UHPLC/MS Analysis of Insulin Variants and Analogs on BIOshell A160 Peptide C18 Using Ammonium Formate as a Mobile Phase Modifier
Materials
Analytical column
CONDITIONS
column
BIOshell A160 Peptide C18, 15 cm x 2.1 mm I.D., 2.7 μm particles (66905-U)
mobile phase
[A] 75:25 (8 mM ammonium formate, pH 2.6 with formic acid:acetonitrile); [B] 50:50 (8 mM ammonium formate, pH 2.6 with formic acid:acetonitrile); (77:23, A:B)
flow rate
0.2 mL/min
column temp.
75 °C
detector
MS, ESI(+), TIC 100-3000 m/z
injection
0.5 μL
sample
Mixture of six insulin variants, 100 μg/mL, 8 mM ammonium formate, pH 2.6 with formic acid
Description
Analysis Note
BIOshell A160 Peptide C18 is an ideal column for reversed-phase separations of small proteins to large peptide sequences. There is over 75% sequence similarity between all six of the insulin variants in the sample; therefore, separation of these variants is achieved through the subtle differences in the polarities of surface residues on the peptides. The use of ammonium formate as a mobile phase modifier yields more efficient peaks and less signal suppression during electrospray ionization (ESI) than some traditional ion-pair reagents (trifluoroacetic acid, formic acid).
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