****************************************************************************** From: Clay Campbell Date: Wed, 16 Oct 1996 18:12:02 -0700 Subject: References for Mixed CI Reagent Gas Organization: * Here's a late followup to Don Magin's question on mixed-component reagent gases and the replies posted here (Dave Parees, Chip Cody, and Dejan Djokovic). To summarize the issue (from Chip's reply), "ions formed by ammonia chemical ionization can react with neutral ammonia. This can cause a loss of analyte ion current ([M+H]+ or [M+NH4]+). Therefore, the better approach is to use a few percent ammonia in methane so that the [NH4]+ reagent ions are produced in abundance, but the neutral environment is dominated by methane molecules, which do not back-react with the analyte ions". The primary references for this technique are: 1. Munson and Field, J. Amer. Chem. Soc. 87, 4242, 1965. 2. Smith, Smith, Jerolamon, Weston, Richton, and Brozowski, Proceedings of the 26th Conference on Mass Spectrometry and Allied Topics, St. Louis, MO, 166-167, 1978. 3. Rudewicz and Munson, Proceedings of the 32nd Conference on Mass Spectrometry and Allied Topics, San Antonio, TX, 809-810, 1984. 4. Rudewicz and Munson, Anal. Chem. 58, 2903-2907, 1986. Clay S. Campbell Quadrupole Product Development Manager Finnigan Corporation 355 River Oaks Parkway San Jose, California 95134, USA E-Mail: campbell@finnigan.com Telephone: 1-408-433-4800, ext. 2400 Voice Mail: 1-408-433-4828, ext. 2400 Telefax: 1-408-433-4822 (or 4823) -------------------------------------------------------------