Pneumatically assisted electrospray-ion mobility spectrometry for quantitative analysis of intact proteins.

In this work, quantitative analysis of intact proteins using ion mobility spectrometry (IMS) is introduced. For this purpose a pneumatically assisted electrospray ionization source with a new design was constructed. Liquid and nebulizer gas flow rates were optimized to achieve the highest response. The pneumatically assisted electrospray-IMS was used for quantitative analysis of insulin, bovine serum albumin (BSA) and human serum albumin (HSA). The analysis of proteins demonstrated that sensitivity of the pneumatically assisted electrospray-IMS is two to three times higher than that of conventional electrospray ionization (ESI) coupled to IMS. The linear dynamic ranges for insulin, BSA and HSA were found to be 1-75, 5-100 and 2-100 μg mL(-1) with detection limits of 0.3, 1 and 0.6 μg mL(-1), respectively. The relative standard deviations (RSD) for five replicate measurements of insulin, BSA, and HSA at 25 μg mL(-1) were recorded as 3, 4 and 1.5%, respectively. The proposed method can be considered as an alternative way for quantitative protein analysis.