Quantitative determination of phospholipids in a pharmaceutical drug by scanning and video densitometry

This paper describes a convenient and practice method for quantitation of surfactant phospholipids (1,2-dipalmitoyl-3-sn-phosphatidyl choline [DPPC] and 1-palmitayl-2-oleyl-3-sn-phosphatidyl glycerol [POPG]) in a recombinant surfactant lyophile (Venticute) by high-performance, thin-layer chromatography (HPTLC) with video densitometry. DPPC and POPG were extracted from Venticute-lyophile using methanol. Separation from the other active ingredients and excipients was accomplished by HPTLC on silica gel F254 plates with a mixture of chloroform, methanol, glacial acetic acid, and water as development solvent. Postchromatographic derivatization by dipping in copper sulphate/phosphoric acid reagent and subsequent heating shows grey-brown bands on a light blue background. These were detected with the video densitometer in the VIS range, and with scanning densitometry at 365 nm. Linear calibration in a working range of 0.7-1.3 microg DPPC and 0.35-0.65 microg POPG was demonstrated by integrating the area under the peaks. Good results were obtained with recovery experiments. When compared to classical slit scanning densitometry, video densitometry represents a fast alternative to quantitate thin-layer chromatograms in surfactant phospholipid analysis.