Ion-association Complex Research Articles

Resonance Light-Scattering Enhancement Effect of the Y(III)–PUFX–Eosin System and its Fluorescence Study

Highly sensitive and rapid method for the determination of prulifloxacin (PUFX) has been developed on the basis of ion association reaction of PUFX, Y(III) and eosin Y (EY). In pH 6.5 BR buffer medium, PUFX reacts with Y(III) to form a 2:1 cationic chelate which further reacts with EY to form 2:1 ion-association complex. As a result, not only the spectra of absorption are changed, but quenching of fluorescence and significant enhancement of resonance Rayleigh scattering (RRS) is observed. Furthermore, a new RRS spectrum would appear, and the maximum RRS wavelength was located at about 375 nm. The fluorescence quenching (FQ) and enhanced RRS intensity were directly proportional to the PUFX concentration in the ranges of 1.5 – 7.6 μg mL–1 and 0.004 – 3.0 μg mL–1 with detection limits 8.5 ng mL–1 and 1.1 ng mL–1, respectively. The optimum conditions of RRS method and the effects of coexisting substances on the reaction were investigated. In addition the composition of ion-association complexes, the reaction mechanism, the energy transfer between absorption, fluorescence and RRS and reasons for RRS enhancement were discussed. The methods were applied to the determination of PUFX in pharmaceutical samples with satisfactory results.

Conductometric Titration for Determination of Trazodone Hydrochloride and Solubility Products of its Ion-Associated Complex Species

Objective: Conductometric determination of trazodone hydrochloride, with two precipitating reagents; Ammonium Reineckate and sodium tetraphenylborate has been investigated.Methods: The formed ion-associates were studied conductomterically for the determination of solubility products and other functions associated with the process of precipitating trazodone hydrochloride were determined. Moreover, two new maneuvers towards equivalence point detection were carried out. In this study, data processing was performed using numerical derivatization (second derivative) and Boltzmann algorithm. Results: Although, the described procedures allowed the determination of trazodone hydrochloride within the range of 2-14 mg using both reagents has less sensitivity other than reported method but has more advantages in simplicity, low cost , relatively short analysis time and direct analysis with good recoveries between 100.01% and 100.07% with relative standard deviation less than 2%. Conclusion: These methods were validated and successfully applied for the determination of trazodone hydrochloride in Trittico® tablets. The obtained results were statistically compared with those of the official method by applying t-test and F-value at 95% confidence level and no significant difference was observed regarding accuracy and precision.

Study on the Chelate Formation and the Ion-association of Anionic Chelate of Molybdenum(VI) with 3,5-Dinitrocatechol and Monotetrazolium Cation

The equilibria of the chelate formation and ion-association in the liquid-liquid extraction system Mo(VI)‒3,5-DNC‒INT‒H2O‒CHCl3 were studied by spectrophotometry. The optimum conditions for the chelate formation and extraction of the ion-associated complex formed between the anionic chelate of Mo(VI)‒3,5-dinitrocatechol (3,5-DNC) and the cation of 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium chloride (INT) were established. The validity of Beer's law was checked and some analytical characteristics were calculated. The effect of various co-existing ions and reagents on the process of complex formation was investigated. The molar ratio of the components in the ternary ion-associated complex Mo(VI)-3,5-DNC-INT was determined by independent methods. The association process in aqueous phase and the extraction equilibria were investigated and quantitatively characterized. The following key constants of the processes were calculated: association constant, distribution constant, extraction constant and recovery factor. Based on this, a reaction scheme, a general formula and a structure of the complex were suggested.

POTENTIOMETRIC DETERMINATION OF GLYCOPYRRONIUM BROMIDE IN BINARY MIXTURE WITH INDACATEROL MALEATE USING POLYVINYL CHLORIDE (PVC) MEMBRANE, COATED GRAPHITE AND CARBON PASTE SENSORS

A novel approach was conducted in this article for the determination of glycopyrronium bromide (GLY) in binary mixture with indacaterol maleate using ion selective electrodes for its selective determination in pure form and pharmaceutical formulation. Four ion selective electrode sensors were designed for determination of glycopyrronium bromide namely; glycopyrronium bromide-polyvinyl chloride (GLY-PVC) membrane, GLY-Coated graphite sensor and GLY-modified carbon paste sensors. The sensors are based on the ion association complexes of GLY cation with sodium tetra phenyl borate (GLY-TPB) and phosphomolybidic acid (GLY-PMA) counter anions as ion exchange sites using dioctylphthalate (DOP) as plasticizer. Validation of the method shows suitability of the proposed sensors for use in the quality control assessment of GLY and for its routine analysis. The results obtained were statistically compared to reported method and there was no significant difference between the proposed methods and the reported method regarding the accuracy and precision. The method was validated according to International Conference on Harmonization (ICH) guidelines and the results were satisfactory.

Disposable gold nanoparticle functionalized and bare screen-printed electrodes for potentiometric determination of trazodone hydrochloride in pure form and pharmaceutical preparations.

In the present study, screen-printed electrodes unmodified and chemically modified with gold nanoparticles were used as sensitive electrochemical sensors for the determination of trazodone hydrochloride. The sensors were based on the use of a tetraphenylborate ion association complex as an electroactive material in screen-printed electrodes with dioctyl phthalate (DOP) as a solvent mediator modified with gold nanoparticles which improve the electrode conductivity and enhance the surface area. The sensors displayed a stable response for 5, 6 and 7 months with a reproducible potential and linear response over the concentration range 1 × 10−5–1 × 10−2 mol L−1 at 25 ± 1 °C with Nernstian slopes of 57.50 ± 0.66, 58.30 ± 0.45 and 59.05 ± 0.58 mV per decade and detection limits of 7.9 × 10−6, 7.6 × 10−6 and 6.8 × 10−6 mol L−1 for sensor 1, 2 and 3 respectively. The analytical performance of the screen printed electrodes in terms of selectivity coefficients for trazodone hydrochloride relative to the number of potentially interfering substances was investigated. The proposed method has been applied successfully for the analysis of the drug in its pure and dosage forms and there is no interference from any common pharmaceutical additives.

New Conductometric Titration Methods for Determination of Diphenhydramine Hydrochloride Using Sodium Tetraphenylborate and Cetylpyridinium Bromide

Sodium tetraphenylborate (TPB) and cetylpyridinium bromide (CPB) were used as titrant for the conductometric determination of diphenhydramine hydrochloride (DPH) drug through ion association complex formation and then the conductance of the solution is measured as a function of the volume of titrant. The effect of the solvent, reagent concentration, temperature and molar combining ratio of the formed ion-associates were studied and evaluated. The suggested method was applied for the determination of diphenhydramine hydrochloride in pure form and pharmaceutical preparations. The described procedures allowed the determination of the studied drug in bi-distilled water in the range of 0.75–16 mg. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method was indicated by excellent recovery and the precision supported by the low relative standard deviation <1%. The sensitivity of the proposed method was discussed and the results were compared with the potentiometric pharmacopoeial method. The proposed procedure was simple, precise and low cost and can be applied for the routine measurements of the cited drug.

UV Spectrophotometric Analysis of Drugs Terbinafine Hydrochloride and Clarithromycin

One simple and sensitive procedure (UV spectophotometric method) for the assay of two drugs namely terbinafine hydrochloride and clarithromycin in pure form and formulations. This method involves the formation of ion-association complex between TRB or CAM and the picric acid. In order to establish the optimum conditions necessary for rapid and quantitative formation of coloured product with maximum stability and sensitivity, the author performed experiments by measuring the absorbance at λmax 350 nm of a series of solutions, varying one and fixing the other parameters in each case such as type, volume and concentration of acid, organic solvent used for extraction, ratio of organic phase to aqueous phase during extraction, shaking time and temperature. The variable parameters were optimized. The results were statistically validated.

Determination of Trace lead (II) by Resonance Light Scattering Based on Pb (II)-KI-MG System

In pH=3.0 weak acidic solution, it is found that Pb2+ can react with I-to form [PbI4]2-, and it further reacted with MG to form ion-association complex. As a result, the new spectra of RLS appeared and their intensities enhanced greatly. Accordingly, a new method developed for the determination of Pb (II).The appropriate reaction conditions were optimized through experiments. The results show that a strong and stable resonance scattering spectra emerge at the wavelength of 338 nm. The resonance light scattering strength (ΔIRLS) has good linear relationship with the concentration of Pb (II) in the range of 0.2 μg/mL ~ 1.0 μg/mL. The detection limits (LOD) is 0.0155 μg/mL. The relative standard deviation (RSD) is 3.61% (n=11) for the determination of 0.6 μg/mL Pb (II) standard solution. And this method was successfully applied to the determination of three environmental water samples (nongfu spring, tap water, laboratory wastewater). Results illustrate that the addition standard recovery are 80%~107% with relative standard deviation (RSD) between 1.8% to 4.6%.

Spectrophotometric and theoretical studies on the determination of etilefrine hydrochloride in pharmaceutical formulations and biological samples

Purpose: To develop a simple and cost effective spectrophotometric method for the determination of etilefrine hydrochloride (ET) in pharmaceutical formulations and human plasma.Methods: The method is based on extraction of ET into chloroform as ion-pair complexes with bromocresol green (BCG) and methyl orange (MO) in acidic medium. The interaction of ET with BCG and MO reagents were investigated using B3LYP/6-31G(d) level of theory. The geometrical parameters of the interacting species and the ion pairs formed were characterized based on their frontier molecular orbitals, atomic charges, electrostatic potential map, as well as NBO analysis.Results: The colored species exhibited absorption maxima at 410 and 479 nm for the two systems in universal buffer of pH range (3.0 - 3.5), with molar absorptivity of 2.4 × 104 and 1.7 × 104 Lmol-1cm-1, for BCG and MO methods, respectively. The methods demonstrated good linearity with correlation coefficient ranging from 0.9987 – 0.9991 in the concentration ranges 0.5 – 16 and 2.0 – 18 μgmL-1 for BCG and MO methods, respectively. The composition ratio of the ion-association complexes was 1:1 in all cases as established by Job’s method. Sandell,s sensitivity, correlation coefficient, detection and quantification limits were also calculated. Molecular descriptors were obtained based on optimized structures of the molecules under investigation, by applying the B3LYP/6-31G(d) method, and used to interpret the mode of interaction between these molecules to form the investigated ion pairs.Conclusion: The proposed methods make use of simple reagents, which a basic analytical laboratory can afford. No interference was observed from common pharmaceutical excipients and additives. ETMO ion pair has a larger interaction energy (higher stability) than ET-BCG ion pair as inferred from their interaction energies.Keywords: Density functional theory, Etilefrine hydrochloride, Ion pair complex, Spectrophotometry, Bromocresol green, Methyl orange, Geometric analysis

Resonance Rayleigh scattering and resonance nonlinear scattering of the palladium(II)–acetazolamide chelate with eosin Y and their analytical application

ABSTRACTA simple, rapid, and convenient method based on ion association for the determination of acetazolamide has been developed. Acetazolamide can react with palladium(II) to form cationic chelate at sodium acetate–acetic acid buffer solution, which can further react with eosin Y to form an ion association complex. As a result, the resonance Rayleigh scattering, second-order scattering, and frequency doubling scattering intensities are enhanced. Analytical wavelengths of resonance Rayleigh scattering, second-order scattering, and frequency doubling scattering located at 298, 558, and 338 nm, and the linearity range are 0.014–2.5, 0.034–2.5, and 0.119–2.4 µg mL−1 respectively. In addition, the optimum conditions and the effect of coexisting substances are investigated. Besides, the structure of ion association complex, the reaction mechanism and the reasons for the enhancement of scattering are discussed through infrared spectra, absorption spectra, and quantum chemical calculations.

Study on the Interaction between Rhodamine Dyes and Allura Red Based on Fluorescence Spectra and Its Analytical Application in Soft Drinks.

Allura red (AR) is a common food additive. It is of significance to detect AR sensitively and selectively in soft drinks. In this report, fluorescence spectra of allura red-rhodamine dyes systems were studied. In a pH 6.0 Britton-Robinson buffer medium, the fluorescence of rhodamine dyes, such as rhodamine B (RB), butylrhodamine B (BRB) and rhodamine 6G (R6G), can be quenched by AR. Impressively, the emission spectrums of the RB and BRB change slightly upon the addition of AR, but it was clear that the emission of R6G decreased dramatically in the presence of AR. Thus, we have succeeded in planning an improved method for specifically detecting AR on the basis of hydrophobic forces and the electrostatic attraction between R6G and AR. The results show that AR could combine with R6G to form an ion-association complex, which causes quenching of the emission intensity of R6G and changes of the UV-visible spectra. In this system, 0.097 - 6.0 μmol L-1 AR could be simply detected owing to the decreased fluorescence of R6G in soft drinks, with a detection limit of 0.029 μmol L-1. In addition, we also optimized the reaction conditions and evaluated the effects of some coexisting substances. According to the fluorescence decay time, the UV-visible absorption spectra and the Stern-Volmer plots, the fluorescence quenching of R6G by AR is a static quenching process.

Ion‐pair switchable‐hydrophilicity solvent‐based homogeneous liquid–liquid microextraction for the determination of paraquat in environmental and biological samples before high‐performance liquid chromatography

An approach involving ion-pair switchable-hydrophilicity solvent-based homogeneous liquid-liquid microextraction coupled to high-performance liquid chromatography has been applied for the preconcentration and separation of paraquat in a real sample. A mixture of triethylamine and water was used as the switchable-hydrophilicity solvent. The pH was regulated using carbon dioxide; hence the ratio of the ionized and non-ionized form of triethylamine could control the optimum conditions. Sodium dodecyl sulfate was utilized as an ion-pairing agent. The ion-associate complex formed between the cationic paraquat and sodium dodecyl sulfate was extracted into triethylamine. The separation of the two phases was carried out by the addition of sodium hydroxide, which changed the ionization state of triethylamine. The effects of some important parameters on the extraction recovery were investigated. Under the optimum conditions (500μL of the extraction solvent, 1mg sodium dodecyl sulfate, 2.0mL of 10mol/L sodium hydroxide, and pH 4), the limit of detection and the limit of quantification were 0.2 and 0.5μg/L, respectively, with preconcentration factor of 74. The precision (RSD, n=10) was <5%. The recovery of the analyte in environmental and biological samples was in the range of 90.0-92.3%.

Vortex-assisted liquid-liquid microextraction of strontium from water samples using 4',4″(5″)-di-(tert-butylcyclohexano)-18-crown-6 and tetraphenylborate.

A vortex-assisted liquid-liquid microextraction method was developed for the chromatographic determination of strontium in aqueous samples. In the method, strontium was complexed with 4',4″(5″)-di-(tert-butylcyclohexano)-18-crown-6 in the presence of tetraphenylborate as the counter anion, which increased the hydrophobicity of the ion-association complex, resulting in its improved extraction into 1-octanol. Strontium from the organic phase was stripped with nitric acid back to aqueous solution and determined by ion chromatography. The optimum microextraction conditions were as follows: 2.0mL aqueous samples with 3mM tetraphenylborate; 150μL of 1-octanol as the extractant phase with 10mM DtBuCH18C6; vortex extraction time for 10s; centrifugation at 6000rpm for 4min; stripping by 0.1M nitric acid. Under the optimum conditions, the detection limit for strontium was 0.005mg/L. The calibration curves showed good linearity over the range between 0.01 and 2.5mg/L. Intra- and interday precisions of the present method were satisfactory with relative standard deviations of 1.7 and 2.1%, respectively.

Resonance Rayleigh scattering method for the determination of chitosan using erythrosine B as a probe and PVA as sensitization

A highly sensitive resonance Rayleigh scattering (RRS) method for the determination of chitosan (CTS) was developed. In the pH 3.8 Britton-Robinson buffer solution, CTS interacted with erythrosine B (Ery B) to form an ion-association complex of [Ery B-CTS] which increased the RRS intensity of the system. With the addition of polyvinyl alcohol (PVA), the RRS intensity was significantly enhanced, and the RRS intensity of the reagent blank(I0) dramatically decreased. The enhanced RRS intensity (ΔI) was linearly proportional to the concentration of chitosan. Taking the medium molecular weight chitosan as the representative, the linear range of the method was 5.0–100.0ng/mL and the detection limit (DL) was 0.47ng/mL. The effect of the molecular weight of CTS on its accurate quantification was studied. Furthermore the dispersion and stability mechanism of PVA was discussed. Accordingly this assay was applied to detect the concentration of CTS in health products with satisfactory results.

Spectrophotometric Study of the Complex Formation of Anionic Chelates of Cobalt(II) with Monotetrazolium Cations

The complex formation and extraction of anionic chelates of Co(II)–4-(2-thiazolylazo)resorcinol (TAR) with cations of monotetrazolium salts (TS) — (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) and 3-(2-naphthyl)-2,5-diphenyl-2H-tetrazolium chloride (TV) — in the liquid–liquid extraction system Co(II)–TAR–TS–H2O–CHCl3 were studied by spectrophotometric methods. The optimum conditions for the extraction of Co(II) were found. The molar ratio of the components and the form of the anionic chelates of Сo(II) in the extracted compounds were determined by independent methods. The association process in the aqueous phase and the extraction process were investigated and quantitatively characterized. The following key constants were calculated: association constant, distribution constant, extraction constant, and recovery factor. The validity of the Beer’s law was checked, and some analytical characteristics were calculated. Based on the obtained results and the lower price of the monotetrazolium salt MTT compared with that of TV, the ion-associated complex of Co(II)–TAR–MTT can be implemented for determination of cobalt(II) traces in alloys and biological, medical, and pharmaceutical samples.

Liquid membrane/polyaniline film coated glassy carbon sensor for highly sensitive and selective determination of fluvoxamine in pharmaceutical and biological samples

A novel and very sensitive potentiometric sensor with excellent electrochemical properties was fabricated for the determination of fluvoxamine. The sensor is based on the use of the PVC-membrane containing ion-association complex of fluvoxamine with reinecke salt coated on the glassy carbon electrode which was modified with polyaniline as a conductive polymeric film. The proposed sensor exhibits a Nernstian slope of 58.9mV per decade for fluvoxamine over a wide concentration range of 1.8×10−7–1.3×10−3M, with a low detection limit of 7.8×10−8M. The sensor has a fast response time, excellent reproducibility and long life time. It can be used within the pH range of 4.0–7.5 in a long time period. The sensor possesses a high selectivity toward a large variety of inorganic and organic co-existing species. The effect of temperature on the sensor potential response was studied and the isothermal coefficient of the sensor was calculated. The sensor has a good thermal stability within the studied temperature range. The developed sensor was used as an indicator electrode in potentiometric titration of fluvoxamine with sodium tetraphenylborate. The sensor was successfully applied in the determination of fluvoxamine in pharmaceutical solution, blood serum and urine samples.

Determination of Sunset Yellow Based on Its Quenching Effect on the Fluorescence of Acridine Orange.

Acridine orange (AO) is widely applied as an organic fluorescent probe. In this work, AO was reacted with sunset yellow (SY) to form an ion-association complex in pH 3.4 Britton-Robinson (BR) buffer solution medium. This resulted in the fluorescence quenching of the former and helped to detect the latter with the maximum excitation wavelengths (λex) and emission wavelengths (λem) near 490 and 530 nm, respectively. The assay exhibits high sensitivity and selectivity with a detection limit of 0.002 μmol L-1 and the remarkable quenching of fluorescence was proportional to the concentration of SY in the range of 0.008 - 9.0 μmol L-1. Herein, this finding was utilized to develop a new strategy for simple, rapid, sensitive and selective detection of SY by combining AO based on fluorescence quenching. In addition, the optimum reaction conditions and the effect of foreign substances were studied. The reasons for fluorescence quenching were also investigated, which showed the quenching of fluorescence of AO with SY was a static quenching process. Furthermore, the proposed method was applied in a real sample analysis with satisfactory results.

Study on the equilibria of the complex formation of molybdenum(VI) with 3,5-dinitrocatehol and 3-(2-naphthyl)-2,5-diphenyl-2H-tetrazolium chloride

The formation of an ion-associated complex between the anionic chelate of Mo(VI)–3,5-dinitrocatehol (3,5-DNC) and the cation of 3-(2-naphthyl)-2,5-diphenyl-2H-tetrazolium chloride (TV) in the liquid–liquid extraction system Mo(VI)–3,5-DNC–TV–H2O–CHCl3 was studied by spectrophotometry. The optimum conditions for the complex formation and extraction of the ion-associated complex were established. The effect of co-existing ions and reagents on the process of complex formation was investigated under optimum extraction conditions. The validity of Beer’s law was checked and some analytical characteristics were calculated. The association process in aqueous phase and the extraction equilibria were investigated and quantitatively characterized. The following key constants of the processes were calculated: association constant, distribution constant, extraction constant and recovery factor. The molar ratio of the reagents was determined by independent methods. Based on this, a reaction scheme, a general formula and a structure of the complex were suggested.

Simultaneous determination of five fluoroquinolones by the selective high performance liquid chromatography associating with sensitive resonance light scattering and mechanism study

A novel and selective high performance liquid chromatography (HPLC) technique incorporating resonance light scattering (RLS) detection approach was developed for the determination of five fluoroquinolones (FQS) synchronously for the first time, including enoxacin (ENO), ofloxacin (OFLX), lomefloxacin (LMLX), gatifloxacin (GFLX) and sparfloxacin (SPLX). In pH4.4 Britton - Robinson (BR) buffer medium, the ENO, OFLX, LMLX, GFLX, SPLX separated by HPLC reacted with erythrosine (ERY) to form 1:1 ion-association complexes, which led to significant enhancement of RLS. The maximum RLS wavelength of the ion-association complexes located at 330nm. The detection limits of ENO, OFLX, LMLX, GFLX, SPLX were 5.1ng·mL−1, 3.1ng·mL−1, 4.2ng·mL−1, 3.8ng·mL−1, 17.5ng·mL−1 respectively at a signal-to-noise ratio of 3. In this work, the optimum experimental conditions and reaction mechanism were investigated in detail. The proposed method could be applied to the determination of ENO, OFLX, LMLX, GFLX, SPLX in water samples synchronously and the results were satisfactory.

Application of membrane-selective electrodes for the determination of Tiemonium methylsulphate

Three ion selective electrodes were developed for the quantification of Tiemonium methylsulphate (TIM). Two of these sensors involve the construction of water insoluble ion-association complexes; namely sensor1 TIM-phosphotungstate (TIM-PT) and sensor 2 TIM-Reinecke (TIM-R). Molecular recognition elements have extensive applications in electrochemical sensors with a significant potential for future development thus a third electrode utilizing molecularly imprinted polymer was constructed; sensor 3 TIM-MIP. The proposed sensors showed fast, stable Nernstian responses of 56.4, 56.1and 57.5mV/decade for sensors 1, 2 and 3, respectively, across a relatively wide TIM concentration range (1×10−4 to 1×10−2molL−1 for sensors 1 and 2 and 1×10–5 to 1×10–2molL−1 for sensor 3) in the pH range of 2–7. Sensor 1 and sensor 2 can be used for five weeks while sensor 3 for 65days without a significant change in sensitivity. The suggested method was used to determine TIM in dosage forms. No measurable difference was obtained when the result statistically compared with respect to accuracy and precision with reported HPLC method.