Computer-assisted development

Occasionally, a binary mixture will not enable the separation to be attained. In this case a ternary mixture may be helpful. There is much in the literature about using more than one organic solvent in the mobile phase for attaining selectivity. Not only do chromatographers share insights about how and why solvents contribute to a separation, but there are also available software routines for computer-assisted development of mobile phases using... 

Galushko, S. et ah, Chromsword Software for Automated and Computer-Assisted Development of HPLC Methods, in HPLC Made to... 

ChromSword Software for Automated and Computer-Assisted Development of HPLC Methods... 

Artificial lift techniques are discussed in Section 9.6. During production, the operating conditions of any artificial lift technique will be optimised with the objective of maximising production. For example, the optimum gas-liquid ratio will be applied for gas lifting, possibly using computer assisted operations (CAO) as discussed in Section 11.2. Artificial lift may not be installed from the beginning of a development, but at the point where the natural drive energy of the reservoir has reduced. The implementation of artificial lift will be justified, like any other incremental project, on the basis of a positive net present value (see Section 13.4). 

In 1967, work was presented from a Sheffield group on indexing chemical reactions for database budding. In 1969, a Harvard group presented its first steps in the development of a system for computer-assisted synthesis design. Soon afterwards, groups at Brandeis University and TU Munich, Germany, presented their work in this area. 

In the development of the CAMEO system (Computer-Assisted Mechanistic Evaluation of Organic reactions) [8 it was decided to treat large classes of mechanistically related reaction types by separate modules. 

Program systems for computer-assisted organic synthesis (CAOS) have been under development since the early 1970s [27]. The program systems for computer-assisted synthesis planning can be subdivided into two groups information-oriented and logic-oriented systems [28]. 

However, better use of spectral information for more rapid elucidation of the structure of a reaction product, or of a natural product that has just been isolated, requires the use of computer-assisted structure elucidation (CASE) systems. The CASE systems that exist now are far away from being routinely used by the bench chemist. More work has to go into their development. 

An alternative approach (78,79) is based on a set of possible reaction schemes that are used to generate potential new pathways. Under both approaches, the problem, in part, is how to evaluate the utiUty of a particular scheme. A computer-assisted approach to predicting potentially useful reactions has been developed (80). The union of existing capabiUties in modeling chemical stmctures with selecting reaction pathways has not yet taken place. 

This paper describes work on equipment and instrumentation aimed at a computer-assisted lab-scale resin prep, facility. The approach has been to focus on hardware modules which could be developed and used incrementally on route to system integration. Thus, a primary split of process parameters was made into heat transfer and temperature control, and mass transfer and agitation. In the first of these the paper reports work on a range of temperature measurement, indicators and control units. On the mass transfer side most attention has been on liquid delivery systems with a little work on stirrer drives. Following a general analysis of different pump types the paper describes a programmable micro-computer multi-pump unit and gives results of its use. 

Current Development. Following success of the prototype IPU a second more comprehensive facility was commissioned. This is capable of up to four pumps of mixed peristalitic or diaphragm types, each linked to specific feed vessels on individual balances. The whole is interfaced to an IBM AT computer (see Figure 7) which in addition to Intelligent liquid additions, has the capacity to absorb modules from the work on temperature control and stirring in a full multi-tasking computer-assisted system, as mentioned above. 

The experimental results obtained in the laboratory by the researchers can be monitored using computer programs with help of empirical equations or models. Most of the computer-assisted procedures have been developed for HPLC separations and mainly for RPLC, and some of them are commercially available. 

Procedures used vary from trial-and-error methods to more sophisticated approaches including the window diagram, the simplex method, the PRISMA method, chemometric method, or computer-assisted methods. Many of these procedures were originally developed for HPLC and were apphed to TLC with appropriate changes in methodology. In the majority of the procedures, a set of solvents is selected as components of the mobile phase and one of the mentioned procedures is then used to optimize their relative proportions. Chemometric methods make possible to choose the minimum number of chromatographic systems needed to perform the best separation. 

Stanton, D. T., Jurs, P. C. Development and use of charged partial surface area structural descriptors in computer-assisted quantitative strucmre-property relationship smdies. Anal. Chem. 1990, 62, 2323-2329. 

Glajch, J.L., Snyder, L.R., editors (1990). Computer-Assisted Method Development for High-Performance Liquid Chromatography. Elsevier, Amsterdam. 

This derivation shows that retention time is dependant on three factors temperature, energies of intermolecular interactions and flow rate. Temperature and flow rate are controlled by the user. Energies of intermolecular interactions are controlled by stationary phase choice. This theory is also the basis for the popular software programs that are available for computer-assisted method development and optimization [4,5,6,7]. More detailed descriptions of the theory behind retention times can be found in the appropriate chapters in the texts listed in the bibliography. 

L. van Heukelem and C.S. Thomas, Computer assisted high-performance liquid chromatography method development with applications to the isolation and analysis of phytoplankton pigments. J. Chromatogr.A 910 (2001) 31—49. 

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