Recent development in the application of immobilized oxidative enzymes for bioremediation of hazardous micropollutants - A review.

During the past several years, abundant progresses has been made in the development of immobilized oxidative enzymes with focus on finding new support materials, improving the immobilization methods and their applications. Nowadays, immobilized oxidative enzymes are broadly accepted as a green way to face the challenge of high amounts of micropollutants in nature. Among all oxidative enzymes, laccases and horseradish peroxidase were used frequently in recent years as they are general oxidative enzymes with ability to oxidize various types of compounds. Immobilized laccase or horseradish peroxidase are showed better stability, and reusability as well as easy separation from reaction mixture that make them more favorable and economic in compared to free enzymes. However, additional improvements are still essential such as: development of the new materials for immobilization with higher capacity, easy preparation, and cheaper price. Moreover, immobilization methods are still need improving to become more efficient and avoid enzyme wasting during immobilization and enzyme leakage through working cycles.

Analyte focusing by micelle collapse for liquid extraction surface analysis coupled with capillary electrophoresis of neutral analytes on a solid surface.

Liquid extraction surface analysis (LESA) has an advantage of directly sampling analytes on a surface, thus avoiding unnecessary dilution by homogenization of the bulk sample commonly practiced in solid sample analysis. By combining LESA with CE, the additional advantage of separating analytes before detection can be accomplished. For neutral molecules, MEKC needs to be used. Since the detection sensitivity of CE in general suffers from the small capillary dimension, analyte focusing by micelle collapse was employed for enhanced extraction in LESA and sample preconcentration for MEKC. In addition, using a commercial CE instrument, the LESA process was performed much faster and more reliably compared to our first demonstration of LESA-CE using a homemade CE setup. Three neutral water-insoluble pesticides sprayed on an apple skin were directly extracted, preconcentrated, and analyzed by the automated LESA-analyte focusing by micelle collapse-MEKC with high sensitivity in 10 min. The relative standard deviations of the migration times and peak heights were 0.8-2.1 and 1.2-3.0%, respectively when ametryn was used as an internal standard. The limits of detection obtained with UV absorbance at 200 nm were 1.8-6.4 ppb.

Chemistry, pharmacology and analysis of Pseudostellaria heterophylla: a mini-review.

Pseudostellaria heterophylla is one of the well-known traditional Chinese medicines and has been used in clinics for 100 years in China. The chemistry and pharmacology of P. heterophylla were reviewed to understand its active compounds. Then analysis of these compounds related to quality control of this herb was discussed. For the analysis of chemicals, three aspects have been discussed in this review. The first two aspects focused on the methodologies for analysis of cyclic peptides and carbohydrates in P. heterophylla, respectively. The last one dealt with the other methods used for identification of P. heterophylla. Some rich chemicals such as oligosaccharides in this plant were rarely evaluated. Many analyses were performed on this plant, however, few of them were accepted as quality control method.

Comparison of Antioxidant Activity and Main Active Compounds Among Different Parts of Alpinia officinarum Hance Using High-Performance Thin Layer Chromatography-Bioautography.

Background: Alpinia officinarum Hance (ginger family) is an important Chinese medicine, especially in Southern China. Objective: A simple and effective high-performance thin-layer chromatography coupled with 2, 2-diphenyl-1-picrylhydrazyl bioautography (HPTLC-DPPH) and electrospray ionization quadrupole time-of-flight tandem mass spectrometry (ESI-Q-TOF-MS/MS) method was developed for the bioactivity-based quality control of A. officinarum. Methods: The HPTLC-DPPH and ESI-Q-TOF-MS/MS were applied for the analysis of different parts of A. officinarum after using methanol extraction for 23 batches of taproot, four batches of aerial, and three batches of fibril parts. Results: The systematic evaluation showed that similar components in taproot and aerial parts make the major antioxidant activity. However, based on our evaluation, the antioxidant ability of the aerial parts is lower than the taproot parts. There is also a significant difference (P < 0.05) between taproot and fibril parts of the root. The chemical structures of compounds with the antioxidant capacity were tentatively identified as 5R-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-heptanone (band 1), kaempferide (band 2), and galangin (band 3) based on ESI-Q-TOF-MS/MS analytical results and further confirmed by standards. Conclusions: This identification indicated that two flavonoid compounds and one diarylheptanoid compound possessed high potentials to be used as the antioxidant biomarkers for the quality control of A. officinarum. Highlights: The comparison of different parts could be considered as guidelines for the usage of A. officinarum.

Hydride generation atomic absorption spectrometric determination of bismuth after separation and preconcentration with modified alumina.

A simple and sensitive method has been developed for the trace determination of bismuth in aqueous samples by a combination of solid-phase extraction and hydride generation atomic absorption spectrometry. The method is based on the use of a column packed with 2-mercaptobenzothiazole immobilized on sodium dodecyl sulfate coated alumina. Different parameters influencing the separation and preconcentration of bismuth such as pH, sample volume, type, and concentration of eluent, and the flow rate of sample and eluent were studied. A sample volume of 500.0 mL resulted in a preconcentration factor of 100. The precision (relative standard deviation, N = 10) at the 300 ng/L level and the limit of detection (3s) were found to be 2.3% and 12 ng/L, respectively. The developed method was successfully applied to the determination of bismuth in natural water samples and two certified reference materials.

Synthesis and characterisation of nano-pore antimony imprinted polymer and its use in the extraction and determination of antimony in water and fruit juice samples.

A solid phase extraction method using antimony ion imprinted polymer (IIP) sorbent combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for the extraction and speciation of antimony. The sorbent has been synthesised in the presence of Sb(III) and ammonium pyrrolidine dithiocarbamate (APDC) using styrene as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross linker. The imprinted Sb(III) ions were removed by leaching with HCl (50%v/v) and the polymer was characterised by FT-IR and scanning electron microscopy. The maximum sorption capacity of the IIP for Sb(III) ions was found to be 6.7 mg g(-1). With preconcentration of 60 mL of sample, an enhancement factor of 232 and detection limit of 3.9 ng L(-1) was obtained. Total antimony was determined after the reduction of Sb(V) to Sb(III). The method was successfully applied to the determination of antimony species in water samples and total antimony in fruit juices.

Combination of solid phase extraction and dispersive liquid-liquid microextraction for separation/preconcentration of ultra trace amounts of uranium prior to its fiber optic-linear array spectrophotometry determination.

A simple and sensitive method for the separation and preconcentration of the ultra trace amounts of uranium and its determination by spectrophotometry was developed. The method is based on the combination of solid phase extraction and dispersive liquid-liquid microextraction. Thus, by passing the sample through the basic alumina column, the uranyl ion and some cations are separated from the sample matrix. The retained uranyl ion along with the cations are eluted with 5 mL of nitric acid (2 mol L(-1)) and after neutralization of the eluent, the extracted uranyl ion is converted to its anionic benzoate complex and is separated from other cations by extraction of its ion pair with malachite green into small volume of chloroform using dispersive liquid-liquid microextraction. The amount of uranium is then determined by the absorption measurement of the extracted ion pair at 621 nm using flow injection spectrophotometry. Under the optimum conditions, with 500 mL of the sample, a preconcentration factor of 1980, a detection limit of 40 ng L(-1), and a relative standard deviation of 4.1% (n=6) at 400 ng L(-1) were obtained. The method was successfully applied to the determination of uranium in mineral water, river water, well water, spring water and sea water samples.

Suspended nanoparticles in surfactant media as a microextraction technique for simultaneous separation and preconcentration of cobalt, nickel and copper ions for electrothermal atomic absorption spectrometry determination.

The aim of this study was to describe a new method of microextraction based on the suspension of alumina nanoparticles in the surfactant media for simultaneous separation and preconcentration of the ultra-traces of cobalt, nickel and copper ions. In this technique, the alumina nanoparticles were suspended in the non-ionic surfactant solution of Triton X-114. The analytes in the sample solution were adsorbed onto the nanoparticles. After the phase separation based on the cloud point of the mixture at 40 °C, the nanoparticles settled down in the surfactant rich phase. Then 120 µL of nitric acid (3.0 mol L(-1)) was added to the surfactant rich phase which caused desorption of the analytes. Finally, the liquid phase was separated by centrifugation from the nanoparticles and was used for the quantification of the analytes by the electrothermal atomic absorption spectrometry (ETAAS). The parameters affecting the extraction and detection processes were optimized. Under the optimized experimental conditions (i.e. pH∼8, Triton X-114, 0.05% (v/v); temperature 40 °C), a sample volume of 25 mL resulted in the enhancement factors of 198, 205 and 206 and detection limits (defined as 3Sb/m) of 2.5, 2.8 and 2.6 ng L(-1) for Co(II), Ni(II) and Cu(II) respectively. The sorbent showed high capacity for these metal ions (30-40 mg g(-1) sorbent). The method was successfully applied to the determination of the analytes in natural water samples.