Acanthaceae. The aqueous bluish purple color extracted from the leaves and stems of Justicia is used in the preparation of a sweet dish by the natives of Kodagu district, Karanataka, India, exclusively during the monsoons. This traditional practice is believed to keep the people healthy throughout the year. Owing to its potential to be used as a natural colorant there is a strong need to develop efficient extraction method for maximum yield of colorant and preliminary scientific study of stability. Microscopy was carried out to find out the location of purple color in both leaves and stem and to study the anatomical details. An optimized microwave extraction method for extraction of colorant from Justicia has been developed. The microwave oven extraction yield of colorant is 9.41 % (±0.8598) under the optimized conditions of extraction time 30 min., extraction temperature 150 °C and ratio of liquid to solid 30 ml/g. The study demonstrated that the purple extract of the plant was stable against pH range 6.0-8.0, low temperature (4 °C), high temperature (≥50 °C) and sensitive to light. Thus these observations recommend the use of J. wynaadensis extract as a food colorant in neutral or slightly alkaline products (bakery, milk, egg etc.) and could be the potential source for the food colorant market.

Measurement of Soluble and Total Hexavalent Chromium in the Ambient Airborne Particles in New Jersey

Hexavalent chromium (Cr(VI)) in ambient airborne particulate matter (PM) is a known pulmonary carcinogen and may have both soluble and insoluble forms. The sum of the two forms is defined as total Cr(VI). Currently, there were no methods suitable for large-scale monitoring of total Cr(VI) in ambient PM. This study developed a method to measure total Cr(VI) in ambient PM. This method includes PM collection using a Teflon filter, microwave extraction with 3% Na₂CO₃-2% NaOH at 95°C for 60 minutes, and Cr(VI) analysis by 1,5-diphenylcarbazide colorimetry at 540 nm. The recoveries of total Cr(VI) were 119.5 ± 10.4% and 106.3 ± 16.7% for the Cr(VI)-certified reference materials, SQC 012 and SRM 2700, respectively. Total Cr(VI) in the reference urban PM (NIST 1648a) was 26.0 ± 3.1 mg/kg (%CV = 11.9%) determined by this method. The method detection limit was 0.33 ng/m³. This method and the one previously developed to measure ambient Cr(VI), which is soluble in pH ~9.0 aqueous solution, were applied to measure Cr(VI) in ambient PM₁₀ collected from three urban areas and one suburban area in New Jersey. The total Cr(VI) concentrations were 1.05-1.41 ng/m³ in the winter and 0.99-1.56 ng/m³ in the summer. The soluble Cr(VI) concentrations were 0.03-0.19 ng/m³ in the winter and 0.12-0.37 ng/m³ in the summer. The summer mean ratios of soluble to total Cr(VI) were 14.3-43.7%, significantly higher than 4.2-14.4% in the winter. The winter concentrations of soluble and total Cr(VI) in the suburban area were significantly lower than in the three urban areas. The results suggested that formation of Cr(VI) via atmospheric chemistry may contribute to the higher soluble Cr(VI) concentrations in the summer.

Optimization of microwave-assisted extraction of polyphenols from Myrtus communis L. leaves

Phytochemicals, such as phenolic compounds, are of great interest due to their health-benefitting antioxidant properties and possible protection against inflammation, cardiovascular diseases and certain types of cancer. Maximum retention of these phytochemicals during extraction requires optimised process parameter conditions. A microwave-assisted extraction (MAE) method was investigated for extraction of total phenolics from Myrtus communis leaves. The total phenolic capacity (TPC) of leaf extracts at optimised MAE conditions was compared with ultrasound-assisted extraction (UAE) and conventional solvent extraction (CSE). The influence of extraction parameters including ethanol concentration, microwave power, irradiation time and solvent-to-solid ratio on the extraction of TPC was modeled by using a second-order regression equation. The optimal MAE conditions were 42% ethanol concentration, 500 W microwave power, 62 s irradiation time and 32 mL/g solvent to material ratio. Ethanol concentration and liquid-to-solid ratio were the significant parameters for the extraction process (p<0.01). Under the MAE optimised conditions, the recovery of TPC was 162.49 ± 16.95 mg gallic acidequivalent/gdry weight(DW), approximating the predicted content (166.13 mg GAE/g DW). When bioactive phytochemicals extracted from Myrtus leaves using MAE compared with UAE and CSE, it was also observed that tannins (32.65 ± 0.01 mg/g), total flavonoids (5.02 ± 0.05 mg QE/g) and antioxidant activities (38.20 ± 1.08 μg GAE/mL) in MAE extracts were higher than the other two extracts. These findings further illustrate that extraction of bioactive phytochemicals from plant materials using MAE method consumes less extraction solvent and saves time.

Extractive-transesterification of algal lipids under microwave irradiation with hexane as solvent

This study describes the use of microwaves (MW) for enhanced extractive-transesterification of algal lipids from dry algal biomass (Chlorella sp.). Two different single-step extractive-transesterification methods under MW irradiation were evaluated: (1) with ethanol as solvent/reactant and sodium hydroxide catalyst; and (2) with ethanol as reactant and hexane as solvent (sodium hydroxide catalyst). Biodiesel (fatty-acid-ethyl-esters, FAEE) yields from these two methods were compared with the conventional Bligh and Dyer (BD) method which followed a two-step extraction-transesterification process. The maximum lipid yields for MW, MW with hexane and BD methods were 20.1%, 20.1%, and 13.9%, respectively; while the FAEE conversion of the algal lipids were 96.2%, 94.3%, and 78.1%, respectively. The algae-biomass:ethanol molar ratio of 1:250-500 and 2.0-2.5% catalyst with reaction times around 6min were determined as optimum conditions for both methods. This study confers that the single-step non-conventional methods can contribute to higher algal lipid and FAEE yields.

Optimized extraction, separation and quantification of twelve intact glucosinolates in broccoli leaves

A new method has been developed and validated to determine twelve intact glucosinolates (glucoiberin, GIB; glucoraphanin, GRA; glucoerucin GER; gluconapin, GNA; glucotropaeolin, GTL; glucobrassicin, GBC; gluconasturtiin, GST; glucoalyssin, ALY; 4-hydroxyglucobrassicin, 4-OH; 4-metoxyglucobrassicin, 4ME; neoglucobrassicin, NEO; sinigrin, SIN) in broccoli leaves using liquid chromatography (LC) coupled to diode array (DAD) and electrospray ionization mass spectrometry (ESI-MS) detection. An extraction procedure has also been proposed and optimized by means of statistical analysis (the Box-Behnken design and analysis of variance); this is based on the deactivation of myrosinase using a microwave and heated water. Low limits of detection and quantification were obtained, ranging from 10 to 72 μg/g with DAD and 0.01 to 0.23 μg/g with ESI-MS, and the resulting recovery values ranged from 87% to 106% in all cases. Finally, glucosinolates were analyzed in broccoli leaf samples from six different cultivars (Ramoso calabrese Parthenon, Marathon, Nubia, Naxos and Viola).