Abstract: The invention relates to new crown ether derivatives of the general Formula I ##STR1## and a process for the preparation thereof wherein Z.sup.1 is a group of the general Formula ##STR2## R.sub.a and R.sub.b may be the same or different and R.sub.a represents an alkyl group having 1-4 carbon atoms and R.sub.b is an alkyl group having 1-20 carbon atoms.The new crown ethers are useful in the preparation of ion-selective electrodes having a long lifetime.

Abstract: New crown ether derivatives of formula (I) ##STR1## wherein R stands for hydrogen or C.sub.1-4 alkyln stands for 1,2,X stands for oxygen, sulphur or a NH-groupY represents hydrogen or nitroZ represents a chemical bond, --CH.sub.2 --, --(CH.sub.2).sub.2-4 --, --CH.sub.2 OCH.sub.2 --, --CH.sub.2 SCH.sub.2 --, ##STR2## or a group of the formula ##STR3## suitable for forming cation complexes, process for the preparation thereof and alkali or alkali earth metal ion-selective membrane electrodes containing said compounds are described.

Abstract: The present invention relates to electro-analytical measuring equipment for the determination--by means of one or more measuring cells comprising sensing elements of chemical similar composition, being in constant galvanic contact with each other--of the concentration and ion-activity of solutions or of the partial pressure of gases. The sensing elements are in contact with sample or with one or more standardizing media separated in time or space. At least two reference electrodes are in direct or in indirect contact--through electrolite--with sample and standardizing medium. The reference electrodes join, in a given case, to electronic signal processor comprising arithmetic unit calculating, by fault compensation, value of one or more parameters to be measured.

Abstract: An electro-analytical measuring process and apparatus for the determination of the concentration and the ion-activity of stationary or flowing solutions or of the partial pressure of gases. The measuring cell of the measuring equipment--connected to an electronic signal processor--comprises, in addition to one or several sensing elements and reference electrodes, at least one fluid clutch capable of galvanically short-circuiting one or more parts of the measuring chain. The measuring cell of the measuring equipment comprises, in a given case, integral sensing unit and standardizing media, being in contact with sensing elements. Further, a control unit for programming short-circuiting belongs to the measuring cell, a fault compensating unit producing signals is connected to the control unit--for calculating the value of the parameter to be measured--is connected to the output of the fault compensating unit.

Abstract: A molecule selective sensor having two permeable membranes in contacting relationship with each other, one membrane being a protein membrane found in nature, as for example, hog intestine membrane, air bladder of fish, epidermal section of mammals and reptiles, etc. and the other membrane being the reaction product of acrylamide, polyvinylalcohol, an enzyme, bovine albumin and glutaric aldehyde.

Abstract: A molecule selective sensor has an enzymatically active membrane which is prepared by reacting an enzyme with glutaric aldehyde on the surface of a protein membrane found in nature. Exemplary is the reaction of glucoseoxidase with glutaric aldehyde on the surface of hog intestine membrane.

Abstract: The invention relates to a process of and equipment for a selective, quick and accurate analysis of liquid samples. According to the process of the invention a liquid or a gas sample absorbed by a liquid is allowed to flow at a constant volume rate and overtitrated with an amount of a reagent adequate to the measurement in a definite time. Then the flow of the reagent is decreased to zero in a definite time, meanwhile continuously following, in a known way, the changes occurring in the reaction mixture. The determination of the concentration is carried out by comparing the time elapsed between the appearances of the two chemical equivalence points with calibration curves prepared with standard solutions, said time having a well defined functional relationship with the concentration of the sample.

Abstract: Highly sensitive, selective halide and sulfide-sensitive electrodes featuring a sensing block of spherical surface and laminar design compensating for the effect of thermal dilatation and the absence of a liquid junction.

Abstract: The invention relates to coulometric measuring for the determination of the concentration and/or factor of acids or bases. A reference electrode and a measuring electrode sensitive to the activity of hydrogen ions of the indicator circuit and an anode and a cathode electrode of the generator circuit, are arranged in the measuring cell of the measuring apparatus. As a depolarizer and potential determining substance, the chloride, bromide or iodide of potassium, sodium, rubidium, cesium, calcium, strontium or barium is added in excess to the supporting electrolyte in the measuring cell.Inaccuracy and instability brought about by the diffusion potentials arising at the diaphragms can thus be eliminated.

Abstract: A selective fluoride-sensitive electrode featuring a sensor block of spherical surface compensating the effect of thermodilatation and prepared from the fluorides of a lanthanide mixture corresponding to the composition of the natural occurrents or from a mixture composed of the majority of lanthanides.