1.0 SCOPE
This standard testing procedure is suitable for the determination of a general and uniform method for the determination of total ash, acid insoluble ash in Choorna/Kvatha Choorna.
2.0 PURPOSE
The purpose of the document is to establish a method for the determination of total ash, acid-insoluble ash in Choorna/Kvatha Choorna.
3.0 RESPONSIBILITY
The expert and trained chemist are responsible for following this procedure. The technical manager is responsible for implementing this procedure.
4.0 REQUIREMENTS
4.1 Apparatus
4.1.1 Dish - Silica or platinum dish/crucible
4.1.2 Muffle Furnace - maintained at 600oC
4.1.3 Ashless filter paper (Whatman41)
4.1.4 Hot Plate
4.1.5 Water bath
4.1.6 Hot air Oven
4.2 Glassware
4.2.1 Desiccator
4.3 Reagent
4.3.1 Hydrochloric Acid-5N
5.0 PROCEDURE FOR TOTAL ASH
5.1 Weigh about 2 to 3 g of the sample in general and 5g in case of herbs into the tared silica dish.
5.2 Heat the dish carefully over the hot plate for 30 minutes.
5.3 Then ignite in the muffle furnace at 600°C till the grey ash is obtained(3 to 4 hours).
5.4 Cool and wet the ash with several drops of water, evaporate carefully to dryness, and heat in the muffle furnace for a further 1 hour at 600°C.
5.5 If the wetting shows the ash to be carbon-free, remove the dish to desiccators containing fresh, efficient desiccant, allow it to cool to room temperature, and weigh without delay.
5.6 If the wetting shows the presence of carbon, repeat the wetting and heating until no specks of carbon are visible and ignite in the muffle furnace for 1 hour after the disappearance of carbon.
5.7 If carbon is still visible, leach the ash with hot water, filter through the ashless filter paper, wash the filter paper thoroughly, transfer the filter paper and contents to the ashing dish, dry, and ignite in the muffle furnace at 6000C until the ash is white. Cool the dish, add the filtrate and evaporate it to dryness in a water bath.
5.8 Heat in the muffle furnace again at 600°C, cool in the desiccators and weigh as previously.
5.9 Repeat these operations until the difference in mass between two successive weighings is less than 0.002 g. Record the lowest mass. Retain the total ash for determining the acid-insoluble ash.
5.10 Calculation
Total ash (on a dry basis), % by mass = {(M2-M)/ M1-M} × 100
Where,
M = Weight of Empty dish, in g
M1 =Dish+ sample (before
ashing) in g
M2 = Dish+ sample (after
ashing) in g
6.0
PROCEDURE FOR ACID INSOLUBLE ASH
6.1
Refer to the total ash procedure till ashing.
6.2
To the ash contained in the porcelain and
silica dish after total ash determination.
6.3
The dish was preserved containing the ash from
the determination of total ash.
6.4
Add 25 ml of dilute hydrochloric acid(5N).
Cover with a watch glass.
6.5
Heat on a water bath for 10 minutes.
6.6
Allow to cool and filter the contents of the
dish through a Whatman filter paper No. 42 or its equivalent.
6.7
Wash the filter paper with hot water until
the washings are free from acid.
6.8
After the filter paper is free from the acid, return
the filter paper to the dish.
6.9
Dry on the hot plate and then Keep it in an oven
at 100 ± 2°C for 3 hours.
6.10 Ignite in
a muffle furnace at 600°C for one hour.
6.11 Cool the
dish in desiccators and weigh it.
6.12 Repeat
this process for heating for 30 minutes, cooling, and weighing until the
difference between two successive weighings is less than one
milligram. Record the lowest mass.
6.13
Calculation
Acid insoluble ash, %
by mass = (M3
– M ) x100
M1-M
Where,
M
= Weigh of the empty dish, in g
M1 =Weigh of dish+ sample (before ashing) in
g
M3 = Weigh of the dish with acid insoluble ash,
in g
7.0 ATTACHMENTS
Appendix-1: Flow chart for total ash.
Appendix 2: Flow chart for acid insoluble ash.
8.0 REFERENCES
8.1 TOTAL ASH
A.P.I. Part I, Vol-VIII; First Edition-2011
8.2 ACID INSOLUBLE ASH
A.P.I. Part I, Vol-VIII; First Edition-2011.
END OF THE DOCUMENT
You may like to read these links:
1. List of All SOPs and Documents for the Chemistry Laboratory
2. List of All SOPs and Documents for Quality Control
3. List of All SOPs and Documents For Quality Assurance Dept.
4. List of SOPs and Documents Required to Achieve NABL Accreditation
5. List of All SOPs and Documents for Laboratory Instruments and Equipment
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