Procedure
1. Follow procedures as specified by manufacturer for each model of instrument.
2. Accuracy of system is demonstrated by making 10 successive determinations
of nitrogen in nicotinic acid and 10 successive determinations of nitrogen in
lysine-HCl. Means of determinations must be within ±0.15 of respective
theoretical values, with standard deviations of £0.15. Standard tryptophan may
be substituted for lysine-HCl. System must not be calibrated with same material
used for accuracy test.
3. Suitable fineness of grind must be determined (for each different material
analyzed) to achieve precision that gives relative standard deviation (RSD) of
£2.0% for 10 successive determinations of nitrogen. RSD, % = (SD/mean % N)
´ 100. Some materials may require analysis of larger quantities of material to
achieve this precision, depending on attainable fineness of grind.
Calculations
Instruments automatically display and/or print out results in percent protein.