Choosing the Right Spectrometer

There are two main categories of spectrometry: radiation spectrometry and mass spectrometry.

Radiation spectrometry (UV-Vis, IR, X-ray, gamma ray) enables the structure of a material to be analyzed through its interaction with the radiation it absorbs, scatters or emits.

Mass spectrometry allows the molecular structure of a gas to be analyzed by ionization.

The type of spectrometer you should choose depends on the material to be detected and whether or not the analysis is invasive (destruction of the sample or not).

The main selection criteria for your spectrometer should be:

• Sensitivity and detection limit
• Wavelength range

If you need to analyze the color of a sample, you will need a spectrometer covering the visible spectrum, between 360 and 740 nm.

• Resolution (the ability of the spectrometer to distinguish between two wavelengths close together)

If the sample spectrum has sharp peaks separated by a distance of at least 0.5 nm, you will need a spectrometer with a resolution of at least 0.5 nm.

In addition to the range of wavelengths and resolution you need, there are secondary criteria to help you make the right choice:

• The overall size of the equipment, especially if it will need to be transportable
• The cost
• The analysis speed
• The signal-to-noise ratio
• The linearity
• The dynamic range
• The thermal stability
• The durability

Bruker Optics FTIR infrared spectrometer

Infrared spectrometry is a type of absorption spectrometry that makes it possible to determine the nature of the chemical bonds present in a molecule. Absorption results from the vibration and rotation of the molecules.

It is used to measure the response of a sample exposed to infrared light.

It offers non-invasive analysis and quantitative determinations with minimal sample preparation.

What is it used for?

• The infrared spectrometer is suitable for surface analysis in the semiconductor industry or in order to quickly determine the amount of water in seeds for agriculture.
• It can also be used to identify raw materials and components in the chemical, cosmetics, plastics or pharmaceutical industries.
• It is useful for monitoring highly absorbent solid products and providing information such as protein, fat, fiber and starch content.
• Infrared spectrometers are available as laboratory models or as portable models for analysis in the field.

Disadvantages

• When the number of different chemical components is large, the spectrum becomes complex and interpretation is difficult, especially for organic compounds.

U-Therm International UV/VIS spectrometer

UV/VIS spectrometry (ultraviolet and visible wavelengths) is a type of absorption spectrometry that enables the analysis of low-complexity liquid or gas samples.

A lamp, usually a deuterium one, turns a visible light spectrometer into a UV-visible unit that can measure from 190 to 1100 nm.

Analysis with a UV-VIS spectrometer is complementary to that with an infrared spectrometer. It enables a better quantification of the components of a sample.

What is it used for?

• The UV-VIS spectrometer is used to check the efficiency of filters in the food industry.

Disadvantages

• This type of spectrometer is easy to use, but can only analze simple samples. Due to the width of the molecular absorption bands, not all components of a complex mixture can be observed in the absorption spectra.

Analytik Jena atomic absorption spectrometer

Atomic absorption spectrometry is used to determine the concentration of metallic elements in a solution previously heated with a flame or in a furnace.

A high-temperature flame evaporates the water from the sample, dissociating it into ions. This manipulation results in a change in the light intensity measured by the detector to determine the concentration of the sample.

Atomic absorption spectrometry has the advantage of being very selective.

What is it used for?

• Atomic absorption spectrometry is used in mining exploration, in the pharmaceutical industry or in environmental research.
• This high-precision analysis is ideal for environmental testing, toxicology and quality control laboratories.

Disadvantages

• It is necessary to prepare an initial solution, i.e. to dissolve the compound with a suitable solvent, before a qualitative and quantitative analysis can be carried out.

Thermo Scientific X-ray spectrometer

X-ray spectrometry is a type of absorption spectrometry that determines the composition of a material by exciting it with X-rays.

What is it used for?

• It is used in geology to determine the composition of a rock.
• In the nuclear industry, it is used to detect uranium, whether for mining purposes or to look for impurities in the fuel.
• It is also used in wastewater treatment to identify the materials to be treated.

Malvern Panalytical X-ray fluorescence spectrometer

X-ray fluorescence spectrometry is a type of emission spectrometry that measures the X-radiation emitted by atoms excited by the absorption of X-radiation.

Atoms can also be excited at a high energy or temperature level and then produce X-rays.

What is it used for?

• It is suitable for measuring very low concentrations.
• It is used for elemental chemical analysis.
• It is used, for example, to detect the presence of lead in paints or pipes, or to determine the thickness and composition of coatings in construction or industry.

Disadvantages

• Fluorescence techniques are more complex to apply than absorption techniques because the particle to be analyzed must first be excited by monochromatic radiation.

Oxford Instruments NMR Spectrometer

Magnetic resonance spectrometry is the most advanced technology for determining the structure of organic compounds. In particular, it provides structural data on an entire molecule but also information on organic reactions.

What is it used for?

• It is used in medical MRI (Magnetic Resonance Imaging) because it allows high-contrast images of different tissu of the human body to be obtained.
• This technique is also used for the detection of explosives or for the study of polar ice caps.

Bruker Optics Raman spectrometer

Raman spectrometry is a type of diffusion spectrometry that enables the analysis of the chemical structure of a sample and the identification of the compounds present in a similar way to infrared spectrometry, but on smaller samples and with better resolution.

A Raman spectrometer allows you to analyze the molecular composition of the external structure of a material.

What is it used for?

• It is used in archeology for non-destructive analysis.
• It enables the identification of organic molecules, polymers, biomolecules and inorganic compounds.
• It allows you to map the distribution of components in mixtures, such as drugs in excipients; to determine the presence of different types of carbon (diamond, graphite, amorphous carbon, adamantine carbon, nanotubes) and their relative proportions; and to measure the stress and crystal structure of semiconductors.

Shimadzu Mass Spectrometer

A mass spectrometer allows you to determine the mass of molecules in the gas phase.
It can be used for qualitative as well as quantitative analysis: each component has a unique, or almost unique, mass spectrum that can be compared with mass spectrum databases, allowing it to be identified and quantified.

This type of spectrometer works with very small samples and makes it possible to know what elements they are composed of.

What is it used for?

• It is used for the rapid analysis of samples in doping control, food safety and the pharmaceutical industry.

Disadvantages

• This technique does not work with very large molecules.

Summary of spectrometers and their applications