The principle of the method specified is complexing of the boron in the extract solution to be analyzed with azomethine H, measurement of the optical density of the resulting colour complex by means of a molecular absorption spectrometer at 415 nm using 20 mm optical cells. Measures the concentration of boron, expressed as its oxide B₂O₃. Applies to the analysis of extract solutions obtained from any kind of glass or glassware including laboratory and pharmaceutical ware made, e.g., from borosilicate glass, neutral glass, tableware and kitchenware.