EP1123500A1 - Atomizing device for dissolved and solid samples - Google Patents

Abstract

The invention relates to an atomizing device for use in atomic absorption spectroscopy utilizing the Zeeman method. In order to analyze liquid samples introduced from the top (10) and solid samples introduced from the side, said device comprises a pipe-shaped atomizing oven (1). Said oven is heated transversally plane by vanes and has pipes extending horizontally. Said vanes extend between the vertically positioned electrodes (2,3). Said vertically positioned atomizer oven (1) is located at the side between magnetic poles (20, 21).

Description

title

Atomizer for dissolved and solid samples

PRIOR ART The state of the art in the field of graphite tube atomic absorption spectroscopy (GF-AAS analysis) is tubular furnace bodies and atomizing furnace based on graphite, as well as Zeeman magnetic field arrangements for compensating for unwanted measurement signals. Detailed descriptions of this are contained in DE 4243766 C2, DE 4243767 C2, EP 0364539 B1, EP 0363457 and DE 21 651 06 C2.

A distinction is generally made between slow-heated and cross-heated furnace bodies, whereby separate sample carriers or so-called “platforms”, or so-called “platforms”, can be provided in the interior of the respective furnace part. The geometry of the cross-heated furnace bodies has clear analytical and economic advantages for the user compared to the slow-heated form.

The state of the art in GF-AAS analysis is to use a separate atomizing device for dissolved (liquid) and solid samples, which is assigned and adapted to the sample shape and type and contains either a cross-heated or a slow-heated furnace body follows that, for example, a laboratory, which has to analyze both sample forms or types, with two different complete systems of atomic absorption spectrometers including the accessories, such as, for example Sample peripheral rate, equipped a must.

The samples are typically introduced into the center of the interior of the furnace body by means of an automatic feeder, also called a "sampler". For loosened samples, they are fed into the furnace body vertically or diagonally from above Solid samples, on the other hand, are first placed on a spoon-like graphite sample holder outside the oven and quantified there by detecting the sample weight. Then the sample holder with the sample is introduced approximately horizontally through lateral openings in the atomizing device

In GF-AAS analysis, it is also common to use the so-called "Zeeman effect" for background compensation. Systems with such a procedure are known, for example, from EP 0364539 B1, EP 0363457 B1 and DE 21 651 06 C2

EP 036357 B1 and DE 21 651 06 C2 show atomic absorption spectrometers, in each of which an oven, through which a beam of measuring light shines, is arranged in the air gap of an electromagnet for the purpose of generating the Zeeman effect

DE 21 6551 06 C2 describes a GF-AAS atomizing device with Zeeman magnets which are transverse to the furnace tube axis, the use of cross-heated furnace bodies not being possible

The closed, cross-heated construction of the atomizing device and the magnetic poles described in EP 036357 B1 does not allow horizontal sample feeding of solids, but only loosened samples can be entered vertically from above via a fill opening End surfaces of the stovepipe can be brought up in order to achieve the maximum magnetic field strength of approx. 1 Tesla required for the analysis, but on the other hand the application area of the analytically so advantageous cross-heated stovepipe in combination with a longitudinal magnetic field arrangement is limited to only detached samples

Description of the invention

The object of the invention is to provide an atomizing device for an atomic absorption spectrometer which is equipped with a cross-heated furnace body and with electromagnet for background correction according to the Zeeman effect and is therefore suitable for the analysis of solid and dissolved samples in the same manner The task is solved by the independent claims. Preferred developments are the subject of the dependent claims.

According to the invention, an atomizing device for both dissolved and solid samples is realized in that a cross-heated furnace tube is clamped in vertically placed electrodes via its contact pieces and the contact pieces of the furnace with hole openings in the center for the entry of dissolved samples, the supply and removal of protective gases and the detection of the tube radiation for the purpose of temperature control of the furnace.

This vertical position of the cross-heated furnace firstly creates the necessary space for the magnetic poles of a transverse (transversely) oriented Zeeman magnetic field arrangement to be brought close to the furnace, and secondly keeps the frontal areas of the tubular part of the furnace clear so that the one side, a horizontal inlet opening for solid samples, which can also be temporarily closed with an optical window, can be formed, preferably on the left-hand side of the furnace.

Another measure according to the invention to create the necessary space for the entry of solid samples is the asymmetrical arrangement of the geometric centers of the furnace and the magnetic poles with respect to one another.

According to the invention, the filling openings for dissolved and solid samples are also equipped with graphite adapters which can be exchanged in a simple manner. On the one hand, this results in a quick geometrical adaptation to the sample dispenser in use and the quick closure of the channel that is not currently being used, and on the other hand it also provides a simple cleaning option that does not require complete dismantling of the atomizing device.

The inventive solution has in particular the advantages of the "Massman" furnace technology with Zeeman magnetic field for solid and dissolved samples, which essentially consist of a semi-closed atomizer with two tubular furnace parts adapted to the possible sample shapes and separate external and internal protective gas streams. The matched sample form Graphitwech- are seiteile - 2 times for stovepipe and 3 times for Channel Adapter - Designed Vice end as a cost-hither ^¬ and easily exchanged graphite wear parts. Brief description of the drawings

The invention and its advantages are described in more detail with reference to the schematic representations mentioned below:

Fig.: Representation of a longitudinal section through the atomizing device with

Atomizing furnace 1;

Upper electrode 2;

Lower electrode 3; Window sockets right / left 4.5;

Oven window right / left 6.7;

Hole in lower electrode 8; outer protective gas channel 9;

Pipetting opening 1 0; Pipetting insert and adapter 1 1;

Housing parts 1 2.1 3;

Hinge between housing parts 1 4; pneumatic actuator 1 5;

Cooling channels 1 6.1 7; Temperature sensor 1 8;

Liquid adapter 1 9;

Oven raw revenge A;

Inlet pipe for internal gas flows ZI, Z2;

Fig. 2: Representation of a cross section along the furnace tube axis A with:

Magnetic poles 20,21; Coils 22,23; Platform 24;

Fig. 3: Representation of an enlarged detail from Fig. 2 with:

Milling 25 in platform 24;

Figure 4: illustration of a longitudinal section through the atomizing furnace with dissolved Pro ^¬ ben long holes 26;

Openings 27.32; Oven wing 28.29; Platform foot 30, bore 31, cutting axis B,

5 spatial representation of the atomizing furnace with dissolved samples,

6 shows a section from FIG. 1 with an illustration of the course of protective gas flows, outer protective gas flow Sa, inner protective gas flows Si,

7 is an exploded view of the elements of the atomizing device for dissolved samples,

8 shows a sectional illustration of the atomizing device for solid samples with flower insert and adapter 32,

Atomizing furnace 33 for solid samples, input channel 34 for solid samples,

9 is an exploded view of the elements of the atomizing device for solid samples,

Fig. 1 0 shows a longitudinal section through the atomizing furnace for solid samples

Fig 1 1 Spatial representation of the atomizing furnace for solid samples

Detailed description of the drawings

1 shows a longitudinal section through an atomizing device according to the invention with a Zeeman magnet, not shown here

The atomizing furnace 1, which is shown in further detail in further figures, is cross-heated and arranged vertically between an upper electrode 2 and a lower electrode 3. Laterally, in the lower electrode 3 there are window sockets 4 and 5 and furnace windows 6 and 7, the furnace windows 6 and 7 each have supply connections ZI, Z2 for supplying internal gas streams In the window connector 6, a Liqiuidadapter 1 9 is provided, which ensures symmetrical conditions for the internal gas streams and is removed from the side in the operating mode "solid for better supply of solid samples

The lower electrode 3 also has a bore 8, through which protective gas is fed from below to the atomizing furnace via an outer gas channel 9. Furthermore, the furnace temperature can be detected via this bore by means of a temperature sensor 18 arranged below this bore 8

In the "Liquid" operating mode, an upper pipetting opening 1 0, which also serves for supplying the liquid samples via a sample dispenser device, not shown, forms the outlet of the outer protective gas stream supplied via the bore 8 and for the inner purge gas streams. This opening contains the operating mode " Liquid "is a pipetting insert accessible from above 1 1

The arrangement is surrounded by two housing parts 1 2, 1 3, the upper housing part 1 2 being designed so that it can be swung open upwards via a hinge 1 4 for the purpose of replacing the atomizing furnace 1. A pneumatic actuating element 15 is advantageously provided here for actuation

In the housing parts 1, 2, 3, cooling channels 1, 6, 7, which are supplied via cooling stubs (not shown) and only indicated schematically, are provided

In the operating mode "solid, which will be discussed in further representations, instead of the pipetting set 11 there is a flower set which extends as far as the furnace body. This can be a sealing plug as shown for example in FIG. 8 with reference number 32

FIG. 2 shows a cross section along the line of the stovepipe axis A according to FIG. 1 with a view in the direction of the arrow

Magnetic poles 20, 21 and coils 22, 23, which laterally enclose the furnace body of the atomizing furnace 1, can be seen, which are optimally guided to the furnace body. It can also be seen that the furnace body is advantageously arranged not asymmetrically in the center axis of the magnetic poles Further elements have already been explained with reference to FIG. 1. A top view of a platform 24 can also be seen in the stovepipe, which is used to hold the liquid sample

FIG. 3 shows an enlarged section of FIG. 2, but without external parts and magnets. Here it can be seen that the platform 24 has a cutout 25 on the inside which receives the dissolved sample. The liquid adapter 1, which is only used in the "liquid" operating mode, is also clearly visible 9

The platform 24 is only in this operating mode "liquid" part of the tube of the atomizing furnace 1, which is replaced in solid mode by another embodiment, as shown in Fig. 8, reference numeral 33, as will be described

4 shows a longitudinal section through the atomizing furnace 1 in “Lιquιd” mode and a side view from direction B, in which a lower longitudinal bore 26 for supplying an outer protective gas channel can be seen, which through openings 27 breaks through the tapering furnace wing 28, whereby the shielding gas streams can exit there and then continue to flow around the furnace body 1 from the outside. The bore 26 is closed at its upper end by the inserted foot 30 of the platform 24. An upper bore 31 serves to supply liquid samples

Through openings 32, which, like the openings 27 in the lower wing 28 in the upper wing 29, have come about, the external protective gas flow partially re-enters and flows upwards out of the pipetting opening 11 (FIG. 1).

In FIG. 5, the atomizing furnace 1 according to FIG. 4 is shown spatially obliquely from the side

FIG. 6 shows part of FIG. 1, with the directions of the outer protective gas flow Sa and the inner protective gas flows Si shown

FIG. 7 shows an exploded view of the elements from FIG. 6, with the window sockets 4, 5 attached to the lower electrode 3

In Fig. 8 the atomizing device for solid analysis is shown in section with the already mentioned flower insert 32 to close the upper half of the furnace withdrawn liquid adapter 1 9. Furthermore, a modified atomizing furnace 33 is provided which does not contain a sample platform 24 with a foot 30

The latter, as shown in FIG. 10 and FIG. 11, is designed in a known manner as double-leaf and cross-heated and has a tapering longitudinal section along the section line d in the first longitudinal section near the stovepipe. The bores 26, 31 are present as in FIG. 4, but they do not extend into the stovepipe here.

The loading takes place from the side via the larger opening of the window connector 4 and an input channel 34 (see FIGS. 7 and 8). The oven window assembly 6 is not attached to the atomizing device 1 in the case of solid analysis; Both the inner and outer protective gas streams Si, Sa can thus emerge laterally via the input channel 34.

FIG. 9 shows an exploded view of the elements of the atomizing furnace for solid samples according to FIG. 8

Fig.1 0 shows two longitudinal sections through the atomizing furnace for solid samples.

In Figure 1 1 the atomizing furnace for solid samples according to Figure 10 is shown with a spatial oblique view from the side.

Claims

claims 1 atomizing device for atomic absorption spectroscopy according to the Zeeman method, in which a tubular atomizing furnace (1), which is heated across wings by itself, with horizontal furnace tube direction, is used both for examining liquid samples with input from above and for examining solid samples with input from the side is located with its oven wings (28, 29) between vertically arranged electrodes (2, 3). 2. atomizing device according to claim 1, wherein the vertically extending atomizing furnace (1) is located laterally between magnetic poles (20,21). 3. atomizing device according to claim 2, wherein the geometric center axes of the atomizing furnace (1) and the magnetic poles (20,21) are displaced asymmetrically to each other. 4. Atomizing device according to claims 1, 2 or 3, in which an atomizing oven (1) with an upward-pointing fill opening into the oven tube and a filling channel running through a wing in the direction of a pipetting opening (1 1) is provided for examining liquid dissolved samples , 5. atomizing device according to claim 1, 2 or 3, in which an atomizing furnace (1) can be loaded laterally for the examination of solid samples and wherein the Filling channel for the dissolved samples on the top of the oven is closed. 6. Atomizing device according to one of claims 1 to 4, characterized in that a laterally removable insert is provided for geometrically adapting the interior conditions of the atomizing device to a sampler for solid samples and for better loading of the tubular section. 7 atomizing device according to one of claims 1 to 6, in which in each case the measuring radiation extends via windows arranged laterally on the stovepipe and at least one internal protective gas stream Si is introduced via the windows or the window frame 8. Atomizing device according to one of claims 1 to 7, in which a channel leading to the atomizing furnace for supplying the external protective gas Sa and / or for detecting the furnace temperature by radiation measurement extends below the atomizing furnace. 9. Atomizing device according to one of claims 1 to 8, in which the outer and inner partial protective gas streams emerge via the pipetting opening (11) in liquid operation. 1 0. Atomizing device according to one of claims 1 to 9, in which an internal protective gas partial flow, which is introduced from the atomizing device side with a window, exits via the side loading side in solid operation.