Curie-Point Autosamplers

In the interest of efficiency, autosamplers have become increasingly important in analytical laboratories. Autosampling systems are now available for all three types of pyrolysis equipment furnaces. Curie point, and resistively heated filament 

Most of the autosampling pyrolysis systems available use a sample magazine or carousel to introduce prepared samples into a conunon heater. In the furnace type, samples are placed into deactivated steel cups that are dropped sequentially into the furnace for pyrolysis, then ejected pneumatically after the analysis. Tanperatures up to 800°C are achievable, and the carousel has space for up to 48 sample cups. 

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Figure 4.2.3. Curie point pyrolyser with autosampling capability (DyChrom model JPS-330).

Different practical constructions of a Curie point pyrolyzer are commercially available. In these systems, the sample is put in direct contact with the ferromagnetic alloy, which is usually in the shape of a ribbon that can be folded over the sample forming a sample holder. The sample and its holder are maintained in a stream of inert gas in a similar way as for resistively heated filaments. The housing where the sample and its ferromagnetic holder are introduced is also heated to avoid the condensation of the pyrolysate but without decomposing the sample before pyrolysis. Autosample capabilities for Curie point pyrolyzers are also commercially available (e.g. DyChrom modelJPS-330) [11, 12]. 

Because the Curie-point filament is heated inductively, no connections are made to the wire. This facilitates autosampling and permits loading the wires into glass tubes for sampling and insertion into the coil zone. Unlike the isothermal furnace, which is on continuously, the Curie-point wire is heated only briefly and is cold the rest of the time. This necessitates heating the pyrolysis chamber separately to prevent immediate condensation of the fragments made during pyrolysis. Therefore, Curie-... 

Two approaches to autosampling with resistively heated filaments are available, one in which multiple filaments are used and one in which a common filament is used. The former uses up to 14 different filament interfaces, each of which is connected sequentially to the gas chromatograph for pyrolysis. The computer permits individual control of each filament, so each sample may be analyzed using a different program. Like the Curie-point systems, the samples may be placed directly onto the heating filament. 

Pyrolyzers have been adapted to provide automatic, imattended control of Py-GC. An early system used precoated pyrolysis wires held in quartz tubes on a turntable. These were sequentially loaded, accurately positioned in the induction coil, pyrolyzed, analyzed by capillary GC, and ejected. An alternative has used an automatic solids injector for samples enclosed in iron foil, and a furnace system has enabled sampling of the Martian surface. Autosampling systems based upon conventional pyrolyzers are now commercially available for resistively heated filaments, microfurnaces, and Curie-point pyrolyzers. One such system... 

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