Pesticide Analyzer Reference - writeframeofmind.biz

Configuring the GC/MS System for Pesticide Analysis
PTV Injector
There are two types of PTV injectors that can be used for pesticide analysis:
• The Brightly Enhanced Sample Transfer (BEST) PTV injector contains very low thermal mass components and can achieve very fast heating and cooling
rates. This type of PTV injector maintains unprecedented sample integrity using the specially designed inert liners and the long vaporizing chamber with
reduced internal diameter. It can provide a virtual discrimination-free sample transfer in any situation, even when using high boiling-point samples. The
PTV injector’s compatibility with dirty samples makes it the ideal complement to the cold on-column injector.
• The Large Volume BEST PTV injector has the same capabilities of the standard PTV injector, but it can accept larger injection volumes. This type of
injector is compatible with dirty sample matrices. It is recommended for injection volumes > 10 μL, which can be injected all at once, while larger
volumes can be programmed to inject slowly.
Note The injection of larger solvent volumes strongly reduces the effect of active surfaces during the injection process, which is caused by the surrounding
solvent vapor momentarily protecting the labile pesticide compounds. For example, when using Endrin breakdown as a tool for diagnosing issues with
excessive injection port activity. Sample preparation time is greatly reduced by shortening the extract evaporation times.
The use of a pre-column for matrix samples is recommended for pesticide analysis. Typically, a pre-column is an empty 0.53 mm inner diameter column
of standard length, as determined by the type of injection volume. When injected, matrix samples are typically deposited in the insert liner and
pre-column. The analytical column is protected from the entry of low volatile matrix components, which preserves the calibrated retention times and
extends the life of the column. We recommend that you occasionally clean and maintain the injector, replace the insert liner, and replace the pre-column.
Always use the appropriate mini-unions or a glass press-fit connector to connect the pre-column. Be aware that leaks can occur when using glass press-fit
connectors with temperature programmed methods.
For increased efficiency when injecting samples, you can upgrade the TRACE GC Ultra with a PTV backflush system, which eliminates the irrelevant parts of
a dirty sample during the cleaning phase. Depending on your injection volume preference, there are two types of backflush systems available:
30 Pesticide Analyzer Reference Thermo Scientific