The preparation of calibration standards for sodium, potassium and chlorine analyses by analytical electron microscopy

Attempts were made to prepare sodium and potassium thin section standards for analytical electron microscopy by introducing, in serial concentrations, a complex between the appropriate salt and macrocyclic polyether ([15] crown-5 for sodium and [18] crown-6 for potassium) into epoxy resin. Of the tested salts, sodium tetraphenylborate, tetrafluoroborate and cyanide failed to produce homogeneous standards, and those standards containing sodium or potassium iodide or bromide were analytically inhomogeneous at concentrations greater than 20 meq 1−1. Only sodium thiocyanate and potassium cyanide standards were analytically homogeneous at concentrations up to 600 meq 1−1. A chlorine standard, which was analytically homogeneous at concentrations up to 1000 meq 1−1, was prepared by incorporating 1,2,4-trichlorobenzene into an epoxy resin.