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8250719 
Journal Article 
Production of standard reference material - Verification of certified phosphorus values in standard reference steels in the range of 59-125 ppm P by primary calibration 
Staats, G 
1982 
0 
Fresenius' Zeitschrift für Analytische Chemie
ISSN: 0016-1152 
312 
5 
444-447 
English 
Deviations were reproduced repeatedly between certified and observed low phosphorus values in commercial standard reference steel samples when being analyzed thoroughly by photometry of the yellow phosphorus vanadato molybdenum complex after extraction by methyl isobutyl ketone. The values observed were by 14 ppm (min 2, max 26) lower as certified. The accuracy of these results on a choice of those samples was achieved and proved by primary calibration with pure substances with an interval of uncertainty of only 1.4ppm (95% confidence interval). As demonstrated this fact demands imparatively the documented application of primary calibration substances and suitable calibration methods when standard reference material is produced. © 1982 Springer-Verlag.