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Exploration of the problems and solutions related to reference introduction prior to calibration of thermal desorber–gas chromatography
Author(s) -
Asfaw Adissu Alemayehu,
Van der Veken Matthias,
Wolfs Kris,
Van Schepdael Ann,
Adams Erwin
Publication year - 2019
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.201900260
Subject(s) - sorbent , thermal desorption , desorption , chromatography , calibration , adsorption , gas chromatography , analyte , chemistry , analytical chemistry (journal) , tube (container) , materials science , organic chemistry , composite material , statistics , mathematics
Reference introduction in thermal desorption with gas chromatography is a critical aspect. It is mostly performed by offline liquid calibration using a micro syringe to inject a liquid standard solution on the sorbent in the thermal desorption tube. This is based on the assumptions that the adsorption‐desorption process is quantitative and that no sample is lost in manipulating the tube. However, for analytical procedures involving thermal extraction of solid matrices, the adsorption‐desorption processes for sample and reference differ and the assumptions are not always fulfilled. This is explored in this work. First, issues related to the online liquid calibration were investigated. With tubes containing only quartz filters, a relative loss of over 80% was noticed for some solvents due to tube manipulation processes. Enclosing a bed of mesoporous silica as sorbent limited the losses to about 25% when samples were immediately analysed, and even better results were obtained when tubes were stored for several hours so that proper adsorption could take place. An additional sweep gas during loading boosted the transfer of analytes with recoveries above 95%. Next, an inline injection system was installed on the thermal desorber instrument. This sorbent free, independent calibration tool avoids the drawbacks of other approaches.