238TP exhibits comparable retention in the same peptide size range as the 218TP polymeric chemistry, but complements the polymeric surface chemistry with subtle differences in selectivity, as shown in figures 1 and 2. This can help you successfully separate peptides that are not resolved or incompletely resolved if only one column has been used.

238TP is available on 5 micron spherical silica for best performance.

Figure 1: Comparing selectivities for hydrophobic peptides on two 300Å C18 silica reverse-phase columns. Note the greater resolution of components in the 18-26 minute range on Vydac's new monomeric-bonded 238TP54 column. The polymeric 218TP54 column, however, gives better selectivity for at least two components emerging at 10-15 minutes. Both columns were 4.6mm ID x 250mm L. Chromatographic conditions were identical.

Conditions: 1.0 mL/min, absorbance at 220 nm, gradient from 10% to 50% ACN with 0.1% TFA (w/v) over 40 minutes.

Sample: Mixture of standard peptides, listed here with peak identification: 1>GY, 2>VYV, 3>neurotensin fragment 1-8 (pELYENKPR), 4>acRGGGGLGLGK-NH2, 5>RGAGGLGLGK-NH2, 6>acRGAGGLGLGK-NH2, 7>acRGVGGLGLGKK-NH2, 8>oxytocin (CYIQNCPLG-NH2), 9>MET ENKEPHALIN (YGGFM), 10>bradykinin (RPPGFSPFR), 11>acRCVVGLGLGK-NH2, 12>neurotensin fragment 8-13 (RRPYIL), 13>angiotensin II (DRVYIHPF), 14>leu enkephalin (YGGFL), 15>neurotensin (pELYENKPRRPYIL), and 16>angiotensin I (DRVYIHPFHL)

Figure 2: Comparing selectivities for an apotransferrin digest on two 300Å, C18 silica, reverse-phase columns, at two different TFA concentrations. Note the greater resolution of components in the 18-26 minute range on Vydac's new monomeric-bonded 238TP54 column.

Conditions: 1.0 mL/min, absorbance at 215 nm, gradient from 0% to 50% ACN with TFA (w/v) concentrations as indicated over 100 minutes.

Sample: Tryptic digests of apotransferrin.

Ordering Information

If you do peptide separations, you should have both of these columns in your toolbox:

Part Number      Description                 
238TP54             Column, Octadecyl (C18)           
                    Monomeric, 5µm, 300Å
                    4.6mm ID x 250mmL

218TP54             Column, Octadecyl (C18)           
                    Polymeric, 5µm, 300Å
                    4.6mm ID x 250mmL

See also a comparison to the PROTO™ 200 and PROTO™ 300
For part numbers and prices, please see the Vydac Price List.