Artikkelit kirjoittajalta Marja-Leena Saastamoinen
Fosforin määrityksestä turpeesta.
English title: On the determination of phosphorus in peat.
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Tekijät
According to the investigations of Kaila, the phosphorus content in Finnish peat-lands varies at the range from 190 ppm to over 2000 ppm. (Kaila 1955, 1956). The amount of organic phosphorus lies between 55 % and 95 %.
The determination of the phosphorus from the matrix of organic matter is a tedious process. (Haiman 1972, John 1970, Alexander and Robertson 1968, Kaila 1955).
The aim of our study was to develop a method for the phosphorus determination in which the metals also could be determined after the same sample treatment.
The most common digestion method for the organic matter is the Kjeldahl wet digestion. It cannot, however, directly be employed to the metal determination with the atomic absorption technique.
We used a small autoclave ( ~ 25 cm3) made from teflon in the sample digestion. The amount of the sample was 0.5—1.0 g and then 11.7 cm3 of perchloric acid
(70 %), 6.7 cm3 of nitric acid (65 %) and 10 cm3 of hydrogen fluoride (40 %) was added. The sample was heated for five hours at 140 °C. The phosphorus was determined according to the method by Lueck and Boltz with the difference, that the absorbance of the solution was measured exactly after one hour since the last reagent addition. The results are presented in Table 1 and Figs. 1 and 2.
The comparative determinations were made after the Kjeldahl digestion with the method by Kaila. The results were in agreement.
The advantage of the autoclave method is its suitability to the routine work in the phosphorus determinations of peat, peat coke and wet carbonized peat, for instance. The same solution can be used to the metal determinations and the use of the autoclave improves the analytical accuracy and reduces the amounts of poisonous gases in the laboratory air.
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Tummavuori,
Sähköposti:
ei.tietoa@nn.oo
- Nyrönen, Sähköposti: ei.tietoa@nn.oo
- Saastamoinen, Sähköposti: ei.tietoa@nn.oo
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