Saturation technique

Supercritical fluid extraction is a potential technique for the purification of pharmaceutical products containing residual solvents. The solubilities of three inhibitors of inflammatory activity, Ketoprofen, Piroxicam, and Nimesulide, in supercritical CO2, measured using a dynamic saturation technique, were reported at pressures between 100 bar and 220 bar and at two temperatures 312.5 K and 331.5 K. The solubilities exhibit a clear dependence on the solvent density, and this has been used to provide a simple and precise correlation of the data (Macnaughton et al., 1996). 

Measurements of pi as a function of temperature were made by capillary gas chromatography for 17 PCN congeners [57]. From these data and reported relative retention indices [58],p values ofall 75PCNswere estimated [57], Koa values were determined as a function of temperature for 24 di- through hexa-CNs using a gas saturation technique [59]. Koa for other di- to hexaCNs were estimated from log Koa = - 1.275 log p] + 6.09 [57]. Other estimation methods for these properties have also been presented for PCNs [60-62],... 

Fig. 1.—The Reaction Rate of D-Glucose with DL-Leucine in Aqueous Solution at pH 9.2 and at Different Temperatures, as Indicated by the Amino Acid Saturation Technique.108...

From Fig. 4 it can be seen that, for finite bandpass detection, one will obtain different fluorescent intensities per emitting molecule depending on the level pumped. This can produce systematic errors in both the determination of absolute concentrations and the use of excitation scans to obtain ground state rotational temperatures (21) Also, the lack of a thermal distribution imposes restrictions on models of and data analysis in optical saturation techniques. 

Kulikov, A. I., Yudanova, E. I. and Likhtenshtein, G. I. (1983). Investigation of the spin-exchange of nitroxide radicals using the continuous ESR spectrum saturation technique. J. Phys. Chem. (Moscow) 56, 2982-2987. (In Russian). 

Collision of nitroxides with fast-relaxing radicals, such as oxygen and metal ion complexes, causes spin exchange that effectively shortens the spin-lattice relaxation time T of the nitroxide (Hyde and Subczynski, 1989). This effect can be measured either by continuous wave (CW) power saturation techniques or by saturation recovery methods. Collision frequency is directly proportional to the accessibility of the paramagnetic reagent to the nitroxide radical and is defined as... 

The most widely used alternative approach in layer construction involves trapping components in a preformed matrix by saturation techniques. In this approach, the matrix of choice is saturated vdth a solution of desired components or reagents. Commonly used preformed matrices include paper, woven fabrics, nonwoven fabrics, and a variety of porous membranes. The availability... 

Ref. 61, l4N spectra, neat CH3N02 external reference in concentric spherical sample containers in order to eliminate bulk susceptibility effects differential saturation technique and full lineshape analysis as in ref. 63, errors quoted are standard deviations for about 200 data points. 

Ref. 38, 14N spectra, originally referred to either internal KNO, (for aqueous solutions, + 3-5 ppm from neat CH,N02, Table VII) or CH3NO, (recalculated according to Table VII) differential saturation technique and lineshape analysis (63). 

Ref. 61,, 4N spectra, concentric spherical sample containers, full lineshape analysis by differential saturation technique, see Table VII for comments. b Ref. 102,14N spectra, referred to external CH3N02. 

Very slow exchange can be detected and the rate measured by the transfer of spin saturation technique, a tool that can be useful in the elucidation of reaction mechanisms causing exchange. One of the signals participating in very slow exchange is saturated by an external radiofrequency (RF) field while the rest of the spectrum is observed. If exchange of the spin-saturated nuclei takes... 

M. R. Bendall, I. L. Cartwright, P. I. Clark, G. Lowe, and D. Nurse. Inhibition of papain by N-acyl-aminoacetaldehydes and N-acyl-aminopropanones. Evidence for hemithioacetal formation by a cross-saturation technique in NMR spectroscopy. Eur. J. Biochem. 79 201 (1977). 

Another interesting and important property of this autoionization is the observed intensity or cross section of about 8 x 10 16 cm2 wh-[ch s much larger than typical values of 10-17 or 10 18 cm. The cross section was measured by a saturation technique. (.5 >1 0 The ion yield at the resonance maximum was determined as a function of the energy density E3 of the ionizing laser pulse to generate the curve shown in Fig. 16 Saturation is indicated by the flat portion of the curve. The point A on the curve is taken as the saturation point characterized by the conditional ... 

The potentiometric titration method possesses some advantages characteristic of potentiometry. The measured e.m.f. values are dependent on the logarithm of the activity (concentration) of the potential-defining ion and this considerably widens the range of concentrations which can be detected. The experimental techniques and routine are rather simple and the obtained results are well reproducible. Owing to the stable activity coefficients of metal cations the measurements can be performed in sufficiently concentrated solutions of the corresponding metal halides. Performing the measurement does not imply any interference in the acid-base processes in the melt studied and the experiment is faster than the isothermal saturation technique discussed above. 

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