Modular spectrometers and accessories can be combined for measurement of various spectral characteristics. In this application note we describe a spectrometer and multifunction accessory appropriate for measurement of absorbance, fluorescence, scattering or any combination of these phenomena.

Background

Spectroscopy is a powerful tool providing a wealth of information with the relatively simple measurement of how light interacts with a sample. Chemical composition, analyte concentration, color and many other sample characteristics are all readily determined with spectroscopy. The power of the modular spectroscopy approach is the ability to take a snapshot of the sample or to collect additional data while avoiding sample changes that can occur while changing setups or moving the sample to a new instrument. When combined with fiber optic spectrometers and accessories, Ocean Optics’ CUV-ALL-UV cuvette holder enables the measurement of absorbance, fluorescence, scattering or any combination of these phenomena from a sample – all in one convenient sampling accessory.

Experimental Conditions

Absorbance and fluorescence were measured for fluorescein using the CUV-ALL-UV cuvette holder and a tungsten halogen light source. The Ocean Optics Torus concave grating spectrometer was chosen to measure absorbance for its superior stray light performance and high throughput. Our QE65 Pro scientific grade spectrometer was chosen to measure fluorescence for its high quantum efficiency and cooled, back thinned detector enabling high sensitivity and long measurement times. The light source was coupled to the CUV-ALL-UV cuvette holder using a 600 μm optical fiber with the Torus coupled directly across from the light source using a 400 μm optical fiber. The QE65 Pro was coupled at 90 degrees relative to the light source using a 600 μm fiber. A mirrored screw plug was placed in the port across from the QE65 Pro fiber to help improve sensitivity by reflecting the emitted light back into the spectrometer collection fiber.

Results

To illustrate the ease of measuring multiple spectra from the same sample using the CUV-ALL-UV, spectral data was acquired from the fluorescein sample simultaneously by both spectrometers. This provided a snapshot of both the absorbance and fluorescence characteristics of the sample (Figure 1).

Figure 1: Simultaneous Measurement of Fluorescein Absorbance and Fluorescence

Conclusions

The possibilities for combined spectroscopy measurements go far beyond this example. For example, you can combine techniques like scattering at 90 degrees with absorbance/ transmission or fluorescence. Also, multiple light sources could be used with uniquely configured spectrometers to capture spectral data over a wider wavelength range or with different optical resolutions. Modular components provide a vast array of measurement options.
The flexibility of the CUV-ALL-UV allows researchers to capture additional data for their samples without the need to change their setups or move samples to another instrument. This approach gives the researcher a true snapshot of the sample. The addition of other sampling accessories and modular components further expands the possibilities by providing instrument setup versatility, maximizing the data available for your sample and eliminating equipment change hassles.

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