Analysis of Potassium Humate
a./ Application range
This standard is used for the Humic acid analysis in Potassium Humate that is made from lignite and weathering coal, etc.
b./ Quality Demand
The quality must meet up with the following standards:
Analysis items Standards
A B
Humic acid(dry basis) 80%min 65%min
Moisture 15%max 15%max
Potassium Oxide 7.5%min 10-12%
Ph value of 1% solution 9-10 9-10
c./ Analysis method (Gravimetric method)
.analyze contents of total Humic acid
1. test facilities and instruments
a./ tropical drying box with temperature controlled at 110±5℃.
b./ centrifuge with rotate speed at least 2000r/min and its volume above 150ml.
c./ tropical water bath
d./ muffle roaster
e./ filter paper.
f./ weighing bottle with ground-glass stopper; diameter 500mm, height 30mm.
2. Reagents and solutions
a./ Sodium Pyrophosphate（HGB-1288）chemically pure
b./ Sodium Hydrate(GB629-81) chemically pure
c./ Alkaline extraction solvent of Sodium Pyrophosphate
Weigh 15g Sodium Pyrophosphate and 7g Sodium Hydrate and then dissolve them into l liter distilled water and keep at airproof place.
3. Process of analysis
a./ dissolve
weigh 0.2g sample(precision 0.0002g) and put into 250ml conical flask, then add 100.00ml Alkaline extraction solvent of Sodium Pyrophosphate，shake it to make sure the sample is wet. Insert glass-filler an put them into boiling water bath, heat and extract for 2hours and shake it in every 30miuntes during this time.
b./ Centrifugation
take out the flask, cool to room temperature(about 20℃), then put whole extraction liquid and residue into centrifugal glass and centrifugalize it for 30minutes at the speed of 2000r/min. .
c./ filtration
put in advance the filter paper and weighing bottle into 105-110℃ drying box and make them constant weight. Pour away the topper clear liquid by inclining the glass, then transfer the whole residue onto constant-weight filter paper, syringe it till the ph value becomes neutral.
d./ drying
put residue together with filter paper into constant-weight weighing bottle and put them into drying box for 2hours under 105-110℃. Take out, covering and cooling for 3minutes; put again into drying box and cool it to around 20℃(about 20minutes) and weigh it; Make inspective drying and weigh in every 30minutes. Stop doing so till the difference of close analysis weight is within 0.001g, weigh the residue(G1).
e./ignition
Move dried residue and filter paper into crucible and then put into muffle roaster with an aperture of 15-20mm, heat from 20℃ to 250-300℃ to slowly ash this product; close the furnace door, ignite it under 815+/-20℃ for 1 hour; take out in the air for 5 minutes and then put into drying box and cool it to about 20℃(around 20minutes), weigh the ash in the residue(G2).
4. Results calculation
The total content of Humic Acid(HA) is expressed by weight percentage(%) and calculated by following formula:
HA’t. ad = (G-G1+G2) ÷ G x 100 – (Mad+Aad)
Remark : G—the sample weight, g
G1 — Weight of residue, g
G2 — Ash weight, g
Mad — moisture in sample, %
Aad — Ash in sample, %
5. Allowable deviation
HA’t, % Same lab Different lab
ad % d%
<50 1.0 2.0
≥50 2.0 3.0
6. Attention matters
a./ be careful during transferring the extraction residue and first syringe to avoid filter paper-perforation.
b./ to keep the same water volume and syringe times during filtration.
c./ the temperature must be lower 200 while the residue start to become partly into ash, so that the filter paper keeps away from fired.
Dear Friend
ReplyDeleteThank you