Conversion to isothiocyanates via dithiocarbamates for the determination of aromatic primary amines by headspace-solid phase microextraction and gas chromatography.

A novel and highly selective method has been developed for the determination of aromatic primary amines by their conversion to dithiocarbamates by reaction with carbon disulphide, and then to isothiocyanates, which are volatile, by heating in the presence of a heavy metal ion. Zinc(II) was selected owing to its low toxicity and optimum yield of isothiocyanates. The latter were sampled by headspace-solid phase microextraction (HS-SPME) on divinylbenzene-carboxen-polydimethylsiloxane fibre, 50/30 μm.

Evaluation of enhanced thermostability and operational stability of carbonic anhydrase from Micrococcus species.

Carbonic anhydrase (CA) was purified from Micrococcus lylae and Micrococcus luteus with 49.90 and 53.8 % yield, respectively, isolated from calcium carbonate kilns.

A bentazone-resistant mutant of cyanobacterium, Synechococcus elongatus PCC7942 adapts different strategies to counteract on bromoxynil- and salt-mediated oxidative stress.

A bentazone-resistant mutant of Synechococcus elongatus PCC7942, called Mu2, tolerated elevated NaCl concentrations. As bentazone and bromoxynil exhibit similar mechanism of action, we investigated whether the mutant also toleratedbromoxynil and found it to be true. The line of investigation was then whether the acclimation strategy for the three stressors, bentazone, bromoxynil and NaCl was same or different.

Partial Purification and Characterization of an Elastase-inhibitory Lipid Derivative from a Cyanobacterium, Microcystis Ku2.

A unicyanobacterial isolate of cyanobacterium, identified as Microcystis Ku2, produced a mammalian elastase-inhibitory lipid derivative. Protease inhibitors in cyanobacteria are unequivocally peptides. Since this metabolite appeared in lipid phase, we worked on a hypothesis that whether metabolite other than peptides could be responsible for the characteristic inhibition.

Zygomycosis caused by Rhizopus microsporus and Rhizopus oryzae in Madhya Pradesh (M.P.) Central India: a report of two cases.

Zygomycosis encompasses infections due to two distinct orders of fungi, Mucorales and Entomophthorales. With rare exception, Entomophthorales are restricted to tropical areas. By contrast, mucorales are ubiquitous opportunistic fungi, which play a crucial part in the natural decay process.

Biomimetic CO₂ sequestration using purified carbonic anhydrase from indigenous bacterial strains immobilized on biopolymeric materials.

The present study deals with immobilization of purified CA and whole cell of Pseudomonas fragi, Micrococcus lylae, and Micrococcus luteus 2 on different biopolymer matrices. Highest enzyme immobilization was achieved with P. fragi CA (89%) on chitosan-KOH beads, while maximum cell immobilization was achieved with M.

Recent advances in applications of single-drop microextraction: a review.

During the past fifteen years since its introduction, single-drop microextraction has witnessed incessant growth in the range of applications of samples preparation for trace organic and inorganic analysis. This was mainly due to the array of modes that are available to accomplish extraction in harmony with the nature of analytes, and to use the extract directly for analysis by diverse instrumental methods. Whilst engineering of novel sorbent materials has expanded the sample capabilities of rival method of solid-phase microextraction, the single-drop microextraction - irrespective of the mode of extraction - uses common equipment found in analytical laboratories sans any modification, and in a much economic way.

Response of multiple herbicide resistant strain of diazotrophic cyanobacterium, Anabaena variabilis, exposed to atrazine and DCMU.

Effect of two photosynthetic inhibitor herbicides, atrazine (both purified and formulated) and [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] (DCMU), on the growth, macromolecular contents, heterocyst frequency, photosynthetic O2 evolution and dark O2 uptake of wild type and multiple herbicide resistant (MHR) strain of diazotrophic cyanobacterium A. variabilis was studied. Cyanobacterial strains showed gradual inhibition in growth with increasing dosage of herbicides.

Role of bacterioferritin comigratory protein and glutathione peroxidase-reductase system in promoting bentazone tolerance in a mutant of Synechococcus elongatus PCC7942.

In this article, we describe the modifications in the antioxidant system of Synechococcus elongatus PCC7942 mutant Mu2 capable of growing at five times higher concentration of bentazone than wild type. Nevertheless, in both the strains, bentazone almost identically induced light-dependent H(2)O(2) production and its extracellular release. However unlike the wild type, peroxide produced upon prolong bentazone incubation was immediately degraded in Mu2.

Solid-phase extraction combined with headspace single-drop microextraction of chlorophenols as their methyl ethers and analysis by high-performance liquid chromatography-diode array detection.

Solid-phase extraction (SPE) of phenol and chlorophenols, their derivatization to methyl ethers, headspace single-drop microextraction (HS-SDME) of methyl ethers using 1-butanol as extraction solvent, and direct transfer of the drop into the injector for high performance liquid chromatography with diode array detection (HPLC-DAD) have been reported. A flanged-end polytetrafluoroethylene sleeve, 3 mm × 0.5mm, placed at the tip of the syringe needle, allowed the use of 10 μL solvent drop for extraction.

Determination of amoxapine and nortriptyline in blood plasma and serum by salt-assisted liquid-liquid microextraction and high-performance liquid chromatography.

A new, selective and sensitive method has been developed for the determination of tricyclic antidepressant drugs, amoxapine and nortriptyline, in human blood plasma and serum, involving their reaction with allyl isothiocyanate and extraction of thiourea derivatives with water-miscible organic solvent acetonitrile. The phase separation was effected by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction. The extract was analyzed by HPLC with UV detection at 254 nm.

Headspace single-drop microextraction and cuvetteless microspectrophotometry for the selective determination of free and total cyanide involving reaction with ninhydrin.

Headspace single-drop microextraction has been used for the determination of cyanide with ninhydrin in combination with fibre-optic-based cuvetteless microspectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres, and has been found to avoid salient drawbacks of batch methods. This method involved hydrocyanic acid formation in a closed vial, and simultaneous extraction and reaction with 2 microL drop of ninhydrin in carbonate medium suspended at the tip of a microsyringe needle held in the headspace of the acidified sample solution. The method was linear in range 0.

Sodium selenate effect on Synechococcus elongatus PCC 7942: appearance of novel enzymatic reaction, ATP:selenate adenylyltransferase, and variation in antioxidant enzyme activities.

Synechococcus elongatus PCC 7942 was grown with SO(4) (2-) or S(2)O(3) (2-) sulfur source with varying concentration of SeO(4) (2-). Up to 150 muM, SeO(4) (2-) was growth supportive and above this it was inhibitory. Selenate is believed to induce ROS production, and to counter, the cells produce increasing amounts of ROS quenching enzymes.

Headspace single-drop microextraction and fibre optics-based cuvetteless micro-spectrophotometry for the determination of chloride involving oxidation with permanganate.

Headspace single-drop microextraction has been investigated for the determination of chloride in conjunction with fibre optic-based cuvetteless micro-spectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres. Method has been evolved for the determination of 0.025-4 mg L(-1) of chloride involving its oxidation with permanganate in sulphuric acid medium, and reaction of chlorine with 2 microL drop of starch-iodide reagent suspended at the tip of microsyringe needle in the headspace of the reaction mixture.

Salt-assisted liquid-liquid microextraction with water-miscible organic solvents for the determination of carbonyl compounds by high-performance liquid chromatography.

A simple and rapid method has been reported for the determination of carbonyl compounds involving reaction with 2,4-dinitrophenylhydrazine and extraction of hydrazones with water-miscible organic solvent acetonitrile when the phase separation occurs by addition of ammonium sulphate, a process called salt-assisted liquid-liquid microextraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 360 nm. The procedure has been optimized with respect to solvent suitable for extraction, salt for phase separation between water and organic solvent, reaction temperature and reaction time.

Liquid-phase microextraction and fibre-optics-based cuvetteless CCD-array micro-spectrophotometry for trace analysis.

Liquid-phase microextraction (LPME) has been investigated for trace analysis in the present work in conjunction with fibre-optic-based micro-spectrophotometry which accommodates sample volume of 1 microL placed between the two ends of optical fibres. Methods have been evolved for the determination of (i) 1-100 microM and 0.5-20 microM of thiols by single drop microextraction (SDME) and LPME in 25 microL of the organic solvent, respectively, involving their reaction with the Ellman reagent and ion pair microextraction of thiolate ion formed; (ii) 70 microg to 7 mg L(-1) of chlorine/chlorine dioxide by headspace in-drop reaction with alternative reagents, viz.

Optimization of physical parameters for lipase production from Arthrobacter sp. BGCC#490.

The physical parameters for the production of thermostable, alkaline lipase from Arthrobacter sp. BGCC# 490 were optimized using response surface methodology (RSM), employing face centered central composite design (FCCCD). The design was employed by selecting pH, temperature and incubation period as the model factors and to achieve maximum yield, interaction of these factors was studied by RSM.

Headspace in-drop derivatization of carbonyl compounds for their analysis by high-performance liquid chromatography-diode array detection.

A simple and rapid method has been reported for the determination of carbonyl compounds involving sample preparation by headspace single drop microextraction using 1-butanol as extraction solvent containing 2,4-dinitrophenylhydrazine for hydrazone formation, and direct transfer of the drop into the injector for high-performance liquid chromatography with diode array detection. An angle-cut polytetrafluoroethylene sleeve, 3mm x 0.5mm, was fixed at the tip of the syringe needle and this allowed the use of 7 microL drop of solvent drop for extraction and derivatization.

Determination of micromol l(-1) level of iron (III) in natural waters and total iron in drugs by flow injection spectrophotometry.

The equilibrium problems, characterized by recurring end-points, involved in the reaction of iron (III) with iodide make the batch iodometric determination of iron (III) unsuitable. Since the flow injection determination does not require attainment of steady state either for mixing of reagents or for the chemical reaction, the iodometric determination has been accurately and precisely performed using this technique in the present work. This method does not require any special reagent, including chelating agents or those which are loxic, and has a limit of detection of 0.

PCR-based detection of microcystin-producing cyanobacterial blooms from Central India.

Microcystin synthetase-gene-specific primers were used to identify hepatotoxic microcystin producing genotypes in six Microcystis spp.-dominant water blooms. Four blooms gave positive PCR reaction.

Coupled in-tube and on-fibre solid-phase microextractions for cleanup and preconcentration of organic micropollutants from aqueous samples and analysis by gas chromatography-mass spectrometry.

Matrix interference removal is an important step when large volumes of aqueous samples are required to be processed to detect trace levels of analytes. A combination of two sample extraction methods has been used in this work with the aim of cleanup and preconcentration of analytes. For first objective, mild but preferential sorption of a range of analytes has been performed with in-tube solid-phase microextraction (SPME) using polytetrafluoroethylene (PTFE) tubing, and for the second, the eluate from in-tube SPME was subjected to on-fibre SPME using DVB/Caboxen/PDMS (30/50 microm) fibre.

Molecular detection of Microsporum persicolor in soil suggesting widespread dispersal in central India.

A survey was conducted from 1999 to 2003 as part of a microbial biodiversity study on geophilic and keratinophilic fungi in central India. Among the keratinophilic fungi recovered were 82 isolates belonging to the dermatophyte genus Microsporum. Species were provisionally identified by morphology and confirmed by PCR-RFLP and sequencing of the ITS regions of rDNA.

Liquid-phase microextraction and GC for the determination of primary, secondary and tertiary aromatic amines as their iodo-derivatives.

Presence of iodine in aromatic amines, introduced by their reaction with iodine, and other electron withdrawing substituents such as chlorine and nitro, has been found to afford excellent liquid-phase microextraction (LPME) in toluene and separation by gas chromatography in the determination of primary, secondary and tertiary aromatic amines. The effect is due to decreased basic nature of amines when electronegative substituents are present. Single drop microextraction (SDME) of the amines in 2mul of toluene and injection of the whole extract into GC, or LPME into 50mul of toluene and injection of 2mul of extract, were used.

A virulent genotype of Microsporum canis is responsible for the majority of human infections.

The zoophilic dermatophyte species Microsporum canis belongs to the Arthroderma otae complex and is known to mate with tester strains of that teleomorph species, at least in the laboratory. Human infections are likely to be acquired from the fur of cats, dogs and horses. Epidemiological studies to reveal sources and routes of infection have been hampered by a lack of polymorphic molecular markers.

Ecological niche of Cryptococcus neoformans var. grubii and Cryptococcus gattii in decaying wood of trunk hollows of living trees in Jabalpur City of Central India.

Cryptococcus neoformans var. grubii and C. gattii were repeatedly isolated from decaying wood of trunk hollows in living trees growing in Jabalpur City in Central India.