ISO 9832 pdf download – Animal and vegetable fats and oils – Determination of residual technical hexane content

ISO 9832 pdf download – Animal and vegetable fats and oils – Determination of residual technical hexane content.
5.1 Technical hexane. with a composition similar to that & hexane used in industrial processing or. if this is not available, n-hexane.
It is recommended that technical hexane be used for the calibration. This reagent usually has an n-hexane content of 50 % (by mass) and consists mainly of C6 isomers but may include C5 and C7 hydrocarbons.
52 Internal standard, n-heptane.
If this is not available, cyclohexane may be used, provided that the solvent (5.1) used for the extraction or calibration has a negligible content of cyclohexane and/or nheptane or components with similar retention times.
5.3 CarrIer gas. e.g. hydrogen, nitrogen or helium, elc, thoroughly dried and with an oxygen content of less than 10 mg/kg
5.4 Auxiliary gases, hydrogen (99.9 % pure, free from organic impurities) and air (free from organic wnpurities).
5.5 Calibration fat, freshly refined end deodorized vegetable fat the technical hexane conlant of which is negligible.
This material should be free from peroxides or other components likely to decompose with the formation of volatile mater*al which could be confused with hydrocarbons during the test.
6 Apparatus
Usual laboratory equipment and, in particular, the following.
6.1 Septum vIals, of 20 ml capacity.
6.2 Septa, inert to fats and solvents, made of a matenal such as butyl rubber or red rubber free from hydrocarbon solvent residues and of a suitable quality that they will not swell under the conditions of use, alumInIum caps suitable for use with the vials (6.1) and crimpIng plIers.
6.3 Tongs, suitable for holding the vials (6.1).
6.4 Syringes, of 10 p1 capacity, used only for the analysis of residual technical hexane. They shall not be cleaned with hydrocarbon solvent
6.5 Syringes, of 1 p1 capacity, used only for the analysis of residual technical hexane. They shall not be cleaned with hydrocarbon solvent
6.6 Syringes, of 1 000 p1 capacity, gas-tight, used only for the analysis of residual technical hexane. They shall not be cleaned with hydrocarbon solvent,
6.7 Gas chromatograph. with a flame ionization detector and an integrator and/or recorder, equipped with either
a) a packed ass column, 2 m to 4 m long and of internal diameter 3,2 mm approximately, packed with an acid• washed and silanized diatornaceous earth support of particle size 150 pm to 180 pm (Chromosorb P NAW 60-SO mesh11 is suitable), and coated with 10% squalane or any other phase permitting the chromatographic separation required, or
b) a glass capillary column, approximately 30 m long and of 0,3 mm internal diameter, coated with methylpolysiloxane of film thickness 0,2 pm.
9.2 Determination
9.2.1 Weigh, to the nearest 0,01 g, a test portion of 5g of the test sample (clause 8) into a vial (6.1) as quickly as possible. Close immediately with a septum and a cap (6.2).
9.2.2 Inject 5 il of the internal standard (5.2) through the septum by means of a scinge (6.4). Mix the contents vigorously by hand for about 1 miii by moving the vial with a circular motion in a horizontal plane in such a way that the fat does not touch the septum. If this happens, reject the vial and start again with a further test portion. (See CAUTION in 9.1.2.) Place the vial up 10 Its neck ii the heating bath (6.8) set at 80 C for 60 miii ± 1 mm.
9.2.3 Then take 1 000 i from the gaseous phase by means of a sunge (6.6) warmed to 60 C. without removing the vial from the heating bath, Immediately Inject into the gas ctiromatograph the gaseous phase so removed.
9.2.4 DetermIne the residual technical hexane content of the sample from the cbrornatogram (see the example given In Figure 1), measuring those peaks identified as being from hexane and not from decomposition products.
9.3 Number of determinations
Carry out the determination on two test portions from the same test sample in rapid succession,
10 Expression of results
The residual technical hexane content of the sample, n. in miligrams per kilogram. is given by the formula.