Chemometrics-assisted development of a validated LC method for simultaneous estimation of temozolomide and γ-linolenic acid: Greenness assessment and application to lipidic nanoparticles.

The described work entails the development of a simple, sensitive, green, and robust high-performance liquid chromatographic (HPLC) method for simultaneous estimation of temozolomide (TMZ) and γ-linolenic acid (GLA). The chemometric factor screening study helped identify the critical method parameters optimized using Box-Behnken design for improved understanding and enhancing the method performance. Chromatographic separation was performed on a Kinetex® C column (150 × 4.6 mm, 5 µm particle size) using methanol: water (pH adjusted to 3.5 using 0.5% v/v O-phosphoric acid) as the mobile phase at 0.5 mL/min flow rate and diode array detection between 210 and 360 nm. The linearity of the method was observed for concentrations of TMZ and GLA ranging between 1 and 100 µg.mL (R = 0.999, p < 0.05). Accuracy evaluation showed good percent recovery within 97.9-100%, while intra- and inter-day precision showed RSD values within 0.37%-1.01%. The limit of detection and quantification for TMZ was found to be 0.75 and 1.0 μg.mL, respectively, while the values 0.55 and 1.0 μg.mL, respectively, were observed for GLA. System suitability (96.9-102.8%), its limits, and robustness evaluation indicated good percent recovery within, while RSD values were found to be within the acceptable limit of less than 2%. The method was specific for its ability to detect the analytes and their degradation products during forced degradation studies, which also indicated that TMZ was highly prone to alkaline conditions while GLA showed mild degradation in all the studied conditions. The estimation of both the analytes from lipid nanoparticles formulation showed good values for total drug content (82.6-85.3%), entrapment efficiency (95.4 to 98.7%), and drug loading (25.2 to 38.4%). Overall, the results indicated that the developed method was reliable for its accuracy, precision, sensitivity, and specificity for simultaneous estimation of the analytes. The method was found to be stability-indicating in nature and suitable for simultaneous estimation of TMZ and GLA from the developed nanoparticles formulation. Further, employing a greenness assessment approach established the method greenness.