BS ISO 13276:2020 pdf download

BS ISO 13276:2020 pdf download.Tobacco and tobacco products — Determination of nicotine purity — Gravimetric method using tungstosilicic acid
1 Scope
This document specifies a method for the gravimetric determination of the purity of nicotine using tungstosilicic acid.
The method is applicable to pure nicotine or nicotine salts used to calibrate analytical methods for the determination of nicotine in the field of tobacco, tobacco products and smoke analysis.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
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4 Principle
Complex formation of nicotine or its salts with tungstosilicic acid to form insoluble nicotine silicotungstate. Determination of the precipitate mass by filtration using either a sintered glass crucible in combination with oven-drying or an ashless filter paper in combination with incineration.
5 Reagents
Use only reagents of recognized analytical reagent grade and distilled water or water of at least equivalent purity.
5.1 Tungstosilicic acid solution (CAS of tungstosilicic acid: 12027-43-9).
Dissolve 12 g of dodeca-tungstosilicic acid (H 4 [Si(W 3 O 10 )4] ⋅ xH 2 O) in 100 ml of water.
Avoid the use of the other forms of tungstosilicic acid such as 4H 2 O⋅SiO 2 10WO 3 ⋅3H 2 O or 4H 2 O⋅SiO 2 12WO 3 ⋅20H 2 O as they do not yield crystalline precipitates with nicotine. Tungstosilicic acid of the CAS 11130-20-4 and 12027-38-2 may be used for this method provided sufficiently crystalline precipitation occurs.
7 Procedure
7.1 Precipitation procedure
A suitable amount of replicates should be measured. Weigh, to the nearest 0,000 1 g, approximately 0,1 g of the nicotine alkaloid (or the equivalent amount of nicotine salt) (m) in each of, for example, five 250 ml beakers (6.2) equipped with glass stirring rods (6.4). Add 100 ml of water to each beaker. Add 2 ml of 20 % hydrochloric acid solution (5.2) to each beaker and stir. Do not remove the stirring rod. Add slowly 15 ml of the tungstosilicic acid solution (5.1) while stirring constantly during the addition. Cover each beaker with a watch glass (6.3), leaving the stirring rod in place, and allow to stand overnight. Before filtering, stir the precipitate to ensure that it settles quickly and is of a crystalline form. Check for complete precipitation with a few extra drops of the tungstosilicic acid solution.
7.2 Filtration procedure
7.2.1 General
Filtration can be performed by either of the procedures given in 7.2.2 or 7.2.3.
7.2.2 Glass filter filtration procedure
Dry each glass filter crucible (6.6.1) in the oven (6.6.4) at (120 ± 5) °C to constant mass (±1 mg). Store in the desiccator (6.5).