Fermentation monitoring based on HPTLC-OPLC technique: the effect of a complex biological matrix on quantification performances

An OPLC method has been established for separation and quantification of eight carbohydrates (glucose, fructose, galactose, lactose, sucrose, raffinose, 1-kestose, nystose, and fructosyl-nystose), which might be simultaneously present in a carbon-rich medium to be fermented by a strain of B. adolescentis. The separation was performed in approximately 33 min on aluminum foil-backed silica gel OPLC–HPTLC plates, using overrunning elution, with acetone– acetonitrile 85:15 as mobile phase. Before performing quantitative analyses, the method was optimized to minimize matrix effects caused by the presence of all the non-carbohydrate components dissolved in the broth. Although, when potentially relevant interferences are present a matrix, the method of standard additions is commonly employed, we believe it is excessively time-consuming, because it involves several stages, when applied in planar chromatography. We propose an alternative validated procedure which also enables reliable quantitative analysis.