Question

Why is split less injection used with purge and trap sample preparation?

Short answer

NOT GIVEN

Step-by-step solution

 a) Splitless injection in purge and trap

Purge and trap are a sample extraction techniques where volatile analytes are removed from liquids or solids, then analytes are concentrated and introduced into a gas chromatograph. In this method, 100% of the analytes are extracted from the sample.

Purge and trap apparatus which is used for measurement of volatile flavor components in carbonated beverages, where helium is used as purge and is bubbled from a stainless-steel needle which is passed through the cola in the sample vial. The specimen is heated to $50°C$to aid evaporation of analytes. Then, purge gas that exits in the sample vial travels in an adsorption tube with three layers of adsorbent particles, starting from a low-strength to a high-strength adsorbent. The gas flow is then reversed, and trap is purged at$25°C$to eliminate most of the water and solvent from the adsorbents. Afterward, the outlet near the low-strength adsorbent is connected to the injection port of a gas chromatograph operating in split less mode and the trap is heated to $200°C$ . Spitless injection is applied because about 80% of the sample can be injected to the column and small fractionation happens during injection. These conditions are important because the objective of the purge and trap method is to extract all the analytes from the sample. The desorbed analytes then flow into the chromatography column where they are concentrated by cold trapping. Separation is initiated by warming the chromatography column.

final answer

Splitless injection is applied because about 80% of the sample can be injected to the column and small fractionation happens during injection. These conditions are important because the objective of the purge and trap method is to extract all the analytes from the sample.