Synthesis of a novel fluorescent probe based on 7‐nitrobenzo‐2‐oxa‐1,3‐diazole skeleton for the rapid determination of vitamin B12 in pharmaceuticals

A new fluorescent probe, 4‐N,N‐di(2‐hydroxyethyl)imino‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (HINBD) was synthesized in a single step with reasonably good yield. The water‐soluble HINBD emits strongly in the visible region (λ_ex = 479 nm, λ_em = 545 nm) and is stable over a wide range of pH values. It was found that vitamin B₁₂ (VB₁₂) had the ability to quench the fluorescence of HINBD, and the quenched fluorescence intensity was proportional to the concentration of VB₁₂. A method for VB₁₂ determination based on the quenching fluorescence of HINBD was thus established. Interference effects of various substances, including sugars, vitamins, amino acids, inorganic cations and some organic substances have been studied. Under optimal conditions, the linear range is 0.0–2.4 × 10^–5 mol/L. The determination limit is 8.3 × 10^–8 mol/L. The method was applied to measure VB₁₂ in pharmaceutical preparations with satisfactory results. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of nucleic acid by [tetra‐(3‐methoxy‐4‐hydroxyphenyl)]–Tb3+ porphyrin as the fluorescence spectral probe in bis(2‐ethylhexyl)sulfosuccinate sodium salt micelle system

A new system for the determination of nucleic acid by rare earth metallic porphyrin of [tetra‐(3‐methoxy‐4‐hydroxyphenyl)]–Tb³⁺ [T(3‐MO‐4HP)–Tb³⁺] porphyrin as fluorescence spectral probe has been developed in this paper. Nucleic acid can enhance the fluorescence intensity of the T(3‐MO‐4HP)–Tb³⁺ porphyrin in the presence of bis(2‐ethylhexyl)sulfosuccinate sodium salt(AOT) micelle. In pH 8.00 Tris–HCl buffer solution, under optimum conditions, the enhanced fluorescence intensity is in proportion to the concentration of nucleic acids in the range of 0.05–3.00 µg mL^?1 for calf thymus DNA (ct DNA) and 0.03–4.80 µg mL^?1 for fish sperm DNA(fs DNA). Their detection limits are 0.03 and 0.01 µg mL^?1, respectively. In addition, the binding interaction mechanism between T(3‐MO‐4HP)–Tb³⁺ porphyrin and ct DNA is also investigated by resonance scattering and fluorescence spectra. The maximum binding number is calculated by molar ratio method. The new system can be used for the determination of nucleic acid in pig liver, yielding satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.     

Enantioselective resolution of 4‐chloromandelic acid by liquid–liquid extraction using 2‐chloro‐N‐carbobenzyloxy‐L‐amino acid

A liquid–liquid extraction resolution of 4‐chloro‐mandelic acid (4‐ClMA) was studied by using 2‐chloro‐N‐carbobenzyloxy‐L‐amino acid (2‐Cl‐Z‐AA) as a chiral extractant. Important factors affecting the extraction efficiency were investigated, including the type of chiral extractant, pH value of aqueous phase, initial concentration of chiral extractant in organic phase, initial concentration of 4‐ClMA in aqueous phase, and resolution temperature. It was observed that the concentration of (R)‐4‐ClMA was much higher than that of (S)‐4‐ClMA in organic phase due to a higher stability of the complex formed between (R)‐4‐ClMA and 2‐Cl‐Z‐AA. A separation factor (α) of 3.05 was obtained at 0.02 mol/L 2‐Cl‐Z‐Valine dissolved in dichloromethane, pH of 2.0, concentration of 4‐ClMA of 0.11 mmol/Land T of 296.7K.     

The role of nuclear factor‐κB in rats of radiocontrast‐media‐induced nephropathy

This study was undertaken to examine the possible role of the DNA‐binding activity of nuclear factor‐kappa B (NF‐κB) in rat of radiocontrast‐media‐induced nephropathy (RCIN) and to explore the characteristic of RCIN in rats and the role of NF‐κB in its occurrence. Forty‐eight adult male Sprague–Dawley (SD) rats were randomly divided into Groups A–D. Rats of Groups A and B were intravenously injected with NG‐nitro‐L ‐arginine methyl ester (L‐NAME) (10 mg/kg) and indomethacin (10 mg/kg), respectively. Rats of Groups C and D were intravenously injected with 1‐M phosphate buffer (PH = 8.4 3 mL/kg) and normal saline (NS 2 mL/kg), respectively. After 30 min, Groups A and D were injected with NS (8 mL/kg) and Groups B and C were injected with diatrizoate (DTZ 8 mL/kg). After injected contrast media (CM) for 6 h, the serum creatinine and blood urea nitrogen of rat in Group B increased sharply as compared with Groups A, C, and D. After 48 h, the data recovered to 49.28 ± 8.81 μmol/L and 6.72 ± 2.75 mmol/L, respectively. Vacuolization of the tubule epithelial cells of the kidney was observed in Group A. Especially, these pathological changes were most obvious in outer medulla. Contrast to group A, the DNA‐binding activity of NF‐κB in rat kidney of Group B reached a peak at the 6th h and recovered to the normal level after the 48th h. CM mainly damages renal tubular–interstitial, which appears the earliest and most serious in the outer medulla. Activation of NF‐κB of renal may be one of the mechanisms of RCIN occurrence. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:416–421, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jbt.20256     

6‐Methyl 3‐chromonyl 2,4‐thiazolidinedione/2,4‐imidazolidinedione/2‐thioxo‐imidazolidine‐4‐one compounds: novel scavengers of reactive oxygen species

The benefits of antioxidants on human health are usually ascribed to their potential ability to remove reactive oxygen species providing protection against oxidative stress. In this paper the free radicals scavenging activities of nine 6‐methyl 3‐chromonyl derivatives (CMs) were evaluated for the first time by the chemiluminescence, electron paramagnetic resonance, spin trapping and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH^?) methods. The total antioxidant capacity was also measured using a ferric‐ferrozine reagent. Compounds having a hydrogen atom at the N3‐position of the β‐ring were effective in quenching CL resulted from the KO₂/18‐crown‐6‐ether system (a source of superoxide anion radical, ) in a dose‐dependent manner over the range of 0.05–1 mmol/L [IC₅₀ ranged from 0.353 (0.04) to 0.668 (0.05) mmol/L]. The examined compounds exhibited a significant scavenging effect towards hydroxyl radicals (HO^? HO^?), produced by the Fenton reaction, and this ranged from 24.0% to 61.0%, at the concentration of 2.5 mmol/L. Furthermore, the compounds examined were also found to inhibit DPPH^? and this ranged from 51.9% to 97.4% at the same concentration. In addition, the use of the total antioxidant capacity assay confirmed that CM compounds are able to act as reductants. According to the present study, CM compounds showed effective in vitro free radical scavenging activity and may be considered as potential therapeutics to control diseases of oxidative stress‐related etiology. Copyright © 2013 John Wiley & Sons, Ltd.     

Capillary electrophoresis coupled with end‐column electrochemiluminescence for the determination of ephedrine in human urine,and a study of its interactions with three proteins

A tris(2,2‐bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺)‐based electrochemiluminescence (ECL) detection coupled with capillary electrophoresis (CE) method has been established for the sensitive determination of ephedrine for the first time. Under the optimized conditions [ECL detection at 1.15 V, 25 mmol/L phosphate buffer solution (PBS), pH 8.0, as running buffer, separation voltage 12.5 kV, 5 mmol/L Ru(bpy)₃²⁺ with 60 mmol/L PBS, pH 8.5, in the detection cell] linear correlation (r = 0.9987) between ECL intensity and ephedrine concentration was obtained in the range 6.0 × 10^–8–6.0 × 10^–6 g/mL. The detection limit was 4.5 × 10^–9 g/mL (S:N = 3). The developed method was successfully applied to the analysis of ephedrine in human urine and the investigation of its interactions with three proteins, including bovine serum albumin (BSA), cytochrome C (Cyt‐C) and myoglobin (Mb). The number of binding sites and the binding constants between ephedrine and BSA, Cyt‐C and Mb were 8.52, 12.60, 10.66 and 1.55 × 10⁴ mol/L, 6.58 × 10³ mol/L and 1.59 × 10⁴ mol/L, respectively. Copyright © 2011 John Wiley & Sons, Ltd.     

Study on the interaction between 2‐mercaptoethanol,dimercaprol and CdSe quantum dots

The interactions between 2‐mercaptoethanol, dimercaprol and CdSe quantum dots (QDs) in organic media have been investigated by spectral methods. The results showed that the fluorescence (FL) emission of CdSe QDs gradually decreased, with a slight red‐shift, after adding thiols to CdSe QDs solutions. With the increase of the concentrations of thiols, the resonance light scattering (RLS) signal of CdSe QDs had been strongly enhanced in the wavelength range 300–500 nm, which was confirmed by the formation of larger CdSe QDs particles. The effect of thiols on the FL emission of CdSe QDs could be described by a Stern–Volmer‐type equation with the concentration ranges 1.0 × 10^–6–7.5 × 10^–4 mol/L for 2‐mercaptoethanol and 1.0 × 10^–7–2.5 × 10^–5 mol/L for dimercaprol. The possible mechanism of the interaction was proposed according to the results of UV‐vis absorption and micro‐Raman spectroscopy. The results indicated that FL quenching was mainly attributable to the exchange of the QDs surface molecules. Copyright © 2008 John Wiley & Sons, Ltd.     

Dual effects of [Tyr6]‐γ2‐MSH(6–12) on pain perception and in vivo hyperalgesic activity of its analogues

[Tyr⁶]‐γ2‐MSH(6–12) with a short effecting time of about 20 min is one of the most potent rMrgC receptor agonists. To possibly increase its potency and metabolic stability, a series of analogues were prepared by replacing the Tyr⁶ residue with the non‐canonical amino acids 3‐(1‐naphtyl)‐L ‐alanine, 4‐fluoro‐L ‐phenylalanine, 4‐methoxy‐L ‐phenylalanine and 3‐nitro‐L ‐tyrosine. Dose‐dependent nociceptive assays performed in conscious rats by intrathecal injection of the MSH peptides showed [Tyr⁶]‐γ2‐MSH(6–12) hyperalgesic effects at low doses (5–20 nmol) and analgesia at high doses (100–200 nmol). This analgesic activity is fully reversed by the kyotorphin receptor‐specific antagonist Leu–Arg. For the two analogues containing in position 6, 4‐fluoro‐L ‐phenylalanine and 3‐nitro‐L ‐tyrosine, a hyperalgesic activity was not observed, while the 3‐(1‐naphtyl)‐L ‐alanine analogue at 10 nmol dose was found to induce hyperalgesia at a potency very similar to γ2‐MSH(6–12), but with longer duration of the effect. Finally, the 4‐methoxy‐L ‐phenylalanine analogue (0.5 nmol) showed greatly improved hyperalgesic activity and prolonged effects compared to the parent [Tyr⁶]‐γ2‐MSH(6–12) compound. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.     

Modified nitrocefin‐EDTA method to differentially quantify the induced L1 and L2 β‐lactamases in Stenotrophomonas maltophilia

Aim: To estimate the ethylene diamine tetraacetic acid (EDTA) concentration at which the L1 enzyme activity in the cell extracts of Stenotrophomonas maltophilia can be mostly inhibited. Methods and Results: The effective inhibition concentration of EDTA against the L1 enzyme in the cell extracts was firstly evaluated by using the L2 isogenic mutant of S. maltophilia KJ, KJΔL2, as the assayed strain. Approximately 92% L1 activity was inhibited by 10 mmol l^?1 EDTA, which is 100‐fold higher than that from previously reported protocols (0·1 mmol l^?1). Three phylogenetic clusters of L1 proteins were revealed from 11 clinical S. maltophilia isolates, with a L1 protein divergence of 0–11%. The EDTA concentration required to inhibit the L1 enzymes of different phylogenetic clusters was estimated to be 10 mmol l^?1. Conclusion: The previous nitrocefin‐EDTA protocol for differentially quantifying the L1 and L2 activity in the cell extracts has been modified by raising the added EDTA concentration to 10 mmol l^?1. Significance and Impact of the Study: A rapid and accurate method for determination of L1 and L2 activity will provide a convenient tool for enzyme characterization and induction mechanism study of S. maltophilia.     

Determination of manganese‐ and manganese‐containing fungicides with lucigenin–Tween‐20‐enhanced chemiluminescence detection

A flow‐injection (FI) method is reported for the determination of Mn(II), maneb and mancozeb fungicides based on the catalytic effect of Mn(II) on the oxidation of lucigenin and dissolved oxygen in a basic solution. The Tween‐20 surfactant has been reported for first time to enhance lucigenin chemiluminescence (CL) intensity in the presence of Mn(II) (53%) and maneb and mancozeb (89%). The calibration graphs were linear in the concentration range of 0.001–1.5 mg L^–1 (R² = 0.9982 (n = 11) with a limit of detection (S/N = 3) of 0.1 µg L^–1 for Mn(II) and 0.01–3.0 mg L^–1 [R² = 0.9989 and R² = 0.9992 (n = 6)] with a limit of detection (S/N =3) of 1.0 µg L^–1 for maneb and mancozeb respectively. Injection throughputs of 90 and 120 h^–1 for Mn(II) and maneb and mancozeb respectively, and relative standard deviations of 1.0–3.4% were obtained in the concentration range studied. The experimental variables, e.g., reagents concentrations, flow rates, sample volume, and photomultiplier tube voltage, were optimized and potential interferences were investigated. The analysis of Mn(II) in river water reference materials (SLRS‐4 and SLRS‐5) showed good agreement with the certified values incorporating an on‐line 8‐hydroxyquinoline chelating column in the manifold for removing interfering metal ions. Recoveries for maneb and mancozeb were in the range of 92 ± 5 to 104 ± 3% and 91 ± 2 to 100 ± 4% (n = 3) respectively. The effect of 30 other pesticides (fungicides, herbicides and insecticides) was also examined in the lucigenin–Tween‐20 CL system. Copyright © 2015 John Wiley & Sons, Ltd.     

Validated spectrofluorimetric method for the determination of carbamazepine in pharmaceutical dosage forms after reaction with 4‐chloro‐7‐‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl)

A sensitive and simple spectrofluorimetric method has been developed and validated for the determination of the anti‐epileptic drug carbamazepine (CBZ) in its dosage forms. The method was based on a nucleophilic substitution reaction of CBZ with 4‐chloro‐7‐nitrobenzo‐2‐ oxa‐1,3‐diazole (NBD‐Cl) in borate buffer (pH 9) to form a highly fluorescent derivative that was measured at 530 nm after excitation at 460 nm. Factors affecting the formation of the reaction product were studied and optimized, and the reaction mechanism was postulated. The fluorescence–concentration plot is rectilinear over the range of 0.6–8 µg/mL with limit of detection of 0.06 µg/mL and limit of quantitation of 0.19 µg/mL. The method was applied to the analysis of commercial tablets and the results were in good agreement with those obtained using the reference method. Validation of the analytical procedures was evaluated according to ICH guidelines. Copyright © 2015 John Wiley & Sons, Ltd.     

Investigation of the binding of AuNPs–6‐mercaptopurine and the sensitive detection of 6‐mercaptopurine using resonance Rayleigh light scattering

A highly sensitive method for the detection of 6‐mercaptopurine (MP) by resonance Rayleigh light scattering (RLS) method was developed. Gold nanoparticles (AuNPs) were synthesized by a modified seed method and characterized using transmission electron microscopy (TEM). AuNPs were bound to MP via covalent bonding to form the MP–AuNPs complex, which increased the RLS intensity of MP at 347 nm (increased by 65.7%). Under optimum conditions, the magnitude of the enhanced RLS intensity for MP–AuNPs was proportional to MP concentration in the range 0.0681–1.702 μg mL^?1. The linear regression equation was represented as follows: ΔI _RLS = 9.31 + 82.42c (r  = 0.9948). The limit of detection (LOD, 3σ) was 3.32 ng mL^?1. The system was applied successfully to detect MP in pharmaceuticals. MP recoveries were 99.9–101.7% with a relative standard deviation (RSD) (n  = 5) of 0.59–0.77% for three synthetic samples, and 97.5–110.0% with an RSD of 0.98–2.10% (n =  5) for tablet samples.     

Resonance light scattering spectrometric study of poly diallyldimethylammonium chloride–antibody–antigen system

The interaction of antigen (Ag) and antibody (Ab) with poly diallyldimethylammonium chloride (PDDA) in aqueous solutions has been studied by optical absorption and resonance light‐scattering (RLS) spectroscopies. The formation of the three‐component‐complex is due to aggregates of Ab or Ag with PDDA by electrostatic interaction and aggregates of Ab with Ag by immunoreaction. The influences of some experimental factors, including incubation time, pH value, concentration of PDDA and concentration of Ab, on the aggregation process have also been studied. A linear relationship between the concentration of Ag and the RLS intensity was found. Under the optimal conditions, for a given concentration of Ab (4.6 µg/mL), the enhancement of RLS intensity is in proportion to the concentration of Ag in the range 0.03–0.83 µg/mL. The RLS could, in combination with immunoassay, be a rapid and sensitive detection method for Ag. Copyright © 2009 John Wiley & Sons, Ltd.     

Determination of sulphite using an immobilized enzyme with flow injection chemiluminescence detection

A ?ow injection method is reported for the determination of sulphite‐based on chemiluminescent detection. Hydro‐gen peroxide is produced from sulphite using on‐line covalently bound immobilized sulphite oxidase packed in a mini‐column, which was mixed downstream and detected via cobalt(II)‐catalysed chemiluminescent oxidation of luminol. The limit of detection (2 × standard deviation of the blank) was 1 × 10^?3 mmol/L with sample throughput 60 h^?1. The calibration data was linear over the range of 0.2–1.0 mmol/L with relative standard deviation (n = 4) in the range 0.9–2.0%. Copyright © 2004 John Wiley & Sons, Ltd.     

Studies on Enantioselective Liquid–Liquid Extraction of Amino‐(4‐nitro‐phenyl)‐acetic Acid Enantiomers: Modeling and Optimization

BINAP‐metal complexes were prepared as extractant for enantioselective liquid–liquid extraction (ELLE) of amino‐(4‐nitro‐phenyl)‐acetic acid (NPA) enantiomers. The influence of process variables, including types of organic solvents and metal precursor, concentration of ligand, pH, and temperature on the efficiency of the extraction, were investigated experimentally. An interfacial reaction model was established for insightful understanding of the chiral extraction process. Important parameters required for the model were determined. The experimental data were compared with model predictions to verify the model prediction, It was found that the interfacial reaction model predicted the experimental results accurately. By modeling and experiment, an optimal extraction condition with pH of 7 and host (extractant) concentration of 1 mmol/L was obtained and high enantioselectivity (α_op) of 3.86 and performance factor (pf) of 0.1949 were achieved. Chirality 26:79–87, 2014. © 2013 Wiley Periodicals, Inc.     

Estimation of the Oxidative Stress and Molecular Damage Caused by 1‐Butyl‐3‐Methylimidazolium Bromide Ionic Liquid in Zebrafish Livers

The present study investigated the toxic effects of 1‐butyl‐3‐methylimidazolium bromide ([C₄mim]Br) in zebrafish livers after exposure to 5–40 mg/L of [C₄mim]Br on days 7, 14, 21, and 28. The results showed that low levels of [C₄mim]Br exposure activated the superoxide dismutase (SOD) activity during early periods of exposure. However, high concentrations (20–40 mg/L) of [C₄mim]Br caused the inhibition of SOD, which, accordingly, led to excess reactive oxygen species and malondialdehyde. The present results indicate that [C₄mim]Br causes oxidative stress in the livers of both male and female zebrafish. Additionally, the DNA damage revealed that [C₄mim]Br has a genotoxic effect on zebrafish livers, even when the concentration of [C₄mim]Br is low (5 mg/L). The DNA damage was demonstrated by quantifying the DNA strand breakage.     

Significant sex difference in the association between C‐reactive protein concentration and anthropometry among 13‐ to 19‐year olds,but not 6‐ to 12‐year olds in Nepal

Life history theory predicts a trade‐off between immunostimulation and growth. Using a cross‐sectional study design, this study aims to test the hypothesis that C‐reactive protein (CRP) is negatively associated with height‐for‐age z‐scores (HAZ scores) and BMI‐for‐age z‐scores (BAZ scores) among 6‐ to 19‐year olds (N = 426) residing in five Nepalese communities. Dried blood spot (DBS) samples were collected and assayed for CRP using an in‐house enzyme immunoassay (EIA). Sex‐ and age‐group‐specific CRP quartiles were used to examine its association with growth in linear mixed‐effects (LME) models. A significant difference was found in the proportion of elevated CRP (>2 mg/L, equivalent to ～3.2 mg/L serum CRP) between 13‐ and 19‐year‐old boys (12%) and girls (4%). Concentrations of CRP were positively associated with HAZ score among adolescent (13–19 years) boys, which may indicate that individuals with greater energy resources have better growth and a better response to infections, thus eliminating the expected trade‐off between body maintenance (immunostimulation) and growth. Adolescent boys with low BAZ and HAZ scores had low CRP values, suggesting that those who do not have enough energy for growth cannot increase their CRP level even when infected with pathogens. Among adolescent girls a positive association was observed between CRP and BAZ scores suggesting the possible effects of chronic low‐grade inflammation due to body fat rather than infection. The association between CRP and growth was less evident among children (6–12 years) compared with adolescents, indicating that the elevated energy requirement needed for the adolescent growth spurt and puberty may play some role. Am J Phys Anthropol 154:42–51, 2014. © 2014 Wiley Periodicals, Inc.     

Enantioseparation of Racemic Flurbiprofen by Aqueous Two‐Phase Extraction With Binary Chiral Selectors of L‐dioctyl Tartrate and L‐tryptophan

A novel method for chiral separation of flurbiprofen enantiomers was developed using aqueous two‐phase extraction (ATPE) coupled with biphasic recognition chiral extraction (BRCE). An aqueous two‐phase system (ATPS) was used as an extracting solvent which was composed of ethanol (35.0% w/w) and ammonium sulfate (18.0% w/w). The chiral selectors in ATPS for BRCE consideration were L‐dioctyl tartrate and L‐tryptophan, which were screened from amino acids, β‐cyclodextrin derivatives, and L‐tartrate esters. Factors such as the amounts of L‐dioctyl tartrate and L‐tryptophan, pH, flurbiprofen concentration, and the operation temperature were investigated in terms of chiral separation of flurbiprofen enantiomers. The optimum conditions were as follows: L‐dioctyl tartrate, 80 mg; L‐tryptophan, 40 mg; pH, 4.0; flurbiprofen concentration, 0.10 mmol/L; and temperature, 25 °C. The maximum separation factor α for flurbiprofen enantiomers could reach 2.34. The mechanism of chiral separation of flurbiprofen enantiomers is discussed and studied. The results showed that synergistic extraction has been established by L‐dioctyl tartrate and L‐tryptophan, which enantioselectively recognized R‐ and S‐enantiomers in top and bottom phases, respectively. Compared to conventional liquid–liquid extraction, ATPE coupled with BRCE possessed higher separation efficiency and enantioselectivity without the use of any other organic solvents. The proposed method is a potential and powerful alternative to conventional extraction for separation of various enantiomers. Chirality 27:650–657, 2015. © 2015 Wiley Periodicals, Inc.     

Anaerobic Hydrogen Production from Sucrose Using an Acid‐Enriched Sewage Sludge Microflora

A novel and high‐rate anaerobic sequencing bath reactor (ASBR) process was used to evaluate the hydrogen productivity of an acid‐enriched sewage sludge microflora at a temperature of 35 °C. In this ASBR process a 4 h cycle, including feed, reaction, settle, and decant steps, was repeatedly performed in a 5 L reactor. The sucrose substrate concentration was 20 g COD/L; the hydraulic retention time (HRT) was maintained at 12–120 h at the initial period and thereafter at 4–12 h. The reaction/settle period ratio, which is the most important parameter for ASBR operation was 1.7. The experimental results indicated that the hydrogenic activity of the sludge microflora was HRT‐dependent and that proper pH control was necessary for a stable operation of the bioreactor. The peak hydrogenic activity value was attained at an HRT of 8 h and an organic loading rate of 80 kg COD/m³ × day. Each mole of sucrose in the reactor produced 2.8 mol of hydrogen and each gram of biomass produced 39 mmol of hydrogen per day. An overly‐short HRT might deteriorate the hydrogen productivity. The concentration ratios of butyric acid to’acetic acid, as well as volatile fatty acid and soluble microbial products to alkalinity can be used as monitoring indicators for the hydrogenic bioreactor.     

Resonance light‐scattering enhancement effect of the protein–Y3+–TTA–SLS system and its analytical application

In this paper, a sensitive resonance light scattering (RLS) method for the determination of protein is reported. In the Tris–HCl (pH 7.50) buffer, protein enhanced the RLS intensity of the Y³⁺–2‐thenoyltrifluoroacetone (TTA)–sodium dodecyl sulphate (SLS) system. The enhanced RLS intensities were in proportion to the concentrations of proteins in the range 8.0 × 10^?9–1.0 × 10^?5 g/mL for BSA, 1.0 × 10^–8–1.0 × 10^?5 g/mL for HSA and 1.0 × 10^–8–1.0 × 10^?6 g/mL for EA, and their detection limits were 5.0, 5.4 and 6.7 ng/mL, respectively. Actual samples were satisfactorily determined. The interaction mechanism was also studied. Copyright © 2008 John Wiley & Sons, Ltd.