The slide had a special spreading layer made of cloth, which enabled the use of whole blood samples. Since then, various DRI-CHEM slides and analyzers have been developed to fulfill the increasing needs of emergency testing, and a range of peripheral items were also developed. For instance, special pipette tips, now called FUJI CLEAN TIPS, were introduced to enable automatic spotting. Because the tips don’t require wiping, there is little danger of operator contamination from blood samples.
The recently introduced FDC series are now widely used in international markets as automatic clinical chemistry systems. The FUJI DRI-CHEM system is used not only in clinical laboratories but also in veterinary clinics.
The system has two major principles of measurement, one is colorimetric and the other is potentiometric.
(Enzymes, General chemistry, Immunology)
For a glucose slide, the actual measurement is conducted as follows. 10 microliters of plasma or serum are spotted on a FUJI DRI-CHEM SLIDE GLU-PIII. After spotting, the sample spreads uniformly on the spreading layer and diffuses into the underlying layer. As the process proceeds, large molecular weight components such as proteins or dye components are filtrated, and only small molecular weight components are able to permeate and diffuse into the reagent layer. Glucoseoxidase (GOD) catalyzes the oxidization of sample glucose to generate hydrogen peroxide. In the presence of peroxidase (POD), hydrogen peroxide reacts with dye precursors and finally forms red dye. The slide is incubated at 37°C for a specified number of minutes in the FUJI DRI-CHEM analyzer and the optical reflection density is measured at 505nm. The aforementioned optical reflection density is then converted into the glucose concentration using a calibration curve preinstalled in the analyzer.
Potentiometric slide (Electrolytes)
Potentiometric analysis is based on measurement of the generated voltage difference between ion selective electrodes applied to a reference solution and to the sample. In the FUJI DRI-CHEM system, ion selective electrodes for sodium (Na), potassium (K) and chloride (Cl) are set into one slide. After spotting 50 microliters of the sample and of the reference solution on the slide, the slide is incubated for one minute in the FUJI DRI-CHEM analyzer and the potentiometric difference between the sample and the reference solution is measured. The potentiometric value is then converted into each electrolyte concentration using a calibration curve preinstalled in the analyzer.