Non-Metal-Analytics (H, C, N, O; Inorganic)

Method
The determination of hydrogen (separate or in combination with N and O) proceeds via the carrier gas hot extraction method (CGHE). The samples are weighed into tin capsules by usually adding melting additives and are heated in graphite crucibles with an electrode furnace under a stream of argon and helium, respectively (T_max. approximately 3000^°C). The quantification of the content of hydrogen succeeds either by a thermal conductivity cell or by detection of H₂O with an IR cell. The calibration is carried out with respective standards or by use of hydrogen gas. The simultaneous determination of nitrogen and oxygen (and hydrogen) is carried out by the carrier-gas-hot-extraction method. The samples are weighed into tin capsules usually by adding melting additives and are heated in graphite crucibles with an electrode furnace in a stream of helium (T_max. approximately 3000^°C). Differences in chemical bonding situations (oxygen and nitrogen, respectively) are selectively determined by controlled successive heating. The determination of the content of oxygen succeeds by detection of CO and CO₂ with highly selective IR-cells, whereas the content of nitrogen is measured by thermal conductivity detectors. The calibration proceeds via standards in the respective range of concentrations. For determination of the content of carbon the samples are burnt by adding metallic combustion catalysators in a stream of oxygen in a high-frequency induction furnace (T_max. approximately 2200^°C). The determination of the content of carbon is carried out via IR cells detecting CO₂. Calibration proceeds by the respective standards.

Sample preparation
No sample preparation necessary.

Required amount of sample
Quantities of approximately 30 – 50 mg for major and minor components and approximately 60 – 500 mg for traces (depending on the desired limit of detection) are required.

Instrumentation
LECO TCH 600:
Hydrogen/Nitrogen/Oxygen (simultaneously) – analyzer with electrode impulse furnace, three IR measuring cells for low and high ranges of concentrations of oxygen, one IR measuring cell for H₂O and one thermal conductivity cell for the determination of nitrogen.
LECO RH 404:
Hydrogen – analyzer with electrode impulse furnace EF 400 and one conductivity cell for the determination of hydrogen.
LECO TC 436 DR/5:
Nitrogen/Oxygen – analyzer with electrode impulse furnace EF 500, two IR-measuring cell for low and high oxygen concentration and one thermal conductivity cell for the nitrogen determination.
LECO C-200 CHLH:
Carbon – analyzer with two IR-measuring cells for low and high ranges of concentrations of carbon.