Method validation and determinations of levofloxacin, metronidazole and sulfamethoxazole in an aqueous pharmaceutical, urine and blood plasma samples using quantitative nuclear magnetic resonance spectrometry

► We developed a qHNMR method for levofloxacin, metronidazole and sulfamethoxazole. ► The method was applied for determining the drugs in aqueous urine and plasma samples. ► Linear ranges of 0.50-68.00, 0.13-11.30 and 0.24-21.00 mg were respectively obtained. ► Instrumental detection limits ≤0.03 mg and recovery % of 96.00-104.20 were obtained. ► Statistical student-t and F tests gave insignificant error and difference in precision.