| 摘要 |
1527225 Test device WELLCOME FOUNDATION Ltd 11 Nov 1975 [11 Nov 1974 (2)] 48714/74 and 48715/74 Heading G1B A test device for comparing with a selected concentration limit the concentration of material in a liquid sample comprises a predetermined amount of an initially coloured indicator on a solid inert support such as a filter paper optionally attached to an impervious support and protected by a semi-permeable membrane, the indication being in amount and of a kind such that in contact with a volume of sample which saturates the solid inert support there takes place a complete loss of colour not attributable to pH change. When the material is boric acid the indicator may comprise an iodine source, an iodine solubilizer such as potassium iodide and soluble starch on a glass fibre filter - PVC supported sheet treated with either collodion solution or a suspension of sodium carbonate in collodion solution, the sodium carbonate being intended to make the sample alkaline before it reaches the indicator. |
