Production of reference material

Summary Carbon has been determined in the certified reference sample Euro CRM Pure Iron 097-1 to 3.98 g C/g (R = 0.15 at P = 95%) by combustion of the sample portion with subsequent indication of the CO₂ by coulometry. A calibration material based on primary sources of carbon was used with a sufficient small interval of uncertainty of the accuracy and an adequate weighing system. The blank could be kept sufficiently small with a fraction of 23% of the total analytical signal. The surface carbon of the 097-1 was determined to approximately 50% of the total carbon. This result of total carbon is considerably lower than the values in the certificate reading up to 20 g/g. This reflects the strong tendency to too high values in the certificates of reference steels with contents of carbon up to 100 g/g. Examples are given.

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Herstellung von Referenzmaterial — Bestimmung von Kohle in Stählen und reinem Eisen im Bereich von 1–100 g/g mit primärer Kalibrierung