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.     

Rapid determination of gatifloxacin in biological samples and pharmaceutical products using europium‐sensitized fluorescence spectrophotometry

A europium‐sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of gatifloxacin (GFLX). The GFLX–Eu³⁺–SDBS system was studied and it was found that SDBS significantly enhanced the fluorescence intensity of the GFLX–Eu³⁺ complex (about 25‐fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 338 and 617 nm, pH 7.5, 3.0 × 10^–6 mol/L europium(III), and 5.0 × 10^–5 mol/L SDBS. The enhanced fluorescence intensity of the system (ΔI_f) showed a good linear relationship with the concentration of GFLX over the range 1.0 × 10^–8–8.0 × 10^–7 mol/L with a correlation coefficient of 0.9990. The detection limit (S:N = 3) was determined as 1.0 × 10^–9 mol/L. This method has been successfully applied for the determination of GFLX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range and good stability. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.     

Gold nanoparticles‐based fluorescence enhancement of the terbium–levofloxacin system and its application in pharmaceutical preparations

A sensitive fluorescence (FL) technique is proposed for the determination of levofloxacin (LVX). The method is based on the fact that the weak FL signal of the Tb(III)–LVX system is strongly enhanced in the presence of gold nanoparticles. Gold nanoparticles were prepared by the citrate reduction of HAuCl₄ and characterized by transmission electron microscopy (TEM). Levofloxacin and Tb(III) ion form a fluorescence complex in aqueous solution, and its maximum emission wavelength was found at 545 nm. Optimal conditions for the formation of the levofloxacin–Tb(III) complexes were studied. Levofloxacin was detected by measuring the FL intensity, which increases linearly with the concentration of LVX in the range 6.2 × 10⁻¹⁰–2.6 × 10⁻⁸ mol/L. Recovery of the target analytes was > 96% with good quality parameters: linearity (r² > 0.996), limit of detection (LOD) and limit of quantification (LOQ) values 2.1 × 10⁻¹⁰ mol/L and 7.2 × 10⁻¹⁰ mol/L, and run‐to‐run and day‐to‐day precisions with relative standard deviations (RSDs) around 3%. Thus, the proposed method can be successfully applied to the routine determination of levofloxacin in pharmaceutical preparations. Copyright © 2011 John Wiley & Sons, Ltd.     

A sensitive method for determination of trace amounts of chromate (III) with terbium (III) sodium hexametaphosphate chelate as fluorescent probe

Based on the fluorescence quenching of Terbium (III)‐sodium hexametaphosphate (Tb/SHMP) chelates in the presence chromate (III), a sensitive fluorimetric method was developed for the determination of trace amounts of chromium (III) in aqueous solutions. Under the optimum conditions, the linear calibration graph was obtained (R = 0.996). The linear range and detection limit of Cr (III) were 7.69 × 10^?7 to 1.15 × 10^?4 mol L^?1 and 4.50 × 10^?7 mol L^?1, respectively. The proposed method had a wider linear range and was proved to be very sensitive, rapid and simple. The method was applied successfully to the determination of chromium (III) in the synthetic samples and real water samples. Moreover, the reaction mechanism was discussed through the fluorescence lifetime and proved to be dynamic quenching behavior. Copyright © 2010 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.     

Investigation on the co‐luminescence effect of europium (III)–lanthanum(III)–dopamine–sodium dodecylbenzene sulfonate system and its application

A novel luminescence, enhancement phenomenon in the europium(III)–dopamine–sodium dodecylbenzene sulfonate system was observed when lanthanum(III) was added. Based on this, a sensitive co‐luminescence method was established for the determination of dopamine. The luminescence signal for the europium (III)–lanthanum(III)–dopamine–sodium dodecylbenzene sulfonate system was monitored at λ_ex = 300 nm, λ_em =618 nm and pH 8.3. Under optimized conditions, the enhanced luminescence signal responded linearly to the concentration of dopamine in the range 1.0 × 10^–10–5.0 × 10^–7 mol/L with a correlation coefficient of 0.9993 (n = 11). The detection limit (3σ) was 2.7 × 10^–11 mol/L and the relative standard deviation for 11 parallel measurements of 3.0 × 10^–8 mol/L dopamine was 1.9%. The presented method was successfully applied for the estimation of dopamine in samples of pharmaceutical preparations, human serum and urine. The possible luminescence enhancement mechanism of the system is discussed briefly. Copyright © 2013 John Wiley & Sons, Ltd.     

Flow‐injection chemiluminescence determination of ofloxacin using the Ru(bpy)2(CIP)2+−Ce(IV) system and its application

This paper reports a flow‐injection chemiluminescence method for the determination of ofloxacin (OFLX) using the Ru(bpy)₂(CIP)²⁺–Ce(IV) system. Under the optimum conditions, the relative CL intensity was proportional to the concentration of OFLX in the range 3.0 × 10^–8–1.0 × 10^–5 mol/L and the detection limit was 4.2 × 10^–9 mol/L. The proposed method has been successfully applied to the determination of ofloxacin in pharmaceuticals and human urine. The chemiluminescence mechanism of the system is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly sensitive spectrofluorimetric determination of trace amounts of prulifloxacin using the aluminium(III)–prulifloxacin system

The fluorescence of the prulifloxacin (PUFX)–Al(III) system was investigated . Experiments indicated that the fluorescence intensity of prulifloxacin could be greatly enhanced by Al(III) and sensitized by sodium dodecylbenzene sulphonate (SDBS). Accordingly, a sensitive spectrofluorimetric method for the determination of prulifloxacin was established. While excited at 275 nm, the enhanced fluorescence intensity at 412 nm of the system (ΔF) showed a good linear relationship with the concentration of prulifloxacin within the range 4.0 × 10^–8–3.0 × 10^–6 mol/L. The regression equation was ΔF = 9.83 + 10.8 × 10⁷c (mol/L); the correlation coefficient and detection limit (3σ/k) were 0.99901 and 2.0 × 10^–8 mol/L, respectively. The proposed method has been successfully applied to determine prulifloxacin in real pharmaceutical samples. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.     

Utility of gold nanoparticles in luminescence determination of trovafloxacin: comparison of chemiluminescence and fluorescence detection

Two novel sensitive sequential injection chemiluminescence analysis and fluorescence methods for trovafloxacin mesylate detection have been developed. The methods were based on the enhancement effect of gold nanoparticles on luminol–ferricyanide–trovafloxacin and europium(III)–trovafloxacin complex systems. The optimum conditions for both detection methods were investigated. The chemiluminescence signal was emitted due to the enhanced effect of gold nanoparticles on the reaction of luminol–ferricyanide–trovafloxacin in an alkaline medium. The response was linear over a concentration range of 1.0 × 10^–9 to 1.0 × 10^–2 mol/L (%RSD = 1.3), (n = 9, r = 0.9991) with a detection limit of 1.7 × 10^–10 mol/L (S/N = 3). The weak fluorescence intensity signal of the oxidation complex of europium(III)–trovafloxacin was strongly enhanced by gold nanoparticles and detected at λ_ex = 330 and λ_em = 540 nm. Fluorescence detection enabled the determination of trovafloxacin mesylate over a linear range of 1.0 × 10^–8 to 1.0 × 10^–3 mol/L (%RSD = 1.2), (n = 6, r = 0.9993) with a detection limit of 3.3 × 10^–9 mol/L. The proposed methods were successfully applied to the determination of the studied drug in its bulk form and in pharmaceutical preparations. The results were treated statistically and compared with those obtained from other reported methods. Copyright © 2015 John Wiley & Sons, Ltd.     

Flow‐injection determination of vitamin A in pharmaceutical formulations using Tris(2,2′‐bipyridyl)Ru(II)–Ce(IV) chemiluminescence detection

A flow injection method with chemiluminescence detection is reported for the determination of vitamin A. The method is based on the enhancement effect of vitamin A on chemiluminescence of tris(2,2′‐bipyridyl)Ru(II)–Ce(IV) in acidic medium. The proposed procedure is used to quantitate vitamin A in the range 1.0–100 × 10^?6 mol/L with a correlation coefficient of 0.9991 (n = 9) and relative standard deviation in the range 1.2–2.3% (n = 4). The limit of detection (3 × blank) was 8.0 × 10^?8 mol/L with a sample throughput of 100/h. The effect of common excipients used in pharmaceutical formulations and some clinically important compounds was also studied. The method was applied to determine vitamin A in pharmaceutical formulations and the results obtained were in reasonable agreement with the amount quoted. The results were compared using spectrophotometric method and no significant difference was found between the results of the two methods at 95% confidence limit. Copyright © 2009 John Wiley & Sons, Ltd.     

Highly sensitive fluorescence detection of glycoprotein based on energy transfer between CuInS2 QDs and rhodamine B

A highly sensitive fluorescence method for glycoprotein detection has been established based on fluorescence resonance energy transfer (FRET) between CuInS₂ quantum dots (QDs) and rhodamine B (RB). Lectins comprise a group of proteins with unique affinities toward carbohydrate structures, so the process of FRET can occur between lectin‐coated QDs (CuInS₂ QDs–Con A conjugates, acceptors) and carbohydrate‐coated RB (RB–NH₂‐glu conjugates, donors). The fluorescence of lectin‐coated QDs was recovered in the presence of a glycoprotein such as glucose oxidase (GOx) and transferrin (TRF), which significantly reduced the FRET efficiency between the donor and the acceptor. Under optimal conditions, a linear correlation was established between the fluorescence intensity ratio I₆₅₄/I₅₇₇ and the TRF concentration over the range of 6.90 × 10^‐10 to 3.45 × 10^‐8 mol/L, with a detection limit of 2.5 × 10^‐10 mol/L. The linear range for GOx is 3.35 × 10^‐10 to 6.70 × 10^‐8 mol/L, with a detection limit of 1.5 × 10^‐10 mol/L. The proposed method was applied to the determination of glycoprotein in human serum and cell‐extract samples with satisfactory results. Furthermore, CuInS₂ QDs–Con A conjugates are used as safe and efficient optical nanoprobes in HepG2 cell imaging. Copyright © 2015 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 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 ampicillin sodium using the cupric oxide nanoparticles–luminol–H2O2 chemiluminescence reaction

A simple and sensitive chemiluminescence (CL) method has been developed for the determination of ampicillin sodium at submicromolar levels. The method is based on the inhibitory effect of ampicillin sodium on the cupric oxide nanoparticles (CuO NPs)–luminol–H₂O₂ CL reaction. Experimental parameters affecting CL inhibition including concentrations of CuO NPs, luminol, H₂O₂ and NaOH were optimized. Under optimum conditions, the calibration plot was linear in the analyte concentration range 4.0 × 10^‐7–4.0 × 10^‐6 mol/L. The limit of detection was 2.6 × 10^‐7 mol/L and the relative standard deviation (RSD) for six replicate determinations of 1 × 10^‐6 mol/L ampicillin sodium was 4.71%. Also, X–ray diffraction (XRD) and transmission electron microscopy (TEM) analysis were employed to characterize the CuO NPs. The utility of the proposed method was demonstrated by determining ampicillin sodium in pharmaceutical preparation. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly sensitive spectrofluorimetic determination of rutin based on its activated effect on a multi‐enzyme redox system

A highly sensitive and simple spectrofluorimetric method for the determination of rutin, based on its activated effect on a haemoglobin‐catalysed reaction, was developed. Under optimum conditions, the concentration of rutin was linear, with decreased fluorescence (ΔF) of the system under optimal experimental conditions. The calibration graph was linear in the range 1.0 × 10^–7–3.0 × 10^–5 mol/L, with a detection limit of 7.0 × 10^–8 mol/L. The relative standard deviation (RSD) was 3.26% for 11 determinations of 1.0 × 10^–5 mol/L. This method was used for the determination of rutin in pharmaceuticals with satisfactory results. Copyright © 2011 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 determination of sulphite using a cyclometalated iridium complex as chemiluminescence reagent

A simple, fast and accurate chemiluminescence (CL) method for the determination of sulphite has been developed, based on its sensitizing effect on the CL reaction between a novel water‐soluble iridium complex, [(dpci)₂Ir(bvbbi)](PF₆) (dpci = 3,4‐diphenylcinnoline; bvbbi = N,N′‐bivinylester‐¹H,^1′H‐[2,2′] bibenzimidazole) and cerium(IV). Under the optimal experimental conditions, the increased CL response was linear, with the concentration of sulphite over the range 5.0 × 10^–7–5.0 × 10^–4 mol/L. The detection limit of the method was 1.6 × 10^–7 mol/L, with a relative standard deviation (RSD) of 2.7% for nine repetitive determination of 1.0 × 10^–4 mol/L sulphite. The method was successfully applied to the quantitative analysis of sulphite in sugar samples. The possible reaction mechanism of sulphite on the [(dpci)₂Ir(bvbbi)](PF₆)–cerium(IV) system is also briefly discussed. Copyright © 2012 John Wiley & Sons, Ltd.     

Application of a lanthanide composite nanoparticle‐sensitized luminescence method for the determination of salicylic acid in pharmaceutical formulations and human plasma

Terbium‐acetylacetone (Tb–acac) composite nanoparticles were synthesized using the ultrasonic method. The nanoparticles are water‐soluble, stable and have extremely narrow emission bands and high internal quantum efficiencies. They were used as fluorimetric probes in the determination of salicylic acid (SA), based on the fluorescence enhancement of nanoparticles through fluorescence resonance energy transfer (FRET). The influence of buffer solution was investigated. Under the optimum conditions, a linear calibration graph was obtained over the SA concentration range 5 × 10^–7–1 × 10^–4 mol/L. The limit of detection was found to be 2.5 × 10^–8 mol/L. The relative standard deviation (RSD) for six repeated measurements of 1 × 10^–4 mol/LSA was 1.75%. The method was applied to the determination of SA in pharmaceutical formulations and human plasma. We believe that the proposed approach has great potential for clinical purposes. Copyright © 2008 John Wiley & Sons, Ltd.     

Chemiluminescence of a cyclometallated iridium(III) complex and its application in the detection of cysteine

Chemiluminescence (CL) of a cyclometallated iridium (III) complex {tris[1‐(2,6‐dimethylphenoxy)‐4‐(4‐chlorophenyl)phthalazine]iridium(III)} in the presence of potassium permanganate and oxalic acid is reported for the first time. Cysteine exhibits sufficient enhancing effect on the CL generated from the cyclometallated iridium(III) complex, which make it possible for the sensitive detection of cysteine using a flow‐injection–chemiluminescence (FI–CL) method. The optimum conditions for the chemiluminescence emission were investigated. Under the optimal condition, the linear range for the determination of cysteine was 1.0 × 10^–9–5.0 × 10^–6 mol/L with a detection limit of 6.9 × 10^–10 mol/L. A relative standard deviation of 1.6% was obtained for eight replicate determinations. The mechanisms of CL are proposed and the emitting species was identified as the metal‐to‐ligand charge‐transfer (MLCT) excited states of the iridium complex. 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.