ISO 9289:1991 pdf download – Oilseed residues – – Determination of free residuall hexane.
8 Apparatus
Usual laboratory apparatus and, In particular, the
1.1 Ga, chromatograpb. with flame ionization deteclor and an integrator andlor recorder, equipped with either
a) a packed steel column approximately 2 m long and of internal diameter approximately 3.2 mm, packed wilh an acid-washed diatomaceous earth support of parlicle size 150 tim to 180 pm (Chromosorb P NAW 60180 mesh’ as suitable), and coated with 10 % squalane or methylpolysiloxane (SE 30” is suitable), or
b) a capillary column, approximately 30 m long and of 0,3 mm internal diameter, coated with methylpolysiloxarie (SE 30h1 Is suitable) havIng a film thickness 01 0,2 pm
The Injeclor and detector temperature shall be set at approximately 120 C and the oven temperature at approximately 40 °C. The carrier gas preestire shall be set at approximately 0.3 bar (30 kPa)
If a capillary column Is used, the apparatus shall have a 11100 split inlection system
NOTE 3 For analyse. In .eii.., It I. recommønd.d Ia use a gas chromalograph having an automatic .am. n,ction system, combined with a healing bath
8.2 HeatIng bath fitted with a rack to hold the flasks
(64). capable 01 being set at 80 C + 2 C and 04 maintaining the set temperature constant to ±01 “C
NOTE 4 For continuous use, glycerol I. recommended a. th, heating llqud
13 Gas syriegs. oF I ml capacity
6.4 S.plum flasks, oF 20 ml f 2 % capacity
1.5 S.pta inert to hexane. ol approxImately 3 mm thickness, made of a matenal such as nitrile rubber (e a Perbunan’1), or bulyl rubber with a polytetrafluoroethylene or polychioropreno seam (eg Neoprene”)
Ensure that the septa used wltl produce a hermetic seal after crimping NOTE 5 The sepia oflen hav, a very high mechanical ressIance, if It Is thought, therefore, that the needle of the gas syrbnqe may be daged by using It to perforate septa. perforate them with a pin bela,. taking the sample fr the head.,pare Reu. 01 sepIa is not recommended
LI Metallic lOll caps br example made of aluminium
6.7 CrimpIng pliers, for Closing the septum flasks. LI Liquid syringes, ot 10 il capacity.
7 SamplIng and sample storage
Sampling shall have been carried out In accordance with ISO 5500 It ii essential that loss of hexane from the sample be prevented
The laboralonj sample shall Oil a hermetically sealed container (preferably a crimped metal box) and shall be stored at 4 °C. Plastic containers shall nol be used
The determInation 01 residual hexane shall be carried out as soon as the container has been opened
8 Procedure
8.1 CalIbration
8.1.1 Weigh, to the nearest 0,1 g, S g of the calibration oilseed residues (55) into each of five septum flasks (6 4) Seal each flask with a septum (6 5). cover with a foil cap (66) and crimp using the pliers (6.7)
8.1.2 Add, using a syringe (6 I), the volume of solvent (5.1) specified in table Ito four of the five flasks Do not add solvent 10 the fifth flask.