****************************************************************************** From: madi@biocell.fundp.ac.be (Marc DIEU) Subject: Desalting primer before electrospray mass spectrometry Date: 13 Oct 1995 11:29:55 GMT Organization: FUNDP (Cellular Biochemistry) Hello, Is there someone who knows the best method for desalting primer before electrospray MS. I tried microcon but the recovery was not good. Thank you by advance Marc DIEU Laboratory of Cellular Biochemistry, Facults Universitaires ND de la Paix, 61, rue de Bruxelles, B-5000 Namur (Belgium). Fax: ++/32/81/72.41.35. Email: fredele@biocell.fundp.ac.be. ****************************************************************************** From: "Andrew N. Eaton" Subject: Re: Desalting primer before electrospray mass spectrometry Date: 18 Oct 1995 08:07:50 GMT Organization: UnipalmPIPEX server (post doesn't reflect views of UnipalmPIPEX) Oligonucleotides are inherently difficult to analyse by electrospray due to the seemingly high level of binding of sodium and potassium to the oligonucleotide backbone.. We have had some success using Micron filters but the extraction of the oligonucleotide is difficult to reproduce on a routine basis. Our biggest success has been to use a capillary column containing a PorosTM packing material (Columns available in Europe through LC Packings). The samples are injected onto the column using a mobile phase of 100% water at 30ul/min. After 5 minutes the olignucleotide having been concentrated on the head of the column and washed of salts is eluted using a 90% acetonitrile 10% water phase. As the compound elutes the mobile phase is reduced to 4ul/min to allow several MCA scans to be acquired. We currently have customers at Glaxo who have completely automated this process using Masslynx software to control an HP1090 LC pump. Although the oligonucleotides are not completely salt free this approach is to date the most successful. John Rontree. Technical Support, VG ORGANIC E-Mail: John.Rontree@instruments.fisons.co.uk Tel: ++44 (0)161 929 9666, Fax: ++44 (0)161 941 5242 Tudor Road, Altrincham, Cheshire WA14 5RZ, United Kingdom