ASTM D7621 Standard Test Method for Determination of Hydrogen Sulfide in Fuel Oils by Rapid Liquid Phase Extraction
6.1 General - The apparatus, as detailed in Annex A1, comprises an air pump, test vessel, heating jacket, filters, H2S specific detector, integral computer, automatic solenoid valves and gas flow detectors.
6.1.1 Procedure A requires the use of a vapor phase processor capable of cooling a specific filter cartridge (see 7.4) to -20 °C +/- 2 °C.
6.2 Analytical Balance, single pan or double pan balance capable of weighing to the nearest 0.001 g.
6.3 Syringe or Burette, able to dispense 20 mL for introduction of the diluent oil (see 7.1), accuracy +/- 1 %.
6.4 Refrigerator (optional), for storing the test sample (see 8.3). The refrigerator shall be of a type suitable for storing flammable, volatile materials.
6.5 Oven/Water Bath (optional), for warming the sample to 40 °C with an accuracy of +/- 2 °C (see 18.104.22.168). The oven shall be of a type suitable for use with volatile materials.
6.6 Pipette, 1 mL positive displacement pipette, for the introduction of the test specimen. The accuracy as stated by the manufacturer should be typically +/- 0.25 %.
6.7 Disposable Syringe, 5 mL or 10 mL, for the introduction of the test specimen. Typical accuracy +/- 1 %. This may be fitted with a needle or extra tube to allow sample to be taken from 3 cm below the surface, if appropriate.
7. Reagents and Materials
7.1 Diluent Oil, proprietary water white API Group 2 base oil with a typical viscosity of 100 mm2s(-1) at 40 °C.
7.2 Reference Materials:
7.2.1 Reference material, pressurized nitrogen, of at least 99.999 % (volume percent) purity, containing a certified level of H2S (23 µmol/mol (ppm v/v) to 27 µmol/mol (ppm v/v)) traceable to a national standard.
7.2.2 Verification solution containing a known concentration of liquid phase hydrogen sulfide.
7.3 Cleaning Materials, technical grade.
7.3.2 Petroleum Ether (60/80).
7.4 Filter Cartridge, see Fig. A1.5, individually packed in a sealed envelope, required for use in the vapor phase processor required for use in Procedure A only.