Preconcentration of milk proteins using octadecylated monolithic silica microchip.

Sample preparation is a bottleneck in systems for chemical analysis and it is a required step in order to remove interference and preconcentrate the target analytes. Much research in recent years has focused on porous monolithic materials since they are highly permeable to liquid flow and show high mass transfer compared with common packed beds. This study has focused on the use of a glass microchip containing an inorganic silica-based monolithic material modified with octadecyl groups for preconcentration of milk proteins from skimmed cows' milk that vary in molecular weight, hydrophobicity, and abundance. Comparison between the fabricated device and a commercial cartridge for the preconcentration of proteins in skimmed cows' milk showed the ability of the device to successfully enrich protein mixtures from the sample. The three replicate experiments showed that the RSD of the mass to charge ratio of milk proteins ranged from 0.01 to 0.46%. In addition, it was found that there were no significant differences between the observed and reported masses of the milk proteins and the relative percentage error of the molecular masses ranged between 0.03 and 0.90%. The fact that the small amounts of sample required and short sample preparation time suggest that this new microfluidic device may be a viable alternative to existing procedures for protein extraction from real samples.