Surface treatment of borosilicate glass beakers for prevention of sodium contamination

Pyrex glass beakers are treated with molten Ca(NO 3) 2-KNO 3 (20:80 mol %) mixture at 500°C for 3 h. Treated beakers can be used successfully in wet oxidation of SRM-1571 Orchard Leaves for sodium determination; at least 10 oxidations can be done without sodium contamination. Mass spectrometry is used to investigate the depth profiles of glass components within 60 nm of the glass surfaces and to clarify the mechanism of the sodium contamination.