Simultaneous determination of diclofenac and its common counter-ions in less than 1 minute using capillary electrophoresis with contactless conductivity detection

Determination of inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions by ion chromatography

In this study, methods for analyzing inorganic ions and carbohydrates in cardioplegia and nephroplegia solutions were developed and validated using ion chromatography with both conductivity and pulsed amperometric detection. The inorganic ions such as sodium, potassium, and calcium were separated by a cation-exchange column with 27 mM methanesulfonic acid as mobile phase at 0.5 mL/min. The anion (chloride) and carbohydrates (mannitol and glucose) were analyzed by an anion-exchange column using a mobile phase of 20 mM sodium hydroxide at 1.0 mL/min. The methods showed a high sensitivity for all analytes, with quantification limits from 0.0002 to 0.06 mg/L. Good linearities between the peak areas and concentrations were found for all analytes within the selected concentration range (R2  > 0.999). Relative standard deviation values for repeatability and interday precision were 0.1%-1.0% and 0.7%-1.6%, respectively. The accuracy was validated by determining the percentage recovery, which was between 98.0% and 101.3% for all analytes, indicating good accuracy of the methods. The robustness was verified by using an experimental design. Finally, real samples were analyzed to determine the content of the analytes. All assay values were between 96.8% and 102.5%.

Screen-Printed Graphite Electrode Modified with Graphene-Co3O4 Nanocomposite: Voltammetric Assay of Morphine in the Presence of Diclofenac in Pharmaceutical and Biological Samples

This work focuses on the development of a novel electrochemical sensor for the determination of morphine in the presence of diclofenac. The facile synthesis of graphene-Co₃O₄ nanocomposite was performed. The prepared material (graphene-Co₃O₄ nanocomposite) was analyzed by diverse microscopic and spectroscopic approaches for its crystallinity, composition, and morphology. Concerning the electrochemical determinations, after drop-casting the as-fabricated graphene-Co₃O₄ nanocomposite on the surface of a screen-printed graphite electrode (SPGE), their electrochemical performance was scrutinized towards the morphine detection. It was also found that an SPGE modified by a graphene-Co₃O₄ nanocomposite exhibited better electrocatalytic activity for morphine oxidation than unmodified electrode. Under optimal conditions, the differential pulse voltammetry (DPV) was employed to explore the present sensor (graphene-Co₃O₄/SPGE), the findings of which revealed a linear dynamic range as broad as 0.02-575.0 µM and a limit of detection (LOD) as narrow as 0.007 μM. The sensitivity was estimated to be 0.4 µM/(µA cm²). Furthermore, the graphene-Co₃O₄/SPGE sensor demonstrated good analytical efficiency for sensing morphine in the presence of diclofenac in well-spaced anodic peaks. According to the DPV results, this sensor displayed two distinct peaks for the oxidation of morphine and diclofenac with 350 mV potential difference. In addition, the graphene-Co₃O₄/SPGE was explored for voltammetric determination of diclofenac and morphine in pharmaceutical and biological specimens of morphine ampoule, diclofenac tablet, and urine, where recovery rates close to 100% were recorded for all of the samples.

Rapid determination of NSAIDs by capillary and microchip electrophoresis with capacitively coupled contactless conductivity detection in wastewater

A simple, rapid method using CE and microchip electrophoresis with C⁴ D has been developed for the separation of four nonsteroidal anti-inflammatory drugs (NSAIDs) in the environmental sample. The investigated compounds were ibuprofen (IB), ketoprofen (KET), acetylsalicylic acid (ASA), and diclofenac sodium (DIC). In the present study, we applied for the first time microchip electrophoresis with C⁴ D detection to the separation and detection of ASA, IB, DIC, and KET in the wastewater matrix. Under optimum conditions, the four NSAIDs compounds could be well separated in less than 1 min in a BGE composed of 20 mM His/15 mM Tris, pH 8.6, 2 mM hydroxypropyl-beta-cyclodextrin, and 10% methanol (v/v) at a separation voltage of 1000-1200 V. The proposed method showed excellent repeatability, good sensitivity (LODs ranging between 0.156 and 0.6 mg/L), low cost, high sample throughputs, portable instrumentation for mobile deployment, and extremely lower reagent and sample consumption. The developed method was applied to the analysis of pharmaceuticals in wastewater samples with satisfactory recoveries ranging from 62.5% to 118%.

Simultaneous determination of vitamin B6 and magnesium using capillary electrophoresis coupled with contactless conductivity detection: Method development, validation, and application to pharmaceutical and nutraceutical samples

Vitamins and minerals are usually incorporated in pharmaceutical and nutraceutical products, but a simple, rapid, and inexpensive analytical method for their simultaneous determination is still lacking. In this study, we developed a quantification method for pyridoxine (vitamin B₆) and magnesium (Mg) by using purpose-made capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C⁴D) instrument. Main analytical conditions include: fused silica capillary (total length 55 cm, effective length 40 cm, inner diameter 50 μm); background electrolyte consisted of 10 mM L-arginine/acetic acid (pH 5) with 20% acetonitrile; separation voltage + 20 kV; hydrodynamic injection (siphoning at 20 cm in 25 s). Detection limits of vitamin B₆ and Mg were 1 and 0.1 mg/L, respectively. Good linearity (R² > 0.999) was observed for vitamin B₆ and Mg calibration curves over concentration ranges of 3-100 and 0.3-200 mg/L, respectively. The method was applied to analyze vitamin B₆ and Mg in several pharmaceutical and nutraceutical samples. The analytical results obtained by our method were in good agreement with reference methods (i.e., HPLC for vitamin B₆ and ICP-OES for Mg). High-efficient and low-cost CE-C⁴D method can accordingly serve as a promising tool for concurrent analysis of inorganic and organic species in pharmaceutical and nutraceutical analysis.

Ultra-rapid capillary zone electrophoresis method for simultaneous determination of arginine and ibuprofen

The combination of arginine and ibuprofen is widely used for pain relief with a faster onset of action than conventional ibuprofen. Therefore, the determination of both compounds in a single run is highly desirable for rapid quality control applications. This paper reports an ultra-fast method (100 injections/h) for simultaneous determination of arginine and ibuprofen using capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation of arginine as cation and ibuprofen as anion was achieved using a background electrolyte composed by an equimolar mixture of 10 mmol/L of 2-(cyclohexylamino) ethanesulfonic acid and boric acid with pH adjusted to 8.4 using potassium hydroxide. The limits of detections were 5.3 and 10.0 μmol/L for arginine and ibuprofen, respectively. The proposed method is simple, fast (one analysis every 35 s), environmentally friendly (minimal waste generation) and accurate (recovery values between 95 and 98%).

Design of an electrochemical platform for the determination of diclofenac sodium utilizing a graphenized pencil graphite electrode modified with a Cu–Al layered double hydroxide/chicken feet yellow membrane

A novel electrochemical sensor based on a Cu–Al layered double hydroxide (Cu–Al LDH)/chicken feet yellow membrane (CFYM) modified graphenized pencil graphite electrode (GPGE) was designed.

Simultaneous electrokinetic stacking and separation of anionic and cationic species on a paper fluidic channel

On-line enrichment is effective for improving the sensitivity of paper-based analytical devices (PADs). Electrokinetic stacking of ionic species - anionic or cationic species, respectively, on a paper-based fluidic channel has been well demonstrated in the literature. In this work, we further demonstrated that both anionic and cationic species can be electrokinetically stacked and separated simultaneously on the same paper fluidic channel. The feasibility of the proposed method was visually demonstrated by using a colored cationic probe of Rhodamine 6G and an anionic probe of Brilliant Blue. With the introduction of a background electrolyte (BGE) consisting of weak acid and weak base salt, two electric field gradients can be developed on the same paper fluidic channel when a DC voltage was applied. Both of the anionic and cationic species from the reservoirs can be simultaneously stacked as separate bands on the two field gradients, respectively. Under optimized conditions, two orders of magnitude enrichment factors can be achieved for the anionic and cationic probes as characterized by colorimetric analysis by smartphone imaging. The applicability of this method was further demonstrated by stacking and separation of copper ions/nitrite and even amphoteric ions-proteins of phycocyanin (blue, pI 4.4)/cytochrome C (brown, pI 10.2). Potential applications can be found not only for a PAD based point of care test (POCT), but also for sample pretreatment in protein analysis considering the friendliness of the BGE to the mass spectrometer.

Rapid quantitation of multiple ions released from HeLa cells during emodin induced apoptosis by low-cost capillary electrophoresis with capacitively coupled contactless conductivity detection

Change in cation concentration, including that of potassium and sodium, is characteristic of apoptosis, therefore it is significant to detect cation concentration changes.

Fast determination of codeine, orphenadrine, promethazine, scopolamine, tramadol, and paracetamol in pharmaceutical formulations by capillary electrophoresis

Paracetamol is an active ingredient commonly found in pharmaceutical formulations in combination with one of the following compounds: codeine, orphenadrine, promethazine, scopolamine, and tramadol. In this work, we propose a unique analytical method for determination of these active ingredients in pharmaceutical samples. The method is based on capillary electrophoresis with capacitively coupled contactless conductivity detection. The separation was achieved on a fused silica capillary (50 cm total length, 40 cm effective length, and 50 μm id) using an optimized background electrolyte composed of 20 mmol/L β-alanine/4 mmol/L sodium chloride/4 μmol/L sodium hydroxide (pH 9.6). Each sample can be analyzed in a single run (≤2 min) and the limits of detection were 2.5, 0.62, 0.63, 2.5, 15, and 1.6 μmol/L for scopolamine, tramadol, orphenadrine, promethazine, codeine, and paracetamol, respectively. Recovery values for spiked samples were between 94 and 104%.

Dual-opposite injection capillary electrophoresis: Principles and misconceptions

Dual-opposite injection capillary electrophoresis (DOI-CE) is a separation technique that utilizes both ends of the capillary for sample introduction. The electroosmotic flow (EOF) is suppressed to allow all ions to reach the detector quickly. Depending on the individual electrophoretic mobilities of the analytes of interest and the effective length that each analyte travels to the detection window, the elution order of analytes in a DOI-CE separation can vary widely. This review discusses the principles, applications, and limitations of dual-opposite injection capillary electrophoresis. Common misconceptions regarding DOI-CE are clarified.

A comprehensive strategy in the development of a cyclodextrin-modified microemulsion electrokinetic chromatographic method for the assay of diclofenac and its impurities: Mixture-process variable experiments and quality by design

A comprehensive strategy involving the use of mixture-process variable (MPV) approach and Quality by Design principles has been applied in the development of a capillary electrophoresis method for the simultaneous determination of the anti-inflammatory drug diclofenac and its five related substances. The selected operative mode consisted in microemulsion electrokinetic chromatography with the addition of methyl-β-cyclodextrin. The critical process parameters included both the mixture components (MCs) of the microemulsion and the process variables (PVs). The MPV approach allowed the simultaneous investigation of the effects of MCs and PVs on the critical resolution between diclofenac and its 2-deschloro-2-bromo analogue and on analysis time. MPV experiments were used both in the screening phase and in the Response Surface Methodology, making it possible to draw MCs and PVs contour plots and to find important interactions between MCs and PVs. Robustness testing was carried out by MPV experiments and validation was performed following International Conference on Harmonisation guidelines. The method was applied to a real sample of diclofenac gastro-resistant tablets.

Screening determination of pharmaceutical pollutants in different water matrices using dual-channel capillary electrophoresis coupled with contactless conductivity detection

In this study, the employment of purpose-made dual-channel compact capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C(4)D) as a simple and inexpensive solution for screening determination of various pharmaceutical pollutants frequently occurring in surface water and hospital wastewater in Hanoi, Vietnam is reported. Five negatively charged pharmaceutically active compounds, namely ibuprofen, diclofenac, bezafibrate, ketoprofen and mefenamic acid were determined using the first channel whereas three positively charged ones, namely diphenhydramine, metoprolol and atenolol were determined with the second channel of the CE-C(4)D instrument. Two different background electrolytes (BGEs) were used in these two CE channels independently. The best detection limits achieved were in the range of 0.2-0.8mg/L without sample pre-concentration. Enrichment factors up to 200 were obtainable with the inclusion of a solid phase extraction step. Good agreement between results obtained from CE-C(4)D and those with the standard confirmation method (HPLC-DAD) was achieved, with correlation coefficients higher than 0.98.

Concurrent determination of anions and cations in consumer fireworks with a portable dual-capillary electrophoresis system

A new automated portable dual-channel capillary electrophoresis instrument was built and applied to the concurrent determination of cations and anions. The system uses a single buffer and hydrodynamic injection of the sample is performed autonomously. A novel engraved flow-cell interface is used at the injection ends of the capillaries allowing the autonomous operation of the system. The engraved flow-cell replaces traditionally used split injectors in purpose made capillary electrophoresis systems and makes the system design easier. A new software package with graphical user interface was employed to control the system, making its operation simple and increasing its versatility. The electrophoretic method was optimized to allow the baseline separation of 12 cations and anions commonly found in fireworks. The system was proven to be useful for the analysis of consumer fireworks, saving time and expenses compared to separate analyses for anions and cations. This is the first time that cationic and anionic compositions of fireworks are investigated together. The analysis of samples revealed several inaccuracies between the declared compositions for the fireworks and the obtained results, which could be attributed to cross-contamination during their manufacture or to a transfer between other components of the pyrotechnic item. The presence of certain unexpected peaks, however, had no apparent reason and might represent an irregularity in the manufacture of some devices.

Recent advances in capillary electrophoretic migration techniques for pharmaceutical analysis

Since the introduction about 30 years ago, CE techniques have gained a significant impact in pharmaceutical analysis. The present review covers recent advances and applications of CE for the analysis of pharmaceuticals. Both small molecules and biomolecules such as proteins are considered. The applications range from the determination of drug-related substances to the analysis of counterions and the determination of physicochemical parameters. Furthermore, general considerations of CE methods in pharmaceutical analysis are described.

Two new electrochemical methods for fast and simultaneous determination of codeine and diclofenac

In this paper, we present two new electrochemical methods for fast and simultaneous determination of codeine (CO) and diclofenac (DCF). The first one is based on batch injection analysis with amperometric detection (BIA-MPA) and the second one is based on capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D). The proposed BIA-MPA method is highly-precise (RSD of 1.1% and 0.9% for DCF and CO, respectively; n=10), fast (300 injections h(-1)) and has low detection limits (1.1 and 1.0 µmol L(-1) for DCF and CO, respectively). The proposed CE-C(4)D method allows the determination of CO and DFC in less than 1 min with high precision (RSD of 0.3% and 0.7% for DCF and CO, respectively; n=10) and low detection limits (11 and 21 µmol L(-1) for DCF and CO, respectively). Both proposed methods were applied to the determination of CO and DCF in pharmaceutical samples with similar results to those achieved by high-performance liquid chromatography (HPLC) at a 95% confidence level.