Cell holders, thermostated

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. 

Actinomycin D dissociation kinetics were measured on a Cary 219 spectrophotometer equipped with a magnetic stirrer and thermostated cell holders. Sodium dodecyl sulfate (SDS) was used to sequester dissociating actinomycin D, and the resulting Increase In absorbance was monitored at 452 nm as a function of time. Stop-flow studies (daunorubicin and daunorubicin/ actinomycin D) were conducted with a Durrum-Glbson Model 110 stopped-flow spectrophotometer equipped with a dual detector accessory and a Tektronix storage oscilloscope Interfaced with a PDF 11/34 computer. Experiments were done In a 0.01M Na phosphate buffer, 0.1M NaCl, 0.001M NaEDTA, pH=7. Dissociation time constants were computed with a multlexponentlal analysis computer program. 

Small changes in laboratory temperature do not affect the absorption spectra and a thermostat is normally unnecessary. But in certain physical studies like the determination of the kinetics or the equilibrium of a reaction, one has to control the temperature carefully. Thermostated cell holders are available for several commercial instruments. Large changes in temperature do produce marked changes in the spectra of some compounds (see... 

Thermostating of cell holder, of compartment at low temperatures drying of cell windows, at high temperatures shielding of electronics and optics. 

The sample was placed in a quartz cell in a thermostated holder (25 + 0.5 °C). The laser line was focused by a lens and mirror system and the scattored light... 

The contrast factors have been measured interferometrically [87] and with an Abbe refractometer, respectively. The sample is contained in a fused silica spectroscopic cell with 200 pm thickness (Hellma). The sample holder is thermostated with a circulating water thermostat and the temperature is measured close to the sample with a PtlOO resistor. The amplitude of the temperature modulation of the grating is well below 100 pK and the overall temperature increase within the sample is limited to approximately 70 mK in a typical experiment [91], which is sufficiently small to allow for measurements close to the critical point. 

An alternative approach involving commercial non-thermostated cells and pellet holders to thermostat the appropriate cell mount has been proposed by Cameron and Jones (1981). Thermostating the mount by flushing the cell body with a liquid or a gas enabled the authors to maintain a sample temperature which varied only by 0.05 °C. 

USP IV. The formulation is placed in a thermostated flow-cell. The dissolution fluid is pumped through the cell in a pulsating manner at a constant rate, typically between 4 and 16 mL/min. Before the inlet flow reaches the formulation, it is passed through a bed of glass pellets to create a laminar flow. A filter is placed in the cell at the outlet side of the formulation. The cell is available in different sizes/designs, and tablet holders are available as an option. 

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