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Low temperature sublimation is shown to significantly reduce the metal and --P--OH containing impurity levels of pracUcal-grade phosphorus oxychloride. Regular distillation and sub-boiling distillation are also effective for removing --P--OH impurities and provide products with I14-I19 ppm of residual --P--OH. The purification efficiencies of these physical methods are compared with that resulting from chemical treatment to convert --P-OH impurities into other species. A method based on chemical reaction followed by low temperature sublimation is described for removal of--POH from practical-grade material and reduction of trace materials to low ng/ml levels.Volatile glass forming reagents of high purity with respect to trace transition elements, --H, and --OH molecular impurities are now widely used for proKey words: trace metal impurities, IR spectra of POCh, sublimation, sub-boiling distillation. duction of optical waveguide glass compositions via vapor-phase oxidation at elevated temperatures. Needs for analytical and purification methods for vapor-phase glass forming chemicals have motivated several previous investigations (1, 2, 3). The advantages and ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-03-17 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.255.6.125 Downloaded on 2015-03-17 to IP