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In industrial liquid separation processes chromatography often has a key function in the optimization of yield and purity. For the design of an industrial system, chromatographic processes are generally simulated using mathematical models, tested and optimized at laboratory level, and then scaled up to pilot and subsequently industrial scale. To describe the system, experimental data and model data need to be fitted and extra column contribution must be determined. This paper describes the influence of extra-column volume on overall separation efficiency for lab scale and its impact on the design of large scale systems. Measurement of extra-column contribution was investigated in terms of mean retention time and variance using two different methods the commonly used zero dead volume connector and as an alternative the zero length column. Further a technique is presented to estimate extra-column contribution to band broadening for different injection volumes, velocities, and tracers based on representative measurements. When scaling up, often contribution of extra-column volume from laboratory equipment is neglected assuming to be on the safe side, however column efficiency is often lower than efficiency measured for the entire chromatographic system. Relation between system efficiency and column efficiency was investigated using laboratory data and the lumped kinetic model. Depending on the ratio of extra-column volume to retention volume in the system, deduced column efficiency was up to 20% smaller than overall system efficiency. This ratio revealed the misleading nature of the term efficiency loss, when describing influence of extra-column volume on column efficiency. A scheme, which relates the relative variance of the system to the relative extra-column volume, provided an assessment of under- or overestimation of column efficiency. In this article it is shown how scaling up a system based on laboratory data, where extra-column volume contribution is not accounted for, may severely overestimate column efficiency. This overestimation results in underestimated column dimensions at pilot and industrial scale, and hence underperformance of the industrial system.

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Further, two different kinds of chromatography can be distinguished by their aim, namely analytical and preparative chromatography. The aim of analytical chromatography is to identify and quantify the contents of a sample. Small volumes are used and sample recovery is not necessary, analytes are sometimes modified, denatured, or labelled and discarded as waste after detection [2]. The aim of preparative chromatography is to collect the eluting sample fractions for further use, while maintaining their functionality. Therefore target components are purified and collected, with focus on fast recovery, high productivity, and desired purity. Chromatography within the food industryExamples of current use of chromatography within the food industry are given in Table 1.1. The chromatographic systems process large product streams. A few examples are production of various whey protein isolate products in a continuous simulated moving bed system SMB with a capacity of over 1 million liters of cheese whey per day [18]. A different type of chromatographic system, where the stationary phase is not packed but rather sedimenting down against the upwards flowing feed stream, expanded bed adsorption chromatography, is used for production of lactoferrin, lactoperoxidase, and immunoglobulins from cheese whey, processing more than 200,000 L of cheese whey per day [18]. In beet sugar processing, sucrose is recovered from molasses by SMB systems with a capacity of over 600 t per day (with 80% dry matter) [19].In the previous chapters experiments were done with single columns using model solutions with viscosifier agents to increase the viscosity. In chapter 5 a multicolumn separation process SMB is used to obtain a γaminobutyric acid enriched fraction from tomato serum. This separation is based on ion-exclusion chromatography IEC. A mathematical model of the process is validated and used to determine the conditions with the highest productivity.The thesis concludes with a general discussion in chapter 6 on the results in the previous chapters. Further addressed are increasing temperature, as a means to work with concentrated streams while minimizing the viscosity increase, and the influence of a change in peak shape on the separation performance at elevated Chapter 1 17.