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摘要
Absolute protein quantification has become an important challenge in modern bioanalytical chemistry. Among several approaches based on mass spectrometric techniques, inductively coupled plasma (ICP) as ionisation source provides element-selective and sensitive detection of heteroatoms, and thus, a potentially emerging tool in protein analysis. In this work we applied coupling of capillary liquid chromatography (mu LC) and inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) to the separation and determination of standard proteins. For quantification purposes, post-column isotope dilution of sulfur was applied and optimised for this type of hyphenated technique. Provided that the protein sequence is known (number of sulfur-containing amino acids, i.e. cysteines and methionines) the protein amount can then be directly calculated from the determined sulfur content in a certain protein fraction. In order to prove the reliability of the presented method, two different certified reference materials were analysed: CRM 393 (human apolipoprotein A-I) and CRM 486 (alpha-fetoprotein). For CRM 393 excellent agreement (37.0 +/- 1.4 mu mol L-1) was obtained with the certificate (37.7 +/- 1.8 mu mol L-1). However, the recovery rate for alpha-fetoprotein in CRM 486 was found to be about 60% indicating incomplete elution of the protein during the chromatographic separation.
- 出版日期2008-5
