Extrem nachweisstarkes gas-chromatographisches Bestimmungsverfahren für Selen nach Abtrennung durch Verdampfen im Sauerstoffstrom

For the determination of the smallest amounts of selenium in high-purity copper, the sample (≤2 g) is heated in a quartz tube at 1100–1150°C. SeO₂ evaporates and is collected quantitatively by condensation of the carrier gas in a micro-trap cooled with liquid nitrogen. After evaporation of the oxygen, SeO₂ is caused to react in the trap with 4-nitro-o-phenylenediamine, forming 5-nitropiazselenol, which is then extracted with toluene and determined in the ppb-range by gas-chromatography with ECD. All separation steps were optimized by the tracer method using ⁷⁵Se. Determining 0.74 ppm of Se, the standard deviation was found to be 0.004 ppm for 15 determinations with samples of 200–600 mg. The detection limit is 1 ppb of Se.