Abstract:
A sampling device for photometric determination of the content of an analyte in a sample of whole blood has at least one measuring chamber having two wall parts, at least one wall part being locally transparent, at least one wall part being sufficiently deformable to facilitate displacement of the whole blood sample from the measuring chamber. The measuring chamber also contains a transparent body having a radiation transmission characteristic dependent upon the concentration of a predetermined analyte in the whole blood sample. The sample device is employed in an analyzer for photometric determination of the content of an analyte in a sample of whole blood and in a method of photometric in vitro determination of the content of an analyte in a sample of whole blood. In the method, a sample of whole blood is transferred directly from an in vivo locality to the sampling device, the measuring chamber therein is deformed in a controlled manner to substantially drain the whole blood from the measuring chamber, radiation is transmitted through the substantially drained measuring chamber, detected, and the analyte content determined.
Abstract:
New apparatus for measuring parameters such as pH, pCO.sub.2, pO.sub.2, and Hb content of physiological fluids, especially blood, is described. The apparatus comprises novel means for suspending reagent vessels (34, 35, 40, 45, 50) having shoulders (51, 52) and containing calibrating solutions, rinsing solutions etc., as well as for suspending a liquid waste vessel (26) by suspending the vessels between rods (53, 54) fed to the analyser. The reagent vessels are provided with caps (55, 58) at the top and include liquid reagent conduit extending from the outlet aperture of the cap down into the liquid. When the vessel is mounted on the analyser a fixed inlet tube extending horizontally outwardly from the analyser penetrates a seal across the outlet aperture and connects with the liquid reagent conduit.
Abstract:
The concentration of molecular oxygen in a sample is determined by exciting oxygen molecules of the sample from the electronic ground state to the excited .sup.1 .DELTA..sub.g state (excited singlet state), measuring a 1270-nm luminescence characteristic of the excited oxygen molecules (singlet oxygen) and correlating the luminescence characteristic measured with the concentration of molecular oxygen in the sample. Normally, the 1270-nm luminescence characteristic is the 1270-nm luminescence intensity. Preferably, the oxygen molecules are excited by being subjected to diffusion contact with a sensitizer such as a porphyrin or a porphyrin-related compound, e.g. a transition metal complex of a porphyrin. The sensitizer is brought into an oxygen-exciting electronic state by absorption of electromagnetic radiation such as light, the oxygen-exciting electronic state optionally being adapted to the measuring system employed by means of a quencher such as a substituted polyene. The sensitizer may be present in an organic solvent or a polymer such as polyvinylchloride. The oxygen-containing sample is preferably a sample of biological origin such as a blood sample.
Abstract:
Method and apparatus for spectrophotometrically determining the concentration of a number of hemoglobin derivatives comprising at least deoxyhemoglobin and oxyhemoglobin or parameters derived from the concentration of individual hemoglobin derivatives, in particular the oxygen saturation fraction, in whole blood, in which light is transmitted to the blood under test, the modification on the light transmitted to the blood which the blood causes is determined at a number of individual wavelengths, and the concentrations (or the derived parameters) are determined on the basis of the light modification at the individual wavelengths and on the basis of predetermined coefficients representing the light absorption characteristics of each of the hemoglobin derivatives at each of the individual wavelengths, any error on the determination values due to turbidity being substantially compensated for by utilizing predetermined coefficients representing an absorption characteristic of turbidity at each of the wavelengths. The measurement is normally performed at a number of wavelengths which is at least equal to the number of hemoglobin derivatives to be determined plus one. Although the turbidity-caused contribution to the total reduction in the light transmission is not based on any direct proportionality between the reduction in light transmission and the concentration of the turbidity-causing components (such as is the case with the hemoglobin derivatives), the "absorbances" caused by the turbidity at each particular wavelength may simply be eliminated from the equation set from which the concentrations of the hemoglobin derivatives are calculated.
Abstract:
In order to counteract coagulation of a blood sample which is collected from an animal or a human body (24) and introduced into a receptacle, such as a syringe chamber (14), an anticoagulant is added to the sample within the receptacle. The anticoagulant may be capable of binding cation species in the blood, which are subsequently to be measured. Such cation species comprise hydrogen ions, ammonium ions, alkaline metal ions such as potassium and sodium ions, and alkaline earth metal ions such as magnesium and calcium ions. In order to compensate for the proportions of selected cation species which are bound by the anticoagulant, an additive containing such cation species is added to the blood sample so as to obtain substantially the same concentration of the selected cation species in an unbound condition in the anticoagulant treated blood sample as in the untreated blood sample.The anticoagulant and the additive are preferably added to the blood sample as a composition which may be deposited on or carried by a carrier body (15) which may be arranged within the receptacle in which the blood sample is introduced. The bulk density of the nonwetted carrier body is preferably smaller than the specific weight of the blood sample so as to avoid trapping of air bubbles within the receptacle. In its wetted condition the bulk density of the carrier body is preferably also different from the specific weight of the blood sample so that the carrier body (15) may be used as an agitating member improving mixing of the anticoagulant composition with the blood sample. The carrier body (15) may, for example, be made of filtering paper.
Abstract:
A capillary tube containing a sample is anaerobicly sealed by means of closure caps each comprising an end wall and a skirt portion. Each open end of the capillary tube is sealed by inserting the open tube end into the cap skirt portion, and in order to avoid that a volume of air is forced into the capillary tube, the space defined between the open tube end and the cap end wall is vented to the atmosphere through one or more venting passages defined in the walls of the closure cap or between the inner surface of the cap skirt portion and the adjacent outer peripheral surface of the capillary tube. The open tube end is brought into sealing engagement with sealing means on the cap end wall, and frictional engagement established between the inner surface of the cap skirt portion and adjacent outer peripheral surface parts of the capillary tube secures that said sealing engagement is maintained.
Abstract:
A reference liquid for calibration or quality control of instruments which determine ionized calcium and pH. The reference liquid contains both a particular calcium ion activity and a pH-buffer and can therefore be used for calibration of both the calcium-sensitive electrode and the pH-electrode in the instruments. The pH-buffer is a nitrogen-containing organic sulphonic acid and the salt of this acid, the acid having a pK in the range of 6.6-7.6. The reference liquid has an ionic strength of 0.15-0.17, a buffer capacity .beta. in the range of 0.04-0.10 and is packed in glass ampoules.
Abstract:
An electrode for polarographic measurement of the partial pressure of oxygen in gases or solutions, comprising a cathode in contact with and outwardly shielded by a gas permeable membrane, a silver/silver bromide half cell serving as anode, and a bromide-containing aqueous electrolyte in contact with the anode and the cathode, the bromide ion concentration of the electrolyte being between 10.sup.-4 and 5 .times. 10.sup.-3 M, preferably 5 - 6 .times. 10.sup.-4 M.
Abstract:
A process for automatic titration wherein the dosage of titrant is controlled by a digital computer, the titration being started with at least one dosage of a preselected size, each dosage of titrant thereafter and throughout the total course of the titration being precalculated and controlled on the basis of transducer signal change per added titrant volume unit at the preceding dosages in such a way that the titrant dosages are relatively smallest around the equivalence point.
Abstract:
Electrochemical measuring electrodes often have a thin foil-shaped membrane, e.g. made of a plastic foil, which is arranged at one end of a cylindrical portion of the electrode and maintained in position by means of a resilient ring-shaped member, e.g. an O-ring, which presses the folded-over edge portion of the membrane against the outside of the cylindrical portion. It is now suggested to guide the ring-shaped holding member in such a way on the cylindrical portion that it protrudes beyond the membrane and thereof. The guiding may be provided by means of a circumferential groove in the cylindrical portion near the membrane end thereof.