This part of ISO 21078 specifies methods of determining boron(III) oxide in refractory products and raw materials, in mass fractions of 0,01 % or greater. It is applicable to the determination of total boron(III) oxide in oxidic materials for ceramics, glass and glazes. The determination of boron(III) oxide is carried out using one of the following four methods: a) alkaline titrimetry, which is applied to samples containing more than 0,5 % by mass of boron(III) oxide; b) azomethine H absorption spectrophotometry, which is applied to samples containing from 0,01 % by mass to 2,5 % by mass of boron(III) oxide; c) curcumin absorption spectrophotometry (rothocyanine method), which is applied to samples containing from 0,01 % by mass to 1,0 % by mass of boron(III) oxide; d) inductively coupled plasma atomic emission spectrometry (ICP-AES), which is applied to samples containing from 0,01 % by mass to 15 % by mass of boron(III) oxide. NOTE 1 The method can be extended to 30 % boron(III) oxide using modified oxidic fluxes. NOTE 2 Interlaboratory test results for this part of ISO 21078 are given in Annex A.