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Sulfur standards helping to improve the quality of your analysis

 

By Dr Hongyuan John Zhao, Product Manager, LGC
03 August 2017

Sulfur is probably the most common and most well-known petroleum contaminant. A concentration of 0.5% sulfur will make crude oil “sour” which will then require longer refining process and result in more expensive final products. Sulfur can also easily become a secondary air pollutant in the form of acid rain. High content of sulfur from emissions of industrial activities and internal combustion engines could lead to human health problems, such as asthma, chronic fatigue syndrome [US EPA and Agency for Toxic Substances & Disease Registry (ATSDR)]. UK, EU, US, China and many other countries are moving to lower sulfur content diesel and petrol.

Table 1 Example of diesel sulfur limits worldwide and the trend for ULSD (data as in Feb 2016, courtesy of dieselforum.org)

Sulfur calibration points

Therefore it is important to have the right reference materials for your analysis!

Our Sulphur standards can help you to improve the reliability of your analysis results. We provide Sulfur in petroleum matrix standards for refinery laboratory analyses, QC processes and Ultra-low-sulfur diesel (ULSD) analysis. VHG standards are manufactured in ISO 9001 and ISO Guide 34 facility. These standards are suitable for ASTM D2622, D3120, D4045, D4294, D5453, D7039, D7212, D7220 and others.

Three commonly used sulfur content measurement techniques for petroleum products – refinery industry are:

  • UV Fluorescence ASTM D5453 - more widely used (ISO20729 for sulfur in natural gas)
  • EDXRF IP 336, EDXRF ISO 8754, EN20844, EN20846
  • Oxidative Microcoulometry ASTM D3120 – (requires high purity of inert gas argon/helium, HP oxygen, glacial acetic acid etc.)

Example of how LGC sulfur reference material is used.

  1. UV Fluorescence ASTM D5453
  2. A hydrocarbon sample is either directly injected or placed in a sample boat.
  3. The sample or boat is inserted into a high temperature combustion tube
  4.      R-S + O2 → CO2+ H2O + SO2 + MOx
  5. Water removed and sulfur dioxide absorbs the energy from the UV light and is converted to excited sulfur dioxide SO2*,
  6. The fluorescence emitted from the excited SO2* as it returns to a stable state
  7.      SO2* + hv’ → SO2 + hv’’
  8. Fluorescence emitted from excited SO2* is a measure of sulfur content
  9. It is important to calibrate the results using standards (including high and low values). Same for other two techniques


Sulfur calibration points 

  • Please note that all methods require a few points including blank and a high concentration one
  • 1 ng/uL = 0.001 mg/mL= 1ug/ml
  • Examples of typical sulfur calibration standards are shown below
Table 2 Typical sulfur calibration ranges and standards concentrations for ASTM D5453 – 12 (UV Fluorescence)

Sulfur calibration points

Table 3 Recommended calibration standards versus desired calibration range for ASTM D3120 – 08 (Oxidative Microcoulometry)

Sulfur calibration points

We offer the following VHG brand reference standards solutions:

  • Sulfur in light mineral oil
  • Sulfur in heavy mineral oil
  • Sulfur in petrol
  • Sulfur in diesel
  • Polysulfide oil standards

VHG Sulfur standards are recommended for initial curve calibration if you use ASTM D5453 or D3120 for reliable results.

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