Sample enrichment factor, defined

Donnan dialysis of conjugate bases of weak acids presents an additional factor for control, namely pH. Cox and Cheng (34) investigated preconcentration of a number of anions in this category. Sample pH was adjusted to ensure that a major fraction of the weak acid system was in anionic form. Maximum enrichment factor, defined as ratio of receiver concentration to sample concentration after some given, fixed time (usually 30 minutes), was obtained when pH of the receiver solution was much less than the... 

One convenient way to compare a given sample to a chosen reference material is the so-called enrichment factor. The enrichment factor (Ej) is defined as the concentration ratio of a given element i and the normalizing element j(Xi/Xj) in the given sample divided by the same ratio in the reference material, i.e.,... 

The enrichment factor, abbreviated EF, is a criterion used most often for evaluating preconcentration systems [9]. Despite its frequent usage, the jflfecise meaning of the term is not well-defined. Theoretically, the term is meant to be the ratio between the analyte concentration in the ccHicentrate, C and in the original sample, C,. i.e.. 

In principle, all effective FI continuous precipitation systems with dissolution may be used to achieve some degree of analyte preconcentration. The only prerequisite is that enough sample is available. Within limits defined by the capacity of the precipitate collector, the enrichment factors EF will be proportional to the amount of sample processed. The efficiencies of different preconcentration systems, however, may be quite different. A quantitative evaluation of the efficiencies of the systems may be made using the criteria originally proposed for on-line column preconcentration methods. i.e., in terms of CE and CL These are calculated for the various methods collected in Tables... 

The enrichment factor of a sample preparation technique is defined as follows ... 

The performance of any type of molecular separator is characterized in terms of its separation factor (enrichment) M and separator yield (efficiency) Y (8). The separator yield is defined as the ratio of the amount of sample entering the mass spectr( eter to that entering the separator, usually expressed as a percentage, it represents the ability of device to allow... 

The typical Rx values presented here are 0, 0.1/99.9,0.5/99.5,1/99, 4/96, 10/90, 20/80, 50/50. The magnification factors indicated by the graphs, allow to compute the uncertainty to be expected on a given quantitative determination of an element by IDMS. The assumption a R) = eR (Eq. (13)) is not applicable to very enriched and depleted samples, and in those cases the uncertainties are worse than indicated by the graphs. However, good mass spectrometers and measurement procedures achieve a constant uncertainty on R measurements for values from 0.01 to 100, i.e. over four useful orders of magnitude. Attention is drawn on the fact that an isotope ratio can be defined as either Nz/N-t or N N2 and therefore it is always possible to choose fix 1-... 

This becomes even more evident from the data in Table III where the phase concentration factors (PCF) are calculated as the percentage of a certain metal association vs. the percentage content of the respective carrier material (phase is defined here as one of the major sediment fractions, for example, Fe/Mn hydroxides, humic acids, carbonates). If the computed value lies above one, an enrichment has occurred in the studied phase if the value is less than one (as for all metals in the residual phases except chromium), the metal concentration in the sample... 

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