Automated solution analysis

The development of FI separation and preconcentration techniques is a logical extension following the advent of FIA. The inception of FIA in turn is the result of a long. search for better laborator> techniques in solution manipulation which could match the efficiency of the computer age. The important stages of development in this quest for efficiency and automation in the chemical laboratory are shown in Figure 1.1.. which also shows the relation between the various techniques for automated solution analysis and the scheme for their classification. 

An important breakthrough in laboratory automation was the introduction of continuous flow analysis by Skeggs in 1957[4]. With this system analytical chemistry was for the first time performed in conduits instead of discrete vessels, which greatly improved the efficiency of serial assays. After being marketed by Technicon under the trade name AutoAnalyzer, the system became the most widely accepted equipment for automated solution analysis before the advent of FIA. Yet the conventional concept of performing... 

Fig.1.1 Stages of development and classification of automated solution analysis.

Non-chromatographic separations based on ion-exchange and adsorption have been used extensively for enhancing the selectivity and sensitivity of analytical methods. Although most procedures involve some kind of continuous flow operation, nevertheless they are mostly off-line batch procedures which require considerable operational efforts. Automation of sorption separation procedures is therefore a topic which has attracted much interest. FI on-line separation and preconcentration by sorption is an area which has shown great promise in this respect, and in fact, is an area which has become one of the most active research fields in automated solution analysis in recent years. 

Nitrite is commonly determined by a colorimetric procedure using a reaction called the Griess reaction. In this reaction, the sample containing nitrite is reacted with sulfanilimide and N-(l-Napthyl) ethylenediamine to form a colored species that absorbs at 550 nm. By using an automated flow analysis instrument, the following results were obtained for standard solutions of nitrite and for a sample containing an unknown amount ... 

With the ever-increasing need to improve quality and productivity in the analytical pharmaceutical laboratory, automation has become a key component. Automation for vibrational spectroscopy has been fairly limited. Although most software packages for vibrational spectrometers allow for the construction of macro routines for the grouping of repetitive software tasks, there is only a small number of automation routines in which sample introduction and subsequent spectral acquisition/data interpretation are available. For the routine analysis of alkali halide pellets, a number of commercially available sample wheels are used in which the wheel contains a selected number of pellets in specific locations. The wheel is then indexed to a sample disk, the IR spectrum obtained and archived, and then the wheel indexed to the next sample. This system requires that the pellets be manually pressed and placed into the wheel before automated spectral acquisition. A similar system is also available for automated liquid analysis in which samples in individual vials are pumped onto an ATR crystal and subsequently analyzed. Between samples, a cleaning solution is passed over the ATR crystal to reduce cross-contamination. Automated diffuse reflectance has also been introduced in which a tray of DR sample cups is indexed into the IR sample beam and subsequently scanned. In each of these cases, manual preparation of the sample is necessary (23). In the field of Raman spectroscopy, automation is being developed in conjunction with fiber-optic probes and accompanying... 

However, even if samples can be analyzed in an automatic fashion by XRD, automated phase analysis by computer based methods is still in its infancy. Typically, XRD patterns have to be inspected manually, and especially if phase mixtures are formed, as it often happens in zeolite chemistry, the analysis of the patterns can become the bottleneck. Work is in progress in different laboratories to solve this problem, but no suitable solution has been published yet. 

Methods of Assay. — The Technicon basic autoanalyser sampler system has been modified for simultaneous sampling of glycoside hydrolases and substrate-buffer solutions. This inexpensive modification allows performance of automated enzyme analysis and enzyme kinetic studies with minimal consumption of substrate and/or enzyme. 

There are multiple ways to spot samples. For instance, the sample and matrix may be mixed before spotting, or either solution may be spotted first with or without drying in-between. Often it is worth trying multiple approaches to sample loading to see which provides the best signal-to-noise ratio. Robotic placement of samples is applicable for the eluates from nano-LC. The signals from automated, sequential analysis of hundreds of spots replicate LC chromatograms. In these applications the MALDl plate is often pretreated with the matrix solution to provide an appropriate surface for the analytes. 

Teledyne Tekmar (2013) Pesticide Analysis Using the AutoMate-Q40 An Automated Solution to QuEChERS Extractions, Application Note April 2013, Teledyne Tekmar, Mason, OH. 

A number of simple, standard methods have been developed for the analysis of ammonium compounds, several of which have been adapted to automated or instmmental methods. Ammonium content is most easily deterrnined by adding excess sodium hydroxide to a solution of the salt. Liberated ammonia is then distilled into standard sulfuric acid and the excess acid titrated. Other methods include colorimetry (2) and the use of a specific ion electrode (3). 

The graphics capabiUties of the CAD/CAM environment offer a number of opportunities for data manipulation, pattern recognition, and image creation. The direct appHcation of computer graphics to the automation of graphic solution techniques, such as a McCabe-Thiele binary distillation method, or to the preparation of data plots are obvious examples. Graphic simulation has been appHed to the optimisation of chemical process systems as a technique for energy analysis (84). 

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