Application Note 20642
The Importance of Autosampler Vial
Selection in the GC-MS Analysis
of Pyrethroid Pesticides at Low
Concentration
Anila I. Khan, Thermo Fisher Scientific, Runcorn, Cheshire, UK
Introduction
Pyrethroids are a class of synthetically produced
insecticides that are mainly used for domestic purposes to
control insects such as house flies and mosquitoes. They
behave very similarly to natural pyrethrins, which are
derived from chrysanthemum flowers, and are extremely
toxic to fish and aquatic organisms but have low toxicity
towards humans. However, repeated exposure to
pyrethroids increases the risk of anaphylaxis and allergic
reaction to very low concentrations and, therefore,
pyrethroid levels should be monitored.
Analyzing pyrethroids at low concentration levels can be
challenging due to their adsorption onto glass surfaces,
such as sample bottles, GC inlet liners and vials. To reduce
adsorption of pyrethroids onto the surface of glass, a
comparison with plastic and high purity clear neutral
borosilicate glass vials was carried out with a GC method
utilizing a Programmable Temperature Vaporizer (PTV)
simulated on-column injection.
The separation of the pyrethroid extracts was carried out
using a Thermo Scientific™ TraceGOLD™ TG-5SilMS
column with a Thermo Scientific GuardGOLD™
pre-column. This column is based on silarylene chemistry,
which provides more stability and lower bleed than
standard 5% phenyl dimethylpolylsiloxane phase GC
columns. This in turn gives rise to better sensitivity due to
reduced background signal. This phase can also partially
resolve complex mixtures of cyfluthrin and cypermethrin
isomers.
Key Words
Pyrethroid pesticides, adsorption, 33 expansion high purity clear neutral
borosilicate glass vial
Abstract
The selection of the correct autosampler vial type is vital to the success of
analyzing pyrethroid pesticides at low levels. A method for the determination
of pyrethroids at 0.10 ng/mL was developed using solid phase extraction
(SPE) for pre-concentration with subsequent analysis by GC with PTV
simulated on-column injection. Careful selection of the autosampler vial type
was needed to minimize adsorption effects.
Bifenthrin
Cypermethrin
Permethrin
Cyfluthrin
