Quality control methods for

22. Reagents and solutions 
The reagents, test solutions and volumetric solutions mentioned in this 
publication are described below. Reagents are denoted by the abbreviation R, 
test solutions by the abbreviation TS, and volumetric solutions by the 
abbreviation VS. The concentration of the reagent solutions is expressed in g/l, 
that is, grams of anhydrous substance per litre of water or solvent, as indicated. 
Where no solvent is indicated, demineralized water should be used. The 
procedures for the preparation of test solutions that require special attention are 
given in detail. The designation d denotes the relative density
, i.e. measured 
in air at 20°C in relation to water at 20°C. Colour Index (C.I.) numbers are 
provided for stains. 
20
20
d
Acetic acid, glacial, R. C
2
H
4
O
2
; d ~1.048.
A suitable commercially available reagent. 
Acetic acid (~300 g/l) TS. A solution of glacial acetic acid R containing about 
300g of C
2
H
4
O
2 
per litre (approximately 5 mol/l); d ~ 1.037. 
Acetic acid (~60g/l) TS. Acetic acid (~300g/I) TS, diluted to contain about 60g of 
C
2
H
4
O
2 
per litre (approximately 1 mol/l); d ~ 1.008. 
Acetone R. C
3
H
6
O. 
A suitable commercially available reagent. 
Acetonitrile R. Methyl cyanide, C
2
H
3
N.
Description. A clear, colourless liquid.
Miscibility. Freely soluble with water. 
A suitable commercially available reagent. 
Aflatoxin mixture TS. 
Procedure. Prepare a mixed working standard in a mixture of 98 volumes of 
chloroform R and 2 volumes of acetonitrile R, containing 0.5 µg of each of
aflatoxins B
1 
and G
1
per ml, and 0.1 µg of each of aflatoxins B
2
and G
2
per ml. 
Note. Aflatoxins are highly toxic and should be handled with care. National
legal requirements should be followed. 
Suitable commercially available working standards.