BS ISO 13276-2020 Tobacco and tobacco products – Determination of nicotine purity – Gravimetric method using tungstosilicic acid

BS ISO 13276-2020 Tobacco and tobacco products – Determination of nicotine purity – Gravimetric method using tungstosilicic acid.
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 gui the nicotine alkaloid (or the equivalent amosrnt of nicotine salt) (iii) in each of. for example, five
250 nil beakers (6.2) equipped with glass stirring rods (6..4).
Add 100 ml of water to each beaker. AcId 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 tungstosllaclc acid solution (5.1) while stirring constantly dunng the addition. Cover each beaker with a watch glass (6.1). leaving the stirring rod in place, and allow to stand overnight. Before lilirring. stir the precipitate to ensure that it settles quickly and is ala 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 722 or 7.21
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 rng). Store In the desiccator (6.5).
Weigh. to the nearest 0,000 I g, each glass crucIble (6.6.1) (m1) and filter the preCipitate directly into the glass filter using the Huchner flask (6.6.2) and vacuum source (6.6.3). Ensure that the precipitate is removed from the sides of the beaker and the glass stirring rod by washing into the filter with hydrochloric acid solution (5.3) approximately three times usIng 15 ml each. Discard the washings
Rinse with a further aliquot portion oihydrodsloric acid solutIon (5.3) (up Lu 400 ml may be required) wluch should be inilected and tested with .i few drops of nicotine solution (5.4) to ensure that no opalescence occurs. i.e. all tungstosilicic acid has been removed
Dry each glass crucible and precipitate in the oven (6.6.4) for 3 haL (120 t 5) C. Allow to cool In the desiccator and weigh to the nearest 0,000 1 g (mi). Place the filters back in the oven for 1 h. allow to cool md reweigh. Repeat, If necessary, until a constant mass (al mg) Is olitalned.
72.3 Filter paper filtration procedure
Filter the precipitate directly onto an ashless filter paper (61.1). Ensure that the precipitate Is removed from the sides of the beaker and the stirring rod by washing Into the filter with hydrochloric acid solution (5,3) approximately three times using 15 ml cads, Discard the washings
Rinse with a further aliqool portion of hydrochloric acid solutIon (5.3) (up to 400 ml may be required) which should be collected and tested with a few drops of nicotine solution (5.4) to ensure that no opalescence occu,’s, i.e. all tungstosilicic acid has been rensoved
Dry each crucible 1,622) on the Bunsen burner (6.7.3) or in the furnace (62.4) at 600 C until constant mass (ii mg). Store In the desiccator (6.5).BS ISO 13276 pdf download.