Development of Square Wave Voltammetric Method for the Electrochemical Determination of Pregabalin as Pregabalin-Cu(II) Complex Using Graphite Electrode

In the present study, a square wave voltammetric (SWV) method was developed for the determination of pregabalin (PREG) in commercial drugs and biological samples as PREG-Cu(II) complex using graphite working electrode. A well-defined voltammetric signal of the complex was observed at nearly – 200 mV, by using Britton Robinson supporting electrolyte (B-R) at pH 7.5. There were some analytical conditions that have been evaluated through this research such as accumulation time and potential, scan rate, amplitude, frequency, and stirring rate to obtain a good voltammetric peak and high current without any overlap. In addition, some metal ions as potential interferences; such as Zn(II), Ni(II) and Cd(II) have been added at different concentrations to evaluate their effects on the voltammetric signal for PREG-Cu(II) complex. The SWV performance was investigated by monitoring parameters such as calibration curve, detection limit, reproducibility, stability and recovery. The calibration curve was studied over the range 5.0 ´10-8–1.0 ´10-6 mol L-1of (PREG) and 5.0 ´ 10-5 mol L-1 of copper ion (n=8, r2 = 0.99), yielded a linear relationship between voltammograms and complex concentrations. The sensitivity of SWV method was evaluated by calculating the detection limit which was found to be 6.5´10-9 mol L-1. The reproducibility, stability and recovery were studied for 5.0 х10-7 mol L-1of (PREG) and 5.0 х 10-5 mol L-1 of copper ion, yielded a relative standard deviation (RSD%) that was calculated to be 0.4% and good stability for the voltammetric signal, while the recovery was recorded to be 93±1.23%. The analytical voltammetric technique (SWV) was applied to determine PREG-Cu(II) complex in pharmaceutical capsules and biological fluids, specifically urine and plasma, where it gave recoveries of 90±1.0%, 89±1.23% and 86±1.23%, respectively

Electrochemical determination of Cd2+ in some Al-Madinah water samples and human plasma by cathodic stripping voltammetry in the presence of oxine as a chelating agent

AbstractA fast, simple, sensitive cathodic adsorptive stripping voltammetric procedure for quantitative analysis of Cd–oxine complex in al-Madinah city water samples and human plasma is described. The technique involves adsorptive accumulation of the complex on the working electrode, followed by square wave voltammetric determination of the preconcentrated analyte. In basic media, a cathodic electrochemical process involving the elimination of two protons occurs, and a mechanism for the reduction process is suggested. The optimal experimental parameters for assay of this complex are: carbonate supporting electrolyte pH 8, accumulation time 30s, accumulation potential −0.1V, scan rate 200mVs−1, pulse amplitude 80mV, frequency 40Hz, surface area of working electrode 0.6mm2 and convection rate 1000rpm. The calibration graph for determination of Cd–oxine was linear over the concentration range 5×10−8 to 4×10−7moll−1 (r=0.998), with a detection limit of 3.5×10−9moll−1. The precision of the proposed procedure was estimated by 10 successive voltammetric measurements of 2×10−6moll−1 Cd with 4×10−6moll−1 oxine, and the calculated relative standard deviation was 0.39%. The percentage recovery, indicating the accuracy of the analytical method, was 94±1.0%. Possible interference by several substances, including metals and ligands, was also evaluated. The electroanalytical method was successfully applied to assaying cadmium in water samples and biological fluids such as plasma

Electrochemical determination of rosiglitazone by square-wave adsorptive stripping voltammetry method

AbstractSquare-wave adsorptive stripping voltammetry technique was used to determine rosiglitazone (ROS) on the hanging mercury dropping electrode (HMDE) surface, in Britton Robinson buffer, pH=5. The voltammetric cathodic peak was observed at −1520mV vs. Ag/AgCl reference electrode. The voltammetric peak response was characterized with respect to pH, supporting electrolyte, accumulation potential, preconcentration time, scan rate, frequency, pulse amplitude, surface area of the working electrode and the convection rate. Under optimal conditions, the voltammetric current is proportional to the concentration of ROS over the concentration range of 5×10−8–8×10−7moll−1 (r=0.9899) with a detection limit of 3.2×10−11moll−1 using 120s accumulation time. The developed SW-AdSV procedure showed a good reproducibility, the relative standard deviation RSD% (n=10) at a concentration level of 5×10−7moll−1 was 0.33%, whereas the accuracy was 101%±1.0. The proposed method was successfully applied to assay the drug in the human urine and plasma samples with mean recoveries of 90±0.71% and 86±1.0%, respectively

Survival implications vs. complications: unraveling the impact of vitamin D adjunctive use in critically ill patients with COVID-19—A multicenter cohort study

BackgroundDespite insufficient evidence, vitamin D has been used as adjunctive therapy in critically ill patients with COVID-19. This study evaluates the effectiveness and safety of vitamin D as an adjunctive therapy in critically ill COVID-19 patients.MethodsA multicenter retrospective cohort study that included all adult COVID-19 patients admitted to the intensive care units (ICUs) between March 2020 and July 2021. Patients were categorized into two groups based on their vitamin D use throughout their ICU stay (control vs. vitamin D). The primary endpoint was in-hospital mortality. Secondary outcomes were the length of stay (LOS), mechanical ventilation (MV) duration, and ICU-acquired complications. Propensity score (PS) matching (1:1) was used based on the predefined criteria. Multivariable logistic, Cox proportional hazards, and negative binomial regression analyses were employed as appropriate.ResultsA total of 1,435 patients were included in the study. Vitamin D was initiated in 177 patients (12.3%), whereas 1,258 patients did not receive it. A total of 288 patients were matched (1:1) using PS. The in-hospital mortality showed no difference between patients who received vitamin D and the control group (HR 1.22, 95% CI 0.87–1.71; p = 0.26). However, MV duration and ICU LOS were longer in the vitamin D group (beta coefficient 0.24 (95% CI 0.00–0.47), p = 0.05 and beta coefficient 0.16 (95% CI −0.01 to 0.33), p = 0.07, respectively). As an exploratory outcome, patients who received vitamin D were more likely to develop major bleeding than those who did not [OR 3.48 (95% CI 1.10, 10.94), p = 0.03].ConclusionThe use of vitamin D as adjunctive therapy in COVID-19 critically ill patients was not associated with survival benefits but was linked with longer MV duration, ICU LOS, and higher odds of major bleeding

Evaluation of inhaled nitric oxide (iNO) treatment for moderate-to-severe ARDS in critically ill patients with COVID-19: A multicenter cohort study

Background: Inhaled nitric oxide (iNO) is used as rescue therapy in patients with refractory hypoxemia due to severe COVID-19 acute respiratory distress syndrome (ARDS) despite the recommendation against the use of this treatment. To date, the effect of iNO on the clinical outcomes of critically ill COVID-19 patients with moderate-to-severe ARDS remains arguable. Therefore, this study aimed to evaluate the use of iNO in critically ill COVID-19 patients with moderate-to-severe ARDS. Methods: This multicenter, retrospective cohort study included critically ill adult patients with confirmed COVID-19 treated from March 01, 2020, until July 31, 2021. Eligible patients with moderate-to-severe ARDS were subsequently categorized into two groups based on inhaled nitric oxide (iNO) use throughout their ICU stay. The primary endpoint was the improvement in oxygenation parameters 24 h after iNO use. Other outcomes were considered secondary. Propensity score matching (1:2) was used based on the predefined criteria. Results: A total of 1598 patients were screened, and 815 were included based on the eligibility criteria. Among them, 210 patients were matched based on predefined criteria. Oxygenation parameters (PaO2, FiO2 requirement, P/F ratio, oxygenation index) were significantly improved 24 h after iNO administration within a median of six days of ICU admission. However, the risk of 30-day and in-hospital mortality were found to be similar between the two groups (HR: 1.18; 95% CI: 0.77, 1.82; p = 0.45 and HR: 1.40; 95% CI: 0.94, 2.11; p= 0.10, respectively). On the other hand, ventilator-free days (VFDs) were significantly fewer, and ICU and hospital LOS were significantly longer in the iNO group. In addition, patients who received iNO had higher odds of acute kidney injury (AKI) (OR (95% CI): 2.35 (1.30, 4.26), p value = 0.005) and hospital/ventilator-acquired pneumonia (OR (95% CI): 3.2 (1.76, 5.83), p value = 0.001). Conclusion: In critically ill COVID-19 patients with moderate-to-severe ARDS, iNO rescue therapy is associated with improved oxygenation parameters but no mortality benefits. Moreover, iNO use is associated with higher odds of AKI, pneumonia, longer LOS, and fewer VFDs

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

A study of adsorptive stripping voltammetric behavior of ofloxacine antibiotic in the presence of Fe(III) and its determination in tablets and biological fluids

AbstractSquare-wave voltammetry was used to explore the adsorption property of ofloxacine complex with iron ion on the hanging mercury drop electrode (HMDE). By employing the adsorptive stripping voltammetric approach, a sensitive electroanalytical method for the quantitative analysis of ofloxacine antibiotic was achieved. A well-developed voltammetric peak was obtained in pH 7.5 Britton–Robinson buffer (B–R buffer) at −1400mV. The cyclic voltammetric studies indicated that the reduction process was irreversible and primarily controlled by adsorption. An investigations of the variation of adsorptive voltammetric peak current with supporting electrolyte, pH, accumulation time, accumulation potential, ion concentration, scan rate, pulse amplitude, SW frequency, working electrode area and convection rate has resulted in the recognition of optimal experimental conditions for ofloxacine analysis. The studied electroanalytical signal showed a linear response for ofloxacine in the concentration range 5×10−7 to 1.7×10−6moll−1 (r=0.999). A limit of detection of 1.1×10−8moll−1 (3.98ppb) with relative standard deviation of 1.21 RSD% and mean recovery of 99.6% were obtained. Possible interferences by several substances usually present in pharmaceutical formulation were also evaluated. The analytical quantification of ofloxacine in commercially available pharmaceutical formulation was performed and compared with data from HPLC technique

Voltammetric determination of a novel 1-(3-Fluoro-benzenesulfonyl)-5-{3-[5-(3-methoxy-phenyl)-2-methyl-2H-[1,2,4]triazol-3-yl]-phenyl}-1H-indole using glassy carbon electrode in a Britton- Robinson buffer

The voltammetric behaviors of 1-(3-Fluoro-benzenesulfonyl)-5-{3-[5-(3-methoxy-phenyl)-2-methyl-2H-[1,2,4]triazol-3-yl]-phenyl}-1H-indole (5b) have been investigated in Britton- Robinson (B-R) buffer pH 7.0 using differential pulse voltammetry (DPV), anodic stripping voltammetry (ASV) and cyclic voltammetry (CV) on a glassy carbon electrode νs Ag/AgCl reference electrode. The preliminary observation for 5b was investigated using DPV technique in B-R buffer pH 7, a broad differential pulse voltammetric oxidation wave at Ea= 0.65V was observed. The voltammetric oxidation process has been shown to be irreversible and the diffusion is controlled with adsorption characteristics. The developed anodic stripping voltammetric (ASV) was used to study some optimized experimental conditions such as accumulation time, accumulation potential, scan rate, frequency, pulse amplitude, other working electrodes and convection rate. A calibration curve for 5b was studied from 2×10-6 to 3×10-5M (correlation coefficient = 0.994, n=8) under optimum conditions and the detection limit was 8×10-8M. The used anodic stripping voltammetric method shows a good reproducibility (n=8) for 5b with relative standard deviation RSD% was 0.54% and a good stability. An accuracy of the developed ASV was evaluated via the mean recovery of 97%±1.0. Some interference, usually present in pharmaceutical compounds, has been also evaluated. The analytical applications of the developed ASV technique were carried out for a direct determination of 5b in medical preparations and biological fluids