Design features and operation of a prototype miniaturized Fast Analyzer are described, and some results obtained with it are presented. The Analyzer occupies only one cubic foot of space. It has a 17-cuvet plastic rotor that rotates through a stationary optical system at speeds up to 5000 rpm. The resulting centrifugal force is utilized to transfer and mix a series of sample(s) and reagent(s) into the cuvets. The ensuing reactions are monitored spectrophotometrically, and the data evaluated in real time by an on-line computer. Samples (1 to 10 µl) and reagents (70 to 110 µl) are loaded into the rotor either discretely or dynamically; various rotor configurations can be used to do this. Many of the standard clinical analyses, including most of the NADH-linked enzymatic analyses, have been adapted for use with this analyzer. Precision obtained ranges from 1 to 4%. This report considers, specifically, analyses of some serum enzymes. Results show that the small analyzer possesses the previously demonstrated advantages of Fast Analyzers and, in addition, has several beneficial features arising from miniaturization.
A modified version of a previously described miniature Fast Analyzer [Clin. Chem. 18, 753 (1972)] was used as the basis for developing a compact, potentially portable, analytical system. This system includes an automated and versatile sample-reagent loader, a miniature Fast Analyzer, several plastic rotors and their cleaning station, and a portable data system. The sample-reagent loader combines a unique turntable assembly and two "Micromedic" pipets to quickly (5 min per rotor), accurately, and precisely obtain, transfer, and dispense small volumes of sample (1 to 10 µl of sample, 50 µl of diluent) and reagent (20 µl of reagent, 50 µl of diluent) into their respective cavities in a 17-cuvet rotor. The loader uses separate sample and reagent carousels, which allows operation of the system in either the single-sample—multiple-chemistry, multiple-sample— single-chemistry, or multiple-sample—multiple-chemistry analytical modes. The miniature Fast Analyzer rotates a loaded 17-cuvet rotor through a stationary optical system at speeds up to 5000 rpm. The resulting centrifugal force is used to mix and to transfer the discrete aliquots of sample(s) and reagent(s) into their respective cuvets. The ensuing reactions are monitored photometrically, and the data are processed in real time by either a portable Data Processor [Clin Chem. 18, 762 (1972)] or an on-line computer. A major improvement to the analyzer has been the addition of a temperature-control system that allows the temperature of the spinning rotor to be monitored and controlled to within ±0.2°C. After completion of an analytical run, the rotor is automatically washed and dried in the rotor cleaning station. Many of the standard clinical analyses, including most of the NADH-linked enzymatic analyses, have been adapted for use with this system.
A miniature Centrifugal Fast Analyzer has been modified for fluorescence and light-scatter measurements by using several rotors developed for this purpose. The modified system has been used to evaluate the feasibility of adapting specific protein analyses, such as IgG, IgA, IgM, C'3 complement component, and α-1-antitrypsin, to the Centrifugal Fast Analyzer. A study of reaction conditions has revealed that the addition of polyethylene glycol 6000 (Carbowax) to the dilution medium increases the rate of reaction and allows apparent equilibrium to be achieved in less than 60 s. Furthermore, scatter intensity is enhanced. This system can be used to make rapid immunoglobulin measurements with only microliter volumes of antibody (2-7 µl), without the need of sample blanks. Determination of antigen excess by a method that involves dynamic injection of antibody is also discussed.
Cr20,2-+ 14H' MnOp + 4H' + EO = +1.52 volts (1) EO = +1.33 volts (2) Eo = +123 volts (3)Fe3+ + e e Fez+ Eo 5 +0.77 volts (5)Thus, there is no problem of any interference from Mn2+ or C r s which are in general present in rocks in small amounts (Mn from 0.05 to 0.2%, Cr from 1 to 4000 ppm). The presence of an appreciable amount of "acid decomposable sulfide" invalidates the ferrous iron determination. Pyrite is not appreciably attacked by mixture of HF and HC1 but other sulfides, such as pyrrhotite, are more extensively decomposed liberating hydrogen sulfide which will result in higher values of ferrous iron. Organic matter other than graphite will completely invalidate the meth- od.The relative 70 deviation has been calculated on the amounts present. CONCLUSIONSFerrous iron can be determined by the iodine monochloride method without any possible aerial oxidation and without any interference from manganese or chromium. Ferrous iron in carbonate and other acid decomposable rocks (which are attacked by HCl or HCl and HF) can also be determined. Acid decomposable sulfides and organic matter other than graphite invalidate the method.
With a newly developed automated sample-reagent loader, for use with a GeMSAEC Fast Analyzer, a 15-place GeMSAEC transfer disk can be automatically loaded with reagent and samples in 3.25 min; manual loading methods required 15 min. The resulting precision and accuracy is equal to or better than that for manual methods of loading. Sample carryover of the system was decreased, and is about 1%.
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