Ultra-sensitive quantification of lysozyme based on element chelate labeling and capillary...

In this study, an ultra-sensitive method for the quantification of lysozyme based on the Gd(3+) diethylenetriamine-N,N,N',N″,N″-pentaacetic acid labeling and capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) was described. The Gd(3+)-tagged lysozyme was effectively separated by capillary electrophoresis (CE) and sensitively determined by inductively coupled plasma mass spectrometry (ICP-MS). Based on the gadolinium-tagging and CE-ICP-MS, the lysozyme was determined within 12 min with an extremely low detection limit of 3.89 attomole (3.89×10(-11) mol L(-1) for 100 nL of sample injection) and a RSD<6% (n=5). The proposed method has been successfully used to detect lysozyme in saliva samples with a recovery of 91-106%, suggesting that our method is sensitive and reliable. The success of the present method provides a new potential for the biological assays and sensitive detection of low-abundant proteins.