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.     

Sensitive determination of 2‐methoxyestradiol in pharmaceutical preparations and serum samples using flow injection chemiluminescence

A rapid and sensitive flow injection chemiluminescence (FI–CL) method is described for the determination of 2‐methoxyestradiol (2ME) based on enhancement of the CL intensity from a potassium ferricyanide–calcein system in sodium hydroxide medium. The optimum conditions for the CL emission were investigated. Under optimized conditions, a linear calibration graph was obtained over the range 1.0 × 10^‐8 to 1.0 × 10^‐6 mol/L (r = 0.998) 2ME with a detection limit (3σ) of 5.4 × 10^‐9 mol/L. The relative standard deviation (RSD) for 5.0 × 10^‐7 mol/L 2ME was 1.7%. As a preliminary application, the proposed method was successfully applied to the determination of 2ME in injection solutions and serum samples. The possible CL mechanism was also proposed. Copyright © 2013 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence of the luminol–potassium periodate system enhanced by TGA–capped CdTe quantum dots for the determination of theophylline

The chemiluminescence (CL) behaviour of the luminol–potassium periodate system enhanced by CdTe quantum dots capped with thioglycolic acid (TGA–CdTe QDs) was studied using kinetic experiments, CL spectra, UV–vis absorption spectra and fluorescence spectra. The production of oxygen‐containing reactant intermediates (O₂^?? and OH^?) in the present CL system was verified by CL. The possible CL mechanism was discussed in detail. Furthermore, theophylline (THP) was determined based on its enhancement of the CL intensity of the CdTe QDs–luminol–potassium periodate system coupled with a flow‐injection technique. Under these optimized conditions, the linear range was found to be from 1.0 × 10^?8 to 1.0 × 10^?5 g/mL with a detection limit of 2.8 × 10^?9 g/mL (3σ). The recoveries for the determination of THP in tablets were from 98.2 to 99.6%.     

Determination of carbamazepine in human urine and serum samples by high‐performance liquid chromatography with post‐column Ru(bipy)‐Ce(SO4)2 chemiluminescence detection

A novel, sensitive and rapid CL method coupled with high‐performance liquid chromatography separation for the determination of carbamazepine is described. The method was based on the fact that carbamazepine could significantly enhance the chemiluminescence of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium(II) in the presence of acid. The chromatographic separation was performed on a Kromasil® (Sigma‐Aldrich) TM RP‐C18 column (id: 150 mm × 4.6 mm, particle size: 5 µm, pore size: 100 Å) with a mobile phase consisting of methanol–water‐glacial acetic acid (70:29:1, v/v/v) at a flowrate of 1.0 mL/min, the total analysis time was within 650 s. Under optimal conditions, CL intensity was linear for carbamazepine in the range 2.0 × 10^?8 ~ 4.0 × 10^?5 g/mL, with a detection limit of 6.0 × 10^?9 g/mL (S/N = 3) and the relative standard detection was 2.5% for 2.0 × 10^?6 g/mL (n = 11). This method was successfully applied to the analysis of carbamazepine in human urine and serum samples. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence determination of olanzapine using N‐chlorosuccinimide–calcein reaction sensitized by zinc (II)

A novel, rapid and sensitive chemiluminescence (CL) method combined with flow‐injection (FI) has been established for the estimation of olanzapine. This method is based on the CL signal generated between N‐chlorosuccinimide and olanzapine in an alkaline medium in the presence of calcein and Zn(II). Under optimum conditions, the CL signal was proportional to the olanzapine concentration ranging from 1.0 × 10^‐10 to 3.0 × 10^‐7 g/mL. The detection limit is 8.9 × 10^‐11 g/mL olanzapine (3σ) and the relative standard deviation for 3.0 × 10^‐9 g/mL of olanzapine is 1.9% (n = 11). The current CL method was applied to determine olanzapine in pharmaceutical formulations and biological fluids with satisfactory results. The possible CL reaction mechanism is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.     

Selective determination of human immunoglobulin G by flow‐injection chemiluminescence

A novel flow‐injection chemiluminescence method was developed for the selective determination of human immunoglobulin G (IgG) in the presence of thiomersal by changing the flow rates of peristaltic pump. The study was based on the independence and additivity of the CL signals of human IgG and thiomersal in the galangin–potassium permanganate–polyphosphoric acid system. In meantime, two equations relating to the concentrations of mixing solutions of human IgG and thiomersal vs the CL intensity were established and solved, on the basis of which the content of thiomersal included in samples was simultaneously determined too. The enhanced CL intensity was in proportion to concerntrations in the range 8.0 × 10^?7 to 8.0 × 10^?5 g/mL for human IgG and 1.0 × 10^?7 to 2.0 × 10^?6 g/mL for thiomersal with the detection limits of 5.0 × 10^?7 g/mL for human IgG and 6.0 × 10^?8 g/mL for thiomersal, respectively. The relative standard deviation for 1.0 × 10^?5 g/mL human IgG was 0.8% and for 2.0 × 10^?7 g/mL thiomersal it was 2.0% (n = 10). The proposed method was applied to determine three synthetic samples with recoveries of 91.5–109.5%. In addition, the possible chemiluminescence mechanisms are discussed as well. Copyright © 2010 John Wiley & Sons, Ltd.     

Chemiluminescence determination of gemifloxacin based on diperiodatoargentate (III)‐sulphuric acid reaction in a micellar medium

A novel flow‐injection chemiluminescence (FI‐CL) analysis method for the determination of gemifloxacin in the presence of cetyltrimethylammonium bromide (CTAB) surfactant micelles is described. Strong CL signal was generated during the reaction of gemifloxacin with diperiodatoargentate (III) in a sulfuric acid medium sensitized by CTAB. Under optimum experimental conditions, the CL intensity was linearly related to the concentration of gemifloxacin from 1.0 × 10^‐9 to 3.0 × 10^‐7 g/mL and the detection limit was 7.3 × 10^‐10 g/mL (3σ). The relative standard deviation (RSD) was 1.7 % for a 3.0 × 10^‐8 g/mL gemifloxacin solution (11 repeated measurements). The proposed method was successfully applied to the determination of gemifloxacin in pharmaceutical preparations and biological fluids. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.     

Flow injection chemiluminescence determination of lercanidipine based on N‐chlorosuccinimide–eosin Y post‐chemiluminescence reaction

A novel post‐chemiluminescence (PCL) reaction was discovered when lercanidipine was injected into the CL reaction mixture of N‐chlorosuccinimide with alkaline eosin Y in the presence of cetyltrimethylammonium bromide (CTAB), where eosin Y was used as the CL reagent and CTAB as the surfactant. Based on this observation, a simple and highly sensitive PCL method combined with a flow injection (FI) technique was developed for the assay of lercanidipine. Under optimum conditions, the CL signal was linearly related to the concentration of lercanidipine in the range 7.0 × 10^‐10 to 3.0 × 10^‐6 g/mL with a detection limit of 2.3 × 10^‐10 g/mL (3σ). The relative standard deviation (RSD) was 2.1% for 1.0 × 10^‐8 g/mL lercanidipine (n = 13). The proposed method had been applied to the estimation of lercanidipine in tablets and human serum samples with satisfactory results. The possible CL mechanism is also discussed briefly. Copyright © 2014 John Wiley & Sons, Ltd.     

Turn‐off–on chemiluminescence determination of cyanide

A flow injection chemiluminescence (FI–CL) method was developed for the determination of cyanide (CN⁻) based on the recovered CL signal by Cu²⁺ inhibiting a glutathione (GSH)‐capped CdTe quantum dot (QD) and hydrogen peroxide system. In an alkaline medium, strong CL signals were observed from the reaction of CdTe QDs and H₂O₂, and addition of Cu²⁺ could cause significant CL inhibition of the CdTe QDs–H₂O₂ system. In the presence of CN⁻, Cu²⁺ can be removed from the surface of CdTe QDs via the formation of particularly stable [Cu(CN)_n]^(n‐1)– species, and the CL signal of the CdTe QDs–H₂O₂ system was efficiently recovered. Thus, the CL signals of CdTe QDs–H₂O₂ system were turned off and turned on by the addition of Cu²⁺ and CN⁻, respectively. Further, the results showed that among the tested ions, only CN⁻ could recover the CL signal, which suggested that the CdTe QDs–H₂O₂–Cu²⁺ CL system had highly selectivity for CN⁻. Under optimum conditions, the CL intensity and the concentration of CN⁻ show a good linear relationship in the range 0.0–650.0 ng/mL (R² = 0.9996). The limit of detection for CN⁻ was 6.0 ng/mL (3σ). This method has been applied to detect CN⁻ in river water and industrial wastewater with satisfactory results. Copyright © 2014 John Wiley & Sons, Ltd.     

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.     

A chelate complex‐enhanced luminol system for selective determination of Co(II), Fe(II) and Cr(III)

A determination method for Co(II), Fe(II) and Cr(III) ions by luminol‐H₂O₂ system using chelating reagents is presented. A metal ion‐chelating ligand complex with a Co(II) ion and a chelating reagent like ethylenediaminetetraacetic acid (EDTA) produced highly enhanced chemiluminescence (CL) intensity as well as longer lifetime in the luminol‐H₂O₂ system compared to metals that exist as free ions. Whereas free Cu(II) and Pb(II) ions had a strong catalytic effect on the luminol‐H₂O₂ system, significantly, the complexes of Cu(II) and Pb(II) with chelating reagents lost their catalytic activity due to the chelating reagents acting as masking agents. Based on the observed phenomenon, it was possible to determine Co(II), Fe(II) and Cr(III) ions with enhanced sensitivity and selectivity using the chelating reagents of the luminol‐H₂O₂ system. The effects of ligand, H₂O₂ concentration, pH, buffer solution and concentrations of chelating reagents on CL intensity of the luminol‐H₂O₂ system were investigated and optimized for the determination of Co(II), Fe(II) and Cr(III) ions. Under optimized conditions, the calibration curve of metal ions was linear over the range of 2.0 × 10^‐8 to 2.0 × 10^‐5 M for Co(II), 1.0 × 10^‐7 to 2.0 × 10^‐5 M for Fe (II) and 2.0 × 10^‐7 to 1.0 × 10^‐4 M for Cr(III). Limits of detection (3σ/s) were 1.2 × 10^‐8, 4.0 × 10^‐8 and 1.2 × 10^‐7 M for Co(II), Fe(II) and Cr(III), respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of a novel chemiluminescence method for the determination of cefazolin sodium in injectable powder and human urine based on a luminol‐Cu(III) complex reaction in alkaline medium

A novel chemiluminescence (CL) method was developed for the determination of cefazolin sodium based on the CL reaction between the [Cu(HIO₆)₂]^5‐Cu(III) complex and luminol in alkaline solution. Results showed that CL emission of Cu(III) complex–luminol in alkaline medium was significantly different from that in acidic medium. A possible mechanism of the enhanced effect of cefazolin on CL emission of the [Cu(HIO₆)₂]^5‐‐ luminol system was proposed. The effect of the reaction conditions on CL emissions was examined. Under optimized conditions, a good linear relationship was obtained between CL intensity and concentrations of cefazolin sodium in the range of 2.0 x 10^‐8 to 2.0 x 10^‐6 g/mL with a correlation coefficient of R² = 0.9978. The limit of detection was 4.58 x 10^‐9 g/mL. The proposed method was applied for the determination of cefazolin sodium in real samples with recoveries of 82.0‐109% with an RSD of 0.7‐2.1%. The proposed method was successfully used for the determination of cefazolin sodium in injectable powder preparations and human urine with satisfactory results. Copyright © 2012 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence determination of haemoglobin in the blood

In this study, a sensitive and simple flow‐injection chemiluminescence (CL) method was developed for the quantitative analysis of haemoglobin. The method is based on the ability of haemoglobin to enhance the CL signal generated by a H₂O₂–K₄Fe(CN)₆–fluorescein alkaline system enhanced by CdTe quantum dots. Under the optimized conditions, haemoglobin can be detected in concentration range 7.35 × 10^–9–2.5 × 10^–6 mol/L, with a detection limit (3σ) of 1.8 × 10^–9 mol/L and a relative standard deviation (RSD; for 5 × 10^–7 mol/L haemoglobin) of 2.06% (n = 11). The present CL method was successfully applied for the determination of haemoglobin in three kinds of blood samples taken from an infant, an adult man, an adult woman and two reference samples. Compared with previous reports, the CL method described in this work is simple and rapid, with high sensitivity. Copyright © 2012 John Wiley & Sons, Ltd.     

Chemiluminescence determination of bromhexine hydrochloride with morin as chemiluminescent reagent

A new chemiluminescence (CL) reaction was observed when cerium(IV) solution was injected into bromhexine hydrochloride–morin solution. Based on this, a flow‐injection CL method for the determination of bromhexine hydrochloride was established. A possible mechanism of the CL reaction was proposed via the investigation of the CL kinetic characteristics, the CL spectrum and the fluorescence spectra of some related substances. Under optimum conditions, the CL signal was correlated linearly with concentration of bromhexine hydrochloride over the range 2.0 × 10^–9–2.0 × 10^–7 g/mL, with a linear correlation of 0.9995. The detection limit was 9 × 10^–10 g/mL bromhexine hydrochloride and the relative standard deviation was 1.0% (c = 2.0 × 10^–8 g/mL bromhexine hydrochloride, n = 11). The method was applied to the determination of bromhexine hydrochloride in pharmaceutical preparations and human urine samples with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Post‐chemiluminescence determination of chloramphenicol based on luminol–potassium periodate system

A post‐chemiluminescence (PCL) phenomenon was observed when chloramphenicol was injected into a mixture of luminol and potassium periodate after the chemiluminescence (CL) reaction of luminol–potassium periodate had finished. The possible reaction mechanism was proposed based on studies of the CL kinetic characteristics, the CL spectra, the fluorescence spectra and the UV‐vis absorption spectra of the related substances. Based on the PCL reaction, a rapid and sensitive method for the determination of chloramphenicol was established. The linear response range was 6.0 × 10^?7–1.0 × 10^?5 mol/L, with a correlation coefficient of 0.9986. The relative standard deviation (RSD) for 5.0 × 10^?6 mol/L chloramphenicol was 2.3% (n = 11). The detection limit was 1.6 × 10^?7 mol/L. The method has been applied to the determination of chloramphenicol in pharmaceutical samples with satisfactory results. Copyright © 2011 John Wiley & Sons, Ltd.     

Chemiluminescence method for the determination of piroxicam by the enhancement of the tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–cerium(IV) system and its application

A simple, rapid chemiluminescence (CL) method was described for the determination of piroxicam, a commonly used analgesic agent drug. A strong CL signal was detected when cerium(IV) sulphate was injected into tris‐(4,7‐diphenyl‐1,10‐phenanthrolinedisulphonic acid) ruthenium(II) (RuBPS)–piroxicam solution. The CL signal was proportional to the concentration of piroxicam in the range 2.8 × 10^–8–1.2 × 10^–5 mol/L. The detection limit was 2 × 10^–8 mol/L and the relative standard deviation (RSD) was 3.7% (c = 7.0 × 10^–7 mol/L piroxicam; n = 11). The proposed method was applied to the determination of piroxicam in pharmaceutical preparations in capsules, spiked serum and urine samples with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly sensitive chemiluminescence determination of tenoxicam using a cerium(IV)–sodium hyposulphite system in micellar medium

A simple, rapid and precise flow‐injection–chemiluminescence (FI–CL) method is presented for the determination of tenoxicam in pharmaceutical preparations and biological samples. The method is based on the weak chemiluminescence signal arising from the reaction of cerium(IV) in a nitric acid medium with sodium hyposulphite being significantly increased by tenoxicam in the presence of sodium dodecyl benzene sulphonate. Several experimental parameters affecting the CL reaction were examined and optimized systematically. Under the optimum conditions, the CL intensity was proportional to the concentration of tenoxicam in the range 7.0 × 10^–11–5.0 × 10^–8 g/mL. The detection limit was 2.3 × 10^–11 g/mL tenoxicam and the relative standard deviation (RSD) was 2.1% for 1.0 × 10^–9 g/mL tenoxicam solution (n = 11). The proposed method was applied to the determination of tenoxicam in pharmaceutical preparations, serum and human urine, with satisfactory results. The possible mechanism of the chemiluminescence reaction is also briefly discussed. Copyright © 2011 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.     

Determination of ferulic acid by flow injection chemiluminescence analysis based on enhancement of the N‐bromobutanimide–eosin–CrCl3 system in alkaline solution

A simple and sensitive flow injection chemiluminescence method has been developed for the determination of ferulic acid (FA) based on the significant enhancement effect of FA on the CL signal of the N‐bromobutanimide (NBS)–eosin–CrCl₃ system in alkaline solution. Under optimum conditions, the enhanced CL intensity is linearly related to the concentration of FA in its pharmaceutical preparations and human plasma samples. The corresponding linear regression equations were established over the 4.0 × 10^–10–1.0 × 10^–7 g/mL for FA tablets and 2.0 × 10^–10–1.0 × 10^–7 g/mL for plasma samples. The limit of detection for FA tablets and limit of quantification for plasma samples were 2.8 × 10^–10 g/mL (3 σ) and 3.04 × 10^–10 g/mL (10 σ), respectively. A complete analysis could be performed within 40 s, including washing and sampling, giving a throughput of ≈90/h. The proposed method was successfully applied to the determination of FA in pharmaceutical preparations and human plasma samples with satisfactory results. The recoveries of pharmaceutical preparations and human plasma samples at three different concentrations were 97.8–102.6% and 96.7–104.0%, respectively. Furthermore, the possible mechanism of CL reactions was also discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.     

The behaviors of metal ions in the CdTe quantum dots–H2O2 chemiluminescence reaction and its sensing application

The behaviors of 15 kinds of metal ions in the thiol‐capped CdTe quantum dots (QDs)–H₂O₂ chemiluminescence (CL) reaction were investigated in detail. The results showed that Ag⁺, Cu²⁺ and Hg²⁺ could inhibit CdTe QDs and H₂O₂ CL reaction. A novel CL method for the selective determination of Ag⁺, Cu²⁺ and Hg²⁺ was developed, based on their inhibition of the reaction of CdTe QDs and H₂O₂. Under the optimal conditions, good linear relationships were realized between the CL intensity and the logarithm of concentrations of Ag⁺, Cu²⁺ and Hg²⁺. The linear ranges were from 2.0 × 10^?6 to 5.0 × 10^?8 mol L^?1 for Ag⁺, from 5.0 × 10^?6 to 7.0 × 10^?8 mol L^?1 for Cu²⁺ and from 2.0 × 10^?5 to 1.0 × 10^?7 mol L^?1 for Hg²⁺, respectively. The limits of detection (S/N = 3) were 3.0 × 10^?8, 4.0 × 10^?8 and 6.7 × 10^?8 mol L^?1 for Ag⁺, Cu²⁺ and Hg²⁺, respectively. A possible mechanism for the inhibition of CdTe QDs and H₂O₂ CL reaction was also discussed. Copyright © 2009 John Wiley & Sons, Ltd.