Hemox Analyzer Components

Optical Bench

The optical bench is of modular construction and is located on the front of the housing base. The light source is a tungsten halogen source, located on the left end of the optical bench. A pair of collecting lenses is focusing the primary beam on the center of the sample cavity, after the heat radiation (IR) has been removed by a heat filter. The cavity is located approximately at the center of the optical bench, where it is mounted in a cored cell housing, containing the cavity heating system as well as a cooling loop for use with an optional cooling bath or tap water cooling. To the right of the cavity is a third collecting lens, which collimates the secondary beam and projects it onto the photo multiplier detection system. A beam splitter diverts 50% of the light to detector l, while the other 50% are falling upon detector 2. Before reaching their respective detectors, the light passes through narrow band monochromatic filters for proper wavelength selection. The two built in, removable filters, provide the best conditions for use with the HEMOX analyzer.


P02 Measurement

The oxygen concentration of an aqueous solution is very easily measured with a CLARK oxygen electrode. This method of measurement not only is accurate, but also reliable and reproducible. The HEMOX ANALYZER uses such a CLARK electrode for determining the oxygen concentration directly in the sample cavity where the absorbance is also being monitored.

Under normal conditions the oxygen concentration or, as it is commonly called, the oxygen partial pressure, under athmospheric conditions of 760 mm of mercury, is 158 mm of mercury for the sample in the cavity. This saturation point is used for full scale calibration of the recorder prior to starting the plotting of the curve.

When the oxygen is being replaced by an inert gas, as for for instance nitrogen, argon or helium, in a continous procedure, hemoglobin becomes deoxygenated according to the following equation: [HbO ] <----> Hb + O

The figure to the right shows a typical association curve of normal blood which was obtained with the HEMOX ANALYZER. The curve recording was started with the blood sample in the deoxygenated state and was then slowly oxygenated. When the x axis reading is approx. 1.5 mm Hg, i.e. the oxygen partial pressure has reached almost zero, and the hemoglobin has been almost completely deoxygenated, the recording of the curve can be started, i.e. the oxygenation can begin, by flipping the gas selector switch into the "AIR" position and setting the pen to to the starting position.

In addition to plotting association curves with the instrument, it is also possible to plot the dissociation curve by starting with the sample in the oxygenated state and slowly deoxygenating it. However, in order to obtain a hysteresis free recording of both curves, the gas flow and stirring speed must be critically adjusted, resulting in a much longer plotting time of one hour or more.

The new Model B has been adjusted specifically for the recording of the association curve. If it is desired to record the dissociation curve, it will require not only adjusting of the stirring speed and gas flow, but also a change of the time constant in the amplifier circuit.