Abstract: Liquid dispensing apparatus comprises a support member which supports a movably mounted dispensing member. The support member is movable between first and second positions. A single drive system causes the dispensing member to move relative to the support member to a number of dispense positions while the support member is in its first position and causes the support member to move to the second position.

Abstract: First and second reactants that give a signal when mixed in the presence of an analyte in a liquid sample, are separately contained in sol-gels that release the reactants in the presence of the liquid. For example, when the first and second reactants respectively comprise an oxidant and a reductant, and the reaction provides a detectable signal, the system can be used to detect the presence of contaminants in a water sample. The sol-gel may be obtained by reaction of water with, per part by volume thereof, at least 2 parts of a metal alkoxide, and drying the resultant gel.