A selective and sensitive assay of berberine using total internal reflected resonance light scattering technique with fluorescein at the water/1,2-dichloroethane interface.

An assay of berberine (BE) was developed with good selectivity and sensitivity based on the total internal reflected resonance light scattering (TIR-RLS) signals from water/1,2-dichloroethane (H(2)O/DCE) interface. Under optimal conditions, amphiphilic complex formed by BE and fluorescein (Flu) was adsorbed to H(2)O/DCE interface, resulting in good separation of BE from the coexisting foreign substances in aqueous phase and significant enrichment of BE at the interface. This enriched species at the interface was found corresponding to enhanced TIR-RLS signals located at 370.

Flow-injection inhibition chemiluminescence determination of indapamide based on luminol-ferricyanide reaction.

A novel and sensitive chemiluminescence (CL) method for the determination of indapamide coupled with flow-injection analysis (FIA) technique is developed in this paper. It is based on the inhibition effect of the studied drug on the chemiluminescence emission of luminol-potassium ferricyanide system. Under the optimum conditions, the decreased CL intensity is proportional with the concentration of indapamide in the range of 1 x 10(-8) to 1.

Cloning and characterisation of the gene encoding HMG-CoA reductase from Taxus media and its functional identification in yeast.

In plants, the first committed step in the pathway for biosynthesis of isoprenoids is catalysed by 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR, EC: 1.1.1.

Sensitive flow-injection chemiluminescence determination of terbutaline sulfate based on enhancement of the luminol-permanganate reaction.

A novel and highly sensitive chemiluminescence (CL) method for the determination of terbutaline sulfate, coupled with flow-injection analysis (FIA), is described in this paper. The method is based on enhancement by terbutaline sulfate of the chemiluminescence emission of the luminol-permanganate system under alkaline conditions. Under the conditions selected the concentration of terbutaline sulfate is proportional to CL intensity in the range 5 x 10(-10)-5 x 10(-7) g mL(-1), with a detection limit of 1.

Study of a bis-furaldehyde Schiff base copper(II) complex as carrier for preparation of highly selective thiocyanate electrodes.

A new highly selective thiocyanate electrode based on N,N'-bis-(furaldehyde)-1,2-phenylenediamine-dipicolyl copper(II) complex [Cu(II)-BFPD] as neutral carrier is described. The electrode has an anti-Hofmeister selectivity sequence: SCN->I->Sal->ClO4->Br->NO2->Cl->NO3->SO4(2-)>SO3(2-)>H2PO4- and a near-Nernstian potential linear range for thiocyanate from 1.0x10(-1) to 5.

Flow-injection chemiluminescence detection for studying protein binding of terbutaline sulfate with on-line microdialysis sampling.

The binding of terbutaline sulfate to bovine serum albumin was studied in vitro using the technique of microdialysis sampling combined with flow-injection chemiluminescence analysis (FIA-CL). In the presence of formaldehyde, terbutaline sulfate can be oxidized by KMnO(4) to produce high chemiluminescence emission in sulfate acid media. The concentration of terbutaline sulfate is proportional with the CL intensity in the range of 1 x 10(-7)-2 x 10(-5) mol l(-1) with a detection limit of 3 x 10(-8) mol l(-1).

[Studies on the resonance nonlinear scattering of aqueous CoFe2O4 nanoparticle].

There are five resonance scattering peaks at 400, 470, 510, 800 and 940 nm for aqueous CoFe2O4 nanoparticles. It is a nonlinear scattering medium. When excited wavelength is at 330 nm, there are a Rayleigh scattering peak at 330 nm, a 1/2 fraction frequency peak at 660 nm and a 1/3 fraction frequency peak at 990 nm.

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of drug-protein interaction.

A flow-injection ultrafiltration sampling chemiluminescence system for on-line determination of cimetidine-bovine serum albumin (BSA) interaction is proposed in this paper. Cimetidine can be oxidized by N-bromosuccinimide (NBS) and sensitized by fluorescein to produce high chemiluminescence emission in basic media. The concentration of cimetidine is linear with the CL intensity in the range 3 x 10(-7) - 1 x 10(-4) mol L(-1) with a detection limit of 1 x 10(-7) mol L(-1) (3 sigma).

Interaction between isopoly-tungstic acid and berberine hydrochloride by resonance Rayleigh scattering spectrum.

In a weak acid medium, when an isopoly-tungstic acid reacts with berberine to form an ion-association complex, strong resonance Rayleigh scattering (RRS) appears and obvious frequency-doubling scattering (FDS) as well as second-order scattering (SOS) come into being. The scattering peaks are located at 288 and 369 nm for RRS, at 290, 370 and 390 nm for FDS, and at 480, 540 and 740 nm for SOS. Under optimum conditions, all three scattering intensities are directly proportional to the concentration of berberine and can be applied to the determination of berberine.

[Effects of light on morphological plasticity and biomass allocation of Momordica charantia].

The growth dynamics, morphological characteristics and biomass allocation of climbing plant Momordica charantia were studied under shading. The results showed that the growth of Momordica charantia had a significant difference under different levels of shading. Under weak light, the plants decreased the chance to increase their modular numbers and accumulate biomass, and had fewer shoots, thinner laminas, longer and thinner petioles, and more slender stems.

Resonance Rayleigh scattering measurement of aminoglycoside antibiotics with Evans Blue.

In a weak acid medium, some aminoglycoside antibiotics, such as kanamycin (KANA), gentamicin (GEN), tobramycin (TOB) and neomycin (NEO), or acid bisazo dye Evans Blue (EB) can only produce very weak resonance Rayleigh scattering (RRS) signals. However, when two agents react with each other to form ion-association complexes, the RRS intensity can be greatly enhanced and a new RRS spectrum with a significant enhancement of the RRS intensity in the wavelength range from 350 nm to 600 nm can be observed. The maximum scattering peak is at 570 nm.

Resonance Rayleigh scattering spectra for studying the interaction of aminoglycoside antibiotics with pontamine sky blue and their analytical applications.

In a weakly acid medium, some aminoglycoside antibiotics, such as kanamycin (KANA), gentamicin (GEN), tobramycin (TOB), and neomycin (NEO), or acid bisazo dye pontamine sky blue (PSB) can only produce very weak resonance Rayleigh scattering (RRS) signals. However, when the two agents react with each other to form the ion association complexes, the RRS intensity can be enhanced greatly and a new RRS spectrum and a significant enhancement of the RRS intensity in the wavelength range 350-600 nm can be observed. The maximum scattering peak is at 580 nm.

[Determination of theanine in tea leaves by HPLC-inhibited chemiluminescence with Co2+ catalyst].

A method for the separation and determination of theanine in tea leaves has been developed, based on inhibited chemiluminescence of cobalt-catalyzed luminol-H2O2 reaction by theanine. Separations were performed on a YWG-C18 column using a mobile phase of 0.01 mol.

A study of the resonance nonlinear scattering of silver atomic clusters.

The Ag cluster in solution has been prepared by a microwave high-pressure procedure. There is a maximum resonance Rayleigh scattering (RRS) peak at 425 nm (7.06 x 10(14) Hz) and a smaller RRS peak at 850 nm (1/2 x 7.

Spectrophotometric determination of vitamin B1 in a pharmaceutical formulation using triphenylmethane acid dyes.

A highly sensitive colour reaction has been developed, based on the fact that vitamin B(1) reacted with a triphenylmethane acid dye such as thymol blue, bromothymol blue, bromophenol blue, bromocresol green, phenol red or cresol red to form an ion-association complex in a weak-base aqueous solution in the presence of some solubilization agents e.g. polyvinyl alcohol, emulgent OP, Triton X-100 or Tween-20.

Resonance Rayleigh-scattering method for the determination of vitamin B1 with methyl orange.

In a pH 2.3-3.0 acid medium, the resonance Rayleigh scattering (RRS) intensity is greatly enhanced when vitamin B, reacts with Methyl Orange to form an ion-association complex.

Resonance Rayleigh method for the determination of proteins with Orange G.

In pH 0.6 - 2.0 HCl-sodium acetate buffer solution, proteins react with an acidic monoazo dye such as Orange G, Methyl Orange, Methyl Red and Orange IV to form a combination product.

Resonance Rayleigh-scattering method for the determination of proteins with some monoazo dyes of chromotropic acid.

In a weak acid medium, protein reacts with a monoazo dye of chromotropic acid, such as Chromazol KS (CALKS), Acid Chrome Dark Blue (ACDB), Chrome Blue SE (CBSE), Acid Chrome Blue K (ACBK), Chlorophosphonazo I (CPAI), Arsennazo I (AAI) and Chromotrope 2R (CT2R), to form a combination product. This results in a significant enhancement of the resonance Rayleigh-scattering (RRS) intensity, and the corresponding RRS spectrum appears. The characteristics of the RRS spectra of the combination products and the optimum conditions for the reactions were investigated.

Resonance Rayleigh scattering technology as a new method for the determination of the inclusion constant of beta-cyclodextrin.

The interaction of procaine hydrochloride and beta-cyclodextrin in aqueous solution was studied using resonance Rayleigh scattering technology. The molar ratio of the inclusion complex was 1:1 established by spectrophotometry. The resonance Rayleigh scattering technology was first applied in the determination of the beta-cyclodextrin inclusion constant.

[Seed rain and seed bank of constructive species in evergreen broadleaved forest at Chongqing Simian Mountain].

The study shows that the early and late seed rains of constructive tree species in evergreen broadleaved forest at Chongqing Simian Mountain had no activity. The bigger the seeds of the species and the earlier or later the seeds of the species matured, the higher the proportion of the seed rain damaged by animals. The quantitative variation of seed rain, active seed rain and seed bank did not take place at the same time.

Resonance Rayleigh scattering study of the interaction of heparin with some basic diphenyl naphthylmethane dyes.

In a near-neutral medium, a combination of heparin with some basic diphenyl naphthylmethane dyes such as victoria blue 4R (VB4R), victoria blue B (VBB), or night blue (NB) can result in a significant enhancement of resonance. Rayleigh scattering (RRS) and their maximum scattering wavelengths lambdamax appear at 523, 534, and 540 nm for VB4R, VBB, and NB, respectively. The characteristics of RRS spectra of the heparin-dye complexes, the influencing factors, and the optimum conditions of these reactions have been investigated.

Resonance Rayleigh scattering method for the determination of trace amounts of cadmium with iodide-basic triphenylmethane dye systems.

In dilute phosphoric acid solution, cadmium (II) reacts with a large excess of I- to form [CdI4]2- which reacts further with basic triphenylmethane dyes such as crystal violet (CV), ethyl violet (EV), methyl violet (MV), brilliant green (BG) or malachite green (MG) to form an ion-association complex. This results in a significant enhancement of resonance Rayleigh scattering (RRS) intensity and the appearance of new RRS spectra. The characteristics of RRS spectra of the ion-association complexes, the influencing factors and the optimum conditions of these reactions have been investigated.