Preparation of Ti(4+)-immobilized modified silica capillary trapping column for on-line selective enrichment of phosphopeptides.

In this work, we have developed Ti(4+)-immobilized capillary trapping column (250μm i.d.) for highly specific on-line enrichment of phosphopeptides in the bio-samples. It minimizes the sample loss and improves the effectiveness of phosphopeptide detection that the limit of detection is as low as 1fmol/μL. It is successfully applied to the detection of phosphopeptides from complex biological samples, such as skim milk, human serum and mouse brain. The results indicate that the Ti(4+)-immobilized capillary trapping column is time-effective and has the great potential of application in low-abundance phosphopeptides on-line analysis. The prepared Ti(4+)-immobilized capillary trapping column will be further used in LC/MS platform for phosphoproteome analysis.