Robotic sample preparation lines as well as some autosamplers are constructed that way that they lift and transport vials with a magnet the size of the vial’s cap. In these cases aluminum crimp or plastic screw caps cannot be used, as these materials won’t react to a magnet. Only metals like steel or tin will do so, however, they will also bear some problems that need to be considered.
One of the most wellknown autosamplers with such a transportation system is the CTC PAL* for GC and Headspace. There are a lot of OEM versions of that autosampler in the market as well as identically constructed ones, but they all have in common that they require caps reacting to a magnet for transportation of vials from the rack into the heating chamber.
* PAL is a registered trademark of CTC Analytics AG, Switzerland. The MACHEREY-NAGEL products is neither endorsed, nor sponsored by or affiliated with the CTC Analytics AG.