Analysing mercury in naphtha and gasoline at ppt level

In 2010 the direct method for determination of mercury in crude oil using Zeeman AAS received an accreditation at ASTM as method D7622:2010. Lumex Instruments offers its RA-915M Zeeman mercury atomic absorption spectrometer with a PYRO-915+ pyrolysis attachment for measurements in compliance with the D7622:2010 method.

But with the method having detection limit at ppb level, many customers worldwide demanded lower concentrations to be determined by direct analysis in a variety of petrochemical samples. So Lumex Instruments has developed an analysis method that allows determination of mercury concentrations down to 0.02 ppb. The method involves a preconcentration step where mercury is extracted from a 1-5 ml sample to a specific solid sorbent, and then analysed directly with the same setup of RA-915M analyzer with Pyro-915+ attachment. Total analysis time is 5-6 minutes per sample. The method is applicable to petrochemical samples like condensate, naphtha, gasoline, diesel etc.

The method has shown excellent reproducibility at such low mercury concentrations that illustrated by a series of measurements of Hg in naphtha below:

Examples of analysis

Powerful Rapid software that comes with RA-915M provides an easy and effective way to control the analysis process with a real-time visualisation of mercury release from the sample. Recently added option of computer-controlled temperature profiling of the atomization ensures that the optimal conditions of sample decomposition are used, and if necessary, applies temperature ramping to the atomiser. Monitoring of the non-selective absorption during the measurement process excludes analysis errors.

Lumex Instruments has prepared a dedicated kit for determination of low Hg concentrations containing the required laboratory accessories and consumables.

For further information, please contact us.