Poisson chromatography

The area of a peak is the integration of the peak height (concentration) with respect to time (volume flow of mobile phase) and thus is proportional to the total mass of solute eluted. Measurement of peak area accommodates peak asymmetry and even peak tailing without compromising the simple relationship between peak area and mass. Consequently, peak area measurements give more accurate results under conditions where the chromatography is not perfect and the peak profiles not truly Gaussian or Poisson. 

The theoretical work that exploited the advantages of the multidimensional separation format appears to have been developed much later than the original experimental work. One of the earliest studies was conducted by Connors (1974), who assumed that the distribution of spots on a two-dimensional thin-layer chromatography (2DTLC) plate could be modeled using a Poisson distribution of data on each retention axis. He then constructed equations that related the number of chromatographic systems needed to resolve a specific number of compounds. One... 

Nonsolvent bath, polymer precipitation by immersion in, 15 808-811 Nonspecific elution, in affinity chromatography, 6 398, 399 Nonstationary Poisson process, in reliability modeling, 26 989 Non-steady-state conduction, 9 105 Nonsteroidal antiinflamatory agents/drugs (NSAIDs) 21 231 for Alzheimer s disease, 2 820 for cancer prevention, 2 826 Nonsulfide collectors, 16 649 Nonsulfide flotation, 16 649-650 Nonsulfide mineral flotation collectors used in, 16 648-649t modifiers used in, 16 650, 651t Nonsulfide ores, 16 598, 624... 

Retention of proteins in ion exchange chromatography is mainly caused by electrostatic effects. Because both the protein and the surface have an electrical double layer associated to it, there is an increase in entropy when the two surfaces approach each other. This is due to a release of counter ions from the two double layers when they overlap. The model that is discussed here is based on a solution of the linearized Poisson-Boltzmann for two oppositely charged planar surfaces. We also show the result from a model where the protein is considered as a sphere and the... 

A stochastic theory provides a simple model for chromatography.11 The term stochastic implies the presence of a random variable. The model supposes that, as a molecule travels through a column, it spends an average time Tm in the mobile phase between adsorption events. The time between desorption and the next adsorption is random, but the average time is Tm. The average time spent adsorbed to the stationary phase between one adsorption and one desorption is rs. While the molecule is adsorbed on the stationary phase, it does not move. When the molecule is in the mobile phase, it moves with the speed ux of the mobile phase. The probability that an adsorption or desorption occurs in a given time follows the Poisson distribution, which was described briefly in Problem 19-21. 

Equation (10) is the basic elution curve equation it is a Poisson function, but when n is large, the function approximates to a normal error function or Gaussian function. In practical chromatography systems, n is always greater than 100 and, thus, all chromatographic peaks will be Gaussian or nearly Gaussian in shape. 

The broadening of a band varies with the / N (or r for column chromatography). N is the number of theoretical plates in the column. From the Poisson distribution, the band width = 4 N. 

A major target in downstream processing is the isolation of a specific biomolecule from a solution that may contain several thousand substances. The ideal situation is a single-step purification procedure, but the statistical probability of isolating a pure molecule from such a mixture by one chromatography step is determined by a Poisson distribution and falls exponentially with the number of compounds [2]. The only way to improve this situation is to increase the affinity of the resin for the target molecule. The affinity constant is defined as [3] ... 

They undergo transfer all the time, but approximately only once for 100 steps of propagation. A new population of macromolecules that participated in transfer reacts slowly with the populations with Poisson distribution. The Af n of the populations participating in the segmental exchange (i.e., intermolecular transfer) is the same, but differs and this appears on the size-exclusion chromatography (SEC) traces, resulting in bimodal and broader distribution. Finally at equilibrium, the value equal to 2, typical for the most... 

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