Laboratory Techniques at Oxford Analytical

Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) is an analytical technique used to quantify mostly metallic elements in a sample. A high energy plasma induces compound breakdown to individual elements, and the atoms and ions absorb energy to move electrons from the ground state to an excited state. The resultant emission wavelengths are indicative of the element, and the most appropriate wavelength is selected to determine the concentration of the element.

Oxford Analytical Services Ltd is equipped with a Perkin Elmer FTIR (Fourier Transform Infrared) Spectrometer, including ATR diamond accessory. The instrument measures the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous form. The resulting IR spectrum can be visualized as a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency or wavelength on the horizontal axis.

Gas chromatography or GC is commonly used in analytical chemistry for separating and analysing volatile compounds. Samples are introduced via a syringe into a heated injection port and separated by interaction stationary phase column. Analytes are separated from each other and potential matrix contaminants by using an oven temperature controlled program, based on their respective volatilities and molecular masses. Non-volatile compounds can be made amenable to GC by derivatisation. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture.

A FID measures the concentration of ions formed during combustion of organic samples in a hydrogen flame. The generation of these ions is proportional to the concentration of of organic material in the gas stream. The measurement of ions per unit time make this a mass-sensitive instrument.

This analytical method combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample. Here a charged tungsten filament source bombards the carrier gas containing the sample with a stream of electrons. This causes the subsequent loss of an electron, resulting in a positively charged compound (M+) amenable for detection by the Mass Spectrometer (MS). Applications of GC-MS include drug detection, fire investigation, environmental analysis, explosives investigation and identification of unknown samples. Additionally, it can identify trace elements in materials that were previously thought to have disintegrated beyond identification. Mass spectrometry, it is a highly sensitive technique like liquid chromatography, which allows the analysis and detection of trace amounts of a substance.

Analysis of small and volatile molecules in the gas phase above the actual sample. BTEX (Benzene, Toluene, Ethyl benzene and Xylene) are a common group of analytes suitable for this technique.

Separates ions and polar molecules based on their affinity to the ion exchanger. It works on almost any kind of charged molecule—including large proteins, small nucleotides, and amino acids.

The two types of ion chromatography are anion-exchange and cation-exchange. Cation-exchange chromatography is used when the molecule of interest is positively charged. In this type of chromatography, the stationary phase is negatively charged and positively charged molecules are loaded to be attracted to it. Anion-exchange chromatography occurs when the stationary phase is positively charged and negatively charged molecules are loaded to be attracted to it. It is often used in protein purification, water analysis and quality control. Cation exchange chromatography is used when the desired molecules to separate are cations and anion exchange chromatography is used to separate anions.

Formerly referred to as high-pressure liquid chromatography, This is a technique used in analytical chemistry to separate, identify, and quantify (each) components in a sample. It relies on the flow of a pressurized liquid (solvent) i.e. mobile phase containing the sample mixture through a column filled with a solid adsorbent material (stationary phase). (Each component in the sample interacts slightly differently with the adsorbent material, causing different rates of elution and therefore retention times leading to the separation of the components (from) on the column.)The sample components interact more or less strongly with the stationary phase which causes the seperation of the sample mixture.

UV Detector: An Ultra-Violet detector is an in-line device that measures the lambda max [(lmax)] UV absorbance of the components in the HPLC eluent and provides a continuous signal that can be used to quantify the amount of chromophoric compounds eluting from the HPLC column.

(Diode-Array Detection (DAD) or Photodiode Array Detection (PDA) is an analytical technique that can be used to determine the purity of an analyte or related impurity peak eluting from a HPLC.)

A Diode-Array Detector (DAD) or Photodiode-Array Detector (PDA) is a common UV detector that monitors the entire UV-vis spectrum of material passing through the flow cell in a HPLC-System using a photodiode imaging sensor, typically consisting of 512 or 1024 pixels or elements. The detector yields both absorbance and spectral data that can be used for quantitation, identification, and peak purity assessments.

Liquid Chromatography with tandem mass spectrometry (LC-MS/MS) is a powerful analytical technique that combines the separating power of liquid chromatography with the highly sensitive and selective mass analysis capability of quadrupole mass spectrometry. Trace analysis in the ppb (µg/kg) region is possible with this technique.

Particle size analysis, particle size measurement, or simply particle-sizing is the collective name of the technical procedures, or laboratory techniques which determines the size range, and/or the average, or mean size of the particles in a powder or liquid sample.

The particle size measurement is typically achieved by Particle Size Analysers (PSA) which are based on different technologies, such as high definition image processing, analysis of Brownian motion, gravitational settling of the particle and light scattering of the particles.

The particle size can have considerable importance in a number of industries including the chemical, food, mining, forestry, agriculture, nutrition, pharmaceutical, energy and building materials industries.

A UV-VIS Spectrometer is routinely used in analytical chemistry for the quantitative analysis of different specimen, such as transition metal ions, highly conjugated organic compounds and biological macromolecules. The analysis is mainly carried out in solutions but solids and gases may also be studied.