ISO 13759 Petroleum products - Determination of alkyl nitrate in diesel fuels - Spectrometric method
4 Reagents
For the analysis described in this International Standard, use only reagents of recognized analytical grade, and water complying with the requirements of Grade 3 of ISO 3696.
4.1 Acetic acid (CH3COOH), glacial.
4.2 Alkyd nitrate standard solution.
Pipette 3.0 ml of alkyl nitrate of composition identical to that to be analysed into a 100 ml flask (5.5) and dilute to the mark with diesel fuel (4.6).
In the absence of knowledge of the specific alkyl nitrate to be analysed, use 2-ethylhexyl nitrate of minimum purity 97 % to construct the calibration curve.
4.3 Sulfuric acid solution.
Add slowly with stirring, 500 ml of concentrated sulfuric acid, 98 % (m/m) (mass fraction 98 %) minimum purity, to 270 ml of cold water.
4.4 Sodium hydroxide solution.
Dissolve 50 g of sodium hydroxide pellets in water, and dilute to 1000 ml with water.
4.5 2,4-dimethylphenol (xylenol) solution.
Dilute 4 ml of 2,4-dimethylphenol [(CH3)2C6H3OH] with acetic acid (4.1) making up to the mark in a 100 ml flask (5.5).
4.6 Diesel fuel or component, clean, stable, containing no additives (blank fuel).
NOTE - Where practicable, the composition of the blank fuel should be similar to that of the sample under test.
4.7 2,2,4-trimethylpentane [CH3C(CH3)2CH2CH(CH3)CH3], 99.75 % minimum purity.
4.8 Propan-2-01 [CH3CH(CH3)OH].
5 Apparatus
5.1 Absorption cells, matched, having a 10.OO mm +/- 0.02 mm path length.
5.2 Spectrometer, capable of measuring absorption in the wavelength range of 452 nm +/- 5 nm.
5.3 Separating funnels, Squibb-type, glass-stoppered, with polytetrafluoroethylene stopcock, 125 ml capacity.
5.4 Shaking machine, automatic, capable of accommodating multiple samples, to shake at a minimum of 250 oscillations/min.
5.5 Volumetric flasks, 10 ml and 100 ml capacity, Class A in accordance with ISO 1042.
5.6 Pipettes, 1 ml and 10 ml capacity, Class A in accordance with ISO 835-1.
5.7 Burette, 10 ml capacity, Class A in accordance with ISO 385-1.
5.8 Graduated cylinders, of 50 ml or 100 ml capacity.
