The use of organic
solvents as eluants in RP-HPLC has an important role to decrease retention time and improve peak shape; however, it has high environmental impacts. Their production and disposal represent economic and
biohazard problems. So, alternatives had to be introduced and studied to minimize such pollution. Combination of
sodium dodecyl sulfate (SDS) together with polyoxyethylene-23-lauryl
ether (Brij-35) was studied as an alternative to the presence of organic
solvents on the separation performance of six
active pharmaceutical ingredients. Response surface methodology was applied to test the impact of three independent variables; concentrations of SDS and
Brij-35, as well as, pH of the mobile phase; on retention, peak symmetry, and resolution of the analytes using a rotatable central composite design. Significant variables were determined and the suggested models for predicting retention and resolution parameters were significant. Meanwhile, the
common cold is the most abundant disease treated with over-the-counter (OTC) medications worldwide. In 2015, the USA recorded $9.56 billion total sales of OTC cold and
cough medicaments alone, with average individual patient expenditure of $338. The worldwide sales and generics of
common cold and
cough products keep growing annually. The six active
pharmaceutical molecules under study, namely,
paracetamol,
guaifenesin,
pseudoephedrine,
ibuprofen,
chlorpheniramine, and
dextromethorphan, are widely used in
common cold products. The predicted optimum conditions were validated using mobile phase consisting of 93.6 mM SDS, 32.0 mM
Brij-35, and 10.0 mM
sodium dihydrogen phosphate, adjusted at pH 5.2, column temperature 35° C, and detection at 215-nm wavelength. The method was successfully applied to determine 12 different combination formulae of the analytes in their
pharmaceutical products and was assessed for greenness on two novel metrics. A thorough comparison to previously reported methods was included and methods were assessed against greenness metrics Green Analytical Procedure Index and Analytical Greenness Metric to demonstrate superiority.