JPH0389147A - Introduction of sample into cell of atomic absorption photometer and hybrid apparatus for implementing the same - Google Patents

Abstract

PURPOSE: To improve the reproduction precision and accuracy of atomic absorption analysis by coupling a hollow tube element for supplying a liquid sample to a cell with an injector through a thin pipe arranged in it coaxially and inserting its end into the cell. CONSTITUTION: A means 2 for arranging the liquid sample includes the hollow tube type element 5 for putting the liquid sample in the cell 3, and the element 5 is connected to the injector 1 through the thin pipe 6. The tin pipe 6 extends in the element 5 coaxially. The element can move reciprocally along the longitudinal axis 7 of the cell 3 and rotate on a longitudinal axis 9 so as to insert its end 8 into the end 4 of the cell 3. A hole 10 for atomizing a sample of a substance to be analyzed over the entire operation surface of the cell 3 is bored in the main body of the element 5 right nearby the end 8. A conic chamber 11 is provided at the end 8 in the means 2 together with the thin pipe 6 which extends through a slight bottom so as to limit a clearance 12 on the internal surface of the element 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to atomic absorption spectrometry and more particularly to a method for introducing a sample into a cell of an atomic absorption spectrophotometer. It also relates to an arrangement for implementing the method.

The invention is applicable to analytical chemistry.

[Conventional technology]

It is known how to introduce a sample into the cell of an atomic absorption spectrophotometer (where sample vapor is supplied to the cell).
("5 pectro chim, acta", 19
82. No. 12, Frech et al., “A New
Furnace Design for Constant
Temperature Blectroth
Ermal Atomic 8BSOR tion 5
pectroscopy, 1021-1028
page).

In this method, the vapor of the liquid sample is generated by first conveying the liquid sample into the pot furnace through the holes in the cell at the temperature of the pot furnace at 60 °C.
The sample vapor is introduced into the cell at 0 °C for 40-60 seconds, where the sample vapor is heated to the sample atomization temperature, which requires a lot of time while the pot furnace performs the atomic absorption analysis. After being heated to vaporization temperature,
supplied to the cell.

Also known is an arrangement for introducing a sample into a cell of an atomic absorption spectrophotometer to carry out the method, comprising an injector for supplying a liquid sample to a means for conveying sample vapor to the cell. (see same article).

In this arrangement, the means for conveying sample vapor to the cell includes a pot furnace communicating with the cell that cannot provide the required reproducibility or desired analytical accuracy due to diffusion of the sample into the body of the furnace. .

a liquid sample of the substance to be analyzed is placed in the cell;
Methods of introducing a sample into the cell of an atomic absorption spectrophotometer are also known (“Aralytical Chemis
try”, 1983, No. 2, 5oterua, etc.
Reduction of Matrix Inter
ferences 1nFurnace Atomic
Absorption Spectrometry”
(See pages 204-208).

In this method, a liquid sample is placed in the cell by injecting the sample in atomized form into an analysis chamber placed inside the cell, but this results in non-uniform deposition of the aerosol on the surface of the chamber and Possible losses of the sample during the injection (the sample is injected at a temperature of 150° C.) result in low reproducibility and low accuracy of the atomic absorption spectrometry.

introducing a sample into a cell of an atomic absorption spectrophotometer to effect a method comprising: a syringe for supplying a liquid sample of the substance to be analyzed, the means for placing the liquid sample into the cell; Arrangements for this are also known (see the same document).

In this arrangement, the means for placing the liquid sample in the cell is an injector for injecting the sample into an analysis chamber placed in the cell, where it is not possible to ensure a set amount of liquid sample that can be injected into the cell. Although it has the shape of a zector,
resulting in lower accuracy of analysis.

[Problem to be solved by the invention]

The present invention provides a method for introducing a sample into the cell of an atomic absorption spectrophotometer, in which a liquid sample of the substance to be analyzed is placed in the cell in order to ensure an even application of the liquid sample to the working surface of the cell. An object of the present invention is to provide a method and an arrangement for introducing a sample into a cell of an atomic absorption spectrophotometer to carry out the method, wherein the means for placing a liquid sample in the cell without loss is provided. The cell is configured to provide a set amount of liquid sample, thereby improving the reproducibility and accuracy of atomic absorption spectroscopy.

[Means to solve the problem]

The object of the invention is achieved by the following method.

In a method for introducing a sample into a cell of an atomic absorption spectrophotometer, wherein a liquid sample of a substance to be analyzed is placed in the cell, according to the invention, a liquid sample is placed in the cell. Before the cell is heated to a temperature 1-2 °C below the boiling point of the liquid sample, and a liquid sample of the substance to be analyzed is placed into the cell by spraying the liquid sample onto all working surfaces of the cell. .

The cell is heated to a temperature 1-2° C. below the boiling point of the liquid sample to facilitate evaporation of the sample without the boiling of the sample normally associated with sample sputtering and possible loss of sample due to sputtering.

The objects of the invention are also achieved by the following arrangement. wherein the sample is placed in a cell of an atomic absorption spectrophotometer for carrying out said method, comprising a syringe for supplying a liquid sample of the substance to be analyzed to means for placing the liquid sample in the cell. In an arrangement for introducing, according to the invention, the means for arranging the liquid sample in the cell are adapted for supplying the liquid sample to the cell, adapted such that the liquid sample is supplied at the end thereof. a hollow tubular element connected to a syringe through a capillary coaxially disposed within the tubular element;
It can be reciprocated along the longitudinal axis of the cell and rotated around its longitudinal axis to insert it into the cell at its end, and ensure spraying of the liquid sample over the entire working surface of the cell. It has a hole made in its body just near its end that can be inserted into the cell to do so.

Said embodiment of the apparatus arrangement for carrying out the method of the invention comprises:
Thanks to the application of a predetermined volume of a homogeneous layer of a liquid sample of the substance to be analyzed to the working surface of the cell, an improved reproducibility and accuracy of the atomic absorption spectrometry is ensured.

In order to carry out the method of the invention, a syringe 1 (FIG. ) is provided for introducing a sample into a cell of an atomic absorption spectrophotometer.

A spectrophotometer is not shown in the drawings as it is not an object of the invention. As the atomic absorption spectrophotometer, any known suitable spectrophotometer can be used. One modification concerns the cell 3, which is adapted to introduce the sample to be analyzed at its end 4.

In an embodiment of the arrangement for carrying out the method of the invention, the means 2 include a hollow tubular element 5 for introducing the liquid sample into the cell 3, which communicates with the syringe 1 through a capillary 6. The capillary 6 (FIG. 2) is the tubular element 5
It extends coaxially within the .

A hollow tubular element 5 (FIG. 1) has its end 8 at the end 4 of the cell 3.
can be reciprocated along the longitudinal axis 7 of the cell 3 and can be rotated about its longitudinal axis 9 (FIG. 2) in order to insert the cells.

In the body of the hollow tubular element 5 (FIG. 3) in the immediate vicinity of the end 8,
Holes 10 are provided on all working surfaces of the cell 3 (FIG. 1) for spraying a sample of the substance to be analyzed. A conically shaped chamber 11 is provided at the inner end 8 (FIG. 3) of the means 2 with a capillary tube 6 extending through its slight bottom to define a clearance 12 on the inner surface of the element 5. The oval end 8 acts as the main bottom surface of the chamber.

In an embodiment of the arrangement for carrying out the method of the invention, a mechanism 13 (FIG. 1) for rotating the hollow tubular element 5 about its longitudinal axis 9 (FIG. 2) and a longitudinal axis 7 of the cell 3. A mechanism 14 (FIG. 1) is provided for imparting a reciprocating movement to the hollow tubular element 5 along the axis.

The mechanism 13 for rotating the element 5 has the form of an electric motor with the tubular element 5 acting as an output shaft. The electric motor is rigidly fixed to a post 15 which is rigidly fixed on a base 16 which can be reciprocated along a Z-shaped guide by a mechanism 14.

This mechanism 14 (FIG. 4) includes an electric motor 18,
This output shaft 19 is operatively connected through a reducing gear 20 to a shaft 21 having outer threads 22 and 23, the threads 22 meshing with inner threads 24 (FIG. 2) in the body of the base 16. , and another thread 23 (FIG. 4) mesh with a gear 25 fixing the bushing 26 of the rod member 27 of the syringe 1 thereon.

The bushing 26 (FIG. 1) is adapted to cooperate through a slot 29 formed in the base 16 with a rod 27 which is spring loaded by a spring 30. The body of the rod 27 (FIG. 4) has a passage communicating with the capillary tube 31 for filling the syringe 1 with a liquid sample of the substance to be analyzed and for cleaning the syringe 1. A cock 32 is provided with a capillary tube 31 to close it.

Referring again to FIG. 1, the post 15 comprises an L-shaped holder 33 of the element 5 extending through a bearing 34 journalled in a hole provided in a place 35 of the L-shaped holder 33.

[For production]

The operating principle of the arrangement for introducing a sample into the cell of an atomic absorption spectrophotometer for carrying out the method of the invention is as follows.

The rotation mechanism 13 (FIG. 1) acts to rotate the hollow tubular element 5, so that the cell 3 is heated to 99°C and the capillary 3
1 is opened and an aqueous solution of a sample of the substance to be analyzed is supplied through the capillary tube 31 (FIG. 1) to clean the means 2 and fill the syringe 1, which Thereafter, the cock 32 (FIG. 4) of the thin tube 31 is closed.

The cell 3 is subsequently blown with an inert gas, after which the hollow tubular element 5 is moved at 90° to the optical axis of the spectrophotometer by means of an electric motor 18 through a reducing gear 20 and a shaft 21.
It is rotated and inserted into the end 4 (FIG. 1) of the cell 3. After inserting the hollow tubular element 5 into the cell 3, and before the beginning of its working part, the pusher 26 is inserted into the shaft 21 meshing with the gear 25. Through the engagement of the outer thread 23 (FIG. 4) movement of the rod 27 of the syringe 1 is caused.The movement of the hollow tubular element 5 (FIG. 1) along the longitudinal axis 7 of the cell 3 is caused by the movement of the hollow tubular element 5 (FIG. 1) The chamber 11 of 5 is supplied with the sample from the syringe 1 through the capillary 6 and through the hole 10 as a result of the centrifugal force caused by the rotation of the hollow tubular element 5.
The sample is sprayed onto the working surface of the cell 3 (FIG. 1).

As a result of a reliable and uniform translational movement and rotation of the hollow tubular element 5, the entire working surface of the cell 3 is evenly covered with the liquid sample of the substance to be analyzed. Application of the sample to the working surface of the cell 3 heated to 99 °C, accompanied by blowing with an inert gas, causes rapid drying of the sample, which prevents the diffusion of the sample into the body of the cell, and atomic absorption spectrometry Improve reproducibility and accuracy. After the rod 27 has expelled all of the sample from the syringe 1, the spraying of the liquid sample onto the working surface of the cell 3 is stopped and the hollow tubular element 5 (FIG. 1) is activated by the electric motor 18.
It is pulled out from the cell 3 by reverse rotation (FIG. 4).

〔Effect of the invention〕

The arrangement for carrying out the method of the invention allows the application of a liquid sample of the substance to be analyzed in an even layer over the entire working surface of the cell (area of 100 mm"). From the boiling point of the sample Spraying of the liquid sample onto the working surfaces of the cell heated to a temperature of 1-2 °C lower and simultaneous blowing of the thus applied sample with an inert gas accelerates drying and into the body of the cell. At the same time, the evaporation of the sample from the working surface of the cell enhances the analytical peaks, resulting in higher accuracy for atomic absorption spectrometry.The spraying of a predetermined amount of liquid sample prevents the analytical Enables higher repeatability.

Furthermore, the arrangement for carrying out the method of the invention increases the useful use surface of the cell by several times, making it possible to increase the volume of the liquid sample supplied to the cell, resulting in a higher accuracy of atomic absorption spectrometry. bring about. 1~ than the boiling point of the liquid sample
Spraying the liquid sample over the entire surface of the cell, which is heated to a temperature 2° C. lower, reduces the time required for drying the sample and thereby expedites the steps involved in performing the analysis.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram in axial projection of an arrangement of the invention for introducing a sample into the cell of an atomic absorption spectrophotometer for carrying out the method of the invention; FIG. 3 is an enlarged longitudinal sectional view of the tubular element of the arrangement shown in the figure; FIG. 3 is an enlarged sectional view of section A of FIG. 1; and FIG. 2 is a mechanical drawing of a mechanism for imparting reciprocating motion to the hollow tubular element of the device; FIG. Explanation of reference numbers used in the drawings: 1. Syringe; 2. Means for placing a liquid sample; 3.
Cell, 4... End, 5... Hollow tubular element, 6... Thin tube, 7... Vertical axis, 8
... end, 9 ... vertical axis, 10 ... hole,
DESCRIPTION OF SYMBOLS 11... Chamber 12... Clearance, 13... Rotating mechanism, 14... Mechanism for imparting reciprocating motion, 15...
Post, 16...Base, 17...Guide, 18.
...Electric motor 19...Output shaft, 20.
...Reducing diameter gear, 21...Shaft, 22.
23...Outer thread, 24...Inner thread,
25...Gear, 26...Pusher 27
...Rondo, 28...Spring, 29...Slot,
30... Spring, 31... Thin tube, 32...
...cock, 33...holder 34...bearing,
35...place, 36...holder

Claims (1)

[Claims] 1. A method for introducing a sample into a cell of an atomic absorption spectrophotometer, wherein a liquid sample of a substance to be analyzed is placed in the cell, the method comprising: placing the liquid sample in the cell; The cell is heated to a temperature 1-2° C. below the boiling point of the liquid sample, and a liquid sample of the substance to be analyzed is placed in the cell by spraying the liquid sample onto all working surfaces of the cell. A method characterized by: 2. For carrying out the method according to claim 1, comprising a syringe (1) for supplying a liquid sample of the substance to be analyzed to the means (2) for placing the liquid sample in the cell (3). an arrangement for introducing a sample into a cell of an atomic absorption spectrophotometer, the means (2) for placing the liquid sample in the cell, the means (2) for placing the liquid sample in the cell at one end (4) of the liquid sample;
), the core hollow tubular element (5) comprising a hollow tubular element (5) for supplying a liquid sample to the cell (3), adapted to be supplied at It connects to the syringe (1) through a capillary (6) arranged coaxially and with its end (4) to the longitudinal axis (7) of the cell (3) for inserting it into the cell (3). It can reciprocate and rotate about its longitudinal axis (9) and can be inserted into the cell (3) to ensure spraying of the liquid sample over the entire working surface of the cell (3). An arrangement characterized in that it has a hole (10) made in its body in the immediate vicinity of its end (8).