Cuvette light-scattering

In these sensors, the intrinsic absorption of the analyte is measured directly. No indicator chemistry is involved. Thus, it is more a kind of remote spectroscopy, except that the instrument comes to the sample (rather than the sample to the instrument or cuvette). Numerous geometries have been designed for plain fiber chemical sensors, all kinds of spectroscopies (from IR to mid-IR and visible to the UV from Raman to light scatter, and from fluorescence and phosphorescence intensity to the respective decay times) have been exploited, and more sophisticated methods including evanescent wave spectroscopy and surface plasmon resonance have been applied. 

UV- VIS absorption was measured with Beckman DU- 70 spectrophotometer, using cuvettes of 10mm or shorter pathlength. Light scattering was measured with Otsuka... 

Figure 7-24. Cuvette design for static and dynamic light-scattering.

Measure the turbidity of each aliquot (amount of light scattered at 90°) in a lO-mmxlO-mm quartz cuvette at 37°C and under magnetic stirring. Before reading, leave each sample in the cuvette for at least 5 min to reach equilibrium. Determine the turbidity of the solution with a fluorometer by setting the excitation and emission wavelengths at 480 nm. 

I,iAXiAK(A)T iA) where is the blank transmittance, and A is the measured sol extinction. In the case of scattering spectmm measurements, one of two identical sample cuvettes is placed in position 9b and the other (10) is replaced with reflector 6 (Fig. 21). It can be shown that the light-scattering flux is given by [87]... 

For fluorescence excitation and emission spectra, cells from 1-5 day-old cultures suspended in the culture medium or isolated chlorosomes were diluted in 10 mM, pH 8 Tris Cl so that the absorbance at 730 nm was about 0.2 in a 1 cm fluorescence cuvette. Fluorescence spectra were measured on an instrument constructed as described previously (8) using an R 928 photomultiplier as the detector. Absorption spectra were measured on the same instmment, which incorporated an integrating sphere to avoid light-scattering artifacts. 

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