Abstract

The Rigaku ZSX Mini II XRF Services X-ray fluorescence (XRF) analyzer was demonstrated under EPA’s Superfund Innovative Technology Evaluation Program. The field portion of the demonstration was conducted in January 2005 at the Kennedy Athletic, Recreational, and Social Park at the Kennedy Space Center on Merritt Island, Florida. The demonstration was designed to collect reliable performance and cost data for the ZSX Mini II analyzer and seven other commercially available XRF instruments for measuring trace elements in soil and sediment. The performance and cost data were evaluated to document the relative performance of each XRF instrument.

This innovative technology verification report describes the objectives and the results of the evaluation and serves to verify the performance and cost of the ZSX Mini II analyzer. Separate reports have been prepared for the other XRF instruments that were evaluated as part of the demonstration. The objectives of the evaluation included determining each XRF instrument’s accuracy, precision, sample throughput, and tendency for matrix effects. To fulfill these objectives, the field demonstration incorporated the analysis of 326 prepared samples of soil and sediment that contained 13 target elements.

The prepared samples included blends of environmental samples from nine different collection sites, and spiked samples with certified element concentrations. Accuracy was assessed by comparing the XRF instrument’s results with data generated by a fixed laboratory (the reference laboratory). The reference laboratory performed element analysis, using:

• Acid digestion and inductively coupled plasma-atomic emission spectrometry in accordance with EPA Method 3050B/6010B
• Cold vapor atomic absorption spectroscopy for mercury only, in accordance with EPA Method 7471A

The ZSX Mini II is a wavelength-dispersive XRF analyzer that can analyze for elements ranging in mass from fluorine to uranium. The ZSX Mini II differentiates the X-ray energies emitted from a sample by dispersing the X-rays into different wavelength ranges using crystals. By contrast, more common energy-dispersive XRF analyzers differentiate between X-ray energies based on voltages measured by the detector. For some applications, wavelength-dispersive XRF analyzers can achieve high resolutions and very good sensitivity through the reduction of interelement interferences.

Historically, wavelength-dispersive XRFs have been large, laboratory-bound instruments with significant requirements for power and cooling. The ZSX Mini II is a smaller, transportable unit that can operate on standard 110-volt circuits and without additional cooling fluids. The unit can employ an economical gas proportional counter as a detector rather than a diode detector with a multi-channel analyzer (common in energy-dispersive instruments) because wavelength resolution is achieved with the crystals.

This report describes the results of the evaluation of the ZSX Mini II analyzer based on the data obtained during the demonstration. The method detection limits, accuracy, and precision of the instrument for each of the 13 target analytes are presented and discussed. The costs of element analysis using the ZSX Mini II analyzer are compiled and compared to both fixed laboratory costs and average XRF instrument costs.

Contact

Dr. Stephen Billets

See Also

Superfund Innovative Technology Evaluation

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