title: An alternative multiple-trapping LC-SPE-NMR system.
abstract: In this paper, we describe approaches that make RP LC-SPE-NMR simpler, and in our opinion, result in more reliable methods for trapping and subsequent transfer of separated trace-level compounds to the NMR. An SPE unit based on a commercially available, low dead-volume 10 port high-pressure column selector gives the possibility of trapping compounds on nine individual SPEs that have standard fittings. This allows the operator to employ specific stationary phases that are not available as SPEs in commercially available LC-SPE-NMR systems. Multiple trappings of small compounds like monuron, 1-(4-chlorophenyl)-3-methylurea, and 4-chlorophenylurea were easily performed employing a porous-carbon SPE material. The system was optimized to elute the SPE-trapped compounds to the NMR probes in as small a volume as possible using back-flushing. The proper match of NMR probe volume and SPE column inner diameter and elution volume was discussed, as well as the necessity of drying loaded SPEs prior to NMR transfer when using porous-carbon SPE material.
authors.affiliation: Department of Chemistry, University of Oslo, Blindern, Oslo, Norway. stevenw@kjemi.uio.no
authors.forename: Steven Ray
authors.initials: SR
authors.lastname: Wilson
authors.forename: Helle
authors.initials: H
authors.lastname: Malerød
authors.forename: Dirk
authors.initials: D
authors.lastname: Petersen
authors.forename: Frode
authors.initials: F
authors.lastname: Rise
authors.forename: Elsa
authors.initials: E
authors.lastname: Lundanes
authors.forename: Tyge
authors.initials: T
authors.lastname: Greibrokk