Automatic water sampling systems

They describe the development of a system employing a Tenax GC filled purge and trap sampler, which collects and concentrates volatile organotins from water samples (and species volatilised by hydrodisation with sodium borohydride), coupled automatically to a gas chromatograph equipped with... 

It consists of a rail-mounted carriage, which carries rows of sample beakers past three stations where each sample receives an aliquot of extractant (usually water), is thoroughly stirred, and has an electrode or electrodes lowered into it. The electrical output from the electrode(s) is passed through an amplifier to a flatbed recorder. Control of the sequence of operations is completely automatic, involving a system of three interlocking motor-driven cam timers, thereby ensuring that each sample receives identical treatment. 

Tropical storms, typhoons, or hurricanes, depending on their strength and geographical context, often deliver torrential rains. Increased river flow during such high intensity, low frequency rainfall events can transport a major portion of annual river N load to coastal systems. Historically, there has been a paucity of data on such events due to their irregular and extreme nature and the generally manual nature of water sample collection for nutrient analyses. However, with the use of in situ automatic water samplers and nutrient analysis systems, data from such events can now more readily be captured. 

With current system improvements in development, a device that automatically detects, classifies with high probability, and extracts a sample which is diverted directly to an automatic rapid test verification system, all without operator intervention, will soon be commercially available. Combined with a suite of other chemical, toxin, and radiological real-time sensors and an integrated data analysis and alert response system, the ultimate water security system is quickly becoming a reality. 

Figure 3. Diagram of automatic column monitoring system. Aliquots of column effluent are injected at regular intervals into the detection system. The injected sample is transported with water to a manifold, where the buffer and fluorescamine are added. Fluorescence is measured and recorded. (From Stein, 1980.)...

Direct determination - pumping the water directly into the Automatic Sampling System. 

Valve/loop injectors are the most common method of introducing the sample, and several models are available. The only special requirement for SEC applications is to ensure that the injection loop is sufficiently large (up to 200 jul). Autoinjectors are available, and are particularly useful for routine or QC-type applications. They enable the chromatograph to run unattended (if coupled to a suitable automatic data acquisition system), but of course still require an operator to make up and filter solutions, load the carousel and process the data. They are particularly useful in high-temperature SEC where solutions must be prepared and injected at temperatures up to 150°C. Jhe Waters 150 C high-temperature chromatograph is provided with this facility. 

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