Sulfur in Diesel Fuel by ICP-MS

Sulfur in Diesel Fuel Oil by Inductively Coupled Plasma – Mass Spectrometry (ICP-MS Testing)

Sulfur is regulated in diesel fuel since the sulfur concentration is directly linked to pollution.  When diesel fuel is combusted in an engine, the sulfur contributes to air pollution that poses risks to human health and environmental effects.

The EPA began regulating the sulfur concentration of diesel fuel in 1993.  Before enacting the regulation, diesel fuel contained as much as 5,000 parts per million (ppm) of sulfur.  In 2006, EPA phased-in regulations that reduce the sulfur concentration to 15 ppm. Fuel that meets this limit is referred to as ultra-low sulfur diesel (ULSD).

EPA’s diesel regulation requires:

  • After 2010, all highway diesel fuel must be ULSD and all highway diesel vehicles must use ULSD
  • After 2014, all nonroad, locomotive, and marine (NRLM) diesel fuel must be ULSD, and NRLM engines and equipment must use this fuel (with some exceptions)

Galbraith Laboratories provides sulfur testing of diesel fuel.  The details of the analysis are outlined below.


Each successful diesel analysis begins by digesting the diesel fuel in a closed vessel using microwave assisted digestion.  Concentrated acids and hydrogen peroxide are used to digest the fuel and convert the sulfur into a form that can be analyzed by the ICP-MS.  Typical sample masses are 300-400 mg.


Sample solutions are introduced into the instrument by way of a peristaltic pump.  The solution is nebulized into an aerosol that is transported to a plasma torch.  Sulfur in the sample solution is subjected to intense heat in a radio-frequency inductively coupled argon plasma.  The sulfur ions are transported from the plasma through a vacuum interface into a quadrupole where they are separated on the basis of their mass to charge ratio (m/z).  Sulfur ion concentrations of unknown samples are determined by comparison to an external calibration of the instrument.


Galbraith’s general method was written from nationally accepted methods, such as EPA SW846 6020.  Click below to view a copy of the method summary:

ME-30 Elements in Digestates by ICP MS


Results are reported in ppm, using the mass of fuel taken for the analysis.

Limit of Quantitation

The LOQ of our method is approximately 1-2 mg/Kg (ppm) in diesel fuel.

If you would like to receive more information on sulfur in diesel fuel, or any of our analytical services, please contact us.