English Abstract The Elemental Analyser Model EA 1108 (Carlo Erba)
enables to determine nitrogen, carbon and sulphur in solid material, in a
fast and simple way. The samples are packed into lightweight containers of
tin and dropped at preset times into a vertical quartz tube, heated at 1020
degrees C, through which a constant flow of helium is maintained. When the
samples are introduced, the helium stream is temporarily enriched with pure
oxygen. Flash combustion takes place, primed by the oxidation of the
container. Quantitative combustion is then achieved by passing the gases
over W2O3. The mixture of the combustion gases is transferred over copper
to eliminate excess of oxygen and after drying the water over MgClO4
introduced into a chromatographic column, heated at 57 degrees C. The
individual components are then separated, eluted in the order N2, CO2 and
SO2, and measured by a thermal conductivity detector (TCD). The instrument
is calibrated by combustion of the standard sulphanylamide and the
calibration is controlled with the standard reference material (SRM)
cystine. The total calibration takes place in 2 hours. The measurement of
one single sample takes place in 15 minutes. Every ten samples the
instrument is controlled with the standard sulphanylamide. After
optimization of the instrument, a Standard Operating Procedure (SOP) for the
determination of carbon, nitrogen and sulphur in solid material, has been
formulated. The detection limit is for carbon 2 mg/g, for nitrogen 2 mg/g,
and for sulphur 5 mg/g. The accuracy for the measurement in cystine is for
carbon 3 mg/g (1.0%), for nitrogen 6 mg/g (5.1%), and for sulphur 6 mg/g
(2.2%).
Rapport in het kort
De elementanalyse van koolstof, stikstof en zwavel in
vaste monsters kan eenvoudig en relatief snel worden uitgevoerd met de
Elemental Analyzer (Model EA 1108) van Fisons Instruments in diverse typen
vaste stof monsters. Een hoeveelheid monster wordt afgewogen en de
Elemental Analyzer bepaalt de elementgehaltes in de gewenste eenheid. De
kalibratie en de controle van de kalibratie duurt in totaal 2 uur. Een
enkelvoudige analyse duurt vervolgens ongeveer 1 kwartier. Na optimalisatie
van het apparaat en de methode is een Standard Operating Procedure (SOP)
uitgebracht voor de elementanalyse van koolstof, stikstof en zwavel in vaste
stoffen. De aantoonbaarheidsgrens bedraagt voor stikstof 2 mg/g, voor
koolstof 2 mg/g en voor zwavel 5 mg/g. De precisie in cystine is voor
stikstof is 6 mg/g (5,1%), voor koolstof 3 mg/g (1,0%) en voor zwavel 6 mg/g
(2,2%).