22 Analytical Instrumentation - Focus on Sulphur Analysis
Fast and Accurate Simultaneous Determination of Sulphur and Chlorine Using Modern Energy Dispersive X-Ray Fluorescence (EDXRF)
Suzanne Moller, Olympus Innov-X, Rudy Haas, HORIBA Scientific, Alain Salaville HORIBA Scientific 16 rue du Canal, 91160 Longjumeau, France Email:
info-sci.fr@
horiba.com • Web:
www.horiba.com/scientific
Featuring simple operation and world-class EDXRF analytical performance, the HORIBA MESA- 6000 delivers the rapid, precise and reliable Sulphur and Chlorine measurement capability needed for today’s demanding petroleum based process control and product quality assurance applications. Tese applications range from the need to characterise crude oil and controlling contaminations in the refining process to ensuring regulatory compliance of finished products. Consequently, the determination of sulphur and chlorine content in a wide variety of petroleum based matrices is essential. Te following is an introductory overview of the HORIBA MESA-6000, with data that demonstrates the power and flexibility made possible by this unique polarised mono-chromatic X-ray beam technology.
Background
Energy Dispersive X-Ray Fluorescence (EDXRF) is a well established technique and is widely utilised due to its ease of operation. However, standard direct radiation EDXRF is not able to achieve ultra low sensitivity requirements without susceptibity to matrix effects.
To meet new tough requirements for low sulphur measurement in automotive fuels and other
petroleum products, the MESA-6000 was developed. Instrumentation
The MESA-6000 is a compact (33W x 52D x 41H cm) and lightweight (22kg) analyser that can readily measure sulphur and chlorine content in petroleum products to part per million levels, in just 180 seconds. The optical path is under vacuum – no helium or other inert gas purges are required.
The instrumentation requires only a stable power source (100/250 VAC); with no other utilities required for this non-destructive and non-combustion technique.
The apparatus features a large and responsive
touch screen display that is easy to use and sample analysis can be initiated with a minimum of user inputs.
Sample preparation and handling are simplified with the use of Mylar®
film sealed disposable plastic
cups, allowing instrument use by non laboratory trained technicians.
MESA-6000 A powerful on-board computer allows a full line-up of data handling, printing, and
processing features that are needed for data transfer and compliance with good laboratory practice requirements.
For safe operation the instrument has an automatic control that de-powers the X-Ray tube anytime that the sample compartment is opened. Optimum X-Ray tube operating status is also ensured by an integrated, self-testing scheme that is initiated each time the instrument is started.
Of particular interest, MESA 6000 users can also simultaneously measure chlorine and sulphur
content from weight percent down to part per million levels. The NEW Technology
The MESA-6000 is based on the latest advances in Energy Dispersive X-ray Fluorescence (EDXRF) technology. It utilises a proprietary X-ray optical technology that produces a Polarised, Mono- chromatic X-ray energy beam. This approach is critical to achieve an ultra low noise background needed for the best limits of detection for both sulphur and chlorine. Also incorporated are; excellent performance at high concentration (multiple wt.% levels), simultaneous multi-element analysis and applicability over a wide range of sample types.
Interferences produced by matrix differences or other elements are also minimised. The MESA- 6000 performance is well established, as it is compliant with ASTM and ISO International Sulphur Determination Norms:
Figure 1: MESA-6000 principle, polarised Mono-chromatic EDXRF Calibration and Linearity
Figure 2a depicts the typical near perfect calibration linearity exhibited by the MESA-6000. The sulphur in mineral oil range of concentration standards used is - 0, 50, 100, 250, 500, 750 and 1000 mg/kg sulphur.
• ASTM D7220 • IP 532
• EN ISO 20847 Principle
• ASTM D4294 • EN ISO 8754
• PrEN ISO 13032
The MESA-6000 features a unique, patented design with a close-coupled, doubly curved HOPG X-ray optic. It simultaneously polarises, focuses, and mono-chromates the X-ray beam.
This yields the ideal X-ray source for measuring chlorine, sulphur and lower atomic number elements at low concentrations. This technique creates an environment with ultra-low background similar to other optics-based X-ray analysers, but retains the EDXRF benefit of allowing for simultaneous analysis of multiple elements.
February / March 2011 •
www.petro-online.com
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