A vessel for low-pressure acid dissolutions of mineral and inorganic samples

Microwave-assisted acid dissolution of minerals and inorganics is rapid, but difficulties in controlling the temperatures of such systems present potential safety problems. This drawback can be overcome by the use of specifically designed equipment which is, however, expensive. Dissolution under conventional heating, although slower, is inherently safer, temperature control being simple and reliable, as well as inexpensive. For laboratories with high sample loads, the importance of the dissolution time can be reduced significantly simply by heating a large number of samples simultaneously. For such systems, microwave heating holds little or no advantage over conventional heating. Presented here is a vessel designed specifically for this purpose. It is constructed of polyvinylidene difluoride, has a volume of 20 mL, and can be used up to 120 °C at 4 atm. This vessel has two major advantages : the use of conventional heating obviates the need for special (and generally expensive) ancillary equipment and the small size and relatively low cost facilitate heating large numbers of such vessels simultaneously. These vessels have been in routine use in these laboratories for the past 8 years. Forty of them are often heated together in a conventional laboratory oven.