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Atomic Spectroscopy is an analysis used to know the elemental composition of an analyte with the help of its electromagnetic or mass spectrum. Many techniques can be used in the analysis, such as flame atomic absorption spectroscopy, ICP-OES, ICP-MS, and graphite furnace AA. With the availability of a variety of atomic spectroscopy techniques, selecting the most appropriate technique is vital in achieving an accurate, reliable, and real-world result. For proper selection, one requires basic knowledge of each technique since they have their advantages and disadvantages.
Below are some of the most important criteria for selecting a technique for analysis.
Analytical working range
Generally, this is the concentration range over which quantitative results can be obtained without having to recalibrate the system. When selecting a technique, it is important to select a technique with an analytical working range that is based on the analyte concentrations. This reduces analysis time by enabling samples with varying analyte concentrations to be analyzed together. You should choose a wide analytical working range to reduce sample handling requirements, reducing potential errors.
The available detection limits achievable for a given element are essential in determining the usefulness of an analytical technique for a given problem. The process requires adequate detection-limit capabilities, and without it, you will perform lengthy analyte concentration procedures before analysis. Typical detection limits range differently with different Atomic Spectroscopy techniques. For instance, use Flame AA if the detection limits range from 1-100ppb, graphite furnace AA if the range is between 1-0.01ppb, and ICP-MS if the range is between 1ppb to more than 0.001ppb.
Sample throughput is the number of samples that can be analyzed per unit time. Analyses performed at the limits of detection or where the precision is key will be more time consuming than less demanding. Where limits of detection are not limiting, the number of elements to be determined per sample, and the analytical technique will determine the sample throughput.
- Flame Atomic Absorption Spectroscopy– Gives a high sample throughput while analyzing numerous samples for a restricted number of elements. Usually takes 3-10 seconds to determine an element. However, this technique requires specific optical parameters and light sources. As a result, it is mainly considered a single-element technique.
- Granite Furnace Atomic Absorption Spectroscopy– This is a single-element technique because it needs one to thermally program the system to separate solvent and matrix components prior to atomization. It has a relatively low sample throughput of about 2-3 minutes per element.
- Inductively Coupled Plasma Optical Emission Spectroscopy– ICP-OES is a multi-element technique that can determine about three elements per minute. However, when determining a few elements, it is limited by the time required for calibration of the plasma with each new element.
- Inductively Coupled Plasma Mass Spectroscopy– this is also a multi-element technique that can determine more than 73 elements per minute in a sample. However, the upper linear concentration range is less than that of the ICP-OES system and may require you to dilute some samples.
Most techniques complement each other, making it unclear as to which is the optimum technique for a particular application. Your choice should be guided by the factors mentioned above to ensure you get optimal results. It would help if you also considered other factors such as costs and ease of use when settling on an Atomic Spectroscopy technique.