5991 3714ENE

5991 3714ENE
materials analysis
Rapid Analysis of Minerals Using
the Agilent Cary 630 FTIR With Diamond ATR
Solutions for Your Analytical Business
Markets and Applications Programs
Abstract
Solution Note
Geochemistry, Minerals and
Mining
Author
Rob Wills,
Agilent Technologies UK Ltd
This report details how the Agilent Cary 630 FTIR spectrometer equipped with
monolithic design diamond Attenuated Total Reflectance (ATR) accessory can be
used for simple, rapid measurement of mineral samples. The resulting spectra
can be used to qualitatively identify the mineral type by cross-reference against a
library of spectra.
Introduction
Fourier-Transform Infra-Red (FTIR) spectroscopy is widely used to characterize
minerals. It is a complimentary technique to X-Ray Diffraction (XRD) because
it has the advantage of being able to identify poorly crystalline “amorphous”
materials which is a limitation of XRD. Historically, minerals analysis by FTIR has
been achieved using “classical” approaches such as preparation of a potassium
bromide (KBr) disk or Diffuse Reflectance (DRIFTS). These techniques are well
suited to the analysis of such inorganic materials because many of the important
absorbance bands found in minerals such as Si-O-Si and Si-O-Al appear below
600 cm-1 so it’s important to use an approach that makes full use of the complete
Mid-IR spectral range extending down to 400 cm-1. However, the main problem
with these techniques is that the sample preparation stage is both tedious
and time-consuming, resulting in low measurement throughput. A much faster
and more convenient approach is to use a “monolithic” diamond Attenuated
Total Reflectance (ATR) accessory 1. This type of ATR offers full spectral range
analysis, and enables the direct measurement of samples without any lengthy
preparation step. In this application note, we will show how the high sensitivity
and wide wavelength range of the Agilent Cary 630 FTIR with diamond ATR
enables high quality data to be collected from a range of mineral samples with a
measurement time of only 15 seconds per sample.
1
Experimental
Results and Discussion
All samples were received as coarsely ground powders and
all were measured without any further preparation using an
Agilent Cary 630 FTIR spectrometer equipped with KBr optics
and complimentary diamond ATR accessory. Measurement
conditions are shown in the table below.
Spectra for each of the common minerals analysed in
this study are shown below. All of the spectra show well
resolved peaks, with excellent signal-to-noise ratio, and with
several of the spectra showing an abundance of peaks below
600 cm-1, the importance of using a monolithic ATR is clear.
Spectral Range
Number of Scans
Spectral Resolution
Apodisation
For the purposes of identifying each mineral type, the Cary
630 MicroLab software allows the creation of libraries from
the user’s own measured spectra against which unknown
samples can be cross-referenced, or spectra can be searched
directly against commercial libraries (including libraries
that have been created in transmission using the KBr disk
approach).
4000 – 400 cm-1
32 (approx. 15 secs measurement time)
4 cm-1
Happ-Genzel
2
3
Conclusion
The results clearly demonstrate that the Agilent Cary 630
FTIR spectrometer is suitable for the analysis of minerals.
The high energy throughput monolithic diamond ATR enables
measurement down to 400 cm-1 with excellent signal-to-noise.
The resulting spectra can be easily identified using a library
search.
References
1. Rob Wills, “Advantages of the Agilent Cary 630 Diamond
ATR”, Agilent Solution Note Reference 5991-3361EN,
published 2013.
Agilent shall not be liable for errors contained herein or
for incidental or consequential damages in connection
with the furnishing, performance or use of this material.
Information, descriptions, and specifications in this
publication are subject to change without notice.
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Markets & Applications Programs
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© Agilent Technologies, Inc. 2014
Published in USA, JUNE 02, 2014
5991-3714ENE
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