A study on losses of pahs, during sample concentration for chromatographicanalysis: Evaporation with a stream of nitrogen

Citation
Fh. Chang et al., A study on losses of pahs, during sample concentration for chromatographicanalysis: Evaporation with a stream of nitrogen, INT J ENV A, 80(1), 2001, pp. 13-26
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
INTERNATIONAL JOURNAL OF ENVIRONMENTAL ANALYTICAL CHEMISTRY
ISSN journal
0306-7319 → ACNP
Volume
80
Issue
1
Year of publication
2001
Pages
13 - 26
Database
ISI
SICI code
0306-7319(2001)80:1<13:ASOLOP>2.0.ZU;2-2
Abstract
Losses of polynuclear aromatic hydrocarbons (PAHs) in methylene chloride du ring evaporation with a stream of nitrogen was systematically studied. The starting sample concentration levels were 0.167 mug/mL and 0.00333 mug/mL f or each PAH. These two sets of test solutions were both evaporated from 300 mL to final volumes of 50, 30, 5, 3, and 1 mL, with a constant stream of n itrogen and in a water bath kept at 40 degreesC. Each sample was analyzed b y GC-FID. Factors affecting the percentage of analyte recovery include boiling points of analytes, the final sample volume and the starting sample concentration . When the diluted solutions were reduced from 300 mL to I mL, the recoveri es for PAHs were all higher than 90%. However, when the concentrated soluti ons were evaporated to 1 mL, recoveries of all analytes dropped below 85%, and naphthalene, the most volatile PAH, dropped to 77.5%. If evaporation wa s halted to a final volume of 3 similar to5 mL, the recovery for PAHs in bo th concentrated and diluted solutions were still almost all higher than 90% . This implies that during evaporation of methylene chloride with a nitroge n stream, no significant losses of semivolatile analytes, regardless of the ir boiling points or concentration levels, were found until or unless the f inal volume reaches below 3-5 mL. Apparently, the solute losses are mainly due to coevaporation instead of vapor partition.