Identical flow injection spectrophotometric manifold for determination of protein, phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds or premixes
Jf. Liu et al., Identical flow injection spectrophotometric manifold for determination of protein, phosphorus, calcium, chloride, copper, manganese, iron, and zinc in feeds or premixes, J AOAC INT, 84(4), 2001, pp. 1179-1186
A simple procedure using an identical manifold was developed for determinat
ion of nitrogen (protein) phosphorus, calcium, chloride, copper, manganese,
iron, and zinc in feeds and feedstuffs. By changing appropriate reagents a
nd detection wavelength, these 8 elements were determined successively with
a simple identical double-line flow injection (FI) manifold. FI spectropho
tometric determinations were made by the blue indophenol reaction for ammon
ium, the molybdenum blue method for phosphate, the cresolphthalein complexo
ne procedure for calcium, and the mercuric thiocyanate procedure for chlori
de. The chromogenic reagents for copper, iron, manganese, and zinc determin
ation were bis(cyclohexanone)oxalydihydrazone (Cuprizone), 1,10-phenanthrol
ine, formaldoxime, and xylenol orange, respectively. Sample digestion catal
yst, Fl manifold, and some chemical parameters were optimized. The proposed
procedure had a sampling rate of 90/h for each analyte. The determination
ranges (mg/L) were 10-60 for N, 1-15 for P and Ca, 5-40 for Cl, and 0.5-15
for Cu, Fe, Mn, and Zn, respectively. Results of the analyses of animal fee
d and feedstuff samples by this procedure did not differ significantly from
those obtained by proven manual methods.