Two green and sensitive spectrofluorimetric approaches for determination of Ambroxol and guaifenesin in their single and combined pharmaceutical formulations

Ambroxol hydrochloride (AMX) and guaifenesin (GFN) are approved drugs utilized to treat coughs through their potent mucolytic and expectorant properties. Due to their massive, combined administration in many illnesses, there is a persistent need for their concurrent estimation in different pharmaceutical formulations. Two sensitive, environmentally friendly spectrofluorimetric methods were developed. AMX was determined using the first method (I) without interference from GFN. This method depends on the quenching of Erythrosine B (EB) native fluorescence at 552 nm after excitation at 527 nm due to the formation of a non-fluorescent AMX-EB ion-pair complex in Britton-Robinson buffer (BRB) solution pH (3.5). The concentration plot is linear over the 0.25-5.0 μg/mL range, with a mean percent found value of 99.74%. Method (II) depends on measuring the native fluorescence of aqueous GFN solution at two analytical wavelengths, either 300 or 600 nm, after excitation at 274 nm. Relative fluorescence intensity (RFI)-concentration plots are linear over the ranges of 0.02-0.5 and 0.1-2.0 μg/ml, with mean percent found at 99.96% and 99.91% at dual wavelengths, respectively. The proposed methods were successfully applied to assay both drugs in raw materials and different single and combined pharmaceutical formulations. These methods have been thoroughly validated following International Committee on Harmonisation (ICH) guidelines. National Environmental Methods Index, Analytical Eco-Scale, and Green Analytical Procedure Index were used to prove greenness, thereby enhancing their applicability. The proposed techniques provide straightforward, precise, and cost-effective solutions for routine formulation analysis in quality control laboratories.

SU8/glass microchip capillary electrophoresis integrated with Pt electrodes for separation and simultaneous detection of phenylephrine and acetaminophen

Introduction: A new microfluidic-based method with electrochemical detection was developed for the simultaneous quantification of acetaminophen (AP) and phenylephrine (PHE) pharmaceuticals in the human blood and pharmaceuticals (e.g. tablet and drop).

Methods: The separation was achieved on a SU8/glass microchip with a 100 µm Pt working electrode that was positioned out of the channel and 2-(N-morpholino) ethanesulfonic acid was used as a running buffer (pH 7, 10 mM). Home designed modulated high voltage power supply and dual time switcher was used for controlling the injection and separation of the analytes in the unpinched injection mode.

Results: The injection was carried out using +750 V for 7 seconds, and the separation and detection voltages were set at +1000 V and +0.9 V, respectively. Critical parameters such as detection potential, buffer concentration, injection, and separation voltage were studied in terms of their effects on the resolution, peak height, and migration times. For each analyte, the correlation coefficients were over 0.99 (n = 6). The developed microchip was able to detect AP and phenylephrine simultaneously with the limit of detection of 7.9 and 5.2 (µg/mL) respectively for PHE and AP and excellent linear range of 10-200 (µg/mL). The recovery of the drugs ranged from 96% to 103%, while the repeatability of the method through inter- and intra-day was lower than 7%.

Conclusion: The developed method offers several advantages, including easy sample pretreatment process, simplicity, very fast analysis compared to other typical chromatographic methods. Thus, the proposed microfluidic-based method is proposed to be used as a time- and cost-effective monitoring method for the analysis of AP and PHE.

Voltammetric Determination of Levodopa Using Mesoporous Carbon-Modified Screen-Printed Carbon Sensors

Levodopa is a precursor of dopamine, having important beneficial effects in the treatment of Parkinson’s disease. In this study, levodopa was accurately detected by means of cyclic voltammetry using carbon-based (C-SPCE), mesoporous carbon (MC-SPCE) and ordered mesoporous carbon (OMC-SPCE)-modified screen-printed sensors. Screen-printed carbon sensors were initially used for the electrochemical detection of levodopa in a 10⁻³ M solution at pH 7.0. The mesoporous carbon with an organized structure led to better electroanalysis results and to lower detection and quantification limits of the OMC-SPCE sensor as compared to the other two studied sensors. The range of linearity obtained and the low values of the detection (0.290 µM) and quantification (0.966 µM) limit demonstrate the high sensitivity and accuracy of the method for the determination of levodopa in real samples. Therefore, levodopa was detected by means of OMC-SPCE in three dietary supplements produced by different manufacturers and having various concentrations of the active compound, levodopa. The results obtained by cyclic voltammetry were compared with those obtained by using the FTIR method and no significant differences were observed. OMC-SPCE proved to be stable, and the electrochemical responses did not vary by more than 3% in repeated immersions in a solution with the same concentration of levodopa. In addition, the interfering compounds did not significantly influence the peaks related to the presence of levodopa in the solution to be analyzed.

Electrochemical Detection of Hydrazine by Carbon Paste Electrode Modified with Ferrocene Derivatives, Ionic Liquid, and CoS2-Carbon Nanotube Nanocomposite

The electrocatalytic performance of carbon paste electrode (CPE) modified with ferrocene-derivative (ethyl2-(4-ferrocenyl[1,2,3]triazol-1-yl)acetate), ionic liquid (n-hexyl-3-methylimidazolium hexafluorophosphate), and CoS2-carbon nanotube nanocomposite (EFTA/IL/CoS2-CNT/CPE) was investigated for the electrocatalytic detection of hydrazine. CoS2-CNT nanocomposite was characterized by field emission scanning electron microscopy, X-ray powder diffraction, and transmission electron microscopy. According to the results of cyclic voltammetry, the EFTA/IL/CoS2-CNT-integrated CPE has been accompanied by greater catalytic activities for hydrazine oxidation compared to the other electrodes in phosphate buffer solution at a pH 7.0 as a result of the synergistic impact of fused ferrocene-derivative, IL, and nanocomposite. The sensor responded linearly with increasing concentration of hydrazine from 0.03 to 500.0 μM with a higher sensitivity (0.073 μA μM-1) and lower limit of detection (LOD, 0.015 μM). Furthermore, reasonable reproducibility, lengthy stability, and excellent selectivity were also attained for the proposed sensor. Finally, EFTA/IL/CoS2-CNT/CPE was applied for the detection of hydrazine in water samples, and good recoveries varied from 96.7 to 103.0%.

Recent Advances in Applications of Voltammetric Sensors Modified with Ferrocene and Its Derivatives

This study is on current developments concerning ferrocene (FC) and its derivatives on the basis of electrochemical biosensors and sensors. The distinct physiochemical characteristics of FC have enabled the development of new sensor devices, specifically electrochemical sensors. Several articles have focused on the implementation of FC as an electrode constituent while discussing its electrochemical behavior. Furthermore, typical FC-design-based biosensors and sensors are considered as well as practical examples. The favorable design of FC-based biosensors and general sensors needs adequate control of their chemical and physical characteristics in addition to their surface immobilization and functionalization.