WAVE™ system chromatography

Helfferich, F. G., Whitley, R. D. Non-linear waves in chromatography II. Wave interference and coherence in multicomponent systems, J. Chromatogr. A, 1996, 734, 7-47. 

Helfferich, F.G. (1997) Non-linear waves in chromatography III. Multicomponent Langmuir and Langmuir-like systems. 

Adsorption Chromatography. The principle of gas-sohd or Hquid-sohd chromatography may be easily understood from equation 35. In a linear multicomponent system (several sorbates at low concentration in an inert carrier) the wave velocity for each component depends on its adsorption equihbrium constant. Thus, if a pulse of the mixed sorbate is injected at the column inlet, the different species separate into bands which travel through the column at their characteristic velocities, and at the oudet of the column a sequence of peaks corresponding to the different species is detected. 

Ion chromatography (see Section 7.4). Conductivity cells can be coupled to ion chromatographic systems to provide a sensitive method for measuring ionic concentrations in the eluate. To achieve this end, special micro-conductivity cells have been developed of a flow-through pattern and placed in a thermostatted enclosure a typical cell may contain a volume of about 1.5 /iL and have a cell constant of approximately 15 cm-1. It is claimed15 that sensitivity is improved by use of a bipolar square-wave pulsed current which reduces polarisation and capacitance effects, and the changes in conductivity caused by the heating effect of the current (see Refs 16, 17). 

There are numerous properties of materials which can be used as measures of composition, e.g. preferential adsorption of components (as in chromatography), absorption of electromagnetic waves (infra-red, ultra-violet, etc.), refractive index, pH, density, etc. In many cases, however, the property will not give a unique result if there are more than two components, e.g. there may be a number of different compositions of a particular ternary liquid mixture which will have the same refractive index or will exhibit the same infra-red radiation absorption characteristics. Other difficulties can make a particular physical property unsuitable as a measure of composition for a particular system, e.g. the dielectric constant cannot be used if water is present as the dielectric constant of water is very much greater than that of most other liquids. Instruments containing optical systems (e.g. refractometers) and/or electromechanical feedback systems (e.g. some infra-red analysers) can be sensitive to mechanical vibration. In cases where it is not practicable to measure composition directly, then indirect or inferential means of obtaining a measurement which itself is a function of composition may be employed (e.g. the use of boiling temperature in a distillation column as a measure of the liquid composition—see Section 7.3.1). 

The outline of this chapter is as follows First, some basic wave phenomena for separation, as well as integrated reaction separation processes, are illustrated. Afterwards, a simple mathematical model is introduced, which applies to a large class of separation as well as integrated reaction separation processes. In the limit of reaction equilibrium the model represents a system of quasilinear first-order partial differential equations. For the prediction of wave solutions of such systems an almost complete theory exists [33, 34, 38], which is summarized in a second step. Subsequently, application of this theory to different integrated reaction separation processes is illustrated. The emphasis is placed on reactive distillation and reactive chromatography, but applications to other reaction separation processes are also... 

Ma, Z., Wang, N.-H. Standing wave analysis of SMB-chromatography Linear systems, AIChE /., 1997, 43, 2488-2508. 

Standing wave analysis of SMB-chromatography linear systems. AIChEJ., 43, 2488-2508. 

Analytical Methods. The analytical method for carbaryl and 1-naphthol by high performance liquid chromatography (HFLC) was recently described for aqueous samples (9). Similarly, these two compounds were analyzed in these studies using a Waters 6000A Solvent Delivery System, WISF Automatic Sample Frocessor, Data Module and Automatic Integrator, and Model 4530 Variable Wave Length Detector, set at 230 nm. A Water uBondapak reverse-phase column (25 cm x 2 mm i.d.) was employed. The following experimental conditions were maintained ... 

We have developed a proprietary acoustic wave device which permits the detection of a specific analyte in a flowing system. By coupling specific chemistry (Protein A) to the surface of the device, the mass loading of the device by the target analyte (Human IgG) was detected as a shift in phase which was measured in real time. Using conditions which mimic a bioprocess separation for IgG, we were able to separate and detect Human IgG at 1 mg/ml and 100 ug/ml in the absence and presence of 10% Fetal Bovine Serum. Such a detector has the potential to increase productivity in process chromatography in biopharmaceutical applications. 

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