Chemiluminescence determination of fluoroquinolones using Fenton system in the presence of terbium(iii) ions

A simple new chemiluminescent, CL, method is described for the determination of fluoroquinolones such as: ciprofloxacin (CF), norfloxacin (NF), and ofloxacin (OF). This method is based on the measurement of terbium(iii) emission. This emission follows an energy transfer to the uncomplexed terbium(iii) ions from the excited products of fluoroquinolone oxidations. Under optimum conditions, calibration graphs were obtained for 2 × 10(-8)-2 × 10(-6) mol L(-1) of NF; 3 × 10(-8)-2 × 10(-6) mol L(-1) of CF and 4 × 10(-7)-5 × 10(-5) mol L(-1) of OF. The detection limits are 7 × 10(-9) mol L(-1) norfloxacin, 1 × 10(-8) mol L(-1) ciprofloxacin and 1.5 × 10(-7) mol L(-1) ofloxacin. The method was successfully applied to the determination of these drugs in pharmaceutical formulations.     

Flow-injection chemiluminescence determination of ofloxacin and levofloxacin in pharmaceutical preparations and biological fluids.

A novel, rapid and sensitive analytical method is described for determination of ofloxacin and levofloxacin by enhanced chemiluminescence (CL) with flow-injection sampling. The method is based on the CL reaction of the Ce(IV)-Na2S2O4-ofloxacin/levofloxacin-H2SO2 system. The enhanced CL mechanism was developed and the optimum conditions for CL emission were investigated. The CL intensity was correlated linearly (r = 0.9988) with the concentration of ofloxacin (or levofloxacin) in the range of 1.0 x 10(-8) - 1.0 x 10(-7) g ml(-1) and 1.0 x 10(-7) - 6.0 x 10(-6) g ml(-1). The detection limit (S/N = 3) is 7 x 10(-9) g ml(-1). The relative standard derivation (RSD, n = 11) is 2.0% for ofloxacin at 4 x 10(-7) g ml(-1) and for levofloxacin at 6 x 10(-7) g ml(-1). This method has been successfully applied for the determination of ofloxacin and levofloxacin in pharmaceutical preparations and biological fluids with satisfactory results.     

Chemiluminescence flow-through sensor for ofloxacin using solid-phase PbO(2) as an oxidant

A novel chemiluminscence (CL) flow-through sensor for ofloxacin is described. It was based on the sensitizing effect of ofloxacin on the CL oxidation of sulfite by PbO(2) in H(2)SO(4) media. By a very simply means, the solid-phase PbO(2) was immobilized inside of the CL flow cell as CL oxidant. The column of solid PbO(2) could be reused about 400 times during a period of 50 h. The calibration graph is linear in the range 0.2-10 mug ml(-1) with a detection limit of 7.8x10(-8) g ml(-1) (S/N=3). This method has been successfully applied to determine ofloxacin in pharmaceutical preparation.     

Flow-Injection Chemiluminescence Determination of Fluoroquinolones

ABSTRACT

A new flow-injection CL method was developed for the determination of fluoroquinolones including ofloxacin, norfloxacin, ciprofloxacin and lomefloxacin in pharmaceutical preparations, based on the chemiluminescence reaction of sulphite with cerium(IV) sensitized by these compounds. The linear ranges are 0.04 to 4.0 μg ml^?1 for ofloxacin and 0.4 to 40.0 μg ml^?1 for norfloxacin, ciprofloxacin and lomefloxacin, respectively. The detection limits are 0.016 μg ml^?1 for ofloxacin and 0.16 μg ml ^?1 for norfloxacin, ciprofloxacin and lomefloxacin, respectively. The relative standard deviations (RSD) are 2.1 to 2.6% (n=10) for these fluoroquinolones. The analytical procedure has been applied to the determination of the fluoroquinolones in pharmaceutical commercial formulations. The results are in agreement with those obtained by the official methods.     

Flow-injection chemiluminometric determination of some thioxanthene derivatives in pharmaceutical formulations and biological fluids using the [Ru(dipy)3(2+)]-Ce(IV) system.

A flow-injection (FI) methodology using tris(2,2'-dipyridyl)ruthenium(II), [Ru(dipy)3(2+)], chemiluminescence (CL) was developed for the rapid and sensitive determination of three thioxanthene derivatives, namely zuclopenthixol hydrochloride, flupentixol hydrochloride and thiothixene. The method is based on the CL reaction of the studied thioxanthenes with [Ru(dipy)3(2+)] and Ce(IV) in a sulfuric acid medium. Under the optimum conditions, calibration graphs were obtained over the concentration ranges 0.002-6 migrograms/ml for zuclopenthixol hydrochloride, 0.5-15 micrograms/ml for flupentixol hydrochloride and 0.05-7.5 micrograms/ml for thiothixene. The limits of detection (s/n = 3) were 4.2 x 10(-9) mol/l zuclopenthixol hydrochloride, 2 x 10(-8) mol/l flupentixol hydrochloride and 4.5 x 10(-8) mol/l thiothixene. The method was successfully applied to the determination of these compounds in dosage forms and biological fluids.     

Direct determination of four fluoroquinolones,enoxacin, norfloxacin,ofloxacin, and ciprofloxacin,in pharmaceuticals and blood serum by HPLC

A rapid, accurate and sensitive method has been developed for the quantitative determination of four fluoroquinolone antimicrobial agents, enoxacin, norfloxacin, ofloxacin and ciprofloxacin, with high in-vitro activity against a wide range of Gram-negative and Gram-positive organisms.A Kromasil 100 C(8) 250 mm x 4 mm, 5 microm analytical column was used with an eluting system consisting of a mixture of CH(3)CN-CH(3)OH-citric acid 0.4 mol L(-1) (7:15:78 %, v/v). Detection was performed with a variable wavelength UV-visible detector at 275 nm resulting in limits of detection: 0.02 ng per 20 microL injection for enoxacin and 0.01 ng for ofloxacin, norfloxacin and ciprofloxacin. Hydrochlorothiazide (HCT) was used as internal standard at a concentration of 2 ng microL(-1). A rectilinear relationship was observed up to 2 ng microL(-1) for enoxacin, 12 ng microL(-1) for ofloxacin, 3 ng microL(-1) for norfloxacin, and 5 ng microL(-1) for ciprofloxacin. Separation was achieved within 10 min. The statistical evaluation of the method was examined by performing intra-day (n=8) and inter-day precision assays (n=8) and was found to be satisfactory with high accuracy and precision. The method was applied to the direct determination of the four fluoroquinolones in human blood serum. Sample pretreatment involved only protein precipitation with acetonitrile. Recovery of analytes in spiked samples was 97+/-6% over the range 0.1-0.5 ng microL(-1).     

Evaluation of luminol-H(2)O(2)-KIO(4) chemiluminescence system and its application to hydrogen peroxide, glucose and ascorbic acid assays

A novel chemiluminescence (CL) system was evaluated for the determination of hydrogen peroxide, glucose and ascorbic acid based on hydrogen peroxide, which has a catalytic-cooxidative effect on the oxidation of luminol by KIO(4). Hydrogen peroxide can be directly determined by luminol-KIO(4)-H(2)O(2) CL system. The detection limit was 3.0x10(-8) mol l(-1) and the calibration graph was linear over the range of 2.0x10(-7)-6.0x10(-4) mol l(-1). The relative standard deviation of H(2)O(2) was 1.1% for 2.0x10(-6) mol l(-1) (N=11). Glucose was indirectly determined through measuring the H(2)O(2) generated by the oxidation of glucose in the presence of glucose oxidase at pH 7.6. The present method provides a source for H(2)O(2), which, in turn, coupled with the luminol-KIO(4)-H(2)O(2) CL reaction system. The CL was linearly correlated with glucose concentration of 0.6-110 mug ml(-1). The relative standard deviation was 2.1% for 10 mug ml(-1) (N=11). Detection limit of glucose was 0.08 mug ml(-1). Ascorbic acid was also indirectly determined by the suppression of luminol-KIO(4)-H(2)O(2) CL system. The calibration curve was linear over the range of 1.0x10(-7)-1.0x10(-5) mol l(-1) of ascorbic acid. The relative standard deviation was 1.0% for 8.0x10(-7) mol l(-1) (N=11). Detection limit of ascorbic acid was 6.0x10(-8) mol l(-1). These proposed methods have been applied to determine glucose, ascorbic acid in tablets and injection.     

Flow-injection chemiluminescence determination of fluoroquinolones by enhancement of weak chemiluminescence from peroxynitrous acid

A flow-injection chemiluminescence (CL) method is described for the determination of fluoroquinolones including ciprofloxacin, norfloxacin and ofloxacin. The method is based on the enhancement by these compounds of the weak CL from peroxynitrous acid. The linear ranges are 1.0×10⁻⁷ to 1.0×10⁻⁵ mol l⁻¹ for ciprofloxacin and norfloxacin, and 3.0×10⁻⁷ to 3.0×10⁻⁵ mol l⁻¹ for ofloxacin, respectively. The detection limits (S/N=3) are 4.5×10⁻⁸ mol l⁻¹ ciprofloxacin, 5.9×10⁻⁸ mol l⁻¹ norfloxacin and 1.1×10⁻⁷ mol l⁻¹ ofloxacin, respectively. The proposed method was applied to the determination of fluoroquinolones in pharmaceutical preparations.     

Chemiluminescence of chlorpromazine hydrochloride based on cerium(IV) oxidation sensitized by rhodamine 6G

A new chemiluminescence (CL) method is proposed for the determination of chlorpromazine hydrochloride, a drug often used to treat the psychiatric patients suffering from clinical depression. The method is based on the reaction between studied drug and Ce(IV) in a nitric acid medium and measurement of the CL intensity produced by rhodamine 6G used as a sensitizer. In the optimum conditions, CL intensities are proportional to concentrations of the studied drug over the range 0-1x10(-5) g ml(-1) with a detection limit of 6.5x10(-9) g ml(-1). The relative standard deviation (R.S.D.) is 4.1% for 1.5x10(-6) g ml(-1) chlorpromazine hydrochloride (n=11). The method has been applied to the determination of studied drug in tablets and biological fluids with satisfactory results.     

Flow injection chemiluminescence determination of thiamine based on its enhancing effect on the luminol-hydrogen peroxide system

A new flow injection chemiluminescence (CL) method is proposed for the determination of thiamine, based upon its enhancing effect on the CL reaction of luminol with hydrogen peroxide in alkaline solution. The method allows the determination of thiamine within 0.05-8 mug ml(-1) range with a detection limit (3sigma) of 0.01 mug ml(-1). The relative standard deviation is 1.4% (n=11, 0.5 mug ml(-1) thiamine) and the sample throughput is about 90 samples h(-1). The method was successfully applied to the determination of thiamine in pharmaceutical preparations.     

Extractive spectrophotometric determination of some fluoroquinolone derivatives in pure and dosage forms

Two simple and sensitive extractive spectrophotometric methods for the determination of some fluoroquinolone derivatives (norfloxacin, NRF; ciprofloxacin, CPF; ofloxacin, OFL; and enrofloxacin, ERF) with Supracene Violet 3B (SV 3B, method A) and tropaeolin 000 (TP 000, method B) are described. The methods are based on the formation of ion-association complexes of fluoroquinolones with these dyes, which are extracted into chloroform and have absorption maxima at 575 nm (SV 3B) and 485 nm (TP 000). The methods obey Beer's law and the precision and accuracy of the methods were checked by UV reference methods. The detection limits were 5.0 mug/ml for NRF and 2.5 mug/ml for CPF in method A and 2.5 mug/ml for OFL and ERF in methods A and B.     

Sequential injection technique employed for stoichiometric studies, optimization and quantitative determination of some fluoroquinolone antibiotics complexed with iron(III) in sulfuric acid media

A sequential injection spectrophotometric method for stoichiometric studies, optimization and quantitative determination of ciprofloxacin and norfloxacin was developed. The work is based on the complexation reaction of ciprofloxacin and norfloxacin with iron(III) in sulfuric acid media and a spectrophotometric measurement of absorbances of the corresponding complexes at 447 and 430 nm respectively. The stoichiometries and formation constants were determined. A 1:2 iron(III) to drug mole ratio was found to give the most predominant complexes for both drugs with 5.00 x 10(-3) M H(2)SO(4) and at 0.20 M ionic strength utilizing Job's method and the molar ratio method. A numerical method was utilized for the calculation of the formation constants, the logarithms of which were found to be 7.756 +/- 0.121 and 7.839 +/- 0.056, for ciprofloxacin and norfloxacin respectively. A factorial design together with the all-model-search method was utilized for the optimization of the concentration and aspiration volume of iron(III) as these were the variables which most affected peak absorbance. Working dynamic ranges of 50-500 ppm and 50-400 ppm were obtained for ciprofloxacin and norfloxacin respectively. The method was found to be suitable for the determination of these compounds in pharmaceutical preparations.     

Flow-injection chemiluminescence determination of quinine using on-line electrogenerated cobalt(III) as oxidant

A novel chemiluminescence (CL) flow system for the determination of quinine is described. It is based on the direct chemiluminescence reaction of quinine and cobalt(III) in sulfuric acid medium. The unstable Co(III) was on-line electrogenerated by constant-current electrolysis. The chemiluminescence intensity was linear with a quinine concentration in the range of 0.1-100 mug ml(-1). The determination limit was 3.3x10(-8) g ml(-1). The whole process could be completed in 1 min. The proposed method is suitable for automatic and continuous analysis, and has been applied successfully to the analysis of quinine in pharmaceutical preparation.     

Chemiluminescence determination of sulfite in sugar and sulfur dioxide in air using Tris(2,2'-bipyridyl)ruthenium(II)-permanganate system

A chemiluminescence (CL) detection for the determination of sulfite using the reaction of Ru(bipy)(3)(2+) (bipy=2,2'-bipyridyl) -SO(3)(2-)-KMnO(4) is described. The concentration of sulfite is proportional to the CL intensity from 5.0x10(-8) to 1.25x10(-4) mol l(-1). The limit of detection is 2.5x10(-8) mol l(-1) and the relative standard deviation is 4.9% for the 2x10(-5) mol l(-1) sulfite solution in six repeated measurements. This method has been successfully applied to the determination of sulfite in sugar and sulfur dioxide in air by using triethanolamine (TEA) as the absorbent material.     

Flow-injection chemiluminometric analysis of some benzamides by their sensitizing effect on the cerium-sulphite reaction

A simple, highly sensitive chemiluminescent method using flow injection is described for the determination of three substituted benzamides, namely: sulpiride, sultopride and tiapride. The method is based on the sensitizing effect of these drugs on the chemiluminometric oxidation of sulphite by cerium(IV). The different experimental parameters affecting the chemiluminescence intensity were carefully studied and incorporated into the procedure. The method permits the determination of 0.05-2.5 mug ml(-1) sulpiride, 0.01-2.5 mug ml(-1) sultopride hydrochloride and 0.01-1.5 mug ml(-1) tiapride hydrochloride with minimum detectability of 0.01 mug ml(-1). The method was applied to the determination of these benzamides in pharmaceutical preparations and biological fluids.     

Spectrophotometric determination of chloride in PtAl(2)O(3)/SiO(2) catalysts with Hg(SCN)(2)Fe(3+) reagent

A method is described for the determination of chloride in PtAl(2)O(3)/SiO(2) catalysts, based on its extraction with alkali followed by reaction with Hg(SCN)(2)Fe(3+) reagent and spectrophotometric measurement at 460 nm. Beer's law is obeyed in the concentration range 5-75 mug of chloride in 25 ml of aqueous solution. The molar absorptivity is 1.99 x 10(3) l.mole(-1).cm(-1). The rapid colour development, excellent reproducibility and absence of interference from the species most often present in the catalysts are the advantages of the method.     

Determination of quinolone antibiotics in urine by capillary electrophoresis with chemiluminescence detection

A novel and simple method is presented for the determination of norfloxacin, ciprofloxacin, and ofloxacin by capillary electrophoresis with chemiluminescence detection. This method is based on the enhancing effect of quinolones on the chemiluminescence reaction of the Ce(SO₄)₂–Ru(bpy)₃²⁺–HNO₃ system. Three quinolones were successfully separated and detected under optimum conditions. The obtained detection limits were 2.3×10^–7 mol/L, 5.2×10^–8 mol/L, and 7.8×10^–8 mol/L for ciprofloxacin, norfloxacin, and ofloxacin, respectively. The RSD of migration time and peak area were less than 1.8 and 3.8% (n = 5), respectively. The applicability of the proposed method was illustrated in the determination of ofloxacin in eye drops and of norfloxacin in human urine samples, and the monitoring of pharmacokinetics for norfloxacin.     

Kinetic determination of Hg(II) in different materials, based on its inhibitory effect on a catalysed process

A new kinetic method for the determination of Hg(II) based on its inhibitory effect on the Pd(II)-catalysed reaction between Co(III)-EDTA and hypophosphite is proposed. The reaction is followed spectrophotometrically at 540 nm by measuring the induction period. Both the influence of the reaction variables and the interference of many ions have been studied. A mechanism for the inhibition process is also proposed. Under the selected experimental conditions of 2.7 x 10(-1)M Co(III)-EDTA, pH-3.2 Britton-Robinson buffer, 0.3M H(2)PO(-)(2), 0.35 mug/ml Pd(II), and temperature 18 +/- 0.2 degrees , Hg(II) was determined in the range 13-120 ng/ml. The method was applied to the determination of Hg(II) in sphalerites and pharmaceuticals.     

Papaverine PVC membrane ion-selective electrodes based on its ion-exchangers with tetraphenylborate and tetrathiocyanate anions

The construction and general performance of novel potentiometric membrane ion selective electrodes for determination of papaverine hydrochloride has been described. They are based on the formation of the ion association complexes of papaverine (PA) with tetraphenylborate (TPB)(I) or tetrathiocyanate (TTC)(II) counter anions as electro-active material dispersed in a PVC matrix. The electrodes show fast, stable, near Nernstian response for 1 x 10(-2) to 6 x 10(-5) M and 1 x 10(-2) to 1 x 10(-5) M for PA-TPB and PA-TTC respectively at 25 degrees C over the pH range of 3-5.0 with a cationic slope of approximately 56.5 +/- 0.5 mV/decade for both sensors respectively. The lower detection limit is 4 x 10(-5) and 8 x 10(-6) M for PA- I and PA-II respectively with fast response time ranging from 20-45 sec. Selectivity coefficients for PA relative to a number of interfering substances were investigated. There is a negligible interference from the studied cations, anions, and pharmaceutical excipients. The determination of 4.0- 3000.0 microg/ml of PA in aqueous solutions shows an average recovery of 99.1% and a mean relative standard deviation of 1.4 at 100microg/ml. The direct determination of PA in some formulations (Vasorin injection) gave results that compare favorably with those obtained using the British Pharmacopoeia method. Potentiometric titration of PA with sodium tetraphenylborate and potassium thiocyanate as titrants utilizing the papaverine electrode as an end point indicator electrode has been carried out.     

The use of phenylfluorone in the presence of cetylpyridinium chloride and Triton X-100 for the spectrophotometric determination of copper(II) in blood serum

A simple and sensitive spectrophotometric method for determination of copper(II) is based on the formation of a blue coloured complex of Cu(II) with 9-phenyl-2,3,7-trihydroxy-6-fluorone (PF) in the presence of cetylpyridinium chloride (CP) and Triton X-100, has been developed. Optimum concentrations of PF, CP, Triton X-100 and pH ensuring maximum absorbance were defined. The complex Cu(II)-PF-CP-Triton X-100 shows maximum absorbance at 595 nm with a molar absorptivity value of 9.67x10(4) l mol(-1) cm(-1). The detection limit of the method is 0.028 mug ml(-1). Beer's law is obeyed for copper concentrations in the range 0.04-0.4 mug ml(-1). The studies of the effect of foreign ions on determination of copper, show that the selectivity of the method is poor. The cations of alkali metals and anions Br(-), Cl(-), I(-), F(-), NO(2)(-), NO(3)(-), CH(3)COO(-), SO(4)(2-), S(2)O(3)(2-), PO(4)(3-), citrates (examined in 1000-fold molar excess over copper) do not affect the determination. All cations forming complexes with PF have an interfering effect. The statistical evaluation of the method was carried out for six determinations using 10 mug of Cu and the following results were obtained: the standard deviation, SD=0.042, the confidence interval mu(95)=10.1+/-0.1 mug Cu. The method has been applied for determination of copper in blood serum.