Analysis and sample preparation

We can receive and prepare samples before analysis by drying, sieving, milling and digesting them.   

For example, we have:

• drying ovens for drying samples
• a freeze dryer
• ball mills for milling soils
• centrifugal mill for milling plant material
• digestion/extraction facilities
• furnaces for loss on ignition 
• facilities to measure the pH of soil and water samples

We can perform a variety of different digestions/extractions, which can be tailored to the item that is being measured. 

Examples include: 

• aqua regia digestions of soils
• nitric acid/hydrogen peroxide digestions of plant material
• calcium chloride extraction for available metals
• hydrogen peroxide digestions to remove organic matter from soils

This list is not exhaustive, and we can tailor to your specific needs.

We can also help design and run bespoke experiments.  Examples of such experiments include:

• adsorption/desorption experiments to determine how contaminants stick to soil
• bioaccessibility experiments

If you can't see a particular technique listed here, it does not mean it is not available. We will modify the sample preparation to suit your needs.   

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Atomic absorption spectroscopy is a common and well-established technique for detecting metals and metalloids. It is a very reliable and simple technique to use with few interferences.

The method is based on the fact that when metal ions are converted to their atomic state by means of a flame, the light of the appropriate wavelength is absorbed and the amount of absorption can be measured against calibration curves and converted into concentration.

Instrumentation

Our School has two Atomic Absorption Spectrometers:

• Varian Spectra AA-300 flame system. The instrument is used for trace metal analysis of geological and environmental samples and used mainly when only a small number of elements are of interest.
• ThermoFisher Scientific ICE 3500 atomic absorption spectrometer with autosampler. The instrument specialises in analysis of environmental samples.

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We can measure inorganic carbon in geological and environmental samples using coulometry.

Coulometry is used to measure carbonate content of rocks and soils. The sample is acidified, converting carbonate into carbon dioxide, which reacts with a coloured liquid. The reaction causes the liquid to lose its colour. The instrument detects the loss of colour, and an electric current is passed through the liquid to regenerate it. The current used is accurately measured and as it is directly proportional to the amount of carbon dioxide gas present. Since this technique uses Faradays Law to measure the carbon dioxide, no calibration is needed. It also means it is an accurate technique over large carbonate concentration ranges. This same instrument can be used to measure dissolved carbonate in water samples.

Your soil/rock samples should be dried and ground to a fine powder before analysis. We have sample preparation facilities which can be used if required.

Instrumentation

• UIC Inc. CM 5012 coulometer
• CM 5130 acidification unit

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Organic elemental analysis is a well-established technique for measuring the amount of carbon, nitrogen, hydrogen, sulfur and oxygen in a sample.

It works by burning the sample at high temperature followed by separating and measuring the gases produced, which allows the amounts of carbon, nitrogen, hydrogen and sulfur to be determined. Oxygen concentrations are determined by high-temperature pyrolysis.

We can measure carbon, nitrogen, hydrogen, sulfur and oxygen in various solid and liquid samples. We have measured a variety of different sample types and routinely analyse soil, sediment and biochar samples. We can also measure the total organic carbon content of rocks and soils.

Most analysis requires less than 10 mg of sample. We have a Sartorius SC2 microbalance for accurately measuring the required sample masses. Your samples should be ground to a fine powder and dried before analysis. We have sample preparation facilities which can be used.

Instrumentation

• Thermo Fisher FlashSmart 2000 Organic Elemental Analyser with a MAS Plus autosampler for solid samples
• AS 1310 liquid autosampler

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We can measure phosphate, nitrate, ammonia and silica concentrations in waters. This is done using a colorimetric reaction in a continuous flow analyser. For soil samples, the nutrient must be removed into liquid before analysis.

Nutrient concentrations are measured using our continuous flow analysers. We are able to measure phosphate, nitrate, ammonia and silica in both soil and water samples. The instrument mixes your sample and reagent to form a coloured complex. The intensity of this colour is measured to calculate the concentration of the nutrient in the sample.

Although we can measure the amount of nutrients in soil samples, all samples must be in a liquid form before they can be analysed. This means we will have to extract the nutrients from the soil into a liquid using one of our extraction methods before we can measure them. 

Soil and water samples should be delivered fresh, and as soon after sampling as possible to ensure the best results.

Instrumentation

• We have three Seal Analytical AA3 instruments

Grain sizes of particles in suspension are measured by laser diffraction.

The technique uses the scattering of light, delivered from a laser, that is passed through a chamber containing the particles in suspension. The scattered light is detected by a photo-detector array. The intensity of light on each detector is then converted into a particle size distribution plot that is calculated by mathematical algorithm. It is an elegant, simple, fast and flexible technique that produces high quality data.

We have two laser diffractometers.

Instrumentation

• A Beckmann Coulter LS100 which measures the grain sizes of particles in suspension in the range 0.4um - 800um.
• A Beckmann Coulter LS230 with PIDS detector and variable speed fluid module. This instrument measures grain sizes in suspension in the range 0.04um-2000um.