Rapid and Sensitive Procedure for the Quantitation of Pimethixene in Human Milk and Plasma by Solid Phase Extraction (SPE) Using HPLC

Abstract

A method is described for the quantitative determination of pimethixene from plasma and milk samples by reversed-phase high performance liquid chromatography using diphenylpyraline as an internal standard.

The sample matrix was processed by a solid phase extraction (SPE) technique using 3 mL C₁₈ Supelco cartridges. The plasma and milk samples were deproteinized using acetonitrile and the liquid layer was combined with water (1:2 v/v), throughly mixed and subsequently passed through pre-conditioned cartridges. The compounds were eluted with 6 mL of methanol. Then the methanolic solution was evaporated to dryness, reconstituted with 1 mL of methanol and analysed with an octyl-ODP column (150 × 6 mm I.D).

The mobile phase consisted of acetate buffer 0.051 M -methanol (62:38 v/v). Detection was perfomed at 254 nm with the sensitivity set at 0.002 AUFS. The overall recovery of pimethixene was 86.82% in plasma and 80.39% in milk. The limit of detection, corresponding to 2 times signal to noise ratio, was estimated as 15 ng/mL in both plasma and milk samples.