Instrumentalanalyse, Automation und Robotics in der Klinischen Chemie

Instrumental Analysis, Automation and Robotics in Clinical Chemistry

Abstract

Clinical chemistry is probably the part of analytical chemistry which is under the greatest pressure with respect to productivity. This results in methods completely different from those used in classical analytical chemistry. Separation methods and the determination of the concentrations of the separated components are usually not possible because of the inherent slowness of the procedures. This is true except in situations where closely related substances that occur as mixtures in biological fluids are to be measured (amino acids, proteins, sugars, fatty acids, drugs and their metabolites). For these special conditions GC-MS, LC-MS and other instrumental methods can be used. For the bulk of tests, however, chemical (photometric), enzymatic, immunological and genetic methods are applied. The components to be measured are specifically determined within the complex biological matrix without prior separation. The often complicated reactions lead to products that can be assessed by photometry, turbidometry, nephelometry or fluorometry. Samples (serum, plasma, urine) are processed in automated devices with high test frequency. Characteristic data are: sample volume 5 to 10 ?l, time of analysis 8 to 10 min, test frequency 200 to 300 tests per hour. For the determination of simple ions ion-selective electrodes are used. Increasingly, robots are engaged for sample preparation, reading of sample identification, centrifugation, decapping of test tubes, aliquoting and identification of aliquot tubes. Instrumental analysis, automation and robotics would be useless without laboratory information systems. Such systems allow the doctor to order the tests from his office terminal. According to the request, barcodes are printed to identify the sample tubes. The samples with barcode but without any accompanying form are taken to the laboratory and the reading of the barcode triggers the download of the request into the laboratory system.