Relative concentrations, relaxed error

Measured errors in concentration were determined relative to the fully relaxed spectnun acquired with a repetition time of 5Ti. 

FlDs with a reduced tip angle increased by a factor of 1.74 for ibuprofen and 1.54 for maleic acid relative to the SIN obtained with 64 FIDs and a 90° tip angle. This is again attributed to the differences in Ti for the two molecules and leads to an inflated ibuprofen concentration (63.1 mM compared to 56.6mM). While the error might be less if the relaxation times are nearly the same for the standard and the analyte, in many quantitation experiments a 90° tip angle and repetition time of >5ri are used, especially if extensive signal averaging is not required. ... 

Henry s equation (2.6) assumes that is low, in which case the double layer remains spherically symmetrical during electrophoresis. For high zeta potentials, the double layer is no longer spherically symmetrical. This effect is called the relaxation elfect. Henry s equation (2.6) does not take into account the relaxation effect, and thus this equation is correct to the first order of Ohshima et al. [19] derived an accurate analytic mobility expression correct to order 1/ka in a symmetrical electrolyte of valence z and bulk concentration (number density) n with the relative error less than 1% for 10 < Ka < 00, which is... 

The above values of certain rate constants are at variance with those quoted by Hammes and Fasella . These workers used the temperature-jump technique to determine the relaxation times associated with intermediates believed to be formed in the course of transamination, but the assignment of the observed phenomena to particular intermediates is somewhat arbitrary. The main source of error in applying this relatively new method to enzyme-catalysed reactions lies in the very high protein concentrations (greater than 10" m) required. It is quite possible that, under these conditions, enzyme-substrate complexes which do not lie on the normal reaction path may be present in significant amounts. 

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