Fast Mineral Analysis Using the Cary 630 FTIR with Diamond ATR from Agilent

Table of Contents

Introduction
FTIR Mineral Analysis
Use of a Monolithic Diamond ATR Accessory
Experimental Procedure
Results and Discussion
Conclusion
About Agilent Technologies Inc.

Introduction

This article explains how the Agilent Cary 630 FTIR spectrometer (Figure 1) fitted with the monolithic design diamond attenuated total reflectance (ATR) accessory can be used for rapid, simple measurement of mineral samples. The resulting spectra can be used for qualitative identification of the mineral type by cross-reference against a stored library of spectra.

Figure 1. The Agilent Cary 630 FTIR spectrometer

FTIR Mineral Analysis

Mineral characterization is normally done using Fourier-Transform Infra-Red (FTIR) spectroscopy. It complements X-ray diffraction owing to its ability to determine poorly crystalline “amorphous” materials, which is not possible with XRD. In the past, FTIR mineral analysis was performed using classical techniques such as preparing a potassium bromide disk or Diffuse Reflectance (DRIFTS).

These methods are ideal for analyzing such inorganic materials as most of the absorbance bands in minerals such as Si-O-Si and Si-O-Al appear below 600 cm-1. Hence, it is essential to use a technique that uses the complete mid-IR spectral range extending down to 400cm-1. The key issue, however, with this technique is that the sample preparation stage is challenging and time consuming, causing a low measurement throughput.

Use of a Monolithic Diamond ATR Accessory

The use of a monolithic diamond ATR accessory is a more rapid and convenient approach. This kind of ATR offers a complete spectral range analysis and allows direct sample measurement without any tedious preparation step.

This article covers how high sensitivity and wide wavelength range of the Agilent Cary 630 FTIR with diamond ATR allow collection of high-quality data from several minerals samples with a measurement time of just 15s per sample.

Experimental Procedure

All the samples were obtained in the form of coarsely ground powders and were measured without further preparation using an Agilent Cary 630 FTIR spectrometer fitted with KBr optics and complimentary diamond ATR accessory. Table 1 shows the measurement conditions.

Table 1. Measurement conditions

   
Spectral Range 4000 – 400 cm-1
Number of Scans 32 (approx. 15 secs measurement time)
Spectral Resolution 4 cm-1
Apodisation Happ-Genzel

Results and Discussion

The spectra obtained for each of the minerals tested in this study are shown in Figures 2 and 3. It can be observed that the peaks for all spectra are well resolved with a very good signal-to-noise ratio and with many spectra showing an abundance of peaks less than 600cm-1. The results clearly demonstrate the advantage of using a monolithic ATR.

Figure 2. Spectra of Brazilian Kaolin, Dartnoor Kaolin, Calcium Carbonate, and Calcium Feldspar

Figure 3. Spectra of Potassium Feldspar, Sodium Feldspar, Dolomite, Muscovite and Organic Rich Ball Clay

In order to identify each mineral type, the Cary 630 MicroLab software enables the creation of libraries from the measured spectra of the user, against which it is possible to cross- reference known samples or direct searching of spectra can be performed against commercially available libraries.

Conclusion

It can be clearly observed from the results that the Agilent Cary 630 FTIR spectrometer is suited for mineral analysis. The high energy throughput monolithic diamond ATR enables measurement down to 400 cm-1 with superior signal-to-noise ratio. Using a library search, it is possible to easily identify the resulting spectra.

About Agilent Technologies Inc.

Agilent is the proven leader in elemental analysis for geochemistry, mining, and metals industries. We offer the broadest atomic spectroscopy portfolio on earth, with AA, MP-AES, ICP-OES and ICP-MS solutions that solve your toughest challenges.

Our innovative and unique solutions also create opportunities for you to advance and define new levels of performance. From exploration and production to mine site rehabilitation, Agilent is the single source you require to achieve rock-solid minerals analyses with maximum speed, accuracy, safety and cost savings.

MP-AES Cost Savings Estimator

Agilent Solutions for Geochemistry, Metals & Mining

  • Rugged, reliable, low cost atomic absorption spectrometers ideal for challenging conditions
  • Revolutionary Microwave Plasma Atomic Emission Spectrometer (MP-AES), which runs on air, enabling unattended multi-element analyses without flammable and expensive gases
  • Robust, productive ICP-OES chosen by mining labs around the world for fast,
  • accurate and reproducible geochemical analysis
  • ICP-MS for ultimate confidence in trace analysis
  • Micro GC for the analysis of mine gas
  • Handheld FTIR for at-site rock and mineral measurement

This information has been sourced, reviewed and adapted from materials provided by Agilent Technologies Inc.

For more information on this source, please visit Agilent Technologies Inc.

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