Continuous Cyclic Voltammetry Research Articles

Application of Adsorptive Voltammetry for the Detection of Sub-nano Molar Cyclizine in Biological Fluids and Tablets Using Fast Fourier Transform Continuous Cyclic Voltammetry in a Flowing System

An easy and fast Fourier transform continuous cyclic voltammetric technique (FFTCV) for monitoring of ultra trace amounts of cyclizine in a flow-injection system has been introduced in this work. The potential waveform, which was applied continuously on an Au disk microelectrode (12.5 microm in radius) consisted of the potential steps for cleaning, accumulation and potential ramp. The proposed detection method has some advantages, the greatest of which are as follows: first, it is no longer necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The detection limit for cyclizine was 1.8 ng ml(-1). The relative standard deviation (RSD) of the proposed technique at 5.0 x 10(-7) was 2.0 for 10 runs. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the cyclizine were considered. The proposed method was applied to the determination of cyclizine in a pharmaceutical preparation.

Electrochemical evaluation of non-electroactive drug erythromycin in trace amount at biological samples by continuous cyclic voltammetry

A fast continuous cyclic voltammetry was used as a detection method for the monitoring of erythromycin in a flow-injection system. A special computer-based numerical calculation method (using Fast Fourier Transformation) is introduced here for enhancing the analyte signal and noise reduction. During the measurements, the potential waveform (consists of potential steps for cleaning, stripping and potential ramp) was continuously applied on an Au disk microelectrode with a 25 μm radius. The objective of the performed experiments was the inspection of the effects of different parameters on the method sensitivity. After the experiments' completion, it was concluded that the method was linear for the concentration range of 7–733,000 pg/ml ( r = 0.998) with a limit of detection and quantitation 2.4 and 7 pg/ml, respectively. The stripping time was less than 200 ms. Effects of rest potential, sweep rate, and delay time on the sensitivity and selectivity of the method were investigated.

Sotalol nanolevel detection at an Au microelectrode in flowing solutions

Sotalol detection in tablets is achieved with the help of a newly developed, time-saving, and simple method, called fast Fourier transform with continuous cyclic voltammetry (FFTCV). Noticeably, FFTCV illustrates two advantages, not being demonstrated by earlier reports. First, there is no requirement for the oxygen removal from the test solution. In addition, the speed of the method for determining any compound is high in a broad range of chromatographic methods. This research includes the observation of effects of various parameters (influence of the pH of the eluent, accumulation potential, sweep rate, accumulation time) on the sensitivity of the detection system. Finally, the technique was found to be linear for the concentration range of 3–14900 pg/ml (r = 0.998) with a limit of detection and quantitation of 0.95 pg/ml and 3 pg/ml, respectively.

Electrocatalytic Oxidation of Some Carbohydrates by Nickel/Poly(o‐Aminophenol) Modified Carbon Paste Electrode

AbstractThis study investigates the electrocatalytic oxidation of glucose and some other carbohydrates on nickel/poly(o‐aminophenol) modified carbon paste electrode as an enzyme free electrode in alkaline solution. Poly(o‐aminophenol) was prepared by electropolymerization using a carbon paste electrode bulk modified with o‐aminophenol and continuous cyclic voltammetry in HClO4 solution. Then Ni(II) ions were incorporated to electrode by immersion of the polymeric modified electrode having amine group in 1 M Ni(II) ion solution. Cyclic voltammetric and chronoamperometric experiments were used for the electrochemical study of this modified electrode; a good redox behavior of Ni(OH)2/NiOOH couple at the surface of electrode can be observed, the capability of this modified electrode for catalytic oxidation of glucose and other carbohydrates was demonstrated. The amount of α and surface coverage (Γ*) of the redox species and catalytic chemical reaction rate constant (k) for each carbohydrate were calculated. Also, the electrocatalytic oxidation peak currents of all tested carbohydrates exhibit a good linear dependence on concentration and their quantification can be done easily.

A new method for the determination of loratadine at an Au microelectrode in flowing systems with the use of fast continuous cyclic voltammetry

This research presents a new method for the fast monitoring of loratadine in pharmaceutical formulation. The method employs the fast Fourier transformation continuous cyclic voltammetry (FFTCV) at a gold microelectrode in a flowing-solution system. Three considerable advantages of the technique are demonstrated. First, there is not any requirement for the oxygen removal from the test solution; second, a subnanomolar detection limit is gained; and, finally, the speed of the method for the determination of a compound is in a broad range of chromatographic methods. A special computer-based numerical method is also introduced for the calculation of the analyte signal and noise reduction. The electrode response was calculated in accordance with the partial and total charge exchanges on the electrode surface after the background current subtraction from that of the noise. The integration range of the currents was set for all potential scan ranges, including the oxidation and reduction of the Au surface electrode in order to obtain a sensitive determination. The objective of the performed experiments was to study the effects of different parameters on the method sensitivity. It was concluded that the method had a linear concentration range of 40–765000 pg/mL (r = 0.999) with a limit of detection and quantitation of 12 and 40 pg/mL, respectively. For the achievement of these optimum results, the parameter values were set to 80 V/s for the scan rate, 0.7 s for the accumulation time, 300 mV for the accumulation potential, and 2 for the pH.

Development of fast Fourier transformations with continuous cyclic voltammetry at an Au microelectrode and its application for the sub nano-molar monitoring of methyl morphine trace amounts

In this work, a new highly sensitive and fast method for monitoring methyl morphine in flow-injection systems is introduced. Mathematical methods such as signal integration and fast Fourier transformation used with continuous cyclic voltammetry. It should be stressed that this technique is simple, precise, accurate, time saving and economical. The effects of various parameters on the sensitivity of the detection system were examined. Eventually, it was concluded that the best condition was obtained within the pH value of 2.1, scan rate value of 80 V/s, accumulation potential of 400 mV and accumulation time of 0.4 s. In addition, a special mathematical based numerical method is used for the calculation of the analyte signal and noise reduction. Where, the electrode response was calculated based on the partial and total charge exchanges on the electrode surface, after the background current subtraction from that of noise. In order to increase sensitivity of the method, the currents were integrated over a selected range of potential (including oxidation and reduction of the Au surface electrode), of the recorded CVs. The resulted signal was calculated based on changes in the charge in the CVs. The potential waveform, consisting of two potential steps for electrochemical cleaning, a step for accumulation and a potential ramp for current measurement, was applied to an Au disk microelectrode continuously. In detail, the noteworthy advantages which this method illustrates in comparison with the other reported methods are the following; no oxygen removal is required from the test solution, a sub-nano molar detection limit and the fast determination of any such compound in a wide variety of chromatographic methods. Calibration curve is linear over the concentration range of 0.02–1.1 μM (5.98 × 10 3–329.2 × 10 3 pg/ml) ( r = 0.997) with a detection limit and a quantitation limit of 0.008 μM (2.39 × 10 3 pg/ml) and 0.01 μM (2.99 × 10 3 pg/ml), respectively. Consequently, the method illustrates the requisite accuracy, sensitivity, precision and selectivity to assay methyl morphine in its tablets.

A novel method for fast determination of vitamin B6 by fast continuous cyclic voltammetry

In this work a novel method for the determination of Vitamin B6 in flow-injection systems has been developed. The fast Fourier transform continuous cyclic voltammetry (FFTCV) at gold microelectrode in flowing solution system was used for determination of Vitamin B6. This method is rapid, simple and highly sensitive procedures allowing the determination of Vitamin B6 in pharmaceutical analysis. The effects of various parameters on the sensitivity of the method were investigated. The best performance was obtained with the pH value of 2, scan rate value of 30 V/s, accumulation potential of 200 mV and accumulation time of 0.3 s. The proposed method has some advantages over other reported methods such as, no need for the removal of oxygen from the test solution, a sub-nanomolar detection limit, and finally the method is fast enough for the determination of any such compound, in a wide variety of chromatographic methods. To obtain a sensitive determination, the integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, while performing the measurements. The potential waveform, consisting of the potential steps for cleaning, accumulation and potential ramp of analyte, was applied on an Au disk microelectrode (12.5 μm in radius) in a continuous way. The detection limit of the method for Vitamin B6 was 2.8 pg/ml. The relative standard deviation of the method at 2.1% was 8 runs.

Development a New Method for the Determination of Chloropromazine in Trace Amounts by Fast Fourier Continuous Cyclic Voltammetry at an Au Microelectrode in a Flowing System

AbstractIn this study a new technique has been developed for the determination of chloropromazine in flow‐injection systems. The technique, named fast Fourier transformation continuous cyclic voltammetry (FFTCV), basically illustrates the benefits of sensitivity, selectivity, simplicity and low detection limit.It is also important to refer to the positive points, presented only by the use of this technique. Firstly, it is no longer necessary to remove the oxygen from the test solution. Furthermore, the quick determination of any such compound in many chromatographic methods is possible. Thirdly, the corresponding detection limit is of sub‐nanomolar level. Additionally, a special computer based numerical method is also introduced for the calculation of the analyte signal and noise reduction. The electrode response was calculated in accordance with the partial and total charge exchanges on the electrode surface, after the background current subtraction from that of noise. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of Au surface electrode, to obtain a sensitive determination.The performed experiments aimed at measuring the effects of different parameters on the method sensitivity. In the end of these measurements, it was concluded that the method was linear for the concentration range of 0.32–31900 pg/mL (r = 0.996) with a limit of detection and quantitation 0.1 and 0.32 pg/mL, respectively. For the achievement of these optimum results, the parameter values were set to 100 V/s for the scan rate, 0.4 s for accumulation time, 800 mV for accumulation potential and 2 for the pH.

Application of Adsorptive Stripping Voltammetry for the Nano‐Level Detection of Tramadol in Biological Fluids and Tablets Using Fast Fourier Transform Continuous Cyclic Voltammetry at an Au Microelectrode in a Flowing System

A novel adsorptive fast Fourier transform cyclic voltammetry (AFFTCV) technique for the fast determination of tramadol in flow‐injection systems has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping, and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, it is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the tramadol were considered. The method was linear over the concentration range of 1.5–900,000 pg/ml (r=0.9968) with a limit of detection and quantitation 0.32 and 1.5 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay tramadol in tablets and in biological fluids.

Sub-second adsorption for the fast sub-nanomolar monitoring of Clindamycin in its pure and pharmaceutical samples by fast Fourier transformation with the use of continuous cyclic voltammetry at an Au microelectrode in a flowing system

For the first time the fast Fourier adsorptive stripping voltammetry at a microgold electrode for the determination of Clindamycin in flow injection systems has been developed. The principal advantages of the method are that it is rapid, simple, and possesses low detection limit. Some investigations were also done, to find the effects of various parameters on the sensitivity of the proposed method. The conditions producing the performance were the pH value of 2, the scan rate value of 40 V/s, accumulation potential of (300 mV), and accumulation time of 0.3 s. Some of the advantages of the proposed method are as follows: the removal of oxygen from the test solution is not required any more, the detection limit of the method is sub-nanomolar and finally, the method is fast enough for determination of such compounds, in a wide variety of chromatographic methods. We also introduce a special computer based numerical method, for calculation of the analyte signal and noise reduction. After subtracting the background current from noise, the electrode response was calculated, based on partial and total charge exchanges at the electrode surface. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, to obtain a sensitive determination. The waveform potential was continuously applied on an Au disk microelectrode (with a 12.5 μm in radius). The method was linear over the concentration range of 4–42,498,400 pg/ml ( r = 0.9957) with a limit of detection and quantitation 1.3 and 4 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay Clindamycin in capsules.

Platinum nanoparticles supported on activated carbon fiber as catalyst for methanol oxidation

Activated carbon fiber (ACF) with high specific surface area has been used as support in the preparation of Pt nanoparticles electrocatalyst (Pt/ACF) for direct alcohol fuel cells. It is found that the Pt nanoparticles on ACF are highly and homogeneously dispersed with a narrow size distribution in the range of 1.5–3.5 nm with an average size of 2.4 nm. In comparison with the commercial E-TEK Pt/C catalyst, the Pt/ACF catalyst exhibits much higher catalytic activity for methanol, ethanol and isopropanol oxidation, which are about 2.4 times as high as that of the former. The Pt/ACF catalyst is observed to be significantly more stable during the constant current density polarization and continuous cyclic voltammetry in comparison with Pt/C catalyst. Both the uniform dispersion of Pt nanoparticles and strong interactions between Pt nanoparticles and ACF are of benefit to achieve the performance improvement of Pt/ACF catalyst.

Nano-Level Detection of Naltrexone Hydrochloride in Its Pharmaceutical Preparation at Au Microelectrode in Flowing Solutions by Fast Fourier Transforms Continuous Cyclic Voltammetry as a Novel Detector

An easy and fast Fourier transform continuous cyclic voltammetric technique for monitoring of ultra trace amounts of naltrexone in a flow-injection system has been introduced in this work. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 microm in radius). The proposed detection method has some of advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The method was linear over the concentration range of 0.34-34000 pg/mL (r = 0.9985) with a limit of detection 8.0 x 10(-4) nM. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay naltrexone in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the naltrexone were considered.

Development of fast Fourier transform continuous cyclic voltammetry at Au microelectrode in flowing solutions as a novel method for sub-nanomolar monitoring of lidocaine in injection and biological fluids

In this work a novel method for the fast monitoring of lidocaine in flow-injection systems has been developed. The fast Fourier transform continuous cyclic voltammetry (FFTCV) at gold microelectrode in flowing solution system was used for determination of lidocaine in its pharmaceutical formulation. The presented technique was very simple, precise, accurate, time saving and economical, compared with all of the previously reported methods. The recommended technique demonstrated some advantages over other reported methods. Firstly, there was no need for the oxygen removal from the test solution. Secondly, a picomolar detection limit was achieved, and additionally, the method was fast enough for the determination of any such compound, in a wide variety of chromatographic methods. The method was linear across the concentration range of 240–1.1 × 10 5 pg mL −1 ( r = 0.996) with a limit of detection and quantitation 117.3 and 240 pg mL −1, respectively. As a conclusion this system offers the requisite accuracy, sensitivity, precision and selectivity to assay lidocaine in injections.

Fast Fourier transformation with continuous cyclic voltammetry at an Au microelectrode for the determination of morphine in a flow injection system

For the fast morphine monitoring in flow injection systems a highly sensitive method is being introduced in this work. The fast Fourier transformation with continuous cyclic voltammetry (FFTCV) in a flowing solution as a detection system was applied for the prompt morphine monitoring. Here it should be stressed that this technique is simple, precise, accurate, time saving and economical. This research includes the observation of the effects of various parameters on the sensitivity of the detection system. Eventually, it was concluded that the best condition was obtained within the pH value of 2, scan rate value of 40 V s −1, accumulation potential of 400 mV and accumulation time of 0.6 s. In detail, the noteworthy advantages which this method illustrates in comparison with other reported methods are the following; no necessity for the oxygen removal from the test solution, a sub-nano molar detection limit and the fast determination of any such compound in a wide variety of chromatographic methods. The method proved to be linear over the concentration range of 285–305,300 pg mL −1 ( r = 0.999) with a detection limit and a quantitation limit of 95.5 and 285 pg mL −1, respectively. Consequently, the method illustrates the requisite accuracy, sensitivity, precision and selectivity to assay morphine in its tablets and biological fluids.

Subsecond FFT‐adsorptive Voltammetric Technique as a Novel Method for Subnano Level Monitoring of Piroxicam in its Tablets and Bulk Form at Au Microelectrode in Flowing Solutions

In this work a novel method for the determination of piroxicam in flow‐injection systems has been developed. A system using fast Fourier transform continuous cyclic voltammetry (FFTCV), at a gold microelectrode in flowing solution, was used for determining piroxicam in its pharmaceutical formulations. The developed technique is very simple, precise, accurate, time saving, and economical, compared to all of the previously reported methods. The effects of various parameters on the sensitivity of the method were investigated. The best performance was obtained with a pH value of 2, scan rate value of 40 V/s, accumulation potential of (400) mV, and accumulation time of 0.4 s. The proposed method has some advantages over other reported methods, such as, no need for the removal of oxygen from the test solution, a picomolar detection limit, and finally that the method is fast enough for the determination of any such compound, in a wide variety of chromatographic methods. To obtain a sensitive determination, the integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, while performing the measurements. The potential waveform, consisting of the potential steps for cleaning, accumulation, and potential ramp of analyte, was applied on an Au disk microelectrode (with a 12.5 µm in radius) in a continuous way. The method was linear over the concentration range of 1.5–364000 pg/ml (r=0.998) with a limit of detection and quantitation of 0.33 and 1.5 pg/ml, respectively. The method has the requisite accuracy, sensitivity, precision, and selectivity to assay piroxicam in tablets.

Fast Fourier Transform Continuous Cyclic Voltammetry Development as a Highly Sensitive Detection System for Ultra Trace Monitoring of Thiamine

In this work, a highly sensitive method for the fast monitoring of thiamine hydrocholoride in flow‐injection systems has been developed. The fast Fourier transform continuous cyclic voltammetry (FFCV) in flowing solution as a detection system was applied for the very fast monitoring of thiamine in its pharmaceutical formulations. This technique is very simple, precise, accurate, time‐saving and economical, compared to all previous reported methods. The effects of various parameters on the sensitivity of the detection system were considered. The best condition was obtained within the pH value of 2, and scan rate value of 25 V s−1, accumulation potential of −400 mV, and accumulation time of 0.6 s. The proposed method has some advantages over other reported methods such as, there is no need for the removal of oxygen from the test solution, has a sub‐nanomolar detection limit, and finally the method is fast enough for the determination of any such compound, in a wide variety of chromatographic methods. This research also introduces a special computer‐based numerical method, for the calculation of the analyte signal and noise reduction. The electrode response was calculated based on partial and total charge exchanges on the electrode surface after subtracting the background current from that of noise. To obtain a sensitive determination, the integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, while performing the measurements. The potential waveform, consisting of the potential steps for cleaning, accumulation and potential ramp of analyte, was applied on an Au disk microelectrode (12.5 µm in radius) in a continuous way. The detection limit of the method for thiamine was 1.0×10−12 M. The relative standard deviation of the method at 1.0×10−8 M was 2.2% for 8 runs.

Novel method for determination of trace amounts of citalopram in tablets by fast fourier continuous cyclic voltammetry at au microelectrode in flowing solutions

In this work, fast Fourier transform continuous cyclic voltammetric technique for the monitoring of ultra trace amounts of citalopram in a flow-injection system has been presented. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The method was linear over the concentration range of 7 - 116 pg mL-1 (r = 0.9960) with a limit of detection and quantitation 2.3 and 7 pg mL-1, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay citalopram in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the citalopram were considered. The proposed method was applied to the determination of citalopram in a pharmaceutical preparation.

Development a new method for the determination of paromomycin in trace amounts by fast Fourier continuous cyclic voltammetry at an Au microelectrode in a flowing system

For the first time the technique of fast continuous cyclic voltammetry is used as a highly sensitive detection method for the monitoring of paromomycin in a flow-injection system. A special computer-based numerical calculation method (using fast Fourier transformation) is introduced here for the enhancement of the analyte signal and noise reduction. This research includes the observation of the effects of various parameters (rest potential, sweep rate and delay time) on the sensitivity of the detection system. Furthermore, a potential waveform, consisting of the potential steps for cleaning, accumulation and the step for the potential ramp of the analyte, was applied to an Au disk microelectrode in a continuous way. Eventually, the method was found to be linear for the concentration range of 160–160,000 pg/mL ( r = 0.999) with a limit of detection (LOD) and quantitation (LOQ) 49.25 and 160 pg/mL, respectively. The stripping time was less than 300 ms, while the detection limit was about 10,000 times lower than that of the most sensitive reported method. As a result, the system illustrates the requisite accuracy, sensitivity, precision and selectivity to assay paromomycin in capsules.

Development of fast Fourier transformation continuous cyclic voltammetry as a highly sensitive detection system for ultra trace monitoring of penicillin V

Fast continuous cyclic voltammetry was used as a detection method for penicillin V in a flow injection system. Additionally, a special computer-based numerical calculation method (using fast Fourier transformation) providing enhancement of the analyte signal and noise reduction is introduced here. During the measurements, the potential waveform (consisting of the potential steps of cleaning, stripping, and the potential ramp) was continuously applied to an Au disk microelectrode (12.5 μm in radius). In particular, the effects of accumulation potential, sweep rate, and delay time on the sensitivity and selectivity of the method were investigated. Eventually, the stripping time was found to be less than 300 ms, the detection limit of the method was 7.0 × 10 −12 M, and the associated relative standard deviation at 5.0 × 10 −6 M penicillin V was 2.3 for eight runs.

A novel method for fast determination of Ranitidine in its pharmaceutical formulations by fast continuous cyclic voltammetry

Introduction A novel method for the determination of Ranitidine in flow injection systems was developed. Methods Some investigations were also done to find the effects of various parameters on the sensitivity of the method. The conditions producing optimal performance were a pH value of 2, a scan rate value of 100 V/s, accumulation potential of (− 100) mV, and accumulation time of 0.4 s. Some of the advantages of the proposed method are as follows: the removal of oxygen from the test solution is not required any more, the detection limit of the method is sub-nanomolar and finally, the method is fast enough for determination of compounds in a wide variety of chromatographic methods. We also introduce a special computer based numerical method, for calculation of the analyte signal and noise reduction. After subtracting the background current from noise, the electrode response was calculated, based on partial and total charge exchanges at the electrode surface. The integration range of currents was set for all the potential scan ranges, including oxidation and reduction of the Au surface electrode, to obtain a sensitive determination. The waveform potential was continuously applied on an Au disk microelectrode (12.5 μm in radius). Results The detection limit of the method for Ranitidine was found to be 25 pg/ml. For 8 runs, the relative standard deviation of the method at 1.1 × 10 − 8 M was 2.1%. Discussion The method was successfully applied for fast determination of Ranitidine in its pharmaceutical formulations. Being very simple, precise, accurate, time saving and economical this method has many advantages compared to all previously reported methods.