Sensitive determination of epinephrine in pharmaceutical preparation by flow injection coupled with chemiluminescence detection and mechanism study

A novel, rapid and sensitive method was described for the determination of epinephrine (EP) using flow injection analysis coupled with chemiluminescence (CL) detection, which based on EP enhanced the weak CL emission of luminol–KIO₄ system in NaOH solution. Parameters affecting the CL intensity and reproducibility were optimized systematically. Under the optimized experiment conditions, the net CL intensity was proportional to the concentration of EP in the range of 5.0 × 10^?8 to 1.5 × 10^?6 mol/L with a detection limit of 1.9 × 10^?9 mol/L. The relative standard deviation (RSD) was found to be 0.7% for 13 replicate determinations of 3.0 × 10^?7 mol/L EP. The applicability of the proposed method was illustrated in the determination of EP in pharmaceutical preparation. The recoveries of EP at different levels in EP hydrochloride injection were between 95.4 and 104.7%. One assay procedure takes only 27 s, and the sampling rate was calculated about to be 130 samples/h. The possible mechanism of the enhanced CL intensity was studied by examining CL spectra and UV–vis spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

A flow injection chemiluminescence method for the determination of lincomycin in serum using a diperiodato-cuprate (III)-luminol system

In this paper, the novel trivalent copper–periodate complex {K₅[Cu(HIO₆)₂], DPC} has been applied in a luminol‐based chemiluminescence (CL) reaction. Coupled with flow injection (FI) technology, the FI‐CL method was proposed for the determination of lincomycin hydrochloride. The CL reaction between luminol and DPC occurred in an alkaline medium. The CL intensity could be greatly enhanced by lincomycin hydrochloride. The relative CL intensity was proportional to the concentration of lincomycin hydrochloride in the range of 1 × 10^?8 to 5 × 10^?6 g mL^?1 and the detection limit was at the 3.5 × 10^?9 g mL^?1 level. The relative standard deviation at 5 × 10^?8 g mL^?1 was 1.7% (n = 9). The sensitive method was successfully applied to the direct determination of lincomycin hydrochloride (ng mL^?1) in serum. A possible mechanism of the lumonol–DPC CL reaction was discussed by the study of the CL kinetic characteristics and the spectra of CL reaction. The oxidability of DPC was studied by means of its electrochemical response. Copyright © 2010 John Wiley & Sons, Ltd.     

High‐sensitivity spectrofluorimetric determination of tiopronin based on inhibition of hemoglobin

A highly sensitive and simple spectrofluorimetric method for the determination of tiopronin based on its inhibitory effect on the hemoglobin‐catalyzed reaction of H₂O₂ and l ‐tyrosine was developed. The concentration of tiopronin is linear with decreased fluorescence (ΔF) of the system under the optimal experimental conditions. The calibration graph is linear in the range 1.23 × 10^?8 to 3.06 × 10^?5 mol L^?1 with a detection limit of 6.13 × 10^?9 mol L^?1. The relative standard deviation was 4.38% for 11 determinations of 6.13 × 10^?6 mol L^?1. This method can be used for the determination of tiopronin in pharmaceuticals with satisfactory results. Copyright © 2010 John Wiley & Sons, Ltd.     

New luminol chemiluminescence reaction using diperiodatoargentate as oxidate for the determination of amikacin sulfate

A new chemiluminescence (CL) reaction between luminol and diperiodatoargentate {K₂ [Ag (H₂IO₆) (OH) ₂]} was observed in alkaline medium. The CL intensity could be greatly enhanced by amikacin sulfate. Therefore a new CL method for the determination of amikacin sulfate was built by combining with flow injection technology. A possible mechanism of the CL reaction was proposed via the investigation of the CL kinetic characteristics, the CL spectrum and the UV absorption spectra of some related substance. The concentration range of linear response was 5.1 × 10^?8 to 5.1 × 10^?6 mol L^?1 with a detection limit of 1.9 × 10^?8 mol L^?1 (3σ). The proposed method had good reproducibility with a relative standard deviation of 2.8% (n = 7) for 5.1 × 10^?7 mol L^?1 of amikacin sulfate. It was successfully applied to determine amikacin sulfate in serum. Copyright © 2009 John Wiley & Sons, Ltd.     

Catalytic properties of three lactate dehydrogenases from potato tubers (Solanum tuberosum)

Two l-lactate dehydrogenase isoenzymes and one dl-lactate dehydrogenase could be separated from potato tubers by polyacrylamide-gel electrophoresis. The enzymes are specific for lactate, while β-hydroxybutyric acid, glycolic acid, and glyoxylic acid are not oxidized. Their pH optima are pH 6.9 for the oxidation and 8.0 for the reduction reaction.The K_m values for l-lactate for the two isoenzymes are 2.00 × 10^?2 and 1.82 × 10^?2, m. In the reverse reaction the affinities for pyruvate are 3.24 × 10^?4 and 3.34 × 10^?4, m. Both enzymes have similar affinities for NAD and NADH (3.00 × 10^?4; 4.00 × 10^?4, and 8.35 × 10^?4; 5.25 × 10^?4, m).The dl-lactate oxidoreductase may transfer electrons either to NAD or N-methyl-phenazinemethosulfate. The K_m values of this enzyme for l-lactate are 4.5 × 10^?2, m and for d-lactate 3.34 × 10^?2, m. Its affinity for pyruvate is 4.75 × 10^?4, m. The enzyme is inhibited by excess NAD (K_m = 1.54 × 10^?4, M) and has an affinity toward NADH (K_m = 5.00 × 10^?3, M) which is about one tenth of that of the two isoenzymes of l-lactate dehydrogenase.     

The determination of glutamine with flow‐injection chemiluminescence detection and mechanism study

The main purpose of this study was to develop an inexpensive, simple, rapid and sensitive chemiluminescence (CL) method for the determination of glutamine (Gln) using a flow‐injection (FI) system. Gln was found to strongly inhibit the CL signal of the luminol–H₂O₂–CuSO₄ system in Na₂B₄O₇ solution. A new FI‐CL method was developed for the determination of Gln. Parameters affecting the reproducibility and CL detection were optimized systematically. Under the optimized conditions, the corresponding linear regression equation was established over the range of 5.0 × 10^?7 to 2.5 × 10^?6 mol/L with the detection limit of 1.8 × 10^?8 mol/L. The relative standard deviation was found to be 1.8% for 11 replicate determinations of 1.5 × 10^?6 mol/L Gln. The proposed method has been satisfactorily applied for the determination of Gln in real samples (Marzulene‐s granules) with recoveries in the range of 98.7–108.6%. The minimum sampling rate was about 100 samples/h. The possible mechanism of this inhibitory CL was studied by fluorescence spectrophotometer and UV–vis spectrophotometer. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence method for the determination of chloramphenicol based on luminol–sodium periodate order‐transform second‐chemiluminescence reaction

A new chemiluminescence (CL) reaction was observed when chloramphenicol solution was injected into the mixture after the end of the reaction of alkaline luminol and sodium periodate or sodium periodate was injected into the reaction mixture of chloramphenicol and alkaline luminol. This reaction is described as an order‐transform second‐chemiluminescence (OTSCL) reaction. The OTSCL method combined with a flow‐injection technique was applied to the determination of chloramphenicol. The optimum conditions for the order‐transform second‐chemiluminescence emission were investigated. A mechanism for OTSCL has been proposed on the basis of the chemiluminescence kinetic characteristics, the UV‐visible spectra and the chemiluminescent spectra. Under optimal experimental conditions, the CL response is proportional to the concentration of chloramphenicol over the range 5.0 × 10^?7–5.0 × 10^?5 mol/L with a correlation coefficient of 0.9969 and a detection limit of 6.0 × 10^?8 mol/L (3σ). The relative standard deviation (RSD) for 11 repeated determinations of 5.0 × 10^?6 mol/L chloramphenicol is 1.7%. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.     

A novel method for sensing of methimazole using gold nanoparticle‐catalyzed chemiluminescent reaction

Based on the inhibition effect of methimazole (MMI) on the reaction of luminol–H₂O₂ catalyzed by gold nanoparticles, a novel chemiluminescence (CL) method was developed for the determination of MMI. Under the optimum conditions, the relative CL intensity was linearly related to MMI concentration in the range from 5.0 × 10^?8 to 5.0 × 10^?5 mol L^?1. The detection limit was 1.6 × 10^?8 mol L^?1 (S/N = 3), and the RSD for 6.0 × 10^?6 mol L^?1 MMI was 4.83 (n = 11). This method has high sensitivity, wide linear range, inexpensive instrumentation and has been applied to detect MMI in pharmaceutical tablets and pig serum samples. Furthermore, a possible reaction mechanism is discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Chemiluminescence determination of naproxen based on europium(III)‐sensitized KIO4–H2O2 reaction

A simple and sensitive chemiluminescence (CL) method combined with flow injection technique was developed for the determination of naproxen. It was based upon the weak CL signal arising from the reaction of KIO₄ with H₂O₂ being significantly increased by naproxen in the presence of europium(III) ion. The experimental conditions that affected the CL signal were carefully optimized and the CL reaction mechanism was briefly discussed. Under the optimum conditions, the increment of CL intensity was proportional to the concentration of naproxen ranging from 5.0 × 10^?8 to 5.0 × 10^?6 g/mL. The detection limit was 1 × 10^?8 g/mL naproxen and the relative standard deviation for 5.0 × 10^?7 g/mL naproxen solution was 2.1% (n = 11). The proposed method was applied to the determination of naproxen in tablets and in spiked human urine samples with satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.     

Improved assay for NADH dehydrogenase of the respiratory chain

The ferricyande assay for Type I NADH dehydrogenase (high molecular weight soluble form) was evaluated. A turnover number of 4.2 × 10⁵ min^?1, based on V_max(ferricyanide) and FMN content, and K_m(ferricyanide) of 2.2 mM were determined for this enzyme. Inclusion of a NAD-recycling system consisting of alcohol dehydrogenase and ethanol is suggested for determination of K_m(NADH). This K_m was found to be 17 μ M in contrast to earlier reported values of around 100 μ M.     

Determination of tannic acid in industrial wastewater based on chemiluminescence system of KIO4–H2O2–Tween40

The oxidation reaction of H₂O₂ with KIO₄ can produce chemiluminescence (CL) in the presence of the surfactant Tween40 and the CL intensity of the CL system KIO₄–H₂O₂–Tween40 can be strikingly enhanced after injection of tannic acid. On this basis, a flow injection method with CL detection was established for the determination of tannic acid. The method is simple, rapid and effective to determine tannic acid in the range of 7.0 × 10^?9 to 1.0 × 10^?5 mol/L with a determination limit of 2.3 × 10^?9 mol/L. The relative standard deviation is 2.6% for the determination of 5.0 × 10^?6 mol/L tannic acid (n = 11). The method has been applied to determine the content of tannic acid in industrial wastewater with satisfactory results. It is believed that the CL reaction formed singlet oxygen ¹O₂* and the emission was from an excited oxygen molecular pair O₂(¹Δ_g)O₂(¹∑^?_g) in the KIO₄–H₂O₂–Tween40 reaction. Tween40 played an important role in enhancing stabilization of the excited oxygen molecular pair O₂(¹Δ_g)O₂(¹∑^?_g) and in increasing CL intensity. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of free cholesterol based on a novel flow‐injection chemiluminescence method by immobilizing enzyme

A novel flow injection chemiluminescence method is proposed for determination of cholesterol in this paper. The cholesterol oxidase was immobilized onto sol–gel and prepared as an enzymatic reaction column. The determination of cholesterol was performed by quantitative determination of hydrogen peroxide produced from an enzymatic reaction. The luminol–H₂O₂–metal chelate diperiodatocuprate(III) system ensured that the method was highly sensitive and selective. Free cholesterol was determined over the range 5.0 × 10^–8 mol/L–5.0 × 10^–7 mol/L, with a limit of detection (3σ) of 1.9 × 10^–8 mol/L. The relative standard deviation (RSD) for 2.5 × 10^–7 mol/L was 2.7% (n = 7). The proposed method offered the advantages of sensitivity, selectivity, simplicity and rapidity for free cholesterol determination, and was successfully applied to the direct determination of free cholesterol in serum. Copyright © 2008 John Wiley & Sons, Ltd.     

Flow injection chemiluminescence determination of naphazoline hydrochloride in pharmaceuticals

A simple and sensitive flow injection chemiluminescence (FI‐CL) method was developed for the determination of naphazoline hydrochloride (NPZ). The method is based on the enhancing effect of NPZ on the weak CL signal from the reaction of KIO₄ with H₂O₂. Experimental parameters that affected the CL signal, including the pH of the KIO₄ solution, concentrations of KIO₄, H₂O₂ and disodium‐EDTA and flow rate were optimized. Under the optimum conditions, the increment of CL intensity was linearly proportional to the concentration of NPZ in the range 5.0 × 10^?6 to 70 × 10^?6 mol/L. The detection limit was 1.0 × 10^?6 mol/L and the relative standard deviation for 50 × 10^?6 mol/L NPZ solution was 2.8% (n = 11). In addition, a high throughput of 120 samples/h was achieved. The utility of this method was demonstrated by determining NPZ in pharmaceuticals. Copyright © 2013 John Wiley & Sons, Ltd.     

Determination of trace amounts of dopamine by flow‐injection analysis coupled with luminol–Ag(III) complex chemiluminescence detection

A novel flow injection analysis‐direct chemiluminescence (FI‐CL) method has been developed for determination of trace amounts of dopamine (DA) based on the enhancing effect of DA on the CL reaction of luminol with an Ag(III) complex in alkaline solution. Under optimum conditions, CL intensities are proportional to the concentration of DA in the range of 1.0 × 10^?10 to 4.0 × 10^?8 mol L^?1. The detection limit is 3.0 × 10^?11 mol L^?1 for DA (3s), with a relative standard deviation (n = 13) of 2.3% for 1.0 × 10^?8 mol L^?1 DA. This method has also been applied for the determination of DA in commercial pharmaceutical injection samples. On the basis of the CL spectra and the results of the free‐radical trapping experiment of this work, a reaction mechanism for this CL reaction is proposed and discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Multiway analysis applied to time‐resolved chemiluminescence for simultaneous determination of paracetamol and codeine in pharmaceuticals

This method is based on the enhancing effect of codeine (COD) and paracetamol (PAR) on the chemiluminescence (CL) reaction of Ru(phen)₃²⁺ with Ce(IV). In the batch mode, COD gives a relatively sharp peak with the highest CL intensity at 4.0 s, whereas the maximum CL intensity of the PAR appears at ~60 s after injection of Ce(IV) solution. Whole CL time profiles allowed use of the time‐resolved CL data in combination with multiway calibration techniques, as multiway partial least squares (N‐PLS), for the quantitative determination of both COD and PAR in binary mixtures. In this work, we found that the impact of Ce(IV) concentration on the CL intensity was different for COD and PAR. Therefore, a Ce(IV) concentration mode was added to the time and sample modes to obtain 3D data. The percent relative standard deviation (%RSD) values for 10 determinations of 1.0 × 10^?5 mol/L of COD and 1.0 × 10^?4 mol/L of PAR were 6.1% and 8.7%, respectively. The limit of detection (LOD) values (S/N = 3) were 0.9 × 10^?8 mol/L and 1.0 × 10^?6 mol/L for COD and PAR, respectively. The proposed method was successfully applied to the determination of PAR and COD in commercial pharmaceutical formulations. Acceptable recoveries (90–110%) were obtained for the quantification of these drugs in the real samples. Copyright © 2016 John Wiley & Sons, Ltd.     

Bull semen nicotinamide adenine dinucleotide nucleosidase. VI. Fluorescence studies of the enzyme with reduced nicotinamide adenine dinucleotide

The binding of NADH to bull semen NAD nucleosidase was observed to be accompanied by a considerable enhancement of the fluorescence of NADH. The fluorescence enhancement observed in the binding of NADH to the enzyme was utilized to study the stoichiometry of binding of this compound to the enzyme. Results obtained from the fluorescence titration of the enzyme with NADH indicated the binding of one mole of NADH per mole of enzyme (36,000 g). The dissociation constant for the enzyme-NADH complex was determined to be 2.52 × 10^?6m. NADH was also found to be a very effective competitive inhibitor of the NADase-catalyzed hydrolysis of NAD, and the inhibitor dissociation constant (K_I) for the enzyme-NADH complex was determined to be 2.99 × 10^?6m which was in good agreement with the value obtained from the fluorescence titration experiments.     

Mannitol Biosynthesis in Pyrenochaeta terrestris I. D-Maunitol-1-Phosphate: NAD Oxidoreductase

Cell-free extracts of mycelial mats of Pgrenochaeta terrestris grown in stationary culture on synthetic glucose or sucrose - salts liquid media contained D-mannitol-1-Phosphate:NAD oxidoreductase (EC 1.1.1.17) activity. Greatest activity occurred early in the growth period. The optimum pH for the reduction of NAD⁺ in the presence of Fru-6-P was 7.4–7.5 while the optimum pH for the oxidation of NADH in the presence of Mtl-1-P was 8.1–8.2. The enzyme was stabilized to some extent in Tris-maleate buffer, pH 7.5, and by the addition of 10% (NH₄)₂SO₄, to this buffer. A 10- to 16-fold purification was attained by a combination of (NH₄)₂SO₄ fractionation and gel filtration on Sephadex G-100. The enzyme was relatively specific in its substrate and coenzyme requirements. The Km values were determined as: Fru-6-P - 3 × 10^?4 M, Mtl-1-P - 1 × 10^?4 M, and NAD⁺ and NADH - 3 × 10^?5 M.     

A novel system of galangin–potassium permanganate–polyphosphoric acid for the determination of tryptophan and its chemiluminescence mechanism

A novel galangin–potassium permanganate (KMnO₄)–polyphosphoric acid (PPA) system was found to have an outstanding response to tryptophan (Trp). Trp determination using this KMnO₄–PPA system was enhanced significantly in the presence of galangin. A highly sensitive flow‐injection chemiluminescence (CL) method to determine Trp was developed based on the CL reaction of galangin–KMnO₄–Trp in PPA media. The presence of galangin, a member of the flavonol class of flavonoid complexes, greatly increased the luminous intensity of Trp in KMnO₄–PPA systems. Under optimized conditions, Trp was determined in the 0.05–10 µg/mL range, with a detection limit (3σ) of 5.0 × 10^?3 µg/mL. The relative standard deviation (RSD) was 1.0% for 11 replicate determinations of 1.0 µg/mL Trp. Two synthetic samples were determined selectively with recoveries of 98.4–100.1% in the presence of other amino acids. The possible mechanism is summarized as follows: excited states of Mn(II)^* and Mn(III ^* types are the main means of generating chemical luminescent species, and Trp concentration and luminescence intensity have a linear relationship, which enables quantitative analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence determination of diazepam by oxidation with N‐bromosuccinimide

A rapid and sensitive flow‐injection chemiluminescence (FI–CL) method is described for the determination of diazepam based on its reaction with N‐bromosuccinimide (NBS) in alkaline medium in the presence of dichlorofluorescein (DCF) as an effective energy‐transfer agent. Under optimum conditions, the proposed method allowed the measurement of diazepam over the range of 2.0 × 10^?6 to 2.0 × 10^?4 mol/L with a detection limit of 5.0 × 10^?7 mol/L. The relative standard deviation for 11 parallel measurements of 2.0 × 10^?5 mol/L diazepam was 2.1%. The method was applied satisfactorily for the determination of diazepam in pharmaceutical preparations, and the results agree well with those obtained by spectrophotometry. The use of the proposed system for the determination of diazepam in urine and plasma samples was also tested. The possible mechanism of the chemiluminescence reaction is discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.     

Flow injection assays for NADH and ethanol using photosensitized rose bengal and luminol–copper (II) chemiluminescence system

The online photoreaction of the rose bengal photosensitized luminol–copper (II) chemiluminescence (CL) system was used for the determination of β-nicotinamide adenine dinucleotide (NADH) and ethanol (EtOH) in pharmaceutical formulations combined with a flow injection technique. NADH can significantly enhance the CL emission of the reaction. For EtOH, alcohol dehydrogenase in soluble form was utilized in the presence of nicotinamide adenine dinucleotide resulting in NADH production. The limit of detection (3σ blank, 𝑛 = 3) of 4.0 × 10⁻⁸ and 2.17 × 10⁻⁵ M, and linear range 1.3 × 10⁻⁷ to 2.5 × 10⁻⁵ M (R² = 0.9998, n = 6) and 0.11–2.17 × 10⁻³ M (R² = 0.9996, n = 6) were obtained for NADH and EtOH respectively. The injection rate was 100 h⁻¹ with a relative standard deviation (n = 3) of 1.5–4.8% in the range studied for both analytes. The procedure was satisfactorily applied to pharmaceutical formulations with recoveries in the range 91.6 ± 3.0% to 110 ± 2.0% for NADH and 88 ± 3.0% to 95.4 ± 4.0% for EtOH. The results obtained were very consistent and did not differ considerably from the reported approaches at a 95% confidence limit. The possible mechanism of the CL reaction is also explained briefly.