UNISOL Colorimetric pH Reagents

A liquid colorimetric reagent for pH in a liquid reagent rather than on paper. It is added to the sample in a cuvette and the colour is read through the solution.

Why it is measured

Paper fails on samples that are coloured, oily, or so poorly buffered that the paper's own indicator shifts them. A liquid reagent mixes into the sample instead of sitting on its surface, and the colour is read through the solution — which is why UNISOL works where a strip gives a doubtful answer.

Where it is used

• poorly buffered water
• coloured or turbid samples
• laboratory pH confirmation
• teaching demonstrations

Why a reagent instead of a paper

A paper carries its indicator on a surface, so a coloured, turbid or oily sample obscures the very colour you are trying to read, and a weakly buffered sample can be shifted by the paper itself. A reagent mixes into the sample and is read through it, which removes both problems.

The cost is that it needs a cuvette, a measured volume and a moment more work — which is why it is kept for the samples where a strip gives a doubtful answer.

Practical note

Use the matching cuvette and the same volume every time; the path length the colour is read through is part of the measurement.

Supplied in 3 presentations covering different measuring ranges. The range is chosen by model: 10, 13.