ISO 6851 pdf download – Photography – Processing waste 一Determination of total amino nitrogen(microdiffusion Kjeldahl method)

ISO 6851 pdf download – Photography – Processing waste 一Determination of total amino nitrogen(microdiffusion Kjeldahl method).
Weigh 134 g ± 0.1 g of potassium sulfate. K2S04, and transfer it c.iantitatively to a 1 litre volumetric flask conforming to Class A of ISO 1042. Add about 650 ml of water and dissolve the potassium sulfate. Carefully add 200 ml of sulfuric acid, H2S04 (DANGER: ((C>)) p 1,84 glrnl, from a graduated measuring cylinder and mix.
Weigh 29 ± 0.1 g of red mercuy( II) oxide. IlgO’ (DANGER: ((B>) ((C)) ((S))), and dissolve it in 25 ml of 3 mo11 sulfuflc acid solution (6.2,4) (DANGER: (C>) in a small beaker Add the contents of the beaker to the acidified potassium sulfate solution, and rinse the beaker into the flask. Dilute the solution to volume when cool, and mrx well, Store mis solution at a temperature above 14 °C to prevent crystallization.
6.2.2 Potassium tetrabotate solution 514 g/l.
Weigh 673 g ± 0,1 g of potassium tetraborate. K2B407 . 4H20, and dissolve It in 550 ml of water in a I litre beaker. Then weigh 247 g ± 0,1 g of potassium hydroxide, KOH (DANGER: ((C>)), and dissolve it in the teiraborate solution. Boil on a hotplate for 5 mm, cool and add 5 ml of a 10% aqueous solution of nonylphenoxypoly (6-10) ethylene oxide, NPPO, or similar wetting agent2l. Transfer the mixture to a 1 litre volumetric flask, rinsing the beaker into the flask several times. When cool, dilute to volume and mix well. Note that the welling agent will separate out on standing: ttierefoe. the flask must be shaken vigorously before each use.
6.2.3 Boric acid absorbent solution
Add about 800 ml of water to a I litre volumetric flask. Stir, using a magnetic stirrer, and add 2 mg to 3 mg of xylene cyanole FF, weighed to the nearest 1 mg. followed by 0,5 ml of NPPO. followed by 5,0 ml of methyl red indicator solution prepared by dissolving 0.125 g of methyl red In 250 ml of methanol (DANGER: (F> (S)). Add 69±0,1 g of bonc acid, H3B03, keeping the contents of the flask stirred until all the constituents are dissolved. Dilute to within aboul 15 ml of the mark and mix. Place 1.5 ml of this solution In the centre of a microdiflusion cell and observe the colour.
If the colour in the cell is nk, add Just sufficient 0,1 mol,1 sodium hydroxide (6.2.9) to the solution in the 1 litre flask to obtain a neutral colour when I ml is viewed in the microdiffusion cell.
Check that excess sodium hydroxide is absent by adding 0,10 ml of 0,002 50 mcI/I sulfuric acid (6.2.7) to 1 ml of the solution, at which point a pink colour should be produced. Note mat the solution in the 1 litre flask will appear red, even when the 1 ml in the microdiffusion cell looks neutral.
6.2.4 SulfurIc acid solution. tfH2SO4) 3 mol (DANGER: (C)).
Carefully add 170 ml of sulluric acid (((C))), p • 1,84 g?ml, to 500 ml of water in a 1 litre volumetric flask while
mixing and coding. Dilute to the mark with water.
6.2.5 SuLfuric acid solution. c(H2S04) 0,5 moth.
Carelully add 28,3 ml of sulfuric acid (((C))), p 1,84 g/ml, to 500 ml of water in a 1 litre volumetric flask while mixing and coding. Dilute to the mark with water.
When digestion is complete，allow the residue to cool and then quantitatively transfer the contents to a 25mlvolumetric flask (7.6). Dilute to the mark with water and insert the glass stopper.Mix well by inverting.
9.2Cleaning microdiffusion cells and covers
Soak the cells and covers in cleaning solution A(6.2.10.1) for 1 h; remove and soak in cleaning solution B(6.2.10.2) for 1 h; then remove and soak in cleaning solution C(6.2.10.3) for 1 h.
Remove the cells and covers, shake them as dry as possible and invert them to dry on a clean towel. Do not touchthe insides of the clean cells and covers.
lf the cleaned cells and covers have not been washed on the day that they are to be used, rinse them with waterand place them on a clean towel to dry before using.
9.3 Liberation of ammonia from samples
Using a syringe (7.11), add 1,50 ml of the boric acid absorbent solution (6.2.3) to the centre of the microdiffusioncell (7.7). Using the 1,00 ml syringe pipette (7.9), add 1,00 ml of the potassium tetraborate solution(6.2.2) to theouter sealing chamber and 1,00 ml to the sample chamber, i.e. the second chamber from the outside.
The tetraborate solution should be vigorously shaken before sampling in order to distribute the NPPo.Great careshall be taken not to splash any tetraborate solution into the centre chamber. Iif this occurs, a green coloration willbe produced and the sample shall be discarded. The tetraborate solution should be deposited on only one part ofthe sample chamber. Leave enough space for the sample to be added without mixing until the cell is sealed.