Flow Injection Analysis of Pharmaceuticals Automation in the laboratory

Flow Injection Analysis of Pharmaceuticals Automation in the laboratory

Flow injection analysis, or non-segmented flow analysis, is now a mature technique. It has taken at least 20 years for it to reach this state; during this time it has been put on a reasonably well-defined theoretical basis, a vast range of procedures have been devised and tested, commercially produced equipment has become available and the whole technology has become trusted and appreciated. Nowhere has its value been greater than in pharmaceutical analysis, and nowhere is its value better demonstrated than in this book.

The author is one of the foremost practitioners and innovators in flow injection analysis. Many of his contributions have been in pharmaceutical analysis, and are clearly described in the text. It is, however, a comprehensive text, dealing with all aspects of the technique that relate to the analysis of pharmaceutical and related products. This means, of course, that a considerable proportion of the information relates to flow injection analysis in general—theory, instrumentation, novel configurations and processes and detectors. Only in the detailed applications is the emphasis placed on pharmaceuticals. I can recommend this text, therefore, as a general description of flow injection processes that will be valuable to all analytical scientists, whatever their area of work. It also presents an excellent description of the power of this technology in one important analytical area, that of pharmaceuticals.


1.1 Fundamentals and Objectives of Analytical Automation

Man has long strived to minimize or replace fully his involvement in a variety of tasks by devising substitute machines and instruments; the chemical laboratory, the ultimate site for chemical analyses, has obviously joined in this trend.

The need to automate analytical processes gradually is unarguable. The earliest serious attempts at automating chemical analyses date from the 1970s. The vast amount of literature and opinion supporting time and labour investments in the automation of the analytical laboratory, aired during the 1970s and early 1980s, is now a thing of the past.

While the path travelled in this direction so far has been highly fruitful, there is still a long way to go (in fact, ways in science have no dead ends). Therefore, the following reasons, advanced to justify automation of the analytical laboratory, remain valid if things are to be further improved:

1 Personnel release. Replacing a human operator in routine or hazardous tasks (e.g.those involving toxic or explosive substances) results in increased safety and avoidance of subjective errors.

2 Improved analytical performance, particularly with regard to precision of the

results.

3 More efficient use of the effective capacity of analytical instrumentation and more

rational management of chemical reagents. Minimizing reagent consumption decreases analytical costs and results in improved environmental safety through decreased disposal of hazardous wastes or diminished exposure of laboratory staff to toxic chemicals, such as the organic solvents typically used in closed flow systems. Increasing instrumental power enables processing of very small samples or use of multi-parameter assemblies for several determinations at once.

In addition to the above ‘analytical chemical’ reasons, the need for laboratory automation is justified by other arguments. Thus, there are management reasonssuch

Flow Injection Analysis of Pharmaceuticals

as the need to minimize costs, extend working days in order to process large numbers of samples (e.g. in clinical laboratories) or perform analyses at odd hours (e.g. production controls, public water supply check-ups, atmospheric pollution controls in zones of heavy traffic, etc.). There are also reasons arising from social demands for increasingly higher living standards; this entails massive, continuous controls of pollution, water potability, food and drink quality, etc., all of which involve analysing large sample batches.

Improving existing automatic processes, cutting costs, automating analytical operational sequences by suppressing manual operations linking other, automatic operations, will remain pending goals until the whole analytical process, from sampling to result interpretation, can eventually be automated.

Fully automated analyses are the ultimate goal of laboratory automation. This inevitably entails performing analyses ‘on site’, i.e. carrying out every operation, from sampling to result delivery, at the site of the sample, thereby avoiding the need to handle it for transfer to the laboratory and altering (contaminating) it during storage or transport. On-site analyses entail the use of specific monitors, mobile laboratories or even remote sensors.

The earliest available fully automatic methods were those used in mining and oil drilling; these were later followed by those employed to monitor industrial processes at some point along the productive chain. More recently, atmospheric analyses have been automated with the aid of spectrophotometric detectors installed in a mobile vehicle (a plane or van), as have determinations of control parameters in waste and drinking waters, and clinical analyses involving direct connection of the patient to the measuring instrument (there are reported instances of blood analyses where the patient’s bloodstream was directly connected to the injection valve of a flow injection analysis (FIA) system).

Automation of the analytical laboratory can be viewed from two different standpoints: the automation of laboratory unit operations (LUOs); and the automation of an operational sequence. It should be noted that, very often, the overall process comprises only one or two unit operations (e.g. in control analyses, determinations of melting and boiling points, pharmaceutical dissolution tests, etc.). There are a number of commercially available devices for automating a unit operation (e.g. the dissolution of solid samples and transfer of the resulting liquid) in the sample preparation step. As regards operational sequences, the trend should be towards automating the whole analytical process, where ‘whole’ is meant to include every operation performed after the sample, properly stored, is received by the analyst. In this respect, it should be borne in mind that any analytical process consists of the following fundamental steps:

  


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