A fast and direct spectrophotometric method for the simultaneous determination of methyl paraben and hydroquinone in cosmetic products using successive projections algorithm

A stability indicating RP-HPLC-UV assay method for the simultaneous determination of hydroquinone, tretinoin, hydrocortisone, butylated hydroxytoluene and parabens in pharmaceutical creams

Multicomponent drugs are medications that combine two or more active pharmaceutical ingredients in a single dosage form. These dosage forms improve the patient compliance, reduce the risk of drug interactions, and simplify dosing regimens. However, quality control of these multicomponent dosage forms can be challenging, especially if the final product contains four or more ingredients that are active (comprise stabilizers, preservatives, excipients, and other components). This problem can be more pronounced if the excipients can interfere with the analysis. In this work, a stability indicating assay method was developed and validated (according to the ICH International Guidelines) for the simultaneous determination of hydroquinone (HQ), tretinoin (TRT), hydrocortisone (HCA), butylated hydroxytoluene (BHT), methyl paraben (MP) and propyl paraben (PP) in commercially available pharmaceutical creams. The proposed method is based on gradient elution using X-Bridge C18 (150 × 4.6 mm, 5 µm) column with a flow rate of 1 mL/min. The linear ranges (μg/mL) were 240-560 for HQ, 24-56 for MP, 132-308 for HCA, 6-14 for PP, 12-28 for BHT, 6.6-15 for TRT. During the validation process, the intra- and interday precision and trueness (evaluated as recovery) were found to be below 2.0% and between 100-102%, respectively. System suitability tests (SST) allow validating the herein proposed procedure specifically for pharmaceutical and industrial applications. SST test shows that the reported procedure fulfill with the Guidelines, allowing excellent separation of the analytes with very sensitive, accurate (precise and true) and reproducible quantitation of each analytes. The method was successfully applied in forced degradation studies of the six analytes. Specifically, acid degradation slightly affected HCA and BHT (91% recovery), while alkaline degradation drastically reduced HCA recovery (5.5%) and moderately affected BHT (85%). Photodegradation primarily influenced TRT quantity, and oxidative degradation intensified the BHT peak (130%).

Green chromatographic methods for determination of co-formulated lidocaine hydrochloride and miconazole nitrate along with an endocrine disruptor preservative and potential impurity

Recently, green analytical chemistry (GAC) is a key issue towards the idea of sustainability, the analytical community is focused on developing analytical methods that incorporate green chemistry principles to minimize adverse impacts on the environment and humans. Herein, we present 2 sustainable, selective, and validated chromatographic methods. Initially, lidocaine hydrochloride (LDC) and miconazole nitrate (MIC) with two preservatives; methyl paraben (MTP) and saccharin sodium (SAC) were chromatographed via TLC-densitometric method which employed ethyl acetate: methanol: formic acid (9:1:0.1, by volume) as the mobile phase with UV detection at 220.0 nm, good correlation was obtained in the range of 0.3-3.0 µg/band for MIC and LDC. Following that, RP-HPLC was successfully applied for separating quinary mixture of LDC, MIC, MTP, SAC along with LDC impurity; dimethyl aniline (DMA) using C18 column, and a gradient green mobile phase composed of methanol and phosphate buffer (pH 6.0) in different ratios with a flow rate 1.5 mL/min and UV detection at 210.0 nm, linearity ranges from 1.00 to 100.00 µg/mL for MIC, 2.00-100.00 µg/mL for LDC and 1.00--20.00 µg/mL for MTP and DMA. No records to date regarding the determination of the two drugs, besides MTP and DMA. The proposed methods were validated according to the ICH guidelines and applied successfully to the analysis of the compounds. The methods' results were statistically compared to those obtained by applying the reported one, indicating no significant difference regarding both accuracy and precision. The methods' greenness profiles have been assessed and compared with those of the reported method using different assessment tools.

CuS nanoparticles decorated MoS2 sheets as an efficient nanozyme for selective detection and photocatalytic degradation of hydroquinone in water

Cost effective and efficient CuS–MoS₂ nanocomposite with enhanced peroxidase enzyme mimetics and photocatalytic activity was synthesized by simple hydrothermal method and successfully utilized for sensing and detection of toxic hydroquinone molecules in aqueous medium.

Chemometric-assisted UV spectrophotometric method for determination of N, N- diethyl-3-methylbenzamide in insect repellents

In recent years outbreaks of vector-borne diseases have caused great concern to the population, especially those diseases transmitted by mosquitoes. Repellents appear as an affordable alternative for prevention, making it increasingly important to control the quality of these products, since the content of the active ingredients are directly related to the efficiency and the protection time provided by the repellent. This paper proposes an analytical method for determining the DEET (N, N- Diethyl-3-methylbenzamide) content in insect repellents in lotion using UV spectroscopy. For this propose five different strategies of regression were evaluated: (a) Partial Least Squares (PLS) using full-spectrum; (b) interval PLS (iPLS); Multiple Linear Regression (MLR) with variable selection by the (c) Genetic Algorithm (MLR/GA), (d) Successive Projections Algorithm (MLR/SPA) and the (e) Stepwise (MLR/SW). Appropriate predictions were obtained with RMSEP values between 0.88 and 0.93%w w^-1. No systematic error was observed and no significant differences were found between the predicted and reference values, according to a paired t-test at 95% confidence level. The results demonstrated the potential of UV spectroscopy associated to multivariate calibration to determine DEET content in repellents as a fast, simple strategy and with a suitable correlation between the values estimated by the model and the reference values.

Application of Rank Annihilation Factor Analysis for Antibacterial Drugs Determination by Means of pH Gradual Change-UV Spectral Data

The main objective of this study was to develop a simple and efficient spectrophotometric technique combined with chemometrics for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) in drug formulations. Specifically, we sought: (i) to evaluate the potential use of rank annihilation factor analysis (RAFA) to pH gradual change spectrophotometric data in order to provide sufficient accuracy and model robustness; and (ii) to determine SMX and TMP concentration in drug formulations without tedious pre-treatments such as derivatization or extraction techniques which are time-consuming and require hazardous solvents. In the proposed method, the spectra of the sample solutions at different pH values were recorded and the pH-spectra bilinear data matrix was generated. On these data, RAFA was then applied to estimate the concentrations of SMX and TMP in synthetic and real samples. Applying RAFA showed that the two drugs could be determined simultaneously with concentration ratios of SMX to TMP varying from 1:30 to 30:1 in the mixed samples (concentration range is 1-30 µg mL^-1 for both components). The limits of detection were 0.25 and 0.38 µg mL^-1 for SMX and TMP, respectively. The proposed method was successfully applied to the simultaneous determination of SMX and TMP in some synthetic, pharmaceutical formulation and biological fluid samples. In addition, the means of the estimated RSD (%) were 1.71 and 2.18 for SMX and TMP, respectively, in synthetic mixtures. The accuracy of the proposed method was confirmed by spiked recovery test on biological samples with satisfactory results (90.50-109.80%).