Operating modes and functions
Static head space measurement mode
In the static head-space mode a defined volume of gas is extracted from a vial into a heated syringe. The gas is subsequently injected into an injection cell, to which the PTR-MS inlet is connected. A controlled flow of clean gas through the injection cell and the programmable injection speed can be used to adjust the dilution rate of the sample gas. This built-in dilution functionality is especially useful for applications where high concentrations would otherwise compromise the measurement, as is often the case for food and flavor samples.
To minimize retention effects, the injection cell is sulfinert coated and heated. After sampling, the syringe can be flushed by a flow of clean air to diminish carry-over effects.
Dynamic head space measurement mode
For dynamic and continuous analysis of the head-space of a vial, the autosampler is equipped with an additional holder to mount the heated inlet hose from the PTR-MS. This allows to connect the PTR-MS inlet capillary to the outlet port of a double needle adapter. The sampling vial is transported to a specific tray position close to the heated hose and subsequently penetrated using the double needle adapter. Head-space is sampled by the PTR-MS, while the flush mode of the syringe is used to replenish the gas.
Our auto sampler allows the implementation of several additional modules. Routinely installed, for example, is a double-needle adapter that also allows to rinse vials with clean air to remove room-air contaminants.