Abstract
Analytical method for insulin was developed using high performance liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). The ESI-MS conditions were optimized for determining human insulin and analogues such as lispro, aspart, glargine. Insulin was also detected for samples such as insulin needles. All insulin analogues and human type were detected as polyvalent ions, and the molecular ion peak was converted by deconvolution. Detection limits of insulins were 0.1 unit/ml (3.8 μg/ml) in scan mode, 0.002 unit/ml (77 ng/ml) in SIM mode. Aspart, glargin and human type of insulins were able to be distinguished by the established LC/ESI-MS method. However, human type was not able to be distinguished from lispro type, because molecular weight was the same. Insulin was detected from the used needle which was left outside for two months.
