Sodium phosphate glass, analysis

Anderson et al. have presented solid-state NMR analysis of local structural environments in phosphate glasses for educational purposes. " In particular, the solid-state NMR wide-line spectra of a series of sodium phosphate glasses have been considered, which can also be simulated by spectral addition of reference solid-state spectra obtained for pure pyrophosphate and metaphosphate salts. The example chosen introduces the principles of solid-state NMR and allows interpretation of the spectrum in terms of the composition and localised phosphate environment. 

Enzyme assays were conducted in a 10 mL screw-neck glass test tube containing 100 fiL of lysate, 90 fiL of a 250 /ng/mL solution of 6-mercaptopurine in 0.01 M HC1, and 15 /uL of 250 mM sodium phosphate buffer (pH 9.2). Reactions were initiated by the addition of 32 fiL of a 3 1 mixture of 250 fiM S-adenosyl-L-methionine and 30 mM dithiothreitol. The final pH was 7.5. After a 1-hour incubation at 37°C, the reaction was stopped by the addition of 850 fjL of ice-cold 3.5 mM dithiothreitol and 50 fih of 1.5 M H2S04. The tubes were then heated at 100°C for 2 hours. To each tube, 500 fiL of 3.4 M NaOH was added, immediately followed by 8 mL of toluene-amyl alcohol-phenyl mercuric acetate. The tubes were shaken for 10 minutes and centrifuged. Then 6 mL of the toluene layer was transferred to a glass-stoppered conical test tube and 0.2 mL of 0.1 M HC1 added. After vortex-mixing and centrifuging, the toluene layer was discarded. Samples (50 fiL in 0.1 M HC1) were used for HPLC analysis. Product formation was linear for up to 120 minutes and 150 /u,L of lysate. 

The usual method of blowpipe analysis was to direct the flame on to a small portion of the material on a charcoal block. The substance under investigation was often mixed with sodium carbonate, borax, or microcosmic salt (sodium ammonium phosphate). When the material was heated alone or with sodium carbonate, it often yielded decomposition products with a characteristic appearance and borax or microcosmic salt fused to a glass to which the unknown material might impart a characteristic colour. After Wollaston had introduced a method of producing malleable platinum in 1800, a platinum wire was frequently used to support the material in blowpipe analysis, particularly in the production of glassy beads with borax and microcosmic salt. 

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