Sustainable high-throughput microwell spectrophotometric methods for avapritinib quality control via charge-transfer complexation

Avapritinib (AVA) is a breakthrough targeted therapy as the first potent inhibitor approved for gastrointestinal stromal tumors (GIST) with PDGFRA D842V mutations. It lacks convenient analytical methods for routine quality control. This study addresses this gap by developing and validating two novel, green, high-throughput microwell spectrophotometric methods (MW-SPMs) for AVA quantification in pharmaceutical tablets-representing the first employment of charge-transfer complexation for AVA analysis. The methods exploit rapid charge-transfer complex (CTC) formation between AVA (electron donor) and two π-acceptors: 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and chloranilic acid (CLA). The reactions, conducted in 96-well plates using only 200 µL total volume, yielded stable colored complexes with absorption maxima at 460 nm and 520 nm for the reactions with DDQ and CLA, respectively. Following ICH-compliant optimization and validation, both methods demonstrate excellent linearity (3.13-100 µg/well for DDQ; 6.25-100 µg/well for CLA), precision (RSD ≤ 1.8%), and accuracy (recoveries: 98.0-101.7%). Job's method confirmed 1:1 stoichiometry, while density functional theory (DFT) uniquely revealed the molecular basis for the stronger binding affinity of DDQ over CLA through dominant π-π stacking and hydrogen-bonding interactions, demonstrating how computational analysis can guide reagent selection in analytical method development. A comprehensive multi-metric sustainability assessment-utilizing ten tools including AES, AGREE, BAGI, RGB, and RAPI-confirmed the methods' excellent greenness (e.g., AES score = 90), superior practicality, and robust analytical performance, achieving a high White Index of 94.2%. With a substantially higher throughput of ~ 500 samples/hour and minimal solvent consumption (200µL/well), the proposed MW-SPMs offers a rapid, sustainable, and cost-effective alternative to conventional chromatographic and spectrofluorimetric techniques for routine pharmaceutical analysis, aligning with multiple United Nations Sustainable Development Goals.