He introduced a method combining pe

He introduced a method combining persulphate oxidant and autoclave heating. The method was slightly modified by D’Elia et al. (1997). A buffer was added to the system keeping the PH at 9.7 at the beginning and 4-5 at the end (Koroleff,1997). The oxidizing agent thus breaks down organic components, releases phosphorus as phosphate and oxidizes nitrogen components to nitrate.
The peroxodisulphate oxidation is supported by heating in an autoclave to about 115°C
with minor modifications the method can be applied. For the determination of total nitrogen, phosphorus and silicate individually, or nitrogen and phosphorus simultaneously.
A persulphate oxidizing agent for the decomposition of organic material containing N and P is commercially available ( oxisolv,merck).
Though manual determination of nutrients are still in use, the majority of samples are analysed by automated flow-analyses. The oxidation procedures for the determination of total nitrogen, phosphorus and silicon as presented in the previous edition of this of this book, have thus been adapted to subsequent flow-analysis of inorganic nutrients without modifications to the manifolds or reagents.
A calibration and calculation procedure is suggested in section (10.2.12.2) which is applicable to all total N, P and Si determinations both in manual and flow-analyses. A calibrated analytical setup is required for the respective inorganic component (nitrate, phosphate, silicate).
The desired sample volumes for the determination of total N , P or Si are poured into the oxidation bottles immediately after sampling. If the bottles are closed tightly, the samples may be stored without further precautions. Total Si samples only be stored in plastic bottles.