Controlled diffusion for laboratory solution preparation

Abstract

We report here on a method for preparation of precise laboratory solutions using controlled diffusion for dosing. The desired chemical is delivered into the target solution from a stock solution through a mass-transport-limiting delivery port that blocks convection but allows reproducible diffusive transport. Solution making with this approach involves a single step irrespective of how low the desired concentration is. Diffusional delivery of chemicals involves no appreciable movement of water and, thus, no addition of volume. The approach is therefore particularly suitable for standard addition. Precise solutions of usual laboratory volumes can be made within a short time period with proper design of the delivery port or ports. Comparison with the performance of conventional methods of routine solution preparation shows that better precision can be achieved with less labor using this approach.