Case micro instrumentation

In the case of the capillary blood, it is extremely important that the specimen not be allowed to stand for extensive periods of time before centrifugation. If the blood is to be transferred to the pH meter, then the collecting tube is sealed at both ends during transportation. It is then aspirated into the pH instrument as soon as practicable since one needs a smooth even flow in order to aspirate a specimen into the conventional micro pH meter. After the whole blood has been sampled for various purposes, it is important that the remaining blood be centrifuged promptly. If not, it will clot. Subse-quentially, centrifuging with a clot will tend to hemolyze the blood. Erythrocytes will adhere to the wall and as they are pulled down by the clot, they will be ruptured. Those who do not observe these precautions will find that it is rather difficult to obtain unhemolyzed blood. 

EC detection is a promising alternative for capillary electrophoresis microchips due to its inherent characteristics, allowing a proper miniaturisation of the devices and compatibility with the fabrication processes, in case of an integrated detection. Moreover, the low cost associated permit the employment of disposable elements. As the EC event occurs on the surface of electrodes and the decrease in size usually results in new advantages (see Chapter 32), the possibilities of incorporating EC detectors are broad. The simplicity of the required instrumentation, portable in many cases, suit well with the scaling-down trend. Moreover, as the sample volume in conventional micro-channel devices is less than 1 nL, a very highly sensitive detector should be constructed to analyse even modest concentrations of sample solutions. Since sensitivity is one of the accepted characteristics of EC detection EC-CE microchips approach to the ideal analytical devices. 

The automation of analysis, sometimes with the aid of laboratory robots, has become increasingly important. For example, it enables a series of bench analyses to be carried out more rapidly and efficiently, and with better precision, while in other cases continuous monitoring of an analyte in a production process is possible. Two of the most important developments in recent years have been the incorporation of microprocessor control into analytical instruments and their interfacing with micro- and minicomputers. The microprocessor has brought improved instrument control, performance and,through the ability to monitor the condition of component parts, easier routine maintenance. Operation by relatively inexperienced personnel can... 

From a practical point of view, the discussion on flow-rate can be summarized as follows. In LC-APCI-MS, the typical flow-rate is 0.5-1.0 ml/min. For routine applications of LC-ESI-MS in many fields, extreme column miniaturization comes with great difficulties in sample handling and instrument operation. In these applications, LC-MS is best performed with a 2-mm-ID column, providing an optimum flow-rate of 200 pFmin, or alternatively with conventional 3-4.6-mm-ID columns in combination with a moderate split. In sample limited cases, further reduction of the column inner diameter must be considered. Packed microcapillary and nano-LC columns with micro-ESI and nano-ESI are rontinely applied inproteomics stndies (Ch. 17.5.2). 

This aspect has led to the production of micro- and nanoelectrospray sources, where the chromatographic eluate flow is in the range 1-10 2 pL/min. A typical instrument setup for nano-ESI experiments is shown in Fig. 1.10. In this case, the supplementary gas flow for spray generation is no longer present and the spray formation is only due to the action of the electrical field. The sprayer capillary, with an internal... 

The elemental analyses were carried out by the Australian Micro-analytical Service, CSIRO, Melbourne. IR spectra were recorded on a Unicam SP200 spectrophotometer in potassium bromide discs (for solids) and as thin films between sodium chloride plates (for liquids). Proton magnetic resonance (PMR) spectra of the monomers were recorded on a Varian HA100 instrument and 13C NMR spectra on a Varian CF7/20. In both cases the chemical shifts (8) are quoted in ppm with tetramethyl silane as the internal standard. 

---