26 May 2016

Soil FTIR analysis and our equipment

Our equipment has always been in high demand for various soil testing practices. Read our application note on soil FTIR analysis using the Golden Gate ATR spectrometer accessory. But what are these green-fingered scientists testing for? Let's find out.

Harmful heavy metals | Soil FTIR analysis

There is a normal level of natural ionizing radiation, present in soils, rocks, air, water, the human body, even food. We're used to it, along with most living things on the planet.

soil FTIR analysis using ATR spectroscopy

But heavy metals are so dense and chemically toxic that they can have a very radioactively adverse effect on the health of people, animals and plantlife.

In a study featured in "Soil Remediation and Plants: Prospects and Challenges", the soils of Bangladesh were analysed for heavy metals and other radioactive contaminants. In this part of the world, agricultural areas are particularly vulnerable to soil contamination from industrial sites, due to the large movement of polluted water, from rivers, through crop irrigation.

"The uptake of heavy metal by plants or food crops from the soil to biota and its impacts on the human health in Bangladesh has been rarely reported" (Hakeem, Sabir, and Ozturk, 2014).

Soil samples from an area around the city of Dhaka and other rural areas of the country, along with a range of leafy and non-leafy plants and vegetables, were collected randomly in triplicate. Our pellet pressing equipment was used in the preparation of the sample.

"For irradiation of the sample with an X-ray beam, 2g of each powdered material was pressed into a pellet of 25 mm diameter with a pellet maker (Specac)... The precision and accuracy were checked" (Hakeem 2015).

preparing soil for FTIR analysis using a Specac hydraulic press

Iron, lead, manganese and zinc were among the most common metals found in soil samples, although iron may well have been partly common due to high levels of natural regional occurrence.

Forensic testing | Soil FTIR analysis

By using FTIR and multivariate analysis, soil provenance can be determined to either link a suspect or object to a known crime scene, or identify the location of an unknown crime scene.

The University of Lincoln, UK carried out an FTIR and multivariate analysis study of soil for forensic purposes, in partnership with the University of Cordoba, Spain.

Soil samples were taken from Lincoln woodland, to a depth of 10 cm with a soil corer. The samples were then air dried, sieved, grinded and sieved again.

The samples were "measured directly on a Golden Gate ATR spectrometer accessory (Specac) housed in a Perkin-Elmer Spectrum 100 FTIR spectrometer" (Lincoln University. 2010).

analyze

The ATR method appears to distinguish samples clearly enough that "a PC model could be used to discriminate between sampling locations at the same site."

Organic contaminants in water | Soil FTIR analysis

The so called 'flocculation' of organic micro-materials is an essential part of water treatment. Clay and other organic contaminants (from soil and other sources) can cause health risks if not adequately precipitated from water.

water flocculation avoids water contamination and spectroscopy can assess flocculation effectiveness

To remedy this contamination, a solution of metallic cations (positively charged ionic metals) is added to mains water during the flocculation process. These metallic coagulants are attracted to the negatively charged organic macromolecules. The two collide and form metallic hydroxides, thereby becoming heavier, larger, stickier and easier to filter out of the water.

It is difficult to assess how the effectiveness of flocculation solutions changes when they become hydrated. An analysis of the effect of hydration on alkaline metallic cations was carried out using ATR-FTIR spectroscopy, by Henri Poincaré University and Aalborg University.

For this study, the accessory used was a "flat horizontal ZnSe crystal prism manufactured by Specac (6 internal reflections on the upper surface, angle of incidence: 45°)" (Berthelin, Huang, and Bollag, 2012).

The ATR FTIR spectroscopy method used allowed "the study of structures at the interface between the hydrated flocs and a ZnSe crystal." 

Check out #SpectroscopySolutions for more.

References

Berthelin, Jacques et al. (2012). Effect of Mineral-Organic-Microorganism Interactions on Soil and Freshwater Environments. New York: Springer Science and Business Media, p331 - 337.

Hakeem, K.R., Sabir, M. and Ozturk, M. (eds.) (2014) Soil remediation and plants: Prospects and challenges. United States: Academic Press.

Lincoln University. 2010. The forensic analysis of soil by FTIR with multivariate analysis. [ONLINE] Available at: https://eprints.lincoln.ac.uk/3584/1/Soil_Analysis.pdf. [Accessed 27 May 2016].