BS EN ISO 3924:2016 pdf download
BS EN ISO 3924:2016 pdf download.Petroleum products一Determination of boilingrange distribution一Gaschromatography method (ISO3924:2016).
4 Principle
A sample is introduced into a gas chromatographic column which separates hydrocarbons in the order of Increasing boiling point. The column temperature Is raised at a reproducible rate and the area under the chromatograrn is recorded throughout the analysis. Boiling temperatures are assigned to the time axis from a calibration curve, obtained under the same conditions by running a known mixture of hydrocarbons covering the boiling range expected In the sample. From these data, the boiling range distribution is obtained.
Annex A presents a correlation model for the calculation of physical distillation (see References Iii. 151 and (6j) equivalent data from boiling range distribution analysis by gas chromatography determined following this International Standard.
Annex B describes an alternative, accelerated analysis (see &2).
5 Reagents and materials
5.1 StatIonary phase for columns, nonpolar. that elutes hydrocarbons In boiling point order.
NOTE The following materials have been used successfully as liquid phases.
For packed columns:
— silicone gum rubber LJC-W98;
— silicone gum rubber GE-SE-30;
— silicone gum rubber OV-1
— silicone gum rubber OV-101;
For capillary columns:
— polydimethylsiloxane.
52 Solid support for packed columns, usually consisting of crushed fire brick or chromatographic diatomaceous earth.
The particle size and support loading shall be such as to give optimum resolution and analysis time. NOTE In general, support loadings of 3% to 10% have been lound most satisfactory.
5.3 CarrIer gas, with a minimum purity of 99.995%, constituted of
a) helium or hydrogen for use with thermal conductivity detectors, or
b) nitrogen, helium, hydrogen or argon for use with flame Ionization detectors.
5.4 Hydrogen. grade suitable for flame ionization detectors.
5.5 Compressed air, free of oil and water regulated for flame ionization detectors.
If stationary phases other than those listed In the note in £1 are used, the retention times of a few alkylbenzenes across the boiling range such as o-xylene. n-butylbenzene. 1,3.5-tri-isopropylbenzene, n-decylbenzene and n-tetradecylbenzene shall also be checked to make certain that the column Is separating according to the boiling point order (see Annex C).
5.7 Reference material, the primary reference material used shall be the ASTM Reference Gas Oil No.1.
5.8 Carbon disulfide, reagent grade (CAS RN 75-15.0).
6 Apparatus
6.1 Chromatograph, any gas chromatograph that has the following performance characteristics may be used.
6.1.1 Detector, of either the flame ionization or thermal conductivity type.
The detector shall have sufficient sensitivity to detect a mass fraction of 1.0 % of dodecane with a peak height of at least 10% of full scale on the recorder under the conditions specified in this International Standard, and without loss of resolution as defined In 82. When operating at this sensitivity level. detector stability shall be such that a baseline drift of not more than 1 % of full scale per hour is obtained, The detector shall be capable of operating continuously at a temperature equivalent to the maximum column temperature employed. The detector shall be connected to the column in such a way that any cold spots between the detector and the column are avoided.
NOTE It Is not desirable to operate thermal conductivity detectors at a temperature higher than the maximum column temperature employed Operation at higher temperatures only serves to shorten the useful life of the detector, and generally contributes to higher noise levels and greater drift.
6.12 Column temperature programmer, capable of programmed temperature operation over a range sufficient to establish a retention time of at least 1 mm for the Initial boiling point and to clute the entire sample within the temperature ramp.
The programming rate shall be sulficiently reproducible to obtain retention time repeatability of bs for each component in the calibration mixture (5.6).
If the initial boiling point is less than approximately 93 °C,an initial column temperature below ambient can be required. However, excessively low Initial column temperatures shall be avoided, to ensure that the stationary phase remains liquid. The initial temperature of the column shall be only low enough to obtain a calibration curve meeting the requirements of this International Standard.
6.1.3 Sample Inlet system, either be capable of operating continuously at a temperature equivalent to the maximum column temperature employed or provide on-column injection with some means of programming the entire column, including the point of sample introduction, up to the maximum temperature required.
The sample inlet system shall be connected to the chromatographic column in such a way that any cold spots between the Inlet system and the column are avoided.
6.2 Column, any column and conditions maybe used, provided that, under the conditions of the test.
separations are in the order of boiling points as given in TableJ.. and the column resolution. CR, is at least
3 (83). Typical column operating conditions are given in Table 2 and 3.
