Quick Dips

Elementary Analysis

Everything from clays to candies is undergoing analysis by X-ray fluorescence spectrometry (XRF) in an unusual venture between two former government scientists and a private company.

As former Landcare scientists, John Hunt and Lee Searle had the XRF expertise, but access only to old equipment. NZ China Clays didn't have the expertise, but was able to provide the researchers with a state-of-the-art Siemens spectrometer. The new company, called SpectraChem Analytical, provides oxide analysis for the clays which NZ China Clays mines in Auckland, and uses XRF techniques to look at a range of other products.

XRF offers an advantage over other methods of analysis in that it is non-destructive, and samples are recoverable for further analysis or examination using alternative techniques. This is particularly important for the analysis of precious metals, such as gold jewellery, and with other small, valuable commodities like archaeological samples. Because XRF measures the sample directly, the technique avoids the costs and time delays involved with methods that require the "digestion" of samples to the liquid phase.

As well as accurate quantitative analysis, a special feature of their instrument is its capability to perform a fast semi-quantitative scan of samples ("Semi-Quant"), where approximate concentrations of over 60 elements are obtained in just a few minutes. "Semi-Quant" is relatively cheap and can pinpoint unusual concentrations of elements, which is particularly useful in pollution studies.

Liquid fertilisers and lollipops have been examined.

"It's a scientific challenge and a business challenge," Searle says.