Use of cuprous thiocyanate as a short-term continuous marker for faeces.

The main technical difficulty in the use of insoluble markers for faeces such as chromium sesquioxide (Whitby and Lang, 1960) or barium sulphate (Dick, 1967) is in the solubilization of these very inert compounds. Digestions with perchloric acid or chelations with EDTA are time-consuming pro-cedures. Accordingly a search has been made for a compound which although insoluble under physio-logical conditions, could be decomposed by relatively mild chemical treatment. Cuprous thiocyanate (CuSCN) is a compound which has solubility characteristics in water rather similar to those of barium sulphate. In neutral or mildly alkaline conditions the solubility is about 0 5 mg % (BaSO4 0.25 mg%)