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ISO 17198:2014 pdf free

ISO 17198:2014 pdf free.Dimethyl ether (DME) for fuels一Determination of total sulfur, ultraviolet fluorescence method
Use either the solvent specified in 4.3.1 or 4.3.2 or a solvent similar to that occurring in the sample under analysis. Correction for sulfur contribution from solvents used in standard preparation and sample dilution is required. Alternatively, use of a solvent with non-detectable sulfur contamination relative to the unknown sample makes the blank correction unnecessary.
Sulfur compounds, compounds with a minimum purity of 99 mass %. Examples are given in 4.4.1 to 4.4.4. Where the purity of these compounds is less than 99 mass %, the concentrations and nature of all impurities are to be established. Certified reference materials from accredited suppliers are suitable alternatives to the compounds listed in 4.4.1 to 4.4.4.
Prepare a stock solution of sulfur content approximately 1 000 mg/l by accurately weighing the appropriate quantity of sulfur compound (4.4) in a volumetric flask (5.9). Ensure complete dissolution with solvent (4.3). Calculate the exact sulfur concentration of the stock solution to the nearest 1 mg/l.This stock solution is used for the preparation of calibration standards. As an alternative procedure, a sulfur stock solution of approximately 1 000 mg/ kg can be prepared by accurately weighing the appropriate quantity of sulfur compound (4.4). Take precautions to ensure that evaporation of the solvent and/or sulfur compounds is not causing weighing errors.
Prepare the calibration standards by dilution of the stock solution (4.5) with the selected solvent (4.3).
Calculate the exact sulfur content of each calibration standard.
Calibration standards with a known sulfur concentration, in mg/l or mg/kg, can be obtained with a volume/volume (or mass/ mass) dilution of the stock solution at 1 000 mg/l or mg/ kg. Other practices are possible but those mentioned above avoid any density correction.
New calibration standards should be prepared on a regular basis depending upon the frequency of use and age. When stored at low temperature, typically in a refrigerator, the calibration standards, with a sulfur content above 30 mg/kg or mg/l have at least a one month use of life. Below this sulfur content (30 mg/kg), the shelf life should be reduced.
These are stable samples representative of the materials being analysed, that have a sulfur content that is known by this test method over a substantial period of time. Alternatively, there are standard materials with a certified value commercially available. Ensure before use that the material is within its shelf life.ISO 17198 pdf download.

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