ASTM D4046 Test Method for Alkyl Nitrate in Diesel Fuels by Spectrophotometry
6. Apparatus
6.1 Absorption Cells, matched, having a 1.000 +/- 0.002-cm path length.
6.2 Separatory Funnel, Squibb-type glass stoppered with TFE-fluorocarbon stopcock, 125-mL capacity.
6.3 Shaking Machine, automatic, capable of multiple samples and 250 oscillations/min.
6.4 Spectrophotometer, capable of measuring absorption in the region of 452 +/- 5 nm.
6.5 Volumetric Flask, 10- and 100-mL capacity.
6.6 Measuring Pipet, 1-mL, 3-mL, 4-mL, and 10-mL.
6.7 Buret, 10-mL capacity.
7. Reagents
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water conforming to Type II of Specification D1193.
7.3 Acetic Acid, reagent grade.
7.4 Alkyl Nitrate.
7.5 Alkyl Nitrate, Standard Solution - Pipet 3.0 mL of the alkyl nitrate to be determined into a 100-mL volumetric flask and dilute to volume with diesel fuel.
7.6 Diesel Fuel, additive-free.
NOTE 1 - Warning: Flammable.
7.7 Isooctane (2,2,4-trimethylpentane). Warning - See Note 1.
7.8 Isopropyl Alcohol, reagent grade. Warning - See Note 1.
7.9 m-Xylenol Solutions - Dilute 4 mL of m-xylenol (2,4-dimethylphenol) to 100 mL in acetic acid.
7.10 Sodium Hydroxide Solution - Dissolve 50 g of sodium hydroxide (NaOH) pellets in 1000 mL of distilled water.
7.11 Sulfuric Acid - Add slowly with stirring, 500 mL of nitrate-free sulfuric acid (H2SO4) (rel dens 1.84) to 269 mL of cold distilled water.
