Chemometric-assisted surface-enhanced Raman spectroscopy for metformin determination using gold nanoparticles as substrate

•SERS with chemometric analysis was explored for metformin determination.•Citrate-AuNPs were used as substrate to perform the SERS scattering signals measurements.•Efficient AuNPs were successfully synthesized by MW-assisted route and thoroughly characterized.•SERS spectra were analysed by using PCA and PLS.•PCA and PLS models allowed an accurate, sensitive and selective determination of metformin in pharmaceutical formulations.