Abstract: A process and an apparatus for performing analyses in liquid chromatography, by means of a pump capable of drawing a fluid and injecting it at high pressure, through at least a control valve, into a separation column. To obtain maximum precision as required by the analysis, before each analysis or each group of analyses, or with respect to each fluid used, a pump stroke is performed with the pump delivery side shut off in order to record and memorize the characteristics of compressibility of the fluid. These characteristics are kept into consideration in the subsequent operative stages to obtain an exactly constant delivery of the feed pump to the separation column.

Abstract: A process and an apparatus for performing analyses in liquid chromatography, by ways of a pump capable of drawing a fluid and injecting it at high pressure, through at least a control valve, into a separation column.To obtain maximum precision as required by the analysis, before each analysis or each group of analyses, or with respect to each fluid used, a pump stroke is performed with the pump delivery side shut off in order to record and store the characteristics of compressibility of the fluid. These characteristics are kept into consideration in the subsequent operative stages to obtain an exactly constant delivery of the feed pump to the separation column.

Abstract: The invention concerns a device for picking up liquid samples to be analyzed, especially in automatic samplers, said device comprising a needle connected to a sucking pump and supported by a support which moves said needle downwards to pick up the sample from a vial containing same and upwards from said vial. In order to perform a washing step after one aspiration and before the subsequent one, the needle support is designed to perform an oscillating movement when the support is in its upward position with respect to the vial. The oscillating movement is performed by the cooperation of cam means and a control rod having at least a pivot axis controlling the alternative movements. The oscillating movement makes the needle plunge into a sidewardly positioned trough containing a washing liquid.

Abstract: Instrument for analyzing, by means of photometric measurements, precisely metered quantities of samples, such as serum, plasma, cerebro-spinal liquid and the like, homogeneously diluted in selectively prechosen reagents.