A FAST MICROWAVE-ASSISTED, ACID-VAPOR, STEAM-CLEANING PROCEDURE FOR AUTOSAMPLER CUPS

A new and fast procedure is proposed for cleaning autosampler cups usi ng acid-vapor steam-cleaning with a miniaturized assembly in a microwa ve-heated sealed Teflon vessel. A glass cactus-shaped holder was made to support six polyethylene autosampler cups (volume, 2.0 mt) inside a 100 mt microwave vessel. Regent-grade nitric acid was added to the ve ssels, and the system was heated in a microwave oven for 5 min at 300 W. Chromium was determined by graphite-furnace atomic-absorption spect rophotometry. The blank values were lower with cleaned cups compared t o untreated cups (i.e., as received from supplier). The quantification limits, estimated from detection limits established with Milli-Q wate r, were 0.66 and 0.95 mu g Cr L-1 for cleaned and untreated auto-sampl er cups, respectively. (C) 1998 Elsevier Science B.V. All rights reser ved.