Cell holders

Figure 2.22. L, lamp J, cooling jacket F, filter holder H, rotating cell holder.

Luminescence instrument LS-3B luminescence instrument LS-5B Accessories low flow cell, cell holders, bioluminescence spectroscopy, fluorescence spectro scopy, recorder/printers, low-temperature luminescence, fluorescence plate reader, polarization accessory, microfilm fluorimeter LS-2B... 

The use of spectrophotometry to monitor enzyme-catalysed reactions (Table 8.6) is a very convenient and popular method owing to the simplicity of the technique and the precision that is possible. The technique lends itself readily not only to temperature control using water-jacketed or electrically heated cell holders but also to the measurement of initial velocities by continuous monitoring and recording techniques or by automated analysis systems. 

Pipette the assay reagent (2 7 ml) into a clean dr i untie anil allow Id attain a temperature of 37 °C in a thermostated cell holder. 

C during the adsorption process using a termostated cell holder in the sample compartment of the spectrophotometer. 

Cell A could be accommodated in the cell holder usually used with the apparatus (6), in which the cell is immersed in a liquid in a larger cylindrical cell equipped with flat entrance and exit windows for the incident beam. This assembly was not used with cells B or C. With these cells, the plane construction results in a difference between the actual scattering angle 6 and the goniometer setting 63 of course, with cylindrical geometry 6 = 83). Thus,... 

Figure 4.4 — (A) Flow-through cells for spectrofluorimetric sensors (a) fused silica tube (1.5 mm ID) packed with 1 mg of CM-Sephadex C-25 (b) micro-cell holder (c) side and (d) front view of a commercially available sensor. (Reproduced from [62] and [64] with permission of the Royal Society of Chemistry and Elsevier Science Publishers, respectively). (B) Flow-through cells for photometric sensors. Side and front views of two commercially available designs. For details, see text. (Reproduced from [80] and [83] with permission of Elsevier Science Publishers and the Royal Society of Chemistry, respectively).

Fill the cuvette and place it in the cell holder, making sure that the orientation is reproducible both longitudinally and rotationally. Mark the cell to allow reproducible orientation in the light beam. 

Fill a cleaned cuvette with a filtered sample from the actual batch of buffer used to dissolve or dialyze the protein, then place the cuvette in the cell holder of the spectrometer in a reproducible orientation (see Strategic Planning, discussion of Cells). Scan this buffer blank using the same instrument settings as are appropriate for the sample, store the spectrum, and check for any unexpected fluorescence bands. 

Cell holders are susceptible to corrosion by salt solutions. Cells should therefore be filled outside the spectrometer. Special care must be taken to position the cuvette reproducibly each time. 

Remove the cuvette from the spectrometer, empty with a protected Pasteur pipet (see Strategic Planning, discussion of Cells) and refill in the same way with the clarified protein solution of known concentration with an absorbance of 0.05 to 0.1 at the wavelength used for excitation. Allow to come to temperature in the cell holder, then scan and store spectrum. 

Place a cuvette containing the carotenoid solution into the sample cell holder of the spectrophotometer. 

Place a cuvette containing a suitably diluted (i.e., 0.3 to 0.7 AU) extract of pharmaceutical, food, or biological material into the sample cell holder of the spectrophotometer. 

When working with organic solvents it is advisable to use stoppered cells to prevent damage to cell holders and other sensitive parts of the instrument, and to avoid evaporation of the sample. 

Before placing the cells in the cell holder, the optical faces can, if necessary, be polished carefully (avoiding any spillage) with a fine tissue. 

FIGURE 6.8 Typical side-on (top) and front-face (bottom) optical arrangements for laser flash photolysis to detect transient changes in the absorption spectrum. Abbreviations S = light source (probe) L = lens C = cell holder + cell (typical path lengths 1-0.5 cm (top) and 0.5-0.2cm (bottom)) M = mirror Mo — monochromator P = photomultiplier. The most commonly used lasers deliver powers equal to or larger than 0.5 MW per pulse. 

X-ray powder diffraction pattern of racemic mandelic acid (Aldrich lot KN07114MT). The aluminum calibration peak from the cell holder is marked. 

A fixed compressive load is applied to the entire cell stack-up between the alumina cell holder and the HastX top plate by means of weights, as shown in the test stand overview, Figure 15. This load must simultaneously compress the cell against the mesh, flow field and foil on the steam/hydrogen side and against the seal around the outer edge of the cell. The outer edge of the cell rests on a window... 

Place the sealed sample cell on the cell holder on the sample side. Similarly seal an a -AI2O3 containing cell, and place it on the cell holder on the reference side. 

Another problem is the ease with which a DSC apparatus degrades. Briefly, after it is used for a long time, it begins to produce noise, such that no definite DSC curve can be obtained. This may be attributable to the contamination of cell holders by gas from samples. The authors have conducted experiments with sealed cells by passing nitrogen gas through them, but contamination and its related noise production could not be avoided. For a time, a DTA apparatus considered less prone to contamination was borrowed from Nippon Kayaku Co., Ltd. and used for investigative purposes. 

---