Abstract—A rapid, simple, selective and specific high performance liquid chromatography (HPLC) method
with UV detection (230 nm) was developed and validated for estimation of guaifenesin from spiked human
plasma. The analyte and internal standard (eplerenone) were extracted with dichloromethane. The chro
matographic separation was performed on HiQSil C 18HS column (250 × 4.6 mm, 5 µm) with a mobile
phase of methanol : water (60 : 40%, v/v) at a flow rate of 1 mL/min. Guaifenesin was well resolved from
plasma constituents and internal standard. The calibration curve was linear in the range of 100−3200 ng/mL.
The heteroscedasticity was minimized by using weighted least square regression with weighing factor of 1/x.
The intra and interday % RSD was less than 15. Results of recovery studies prove the extraction efficiency.
Stability data indicated that guaifenesin was stable in plasma after three freeze thaw cycles and upon storage
at ⎯20°C for 30 days.
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