Overcoming lithium analysis difficulties with a simple colorimetric/spectrophotometric method

The analytical determination of lithium ions is usually performed by atomic absorption and X-ray fluorescence methods. Chemical analysis based on polyfluoroporphyrin chromogenic methods is also being employed, especially for biological samples. However, all existing methods are expensive and not suitable for routine work or field assays. The alternative method proposed here is based on the formation of a LiKFe(IO₆) compound which is converted into a tris(1,10-phenanthroline)iron(ii) complex and monitored by spectrophotometric or colorimetric methods, the latter using a smartphone app. Under similar conditions, these two methods proved superior to the X-ray fluorescence method. A one pot analysis of lithium ions is also described, using an Eppendorf microtube previously modified for performing reaction, filtration and detection. This method is simple and very convenient for didactic and field assays.