Fast ultrasound‐assisted extraction followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector for the trace determination of tebuconazole in garlic,soil and water samples

A fast and an efficient ultrasound‐assisted extraction technique using a lower density extraction solvent than water was developed for the trace‐level determination of tebuconazole in garlic, soil and water samples followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector (GC–NPD). In this approach, ultrasound radiation was applied to accelerate the emulsification of the ethyl acetate in aqueous samples to enhance the extraction efficiency of tebuconazole without requiring extra partitioning or cleaning, and the use of capillary GC–NPD was a more sensitive detection technique for organonitrogen pesticides. The experimental results indicate an excellent linear relationship between peak area and concentration obtained in the range 1–50 μg/kg or μg/L. The limit of detection (S/N, 3 ± 0.5) and limit of quantification (S/N, 7.5 ± 2.5) were obtained in the range 0.2–3 and 1–10 μg/kg or μg/L. Good spiked recoveries were achieved from ranges 95.55–101.26%, 96.28–99.33% and 95.04–105.15% in garlic, Nanivaliyal soil and Par River water, respectively, at levels 5 and 20 μg/kg or μg/L, and the method precision (% RSD) was ≤5%. Our results demonstrate that the proposed technique is a viable alternative for the determination of tebuconazole in complex samples.     

Extraction of aroma compounds in blackcurrant buds by alternative solvents: Theoretical and experimental solubility study

This study was designed to evaluate the performance of nine alternative solvents (α-pinene, MeTHF, ethyl acetate, methyl acetate, ethyl lactate, butanol, isopropanol, ethanol and CO₂ supercritical fluid) for extracting aromas from blackcurrant buds (Ribes nigrum L) compared to that of n-hexane, commonly used. This study has been performed via experimentation and simulation using Hansen solubility methodology for the comprehension of the dissolving mechanism. Experimentally, the extracts were analysed to compare the solvents performance in terms of aroma compositions. The results indicated that an alternative solvent, i.e. MeTHF, could be the most promising one for n-hexane substitution with good yield and selectivity of aromas.     

Extraction of valuable biocompounds assisted by high voltage electrical discharges: A review

The application of strong electric fields in gases, water and organic liquids has been studied for several years, because of its importance in electrical transmission processes and its practical applications in biology, chemistry, and electrochemistry. More recently, electrical discharges have been investigated and are being developed in water for enhancing the extraction of biocompounds from different raw materials. This paper reviews the current status of research on the application of high voltage electrical discharges for promoting cell disruption in aqueous suspension of biological materials, with particular emphasis on application to biocompounds extraction.     

Chemical modification of cellulose extracted from sugarcane bagasse: Preparation of hydroxyethyl cellulose

Cellulose was extracted from sugarcane bagasse by alkaline extraction with sodium hydroxide followed by delignification/bleaching using sodium chlorite/hexamethylenetetramine system. Factors affecting extraction process, including sodium hydroxide concentration, hexamethylenetetramine concentration and temperature were studied and optimum conditions for alkaline extraction were found to be boiling finely ground bagasse under reflux in 1 N sodium hydroxide solution and then carrying out the delignification/bleaching treatment at 95 °C using 5 g/l sodium chlorite together with 0.02 g/l hexamethylenetetramine. The extracted cellulose was used in the preparation of hydroxyethyl cellulose through reaction with ethylene oxide in alkaline medium. Factors affecting the hydroxyethylation reaction, like sodium hydroxide concentration during the alkali formation step, ethylene oxide concentration, reaction temperature and reaction duration were studied. Optimum conditions for hydroxyethylation reaction were using 20% NaOH solution and 200% ethylene oxide (based on weight of cellulose), carrying out the reaction at 100 °C for 60 min.     

Radioimmunoassay of Triazolam

Abstract

Two radioimmunoassay (RIA) assay methods (I, II) have been developed for triazolam (T, U-33,030) in serum and plasma. The parameters of equilibration time, serum blank, antibody specificity, extraction efficiency, and drug-binding to glass were studied. Of the various triazolam analogs tested for cross reactivity, only the hydroxy metabolites interfered significantly. At the levels normally found in plasma or serum, a background blank was encountered from constituents such as fatty acids, lysolecithin, lecithin, and cholesterol. However, serum or plasma samples could be analyzed with (I) by constructing standard curves in which blank serum from the same subject was used. An alternate method (II) was found which simultaneously extracted and precipitated the interferences. Both methods could be employed for analysis of plasma or serum samples. However, II detects T metabolites less efficiently than I. The within day and between day coefficients of variation for method I were found to be 5.7% and 3.9% respectively at the 8 ng/ml level. Method I is suitable for measuring large numbers of samples where blank subject serum can be obtained and where detection of T metabolites in addition to T would not present a problem.     

Separation of chromium (VI) using complexation and its determination with GFAAS

In acidic medium and in the presence of chloride ions 2-[2-(4-methoxy-phenylamino)-vinyl]-1,3,3-trimethyl-3H-indolium chloride forms complex with Cr(VI). The optimum conditions (pH, concentration of Cl^- and the complex forming reagent) of the separation and extraction of Cr(VI) into toluene using this basic dye as a complexing reagent have been determined and the possible interferences of Ca, Mg, Na, K, Cr(III), Ni, Pb, Hg, Mn, Al, Cu have been studied. An electrothermal atomic absorption spectrometer (GFAAS) was used for the determination of Cr(VI). The detection limit of the method for Cr(VI) found to be 0.15 μg dm^− 3 and RSD for spiked drinking water was better than 3%.     

TBP和一些含氧类萃取剂对乙酸萃取规律与机理的研究

研究了戊醇、乙酸乙酯、环已酮和TBP萃取乙酸的萃取规律及其机理，萃取规律为：戊醇（正已烷）＞乙酸乙酯（石油醚）＞TBP（环已烷）＞环已酮（石油醚）。     

蒙药呼和嘎日迪-9多糖的提取与含量测定

采用热水提取-乙醇沉淀的方法从蒙药呼和嘎日迪-9中提取多糖,分光光度法测定糖含量,求得校准曲线的回归方程为y=0.00656x＋0.324,相关系数为r=0.9994,平均回收率为101.2%,RSD=0.90%（n=5）。     

Liquid–liquid equilibria of aromatics removal from middle distillate using NMP

We investigated the removal of aromatics from a typical Kuwait middle distillate using liquid–liquid extraction. A multicomponent system; dodecane + hexadecane + 1,3,5-trimethyl benzene (mesitylene) + butylbenzene; was used to represent the middle distillate mixture. N-methyl-2-pyrrolidone (NMP) was used as a solvent. The liquid–liquid equilibria (LLE) of the mixture was studied over a temperature range of 293–323 K and at different solvent to feed ratios (1.35–1.97). The selectivity and distribution coefficient of the solvent were correlated successfully using the universal quasi-chemical (UNIQUAC) model for the pseudo-ternary system (paraffins (1) + aromatics (2) + NMP (3)) at the studied temperature range. The UNIQUAC model fit the experimental data with an average percentage root mean square deviation (rmds) of 0.2980%.     

Boronate functionalized magnetic nanoparticles and off-line hyphenation with capillary electrophoresis for specific extraction and analysis of biomolecules containing cis-diols

In recent years, functionalized magnetic nanoparticles (MNPs) have drawn continuously increasing attention due to their great potential for capturing biological molecules or species. However, functionalized MNPs as nanoextraction probes and the coupling with a separation platform for chemical analysis have not extensively investigated yet. In this study, boronate functionalized MNPs were synthesized and employed as extracting probes to capture and enrich cis-diol-containing biomolecules, and an off-line coupling method of the MNPs-based extraction with capillary electrophoresis (CE) was established by using pH junction, an on-line preconcentration technique in CE, as a bridge for the coupling. The prepared MNPs exhibited specific selectivity and sufficient capacity. The pH junction compressed a large injected sample volume into a much narrower sample zone and therefore significantly improved the detection sensitivity, solving the sensitivity mismatch between the MNPs-based extraction and CE. Experimental conditions for the pH junction and the desorption were optimized. Under the optimized conditions, the sensitivity was enhanced by 42-fold as compared with regular CE. N,N-dimethylformamide was found to be an effective desorption promoter, which reduced the desorption time to a few minutes. With the established method, riboflavin in a human urine sample was determined.