This study was designed to develop and validate a new reversed-phase high-performance liquid chromatography (RP-HPLC) method based on Q2 (R1) International Conference on Harmonization (ICH) guideline for determination of curcumin in pharmaceutical samples.
The HPLC instrument method was optimized with isocratic elution with acetonitrile: ammonium acetate (45:55, v/v, pH 3.5), C18 column (150 mm×4.6 mm×5 µm particle size) and a flow rate of 1 ml/min in ambient condition and total retention time of 17 min. The volume of injection was set at 20 µl and detection was recorded at 425 nm. The robustness of the method was examined by changing the mobile phase composition, mobile phase pH, and flow rate.
The method was validated with respect to precision, accuracy and linearity in a concentration range of 2-100 µg/ml. The limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.5 µg/ml, respectively. The percentage of recovery was 98.9 to 100.5 with relative standard deviation (RSD) The method was found to be simple, sensitive and rapid for determination of curcumin in pharmaceutical samples and had enough sensitivity to detect degradation product of curcumin produced under photolysis and hydrolysis stress condition.

In this work, a carbon paste electrode modified with multiwall carbon nanotubes (MWCNTPE) was used for the sensitive voltammetric determination of acetaminophen (AC) in biological and pharmaceutical samples. The electrochemical behavior of acetaminophen was investigated employing cyclic voltammetry. It was revealed that the standard electrode potential of half reaction for AC(O), H+/AC(R) was 0.898 V. under the optimized experimental conditions, the oxidation peak current for acetaminophen was found to vary linearly with concentration range of 0.12 to 99 µM with detection limit of 0.06 µM using differential pulse voltammetry. DFT-B3LYP/6-31G (d,p) and HF/6-31G (d,p) calculations were performed for deoxidized acetaminophen (AC(R)) and its oxidized form (AC(O)). The calculated standard electrode potentials are relatively in agreement with experimental data. This electrode  was employed for determination of acetaminophen in hospital waste water, hair, blood and pharmaceutical samples considering its high sensitivity, low detection limit, good reproducibility and its non-existent interference at trace levels in clinical and quality control laboratories.

The possibility of electrochemical oxidation of omeprazole on CoO(OH) for electrochemical analysis in vitro and in vivo has been evaluated by theoretical means. The corresponding mathematical model was analyzed by means of linear stability theory and bifurcation analysis. It was demonstrated that cobalt (III) oxy-hydroxide may be used as an electrode modifier for the electrochemical detection of omeprazole in pharmaceutical samples. The possibility for electrochemical instabilities has also been evaluated.

High-performance liquid chromatography (HPLC) is recognized as a primary separation technique in modern pharmaceutical and biomedical analyses due to its exceptional efficiency and high sensitivity in detecting the analyte of interest. In the analysis of pharmaceutical samples, it is essential to ensure the reliability of the produced results. Method validation is a critical stage in the development of analytical methods, determining whether these methods are suitable and reliable for their intended purposes. The databases including PubMed, PubMed Central, Google Scholar, and ICHQ2R2 were searched using keywords such as HPLC, Validation, Accuracy, and Precision. To meet the requirements set by Good Manufacturing Practice (GMP) guidelines, pharmaceutical companies must establish a program to monitor and evaluate all their processes. The primary goal of this effort is to standardize all processes involved in the industry, including development, manufacturing, production, and analytical methods. This review article aims to provide insightful guidance on conducting validation for analytical methods that employed in pharmaceutical analysis. Specifically, it focuses on the validation process as per ICH Guidelines, which encompasses a comprehensive evaluation of performance characteristics such as accuracy, precision, specificity, linearity, working range, limit of detection, limit of quantification, robustness.

In this study, the electrochemical behaviour of 2-thiouracil (2TU) has been investigated using cyclic, differential pulse and square wave voltammetric techniques. The electrochemical studies were carried out in pH 3 with 0.2 M phosphate buffer as supporting electrolyte. Cyclic voltammetric studies were performed in a wide range of sweep rates and various concentrations of 2TU. The effect of surfactants was studied. The anodic peak was characterized and process was adsorption-controlled. According to the linear relation between the peak current and the 2TU concentration, differential-pulse voltammetric method for the quantitative determination in pharmaceuticals was developed. The linear response was obtained in the range of 1–11 μM with a detection limit of 2.05×10-8 M with good selectivity and sensitivity. The proposed method was successfully applied to 2TU determination in pharmaceutical samples and for the detection of 2TU in urine as a real sample.

An electrochemical potentiometric sensor was introduced for Fluoxetine (FLX) analysis in pharmaceutical formulations using conducting polymer coated on a solid-state contact. FLX is one of the antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. For this purpose, pyrrole was electrochemically polymerized on the surface of a solid contact made of graphite to form a thin layer of poly(pyrrole) (PPy). After this step, a thin layer of another polymeric composite composed of poly(vinyl chloride), dibutyl phthalate and ion-pair compound of FLX and phenyl borate was covered on the treated surface. The modified graphite rod was finally used as a working electrode in a potentiometric cell assembly. Linear concentration range of 1.0×10−6 to 1.0×10−3 mol L-1, lower detection limit of 6.3×10−7 mol L-1, 8s response time, and two months lifetime were the characterizations of the proposed sensor. Finally, FLX content of some pharmaceutical samples were analyzed by the prepared sensor accurately and precisely.

Ethinylestradiol (EE2) is classified as an estrogenic pharmaceutical compound. It is an agonist of the estrogen receptors and is approved for treating estrogen deficiency and osteoporosis prophylaxis in the short term when a choice of medicines is limited. EE2 is administered for the treatment of female hypogonadism and menstrual disorders. This strong estrogen is known to cause nausea, fluid retention, and thrombosis as side effects. It is, therefore, necessary to monitor EE2 levels in biological, environmental, and pharmaceutical samples. Various ultra-sensitive analytical methods were introduced during the last decades but modified electrochemical methods have great attention due to their undeniable properties. Here, all electrochemical analytical methods used for the determination of EE2 are considered and discussed.

This study describes a rapid and sensitive method for determination of Losartan potassium (LOS-K) in pure and medication forms. The method is depended upon the reaction of LOS-K with Silicotungestic acid in salt medium for the formation of a white precipitate. The new precipitate was monitored and measured using homemade Ayah 6SXI-T-2D Solar cell analyzer in combination with a continuous flow injection technique. Reagent concentration, acid medium, flow rate, sample volume, purge time, and delay coil reaction are all chemical and physical characteristics that have been investigated and optimized. The linear dynamic range of LOS-K was 0.05-2 mMol/L with linearity percentage (r2%) 99.56 %. Limit of detection (LOD) was 3.62 µg/sample and LOQ=18.28 µg/sample. A comparison between developed method and classical methods (UV-Spectrophotometry at λmax= 232 nm) was made. The proposed method was successfully applied for determination of LOS-K in the pharmaceutical samples and can be used as an alternative method.

Sulfapyridine is one of the most important antibiotics drug with some side effects and determination of this drug is very important in biological and pharmaceutical samples. In this research, an electrochemical amplified sensor was fabricated as analytical tool for determination of sulfapyridine in drug samples. For fabrication of sulfapyridine sensor, a carbon paste electrode (CPE) was amplified with copper oxide decorated single wall carbon nanotubes (CuO/SWCNTs) as conductive mediator. The CuO/SWCNTs/CPE was used for voltammetric determination of sulfapyridine and results showed an increasing in oxidation current sulfapyridine about 2.35 times and decreasing 80 mV in oxidation potential in the same condition. The cyclic voltammetric (CV) investigation confirm pH dependent redox reaction for sulfapyridine in the presence of one electron and one proton with maximum sensitivity at pH=7.0. Analytical investigation showed a linear dynamic range 50 nM- 400 µM with detection limit 10 nM. In the final step, CuO/SWCNTs/CPE was used for determination of sulfapyridine in tablet, drinking water and dextrose saline sample with acceptable recovery data between 99.13% - 103.35%.

In this study, the application of a partial least squares algorithm (PLS) was proposed for simultaneous spectrophotometric determination of acetaminophen, celecoxib, diazepam, and famotidine in hair, wastewater, and urban water samples. Although the determination of these drugs is very important in biological and pharmaceutical samples, spectrophotometric measurements were reported at the same time due to the spectral overlap. The results of applying PLS showed that acetaminophen, celecoxib, diazepam, and famotidine could be simultaneously determined within the concentration ranges of 4-20 ppm, 4-20ppm, 2-10 ppm, and 4-20 ppm respectively in calibration set, prediction set, and real samples. The proposed method does not require spectral correction and chemical pretreatment for quantitative analysis of the mentioned drugs.