Manual of basic techniques for a health laboratory - libdoc.who.int

2. Setting up a peripheral health laboratory 29(a)0.50.30.11240M /cm0(b)0.50.30.11240M /cmFig. 2.35 Measuring the resistivity of demineralized waterWHO 01.203Change of colour in resinIf the resin changes colour (e.g. it turns black), consult the instructions for usesupplied by the manufacturer.It may need to be reactivated or replaced, as described below.Replacement or reactivation of ion-exchange resinThis can be done in one of the following ways, depending on the model:● The cartridge is replaced by another filled with ion-exchange resin granules.●●The column of the apparatus is refilled with ion-exchange resin or a mixture oftwo resins.The exhausted ion-exchange resin is reactivated by passing a solution of ammoniathrough the apparatus. Follow the instructions supplied by the manufacturer.UsesDemineralized water can be used for:— rinsing glassware before drying;— preparing almost all the reagents used in medical laboratories, including stains.2.4.4 Buffered waterDistilled water is usually acid and demineralized water becomes acid on exposureto the air. For a number of laboratory procedures (preparation of stains, etc.) the