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Elution Selectivity Maldi Ms

Product No: P 1617

Plate Elution Selectivity - MALDI-MS

Figure 4. MALDI mass spectra of A) Crude ß-casein tryptic digest (4.5 pmol/5L) prior to loading on the PHOS-Select Plate and B)-E) purified phosphopeptides after elution from the PHOS-Select Plate under various elution conditions. Eluents are as described in Figure 2.

Binding Capacity Study
Species Molecular
Weight (Da)
phosphate (MUP)
256.14 0.9 4.5
2061.96 0.5 8.0
3122.92 1.0 5.5
Binding capacities for the two formats were determined using purified phosphorylated molecules. Binding of MUP was determined via a fluorescence assay. Binding of the mono and tetraphosphopeptides was determined using HPLC-MS analysis.

Table 1 Elution Conditions
Elution Solutions Comments
0.2 M sodium phosphate, pH 8.4 Provides competitive displacement. Requires salt removal for MALDI-TOF-MS.
0.15 to 0.4 M ammonium hydroxide Provides significant recovery of phosphocompounds. Compatible with MALDI-TOF-MS.
0.15 M ammonium hydroxide with 25% acetonitrile Provides significant recovery of phosphocompounds. Compatible with MALDI-TOF-MS.
1 to 5% TFA in water Provides significant recovery of monophosphocompounds. Compatible with MALDI-TOF-MS.