SU1578641A1 - Apparatus for taking samples and introducing them to analyzer of composition - Google Patents

Abstract

The invention relates to analytical instrumentation and can be used for the selection and input of samples in gas and liquid chromatographs. The purpose of the invention is to increase the reproducibility of dosing while reducing (by the order of A channel is made in the device case that connects the internal volume of the syringe with the capacity of the flushing unit. The syringe piston is located in the needle connected to the housing with a sealing sleeve. A longitudinal groove is made on the side surface of the piston, the length of which exceeds the length of the sealing sleeve by an amount larger than the diameter of the syringe piston. 2 Il.

Description

(P

with

The invention relates to analytical instrumentation, in particular to devices for introducing samples into gas and liquid chromatographs, and can be used in automatic dispensers for liquid samples.

The purpose of the invention is to increase the reproducibility of dosing while reducing (by an order of magnitude) the size of the dosing volume.

The invention is illustrated in FIG. 1.2.

The device comprises a housing 1 with a tip 2 and an outer guide tube 3 disposed therein, moving along the inner guide tube 4, inside which is located a piston 5 connected with a button 6 and tube 3. A needle is fixed in the tip 2 by means of a cap nut 7 8, sealed by the sleeve 9. The piston 5 passes through the hole

bushings 9 and, in the initial position, occupies the entire internal volume of the needle 8. At a distance of 2-3 mm from the end of the piston 5, located in the needle 8; A groove 10 is made, the length of which is 1.2-1.5 times the length of the sleeve 9. In the tip 2, a channel 11 is made connecting the internal volume of the tube 4 with a source of washing liquid (not shown). In the upper part of the housing 1 there is a seal 12.

The device works as follows.

Before sampling, the piston 5 moves to the extreme upper position, in which the groove 10 of the piston 5 is aligned with the sleeve 9 and connects the internal volume of the tube 4 and the internal volume of the needle 8. Through the channel 11 the flushing fluid flows, which passed through the groove 10 and the gap between the conel

00

oh

four

the piston 5 and the inner walls of the needle 8 fall into the internal volume of the needle 8. This causes washing of the groove 10, the end of the piston 5, the area of the needle 8 near the sealing sleeve 9 and the inner surface of the needle 8, through which the flushing fluid is drained from the needle 8 into drive (not shown). The flushing time and the amount of flushing fluid pumped through the syringe is selected by the operator depending on the desired flushing quality. The sleeve 9 is made of fluoroplastic having relatively low ductility, therefore, during the flushing time (10-60 s), the groove 10 in the piston 5 does not fill with the material of the sleeve 9.

At the end of the flushing piston 5

moves to the lowest position, with the entire free volume of the needle 8 and the groove 10 remaining filled with the washing liquid (usually the diluent in which the sample is dissolved). The supply of flushing fluid is stopped and channel 11 is connected to the atmosphere, while the internal volume of the syringe displaces some of the liquid that has entered the gaps between the piston 5 of tube A and tube 3. The displacement occurs due to compressed (fluid pressure) air flowing through the gap between the tube 3 and the housing 1. A small amount of washing fluid is constantly present in the above gaps, helping to reduce friction (wear) between the rubbing parts of the syringe and reducing the force of displacement of the syringe piston 5, which is important When using the syringe in an auto magic dispensers of liquid samples.

Next, the analyzed fluid is sampled, for which the end of the needle 8 is placed in the vessel with the analyzed fluid, and the piston 5 is moved to a distance corresponding to the volume of fluid being withdrawn. This completely eliminates the possibility of air bubbles entering the internal volume of the needle 8. To eliminate

§

0

five

0

0

five

0

five

partial dilution of the test fluid with the solvent in the needle 8 takes several cycles of collection and discharge of the test fluid. After sampling, it is introduced into the chromatograph, and then the operation of washing the syringe is repeated. The groove 10 can also be located in the middle part of the piston 5 or at the very end of the piston 5, while in the first case the reproducibility of dosing increases, but the range of dosing volumes decreases simultaneously, and in the second case the quality of flushing of the end of piston 5 interacting with the breakdown decreases.

The length of the sleeve 9 and, accordingly, the groove 10 should be minimal, since their increase leads to an increase in the parasitic volume inside the syringe and, accordingly, to a decrease in the reproducibility of the sample dosing. The most appropriate use of this syringe in automatic dispensers of liquid samples, as it allows you to easily automate the washing operation and ensures the accuracy and repeatability of the selection with the same movement of the piston 5 (there is no air in the internal volume of the needle 8).

Claims (1)

Invention Formula A device for taking and entering samples into the composition analyzer, comprising a dosing unit with a washing unit and a dosing syringe, in the body of which a channel is made connecting the internal volume of the syringe with the capacity of the washing unit, so as to increase the reproducibility of dosing and reduce of the dispensed volume, the syringe piston is located in the needle, the needle and the syringe body are connected through a sealing sleeve that interacts with the piston, on the side surface of which a longitudinal groove is made, the length of which is extends the length of the sealing sleeve by an amount greater than the diameter of the syringe piston. 1 AT 10 Aa