Sulphur Analysis – Determination of Sulphur Content by LSM Analytical Services

Background

LSM Analytical Services offer a large and diverse range of modern analytical testing facilities that cater for a vast range of industry sectors. LSM’s success has been achieved by building on a strong reputation for low cost, fast accurate turnaround. The laboratory activities are backed up by accreditation to the ISO 17025 (UKAS) and 9001:2000 laboratory and quality management standards. LSM is able to offer complete analytical solutions from its internationally recognised team of technical experts, with in depth knowledge, allowing its customers to benefit from impartial guidance.

LSM’s range of analytical services includes:

•        X-Ray Fluorescence Spectrometry (XRF)

•        X-Ray Diffraction (XRD)

•        ICP Optical Emission Spectrometry (ICP-OES)

•        Atomic Absorption Spectrometry (AAS)

•        Carbon, Sulphur, Nitrogen, Oxygen Analysers

•        Boron analysis by the Neutron Transmission method

•        Colorimetric and Volumetric Analysis

•        Particle Size Analysis

Sulphur Analysis

LSM Analytical Services large range of analytical techniques includes instrumentation for Sulphur analysis.

How Sulphur Content is Determined

The principle of Sulphur analysis is to oxidise the sample by heating in an Oxygen atmosphere to form SO₂, which is then measured by infrared detector.

Heating of Samples to Determine Sulphur Content

The heating is generally done in a high frequency induction furnace as this provides both speed and accuracy. The sample is placed in a ceramic crucible and an accelerator is often added to ignite the sample and can also act as a flux to dissolve any oxide skins to improve melt fluidity, which allows the Sulphur in the sample to be oxidised in a short time. It is imperative that complete combustion is achieved in order to gain accurate results. There is a large range of accelerators used and the choice depends on the base material being analysed. One feature of any accelerator is a low Sulphur (and Carbon as this is often analysed for in a similar way) content.

The Accuracy of Sulphur Determination Measurements

In the test a signal will be obtained that is not attributable to the sample. The cause is a combination of impurities in the gas, crucible and accelerator. The average contribution to the Sulphur signal from these sources is determined to allow the sample contribution to be calculated. The inconsistency of impurity levels from these sources cannot be completely eliminated and this affects the ability to determine accurately to very low levels. As the method is relatively quick, repeat determinations are often requested to improve the accuracy of the determination (by taking the average of several results).

The Affect of Water on Sulphur Content Measurements

Sulphur results can be affected if water is present in the sample. However dealing with this issue is not straightforward. Residual water can be dealt with by heating the sample to 110°C for one hour. Crystalline water is less easy to deal with as the high temperatures required to dissociate it also mean combustion of the Sulphur.

Source: LSM Analytical Services

For more information on this source please visit LSM Analytical Services