X-ray Fluorescence Spectrometry: Ready for the Classroom

Charles Wu, Senior Research Scientist and X-ray fluorescence (XRF) Course Coordinator at the University of Western Ontario, discusses some of his experiences with XRF and his upcoming sessions at Pittcon 2011.

How did you get started using XRF?

Wu: X-ray fluorescence (XRF) spectrometry was one of the techniques I used in my Ph.D. dissertation to study the geochemical characteristics and origin of various granitic intrusive rocks in central Ontario, Canada, in the early 1980s. Although there was a Philip PW1450 wavelength dispersive spectrometer available with a few pages of operation instructions, no one in the department could run the instrument or knew how to obtain data. I learned everything from scratch, including X-ray fundamentals and instrumentation, to develop analytical methods and to write the computer codes for matrix correction and data reduction.

I still remember in those days the instrument intensities had to convert from a teletype ribbon into punched cards before feeding through a card reader of the mainframe computer to receive the results. The sample preparation, such as doing borate fusion manually with a blast burner one at a time, was another tedious and time consuming job. I could analyze only a few dozen samples a week.

What is the focus of your current research using the technique?

Wu: My research is continuously trying to improve the accuracy and precision of major and trace element analysis of various geological materials by wavelength dispersive X-ray fluorescence (WDXRF) spectrometry. In addition to that, I am currently doing research on methods for analyzing oil and plastics using a bench-top energy dispersive XRF spectrometer (EDXRF) instrument as well as in-situ soil contaminants analysis by portable XRF analyzers.

What is the most interesting advancement you seen in XRF technology?

Wu: The advances in computing technology have made the complicated calculation of matrix corrections easier. The "standardless" XRF analysis based on X-ray physics and individual instrument configuration became possible. Commercially available software offers users a tool for analyzing specimens of unknown matrices, uneven shape and size with a reasonable result.

You have organized the XRF course at the University of Western Ontario for the last 20 years. How has the course evolved over that period?

Wu: Due to the great demand from industry to have XRF operators receiving proper and better training, the annual short course in Modern X-ray Spectrometry at the University of Western Ontario was born in 1990 with the collaboration of Dr. Jams Willis, Dr. Andy Duncan, Dr. Fernand Claisse, and Mr. Gerry Lachance.

The short course is a tightly integrated two-week course on the fundamentals, instrumentation, qualitative analysis, sample preparation, quantitative analysis, and data reduction methods of XRF spectrometry.

The original curriculum of the course was adopted from a similar course taught by Dr. Willis and Dr. Duncan at the University of Cape Town, South Africa. Its original focus was the analysis of geological samples with WDXRF. With the increasing applications of EDXRF, the course contents expanded to include both WDXRF and EDXRF in 2000.

Ms. Maggi Loubser, Mr. Alexander Seyfarth, Dr. Mike Hinds, and Dr. Bruno Vrebos joined the short course in 2005 to replace the retired faculty members.

The XRF 2011short course will be held June 6–17 this year with a completely new curriculum. Built on the solid fundamentals in the first week, the classes in the second week provide more on how to develop methods for new applications with a practical approach.

With increasing popularity of using fundamental parameter (FP) method for matrix corrections and quantitative analysis, we have designed a unique way to "work" attendees through the process step-by-step.

There are also two special topics ofworkshops: (1) Sample Preparation Methods for XRF Analysis; and (2) Portable XRF Analyzer - Analysis and Interpretation of XRF Data from Non-uniform Objects.

You are scheduled to give two short courses while at Pittcon this year: "How About Teaching XRF?" and "Primer on XRF Spectroscopy: Instrumentation." Can you tell us a little about each of those short courses? What would attendees gain from attending them?

Wu:This is the third year that the “Primer on XRF Spectroscopy: Instrumentation” short course will be offered at Pittcon. As the title indicates, it is a brief introduction of the XRF technique from the function of each component of a WDXRF and an EDXRF spectrometer. I will teach the WDXRF part while Alexander Seyfarth will present the EDXRF portion. We expect the attendees to gain a basic understanding about the difference in beam path of these two types of XRF spectrometers.

“How about Teaching XRF?” — this question has been asked for quite a while. Because XRF is not a "fashion" technique like mass spectrometry, teaching of X-ray fundamentals and its application has been ignored or neglected in college/university chemistry courses.

With the improved hardware design, the portable XRF analyzer can now be a practical tool for teaching XRF fundamentals and some applications in the classroom. This short course at Pittcon will be living proof. Alexander Seyfarth will be the lead instructor.