Application Note EDXRF1272
Scope
This application note demonstrates the analysis of sulfur in ULSD (ultralow sulfur diesel) and the measurement of ultralow sulfur in gasoline using NEX QC+.
Background
Regulations around the world have limited the amount of sulfur in various fuels oils with particular attention to diesel fuel. For many years, road diesel has been limited to a maximum sulfur concentration between 10 – 15 ppm, depending on the global region. Now, these limits are expanded to all diesel fuel, including use in large engines and off-road diesel engines.
Diesel
Calibration
Empirical calibration was built using a suite of six certified diesel calibration standards.
| Element: S Units: ppm |
||
| Sample ID | Standard value | Calculated value |
| STD 1 | 5.0 | 4.7 |
| STD 2 | 10.0 | 10.1 |
| STD 3 | 15.0 | 15.5 |
| STD 5 | 25.0 | 24.7 |
| STD 6 | 50.0 | 50.0 |
Precision
Instrument repeatability (precision) is determined by ten repeat analyses of a sample in static position.
| Element: S Units: ppm |
||||
| Sample | Standard value | Average value | Std. dev | % Relative |
| STD 2 | 10.0 | 10.2 | 0.48 | 4.8 |
| STD 6 | 50.0 | 50.9 | 0.50 | 1.0 |
Gasoline
Calibration
Empirical calibration was built using a suite of seven certified isooctane calibration standards to simulate gasoline.
| Element: S Units: ppm |
||
| Sample ID | Standard value | Calculated value |
| STD 1 | 5.0 | 5.1 |
| STD 2 | 10.0 | 10.4 |
| STD 3 | 15.0 | 14.5 |
| STD 4 | 20.0 | 19.8 |
| STD 5 | 25.0 | 25.1 |
| STD 6 | 50.0 | 50.1 |
Precision
Instrument repeatability (precision) is determined by ten repeat analyses of a sample in static position.
| Element: S Units: ppm |
||||
| Sample | Standard value | Average value | Std. dev | % Relative |
| STD 2 | 10.0 | 9.71 | 0.20 | 2.0% |
| STD 5 | 50.0 | 50.2 | 0.47 | 0.9% |
International standard test methods
The Rigaku NEX QC+ complies with ISO 13032 for the measurement of ultra- low sulfur between 8 – 50 mg/kg in diesel fuels and gasoline. NEX QC+ also
complies with the following ASTM and international standard test methods for the measurement of sulfur up to 5% in various petroleum oils and fuels.
| ASTM D4294 | ISO 20847 | ISO 8754 | IP 496 | IP 336 | JIS K 2541-4 |
| 16 ppm - 5% | 30 - 500 mg/kg | 100 mg/kg - 5% | 100 mg/kg - 5% | 100 mg/kg - 5% | 0.01 - 5% |
Conclusion
The results shown here indicate the Rigaku NEX QC+ EDXRF analyzer gives excellent performance for the measurement of ULSD and ultralow sulfur gasoline in accordance with ISO 13032. The versatility of the NEX QC+ also makes it an ideal tool for the measurement of many other elements and oil matrices throughout the petroleum industry.
