There is disclosed a method of determining the toxicity of a fluid sample comprising the steps of: (i) mixing the sample with a suspension of light emitting organisms; (ii) monitoring the light output (E) of the mixture continually over a period of time (t.sub.o -t.sub.n) using a photodetector device sensitive to the wave length of the emitted light; and (iii) determining the differential d(log E)/dt to give a measure of toxicity concentration.

A highly sensitive assay for the determination of Cr(VI), in the presence of Cr(III) and in the presence of other cations by cyclic voltammetry. The determination is carried out with a gold or gold-plated electrode with a self-assembled monolayer of a pyridine derivative of the kind of 4-(2-ethanethiol) pyridine. Determinations can be affected at extremly low levels of the order of 1 ppt (part per trillion 10.sup.12).

An apparatus for determining the concentration of a first component in a mixture of at least two components, which have different absorption properties in the IR range, comprises image recording means which are adapted to image the mixture by means of IR radiation to produce at least one image. The apparatus further comprises image processing means which, with the aid of intensity values for pixels in the image which represent the mixture, determine the concentration of the first component in th...

The invention relates to a method for the determination of the object distance between an opto-electronic sensor working according to the principle of triangulation and an object, wherein the sensor has at least one measuring channel between a transmission unit for the emission of electromagnetic sensing rays into the measuring region and a reception unit for the detection of sensing rays reflected and/or remitted from the measuring region; wherein the sensor has at least one additional channel ...

Apparatus for the determination of biomass in a suspension and its use in a fermentation apparatus. The apparatus includes electrodes to be placed in the suspension and the following other components: circuit for applying an alternating voltage between the electrodes; circuit for providing a current signal indicative of the current in the current electrode circuit; circuit for providing a voltage signal indicative of the voltage between the ratio between the value of the voltage signal and the v...

The present invention relates to the determination of thrombocytopenia induced by an inductor drug such as heparin. According to the invention, a sample is mixed with a complex of an antigenic substance such as platelet factor 4 (pF4) and heparin to determine if the sample contains antibodies which react with the complex. The presence of these antibodies is indicative of heparin-induced thrombocytopenia.

The cleanliness of water-rinsed surfaces originally carrying hazardous compositions is determined by using a surface active agent as a marker in said material prior to placing the composition into contact with the surface.

A method for the liberation of polysaccharide antigens from bacteria or fungi in biological probes or in grown cultures of these probes is described. In the majority of cases such a liberation is necessary in order that subsequently the polysaccharide antigens can be determined immunologically in a manner known per se. This liberation is effected by treating the biological probe or the grown culture with an aqueous phenol solution. A 1-10% phenol solution is conveniently used, with a 2.5% phenol...

A system for positional determination includes an array of piezoelectric sensor electrodes connected to an array of output lines via resistors for providing a binary code in response to activation of the sensor electrodes; and an array of further output lines also connected to the array of sensor electrodes via resistors for providing a binary error code in response to activation of the sensor electrodes. By combining the resultant binary code and binary error code, an accurate determination of ...

A position-coding pattern (3) which extends across a surface and codes a plurality of positions (7a, 7b) on the surface is described. The coding in a first dimension is based on the use of a first and a second string of symbols, each containing a predetermined number of symbols and each having the characteristic that if a specific number of symbols is taken from the first string of symbols, the location of these symbols in the string of symbols is unambiguously determined. By means of displaceme...