Development and validation of a microwave-assisted digestion technique as a rapid sample preparation method for the...

Selenium is a class 2B element according to the International Council for Harmonization Q3D guidelines. Selenium sulfide is an anti-infective agent with antifungal and antibacterial properties used to treat dandruff and seborrheic dermatitis. The literature survey revealed that most of the analytical techniques to estimate selenium were time-consuming and/or required high skill levels. The process involved identifying the isotopes, selecting the measurement approach, and optimizing a typical microwave-aided digesting procedure. Ammonium hydrogen difluoride, water, and concentrated nitric acid were added to the samples. The confirmed microwave digestion program was a two-step program where in the initial step, the samples were ramped at 200°C for 20 min and held for 5 min. Later, samples were cooled and neutralized by boric acid, then ramped for 20 min to a temperature of 180°C and held for 10 min. Selenium was estimated at 196.090 nm by inductively coupled plasma optical emission spectroscopy (ICP-OES). System suitability was run before initiating analysis to ensure that system performance was consistent. Analytical validation parameters, such as the specificity of the method, were demonstrated at 196.090 nm, linearity was proven from 10 ppm to 150 ppm of selenium concentration, the detection limit was 1.28 ppm, and the limit of quantification was 3.89 ppm. Robustness was confirmed for small changes to ICP-OES operating conditions. The precision of the method demonstrated by analyzing the percentage relative standard deviation for six injections was found to be less than 2.0%. Accuracy was confirmed from 10 ppm to 150 ppm, and all the samples were observed to be within the range of 95%-105%. A common microwave-assisted digestion technique was developed and validated as well. The precision, specificity, linearity, accuracy, and robustness of the method for estimating selenium in selenium sulfide drug substances and various pharmaceutical dosage forms were demonstrated. This newly developed microwave-assisted digestion technique has optimum sensitivity and is highly reproducible and time-saving than the existing methods This method can be applied to numerous matrices for a finished dosage of selenium sulfide formulations.