Ambient analysis of saturated hydrocarbons using discharge-induced oxidation in desorption electrospray ionization.

Saturated nonfunctionalized hydrocarbons can be oxidized in situ by initiating an electrical discharge during desorption electrospray ionization (DESI) to generate the corresponding alcohols and ketones. This form of reactive DESI experiment can be utilized as an in situ derivatization method for rapid and direct analysis of alkanes at atmospheric pressure without sample preparation. Betaine aldehyde was incorporated into the DESI spray solution to improve the sensitivity of detecting the long-chain alcohol oxidation products. The limit of detection for alkanes (C(15)H(32) to C(30)H(62)) from pure samples is approximately 20 ng. Multiple oxidations and dehydrogenations occurred during the DESI discharge, but no hydrocarbon fragmentation was observed, even for highly branched squalane. Using exact mass measurements, the technique was successfully implemented for analysis of petroleum distillates containing saturated hydrocarbons. 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.