The samples were digested with nitric acid and perchloric acid
to release minerals for analysis. The inorganic phosphorous in
the digested solution was determined by ‘‘molybdenum blue
complex’’ reported. The blue color of the phosphorous complex was measured on a spectro-
photometer at 880 nm wavelength and the amount of un-
known phosphate was determined from a standard plot of
absorbance vs concentration
Zinc, iron, copper, magnesium and manganese were ana-
lyzed by using atomic absorption spectrophotometer model
Perkin Elmer 3100 while sodium and potassium ions were mea-
sured using a flame photometer (Sherwood Flame Photometer
410, Sherwood Scientific Ltd. Cambridge, UK) according to
the standard method