1 sample

Weighing the solid sample 0.20~1.00g or semi-solid specimens of 1.00~2.00g or from 2.00~10.00ml liquid sample (total law quite nitrogen 5~25mg trace method, a nitrogen 30~200mg)

2 digestion

The sample into the dry 250ml or 500ml digestive tube, plus 0.2g copper sulfate and 6G potassium sulfate and 12ml sulfate, after shaking in the digestion furnace mouth, put a small funnel or mounted on a gas suction pump cover device or exhaust after heating, semi - solid, liquid or fat is relatively high initial heating of samples be careful when you control, the contents of all the carbonization, bubble completely stopped, strengthen the fire. The entire process takes about 40~60 minutes. Digest solution is blue green clear and transparent after heating 5~10 minutes. The digestive tube cooled, wash bottle washing water nozzle, about 20ml.

The 3 distillation

Distilling apparatus in every time after startup, open the condensed water, set the conditions of air steam a sample to a clean line, automatic constant concentration of nitrogen analyzer to choose a good standard solution, usually sulfuric acid standard titration solution c (1/2H2SO4) =0.1000mol/L or hydrochloric acid standard titration solution c (HCl) =0.1000mol/L, the concentration of standard solution can also be make appropriate adjustments according to the nitrogen content.

Method: 1) the full amount of the sample digestion good with distillation unit, pull off protective cover, amount of sample and reagent K06 sample number, amount set up after the (general 30~50ml boric acid, sodium hydroxide 70~100ml) press the run button, buzzer hint in the sample after titration, the results displayed on the LCD screen. Or through the RS232 serial port to connect computer print directly formal inspection report. K05 and K02 boric acid and indicator on the flask, K05 set up the alkalinity and distillation time, singing tips in after distillation; K02 in accordance with the preheating - alkali distillation sequence, in turn, look on the back wall of alkali scale add; distillation after the completion of the empty steamed for one minute, wash and remove triangle bottle, began to record acid standard solution titration, consumption volume.

2) trace method: good digestion of the sample into the 100ml or 250ml volumetric flask, and with a small amount of water washing the digestive tube, fluid into the volumetric flask, add water to the scale, mixing stand-by. Pipet 10.00~25.00ml sample treatment solution to clean the alimentary canal, the remaining steps are the same with the full amount method.

4 Results

(V1-V0) x C x0.01401 x F

X= X100

M x V2/V3

The protein content in X------ sample, in units of g each hectogram or grams per 100 ml (g/100g or g/100ml)

The V1------ sample consumption of sulfuric acid or hydrochloric acid standard titration solution volume, unit for the ML (ML)

V0------ reagent consumption of sulfuric acid or hydrochloric acid standard titration solution volume, unit for the ML (ML)

C------ sulfuric acid or hydrochloric acid standard solution concentration, units as moles per liter (mol/L)

0.01401------1.0ml [c sulfate (1/2H2SO4) =1.000mol/L] or [c hydrochloride (HCl) =1.000mol/L] standard titration solution is nitrogen quality, in units of G (g)

The m------ sample mass or volume, in units of G or ml (g or ml)

V2------ draw sample processing fluid volume, unit for the ML (ML)

The V3------ sample digestion solution volume, unit for the ML (ML)

F------ nitrogen conversion for the protein factor. General food for 6.25 to 6.38; dairy products; flour is 5.70; corn, sorghum is 6.24; peanut is 5.46; 5.95 meters; soybean and its products is 6.25; meat and meat products was 6.25; barley, millet, oats, rye was 5.83; sesame, sunflower for 5.30.

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