Abstract: Provided is a method for preparing a fluid containing size-controlled particles that is optimized with respect to use of a target fluid as a matrix fluid under conditions approximating actual conditions. In a preferred embodiment, size-controlled SiO2 particles are obtained by mixing and dispersing SiO2 starting particles having various sizes in a N2 carrier gas followed by fractionation with a fractionator. The size-controlled particles are electrostatically collected by a porous member from the carrier gas flow. Ultrasonic vibrations are then applied to the porous member while a HCl matrix fluid flows through the porous member loaded with the size-controlled particles. This causes release of the size-controlled particles from the porous member and their admixture and dispersion into the HCl matrix fluid.

Abstract: A process to detect metal impurities in a gas or gas mixture including the steps of directing the gas or gas mixture through non-metallic pipings to a sampling device and sampling the gas or gas mixture for metal impurities detection, wherein the sampling device is close to an inlet and/or outlet of a machine employing the gas or gas mixture as a processing gas, the machine being surrounded by a booth containing a gaseous atmosphere which is continuously circulated in the booth, partially renewing said atmosphere continuously, and exhausting excess atmosphere.