Phosphorus was analyzed after prior wet mineralization with nitric acid (HN[O.sub.3]) and perchloric acid (HCl[O.sub.4]) according to the ammonium vanadomolybdate method using a Specol
11 spectrophotometer (Carl Zeiss, Jena) at a wave length of 470 nm.
The absorbance of the solutions was recorded on the spectrophotometer SPECOL
10 at wave lengths 420-450 nm.
All enzymes were assayed spectrophotometrically by tracing the changes in absorbance at 27[degrees]C using UV-VIS SPECORD or SPECOL
IN has been determined by the spectrophotometric method using a SPECOL
10 Karl-Zeiss Jena spectrophotometer, due to its ability to form a colored complex (absorption maximum at 520 nm) with vanillin in the presence of concentrated sulphuric acid.
The absorbance of the samples was recorded by a spectrophotometer SPECOL
[C.sub.total] and [N.sub.total] content were determined with a Perkin-Elmer CHN analyzer; [S.sub.total] was determined turbidimetrically (Specol
220, VEB Carl Zeiss Jena).