Determination of bisphenol A using a flow injection inhibitory chemiluminescence method.

A new flow injection chemiluminescence (CL) method has been developed for the determination of bisphenol A (BPA), based on the inhibitory effect of BPA on the chemiluminescence reaction between luminol and potassium hexacyanoferrate. Under optimum conditions, the decrease in CL emission intensity was linear with BPA concentration in the range 8.0 x 10(-7)-1.2 x 10(-5) mol/L, and the detection limit was 3.1 x 10(-7) mol/L. The relative standard deviation (RSD) of 11 replicate measurements was 2.6% for 2.0 x 10(-6) mol/L BPA (n = 11). The sampling frequency was calculated to be ca. 120/h. This method has been successfully used to determine the content of BPA in aqueous solution of polycarbonate materials. A brief discussion on the possible chemiluminescence reaction mechanism is presented.     

Determination of cardamonin using a chemiluminescent flow-injection method

A sensitive and selective flow injection chemiluminescence method for the determination of cardamonin over the range 1.0 x 10(-8) to 8.0 x 10(-6) g/mL is described. The method is based on the enhancement by cardamonin of the chemiluminescence of the reaction between cerium (IV) and rhodamine 6G in sulphuric acid medium. The optimised flow injection procedure yielded a detection limit for cardamonin of 8.8 x 10(-9) g/mL, whilst the relative standard deviations of intraday and inter-day precision were below 2.5%. The method has the advantages of high sensitivity and a wide linear range. It was successfully applied to the determination of cardamonin in Alpinia katsumadai Hayata. The mechanism of the chemiluminescence reaction is proposed.     

Study of the catalytic effect of PAR on the luminol-potassium ferricyanide reaction using a flow-injection chemiluminescence method.

We discovered that 4-(2-pyridylazo) resorcinol (PAR) has a strong catalytic effect on luminol-potassium ferricyanide chemiluminescence (CL). Results indicated that the chemiluminescence intensities at maximum light emission were linearly corrected with the concentration of PAR over the range 1.0 x 10(-5)-1.0 x 10(-7) mol/L. A detection limit of 5.7 x 10(-8) mol/L for PAR was achieved. It was found that some metal ions strongly affected this catalytic reaction. Based on this finding, the luminol-potassium ferricyanide-PAR reaction was developed for the determination of metal ions. The detection limits (S/N = 3) for Ni2+, Cr3+, Zn2+, Co2+ and Mn2+ were determined to be 1.0 x 10(-9) mol/L, 5.0 x 10(-9) mol/L, 5.0 x 10(-8) mol/L, 1.0 x 10(-9) mol/L and 1.0 x 10(-8) mol/L, respectively. In addition, the relative standard deviation values for these metal ion assays were in the range 0.82-2.72% (n = 6).     

An assay for inorganic mercury(II) based on its post-catalytic enhancement effect on the potassium permanganate-luminol system.

A strong chemiluminescence (CL) response is observed when potassium permanganate solution is injected into basic luminol solution. When the CL reaction terminates, subsequent injection of Hg2+ solution into the reaction mixture results in a new CL reaction. Based on the post-catalytic enhancement effect of Hg2+ on the potassium permanganate-luminol system in basic media, a fast and simple CL-coupled flow injection analysis for the determination of Hg2+ was developed. In optimum conditions, CL intensity is proportional to Hg2+ concentration over the range 1.0 x 10(-8)-1.0 x 10(-5) g/mL, with a detection limit of 2.0 x 10(-9) g/mL. The relative standard deviation (RSD) is 3.6% for 1.0 x 10(-7) g/mL Hg2+ (n = 11). After pretreatment with sulphydryl cotton fibre, environmental water samples were analysed by the proposed method for total mercury determination with satisfactory results. The results were in good agreement with those given by hydride generation-cold vapour atomic absorption spectrometry (HG-CVAAS).     

Flow injection–chemiluminescence determination of acyclovir

The chemiluminescence (CL) reaction of acyclovir (ACV)–potassium permanganate, with formaldehyde as an enhancer, was investigated by the flow‐injection system, and a new method is reported for the determination of ACV on the basis of the reaction. The method is rapid, effective and simple for the determination of acyclovir in the range 0.2–80 mg/L, with a limit of detection of 0.06 mg/L (3 S:N), a relative standard deviation (RSD) of 3.7% for the determination of 1.0 mg/L acyclovir solution in 11 repeated measurements. The method has been applied to the determination of acyclovir in pharmaceuticals, with satisfactory results. The possible reaction mechanism is also discussed briefly. Copyright © 2011 John Wiley & Sons, Ltd.     

Determination of parathion residues in rice samples using a flow injection chemiluminescence method

A sensitive ?ow injection chemiluminescence method is described for the determination of parathion pesticide, based upon its direct chemiluminescence reaction with luminol and hydrogen peroxide in the presence of non‐ionic surfactant polyethylene glycol 400. Under the selected experimental conditions, the concentration of parathion is proportional to the CL intensity in the range 0.02–1.0 mg/L. The detection limit was 0.008 mg/L and the relative standard deviation was 2.8% for 0.2 mg/L parathion solution (n = 11). This method was successfully applied to the determination of parathion residue in rice samples. Copyright © 2003 John Wiley & Sons, Ltd.     

A sensitive inhibition chemiluminescence method for the determination of trace tannic acid using the reaction of luminol-hydrogen peroxide catalysed by tetrasulphonated manganese phthalocyanine.

A novel CL method for the determination of tannic acid (TA) was established based on TA inhibition of the chemiluminescence (CL) emission of the luminol-hydrogen peroxide CL system catalysed by tetrasulphonated manganese phthalocyanine (MnTSPc) under alkaline conditions. The peak height is proportional to the natural logarithm of concentration of TA in the range 1.0 x 10(-7)-3.0 x 10(-10) mol/L with a detection limit of 5.6 x 10(-11) mol/L and the relative standard deviation was 2.5% for the determination of 1.0 x 10(-8) mol/L TA (n = 11). The proposed method has been successfully applied to the determination of TA in Chinese gall and industrial wastewater.     

Determination of oxytetracycline by flow injection with chemiluminescence detection.

A flow-injection chemiluminescent method for the determination of oxytetracycline was developed. The method is based on an enhancement by oxytetracycline of the chemiluminescence light emission of tris(2,2'-bipyridine) ruthenium (II), generated by the continuous oxidation of tris(2,2'-bipyridine) ruthenium (II) by cerium (IV) sulphate in sulphuric acid. Under the optimum conditions, the calibration curve was linear over the range 1.0 x 10(-7)-1.0 x 10(-5) g/mL for oxytetracycline with the linear equation: DeltaINT = 148.77 x C + 0.6637 (R2 = 0.9994). The detection limit was 4.52 x 10(-8) g/mL. The proposed method was also successfully used to determine oxytetracycline in pharmaceutical formulations. The mean recovery of determination of oxytetracycline was 92.73%. A mechanism for the chemiluminescence enhancement by oxytetracycline of tris(2,2'-bipyridine)-ruthenium (II) and cerium (IV) sulphate system is also proposed.     

Chemiluminescence behaviour of CdTe–potassium permanganate enhanced by sodium hexametaphosphate and sensitized sensing of l‐ascorbic acid

A highly sensitive flow‐injection chemiluminescence (FIA‐CL) method based on the CdTe nanocrystals and potassium permanganate chemiluminescence system was developed for the determination of l ‐ascorbic acid. It was found that sodium hexametaphosphate (SP), as an enhancer, could increase the chemiluminescence (CL) emission from the redox reaction of CdTe quantum dots with potassium permanganate in near‐neutral pH conditions. l ‐Ascorbic acid is suggested as a sensitive enhancer for use in the above energy‐transfer excitation process. Under optimal conditions, the calibration graph of emission intensity against logarithmic l ‐ascorbic acid concentration was linear in the range 1.0 × 10^?9–5.0 × 10^?6 mol/L, with a correlation coefficient of 0.9969 and relative standard deviation (RSD) of 2.3% (n = 7) at 5.0 × 10^?7 mol/L. The method was successfully used to determine l ‐ascorbic acid in vitamin C tablets. The possible mechanism of the chemiluminescence in the system is also discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Chemiluminescence determination of fluoroquinolone antibiotics using a soluble manganese (IV)-sulphite system.

The reaction of soluble manganese (IV) with sulphite in acidic condition was found to elicit weak chemiluminescence (CL). The CL signal was remarkably enhanced in the presence of three fluoroquinolones, viz. norfloxacin, ofloxacin and ciprofloxacin. Based on these observations, a new flow-injection CL method was developed for the determination of these fluoroquinolones. The method allows determination in the range 5.0 x 10(-8)-1.0 x 10(-6) mol/L for norfloxacin, 1.0 x 10(-7)-8.0 x 10(-6) mol/L for ofloxacin and 1.0 x 10(-7)-3.0 x 10(-5) mol/L for ciprofloxacin, with detection limits of 3 x 10(-8) mol/L, 5 x 10(-8) mol/L and 3 x 10(-8) mol/L, respectively. The method was applied to the determination of fluoroquinolones in pharmaceutical preparations.     

Oxidative stress of liver in hamsters infected with Leishmania (L.) chagasi

Oxidative stress as a mediator of hepatic tissue damage concurrent with Leishmania (L.) chagasi infection was investigated. Chemiluminescence in liver supernatant of hamsters infected with Leishmania (L.) chagasi showed a ratio of 1.53/ mg protein and 2.10/liver weight 90 days after infection when compared with the control. The malondialdehyde (MDA) levels also increased significantly both with and without addition of Fe3+/ascorbic acid in the reaction mixture, with a ratio of 2.12 and 1.55/mg protein or 2.91 and 2.12/liver weight, respectively. The parasite burden in the spleen, as a measure of infection severity, was 9.1+/-1.33 x 10(8) parasites/organ. On the 10th day of infection, the chemiluminescence also was significantly higher in infected hamsters than in the controls (ratio = 1.36/mg protein or 1.34/liver weight); however, the MDA levels were not different from those of controls. After 90 days of infection, significant correlations were observed between chemiluminescence and MDA concentration with and without the presence of Fe3+/ascorbic acid (r = 0.54, P = 0.0001; r = 0.56, P = 0.0001; respectively). The high infection/control ratio of both chemiluminescence and MDA concentration and the significant correlation between those events strongly indicate the occurrence of oxidative stress and lipid peroxidation as a mechanism of liver damage in cases of chronic infection by L. chagasi. The significant increase in chemiluminescence at 10 days of infection demonstrates that oxidative stress occurs very early, first consuming the antioxidants and then inducing lipid peroxidative damage later in the chronic stage of this disease.     

Investigation on the interaction between dihydroxybenzene and Fe3+- H2O2-Rh6G system based on enhancing chemiluminescence.

A highly sensitive flow-injection chemiluminescence (FI-CL) method has been developed for the determination of dihydroxybenzene, based on the hydroxyl radical reaction. Hydroxyl radical (.OH) produced by the reaction of Fe(3+) and H(2)O(2) oxidize rhodamine 6G to produce weak CL. It was observed that catechol and hydroquinone greatly enhanced the weak CL reaction. However, the proposed CL system is not suitable for determination of resorcinol because the enhancement reaction is very slow. The proposed procedure has a linear range of 0.01-2 mg/L for catechol, with a detection limit of 0.006 mg/L, and 0.008-1 mg/L for hydroquinone, with a detection limit of 0.004 mg/L. The possible mechanism of the CL system is discussed.     

A study on the micelle-sensitized Ce(IV)-Na2S2O3-norfloxacin chemiluminescence system and its applications.

A new chemiluminescence (CL) flow-injection method was developed for the determination of norfloxacin. The method is based on the CL reaction of norfloxacin with sodium thiosulphate and Ce(IV) in sulphuric acid medium sensitized by sodium dodecylsulphate. Under optimum conditions, the CL intensity is proportional to the concentration of the norfloxacin in the range 3.89 x 10(-8)-7.18 x 10(-6) g/mL. The detection limit (3 s/k) was 2.21 x 10(-9) g/mL for norfloxacin. The method has been applied successfully to the determination of norfloxacin in pharmaceutical formulations and human urine. The mechanism for this chemiluminescence system is discussed.     

A novel chemiluminescence method for the determination of orciprenaline based on ferricyanide-rhodamine 6G.

A novel flow injection chemiluminescence method for the determination of orciprenaline was developed. The method is based on the chemiluminescence (CL) reaction of orciprenaline with potassium ferricyanide in sodium hydroxide medium, sensitized by the fluorescent dye rhodamine 6G. The proposed procedure allows quantitation of orciprenaline in the concentration range 0.01-1.2 microg/mL, with a detection limit of 7.2 x 10(-3) microg/mL. The relative standard deviation (RSD) is 2.7% for 0.1 microg/mL orciprenaline (n = 9). The sampling frequency was calculated at approximately 120/h. The method was successfully applied to the determination of orciprenaline in pharmaceutical preparations. A brief discussion on the possible CL reaction mechanism is presented.     

Determination of tetracycline, chlortetracycline and oxytetracycline by flow injection with inhibitory chemiluminescence detection using copper(II) as a probe ion.

This paper reports an indirect flow-injection (FI) method for the determination of the tetracycline drugs (TCs), tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC), using copper(II) as a probe ion. The method was based on the inhibition caused by these TCs to the copper(II)-catalysed chemiluminescence (CL) reaction between luminol and H(2)O(2). The CL reaction was induced on-line and injection of the sample produced negative peaks as a result of the copper(II) complexation or displacement by the analytes. The height of the peaks was proportional to the drug concentration in the sample. The choice of the catalyst ion, the concentration of luminol, H(2)O(2) and copper(II) are discussed. The linear range was 3.6 x 10(-8)-1.0 x 10(-5), 1.1 x 10(-7)-1.0 x 10(-5) and 1.9 x 10(-7)-1.0 x 10(-5) mol/L for TC, CTC and OTC, respectively. The detection limit was 5.0 x 10(-9) mol/L for TC, 1.0 x 10(-8) mol/L for CTC and 2.0 x 10(-8) mol/L for OTC (3sigma), respectively. The method was applied to the determination of TCs in pharmaceutical preparations and human urine with recoveries in the range 95-105%.     

Determination of ampicillin and amoxycillin by flow injection chemiluminescence method based on their enhancing effects on the luminol–periodate reaction

In this work, a new flow injection chemiluminescence method is described for the determination of ampicillin and amoxycillin. The method is based on the strong enhancing effects of these antibiotics on the luminol–periodate reaction. The present method allows the measurements of ampicillin in the range 0.02–1.0 mg/L range and amoxycillin in the range 0.1–10.0 mg/L range with the relative standard deviations within 0.8–2.0%. The sampling frequency was calculated about 90/h. The method was successfully applied to the determination of ampicillin and amoxycillin in pharmaceutical preparations. A brief discussion on the possible chemiluminescence reaction mechanism is presented. Copyright © 2003 John Wiley & Sons, Ltd.     

一种高尿酸血症大鼠模型诱导方法的改良和效果评价研究

目的: 探索短期内诱导高尿酸血症大鼠模型的有效方法,并对模型效果进行评价。方法: 雄性SD大鼠随机分为对照组(CT组,6只)和5个模型组(M1-M5组),每组8只;M1组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg 2次灌胃,于模型诱导的第7日1次性腹腔注射氧嗪酸钾300 mg/kg)、M2组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃2次,于模型诱导第1、3、7日每天腹腔注射1次氧嗪酸钾300 mg/kg)、M3组(每天酵母膏10 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M4组(每天酵母膏20 g/kg+腺嘌呤100 mg/kg灌胃 2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、M5组(每天酵母膏30 g/kg+腺嘌呤100 mg/kg灌胃2次,每天腹腔注射1次氧嗪酸钾300 mg/kg)、CT组(5个模型组按相同的时间、体重计算等体积灌胃和腹腔注射生理盐水),造模7 d;分别在造模结束时和2周后采集24 h尿样和血样检测尿酸、肌酐水平,取肾脏和胃称重,观察肾脏病理变化。结果: 与CT组相比,造模结束后,所有模型组大鼠体重均显著降低(P＜0.01);除M2组外,其他造模组大鼠均有亡,M4组和M5组因死亡率高未做后续分析,M1和M3组分别死亡4例和2例;造模结束后,模型大鼠血尿酸、尿尿酸水平明显升高(P＜0.01),并且M2组的血尿酸水平显著高于其他各组(P＜0.05);继续喂养2周后,各模型组的血尿酸和尿尿酸水平仍显著升高(P＜0.05);各模型组大鼠肾脏重量也明显增加(P＜0.01);病理检查显示,模型组大鼠肾脏出现明显炎症反应和结构破坏。结论: 采用酵母膏(10 g/kg)、腺嘌呤(100 mg/kg)联合氧嗪酸钾(300 mg/kg)间隔(第1、3、7日)注射的方案可在短期内安全地诱导高尿酸血症大鼠模型,模型效果持续时间较长,适合在相关研究中应用。     

Flow-injection chemiluminescence determination of catecholamines based on their enhancing effects on the luminol-potassium periodate system.

A rapid and sensitive chemiluminescence (CL) method using flow injection analysis is described for the determination of four catecholamines, dopamine, adrenaline, isoprenaline and noradrenaline, based on their greatly enhancing effects on the CL reaction of luminol-potassium periodate in basic solutions. The optimized chemical conditions for the chemiluminescence reaction were 1.0 x 10(-4) mol/L luminol and 1.0 x 10(-5) mol/L potassium periodate in 0.2 mol/L sodium hydroxide (NaOH). Under the optimized conditions, the calibration graphs relating the CL signal intensity (peak height) to the concentration of the analytes were curvilinear and they were suitable for determining dopamine, adrenaline, isoprenaline, and noradrenaline in the range 0.1-10 ng/mL, 0.1-100 ng/mL, 1-100 ng/mL and 5-50 ng/mL, respectively, with the relative standard deviations of 0.8-1.7%. The detection limits of the method are 0.02 ng/mL for dopamine, 0.01 ng/mL for adrenaline, 0.1 ng/mL for isoprenaline and 2.0 ng/mL for noradrenaline. The sampling frequency was calculated to be about 60/h. The selectivity of the method was good, because a series of common ions or excipients, such as K(+), Ba(2+), CO(3)(2-), NO(3)(-), SO(4)(2-), PO(4)(3-), sodium citrate, sodium bisulphite, oxidate dopamine, starch, lactose, carbamide and gelatin, could not produce interference when their concentrations were 1000-fold than those of dopamine. The present method was successfully applied to the determination of the four catecholamines in pharmaceutical injections.     

Chemiluminescence of daphnia cultivating medium and optimization of conditions for its determination

The article deals with the optimization of conditions for the chemiluminescence determination. The Daphnia habitat was shown to have no spontaneous chemiluminescence. This was revealed using hydrogen peroxide and luminol, the optimal concentrations of which were 23 and 1.6 x 10(-2) mmol/L. p-Iodphenol at low concentrations (4 x 10(-5)-2 x 10(-3) mmol/L) did not render its effect chemiluminescence signal while at high concentrations (4 x 10(-2) mmol/L) an inhibition of chemiluminescence was observed. To obtain the needed intensity of chemiluminescence no more than 5 daphnia persons is required to incubate in volume of 10 mL of sample for analyzing. The intensity of chemiluminescence of daphnia cultivating medium and the sensitivity of this organism to potassium chromate increased at the temperature increasing from 24 to 32 degrees C. Daphnia cultivating medium can be preserved in refrigerator for several hours without lost of chemiluminescence signal.     

Improved and simplified LC-ESI-MS/MS method for homocysteine determination in human plasma: application to the study of cardiovascular diseases

A liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was developed and validated for the determination of human plasma homocysteine (Hcy), an important independent risk factor for cardiovascular disease, with a simplified sample pretreatment procedure and a zero blank free of endogenous Hcy for calibrator/QC preparation. Following protein precipitation, chromatographic separation was performed on Hypersil Aquasil C18 column (50 mm x 2.1mm, 5 microm, Thermo) using mobile phase of aqueous 10% methanol containing 0.02% formic acid at 0.25 mL/min. Hcy and deuterated internal standard were detected in the multiple reaction monitoring mode with precursor to product ion transitions of m/z 136.1/90.0 and 140.1/94.0, respectively. The retention time was 1.2 min, and the total run time was 2 min per injection. A streamlined three-point calibration curve and one-point QC was used. Excellent linearity was observed with correlation coefficient (r)>0.99. The intra- and inter-batch were < or =3.24% and < or =4.04%, and accuracy was within +/-10%. Method comparison between the proposed method (y) and FPIA assay (x) demonstrated a correlation equation of y=1.003x + 0.4318 (r=0.9589). The developed method, improved for automation with cost-effective reagents, was proven to be suitable for high-throughput quantitative determination of Hcy in clinical practice by successfully applying it to the cardiovascular disease study.