A-TEEM spectroscopy refers to the ability to simultaneously acquire Absorbance, Transmittance and a fluorescence Excitation Emission Matrix (A-TEEM) of a particular sample. HORIBA pioneered this technique with the patented Aqualog and Duetta system, which combines A-TEEM spectroscopy with simultaneous multichannel CCD detection to provide extremely fast results.
A-TEEM spectrometers can be used for fluorescence EEMs or for absorbance measurements for multi-component analysis, but its real power is derived from the fact that the EEMs collected by the instrument are corrected for inner filter effect. This means they are true and accurate representations of the molecules of interest over a much broader and more useable concentration range (typically up to ~2 absorbance units).
Most components of CDOM have broad overlapping fluorescence excitation and emission spectra in the UV and visible range. Many sample measurements are used to create a model and then use chemometrics to get scores of each component in an individual sample. The very unique thing about a fluorescence EEM is that it can be used as a molecular fingerprint. Changes in the emission spectrum, the excitation spectrum, or both can be tracked very easily using this 3D fluorescence method for water analysis as well as many other applications.
Applications using A-TEEM
Helical Folding Angle
In this instance, the specific geometry can be understood in terms of the wrapping vector containing the length – that is the tube’s circumference – and a helix angle ranging from 0 to 30 °. The two numbers are shown (n,m) are therefore used for SWCNT definition.
Monitoring cell culture media
With the rise of protein production using mammalian cell culture, it has become increasingly important to control the quality of the cell culture media for use in production processes.
Cell culture media are usually prepared as aqueous solutions, and should provide everything a cell line needs for optimal cell growth as well as product yield and quality.
In any given bioreactor process it is important to identify the proper type of cell culture medium and its quality, because even subtle variations in composition could have a noticeable impact on the growth rate of the cell culture and its yield. Therefore, the composition and quality of cell culture media in bioreactors must be tightly controlled in order to maintain an optimal bioreactor process. As a result, methods of identifying and analysing the quality of cell culture media have become an important focus in this field
What is Synchronous scan?
A synchronous scan is when the excitation monochromator scans at the same time as the emission monochromator and the fluorescence emission is read out. Typically, one can set an offset between the excitation and emission monochromators that matches the Stokes Shift (difference between excitation and emission peaks). These types of synchronous scans have been historically used for component analysis, but due to the more modern instruments for measuring EEMs with CCD detectors, the EEM gives more information and takes the same amount of time
An offset of 0 nm can be set so that the excitation and emission are scanning together at the same wavelengths. This is what is called right-angle light scattering, or RALS, and results in what is really a right-angle reflectance spectrum. This type of synchronous scan measures the reflected or scattered light from the excitation.
Click here for more information on the fluorescence spectrometers we provide here.
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