EP0877928A1 - Four d'atomisation tubulaire chauffe longitudinalement ou transversalement - Google Patents

Four d'atomisation tubulaire chauffe longitudinalement ou transversalement

Info

Publication number
EP0877928A1
EP0877928A1 EP97930496A EP97930496A EP0877928A1 EP 0877928 A1 EP0877928 A1 EP 0877928A1 EP 97930496 A EP97930496 A EP 97930496A EP 97930496 A EP97930496 A EP 97930496A EP 0877928 A1 EP0877928 A1 EP 0877928A1
Authority
EP
European Patent Office
Prior art keywords
furnace
sample carrier
atomizing
tube furnace
sample
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP97930496A
Other languages
German (de)
English (en)
Inventor
Klaus Eichardt
Bernd Thiele
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SGL Carbon SE
Original Assignee
SGL Carbon SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE29612065U external-priority patent/DE29612065U1/de
Application filed by SGL Carbon SE filed Critical SGL Carbon SE
Publication of EP0877928A1 publication Critical patent/EP0877928A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/71—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited
    • G01N21/74—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light thermally excited using flameless atomising, e.g. graphite furnaces

Definitions

  • the invention relates to an electrically transverse or longitudinally heated atomizing furnace consisting of a carbon material, with a tubular furnace chamber in which the atomization takes place and with a sample holder arranged essentially outside the measuring beam path in the furnace chamber.
  • atomizing furnaces are preferably used for flameless atomic absorption spectrometry based on graphite tube technology (GF-AAS) for the vaporization and atomization of solid and liquid samples.
  • the sample holder is only designed to hold small analyte volumes ( ⁇ 10 ⁇ l) and should only be made from glassy carbon or pyrocarbon. Glass-like carbon as well as solid pyrolytic carbon can only be used as materials for sample carriers to a limited extent, since the analytical determination of refractory carbide-forming GF-AAS analytes from surfaces of this type is not possible, and the required material purities are difficult to achieve. and the price-performance ratio is unfavorable for the user. Transverse heated atomizing furnaces have been known since 1987 (DE-GM 87 14 670).
  • EP 0 321 879 A2 describes an atomizing furnace with a sample carrier in a longitudinally and transversely heated design, which is non-detachably connected to the inner wall of the furnace via a web symmetrical to the center of the furnace.
  • the sample holder and oven form a material unit that is made from a raw body.
  • the sample carrier part only extends over a central area of the furnace part. This means that there is only a small volume of analyte uptake.
  • the connecting web itself has several cross holes as a material-reducing measure.
  • Such an atomizing furnace shape from a solid graphite blank can only be produced with great technical effort. This has a negative impact on the user price for this wearing part.
  • Sample carriers with retaining rings for cross-heated atomizing furnace according to DE 42 43 767 C2 are also only cost-intensive and technically complex to produce, although both the sample carrier and the furnace can be manufactured as individual parts.
  • the object underlying the invention was to design sample carriers in this way and to adapt them to the conditions in the surrounding atomizing furnace in such a way that the technical and analytical deficiencies of the known prior art no longer occur when working with them.
  • the sample carrier should be designed and accommodated in the tube furnace in such a way that when analyzing with this arrangement, compared to the prior art, sharper measurement signals are obtained and a fast one
  • a further task was to create, in connection with the above-mentioned task characteristics, a combination tube furnace-sample carrier made of a material, which allows the determination of the content of all elements typically analyzable according to GF-AAS, namely 59, to be carried out.
  • the furnace body and the sample holder are made of electrographite with the same or similar physical and chemical properties. They are each made for themselves and only then put together. After the assembly, the gas-accessible surfaces of the combination of sample holder and furnace body are coated with a pyrocarbon layer. The porous surfaces of the electrographite are thereby sealed in a liquid-tight manner. Only then is the arrangement ready for use.
  • the sample carrier is bowl-shaped and has on its underside with respect to its longitudinal and transverse extension a centrally arranged pin which faces the lower part of the furnace inner wall. This peg is in one of the shape of the
  • the sample carrier in the furnace is form-fitting in the furnace and, due to the pyrocarbon coating, is also clearly and reproducibly fixed in a material-locking manner.
  • the sample carrier is minimized in terms of its mass and, with its tub-like or bowl-like part, it preferably extends over as large a part of the furnace interior as is available to it. Where this is sufficient for the solution of the work tasks, the sample holder can also have a smaller length.
  • the sample carrier preferably extends over a range of 50 to 85% of the longitudinal extension of the interior of the furnace.
  • the length of the sample carrier is preferably 75% of the length of the interior of the furnace and more and particularly preferably at least 80%.
  • the walls of the bowl-shaped part of the sample carrier preferably have a wall thickness of less than 0.5 mm, particularly preferably less than 0.3 mm.
  • the trough-like or bowl-like part of the sample holder is able to hold up to 50 ⁇ l for cross-heated furnaces and up to 40 ⁇ l analyte solution for longitudinally heated furnaces. All parts are designed so that their production requires the least effort.
  • the body of the sample carrier is essentially formed from the two function-determining parts of the pin and the sample pan and has a minimum mass, typically and in deviation from known solutions, less than 100 mg.
  • the mass of the sample pan means that heat conduction is largely avoided. An electrical heating by Joule 'see heat is excluded with this arrangement anyway. As a result, an analysis sample in the sample pan is wanted after the time-delayed heating of the inner wall of the furnace is extremely quickly heated to atomization temperature solely by heat radiation. As the lack of memory effects when working with the arrangement according to the invention shows (see FIG. 9), the analyte introduced is completely evaporated and, after the measurement process, is also completely removed from the atomization zone of the tube furnace.
  • the bowl-shaped part of the sample carrier which is preferably designed to hold analyte volumes of up to 50 ⁇ l, preferably has an additional groove along its bowl bottom with preferably vertical walls. This groove serves as an additional obstacle to the running of the analyte solutions.
  • the arrangement according to the invention consisting of a sample holder and tube furnace can be used for both transverse and longitudinally heated atomizing furnaces and for working with liquid as well as with solid analytes without constructive changes to the sample holder. Due to the unchangeable determination of the sample carrier in the tube furnace, which has already been carried out by the manufacturer. considerable advantages when handling and working with the analysis arrangement according to the invention, e.g. Damage or misadjustments of the sensitive Probert carrier are excluded. During analytical work with the arrangement according to the invention, practically no memory effects are found. This makes it possible to carry out a large number of analysis processes one after the other. This results in cost advantages for the user.
  • the type of fastening of the sample carrier in the tube furnace according to the invention also ensures a maximum heating delay of the sample carrier in direct comparison to the heating of the inner wall of the atomizing furnace.
  • the arrangement according to the invention allows the task and atomization of a very large amount of analyte of up to 50 ⁇ l in connection with a maximum heating rate of equal to or greater than 2000 K / s.
  • the heating takes place after a desired delay compared to the heating of the furnace inner wall.
  • the analytical arrangement according to the invention brings about good long-term stability of sensitivity and reproducibility (relative standard deviation (RSD) less than 2% for aqueous acidic standard solutions) and an expanded linear concentration working range with regard to the process-related time-integrated extinction (area integral of the signal curve).
  • RSD relative standard deviation
  • area integral of the signal curve area integral of the signal curve.
  • the combination of the tube furnace part and the sample carrier was designed in such a way that the sample carrier is arranged within the tubular part in such a way that it lies essentially outside the optical beam path and has only one attachment location, which is located on the common central axis of the two parts. This ensures a maximum of geometric symmetry between the two components for transverse and longitudinally heated tube furnaces and the current flow through the sample holder is completely avoided.
  • the hollow bowl-shaped design of the sample holder over a large part of the entire length of the tube furnace enables the application and safe storage of a maximum analyte volume.
  • the pin used to fix the sample holder in the tube furnace part preferably has a non-circular cross-section in order to position the sample carrier against rotation in a complementary recess of the tube furnace.
  • the pin is formed at least in two stages and only its part facing the inner wall of the furnace is located in the depression in the inner wall of the furnace. The wider part of the pin lies on the
  • the inner wall of the oven and keeps the bowl-shaped part of the sample holder at a distance from the inner wall of the oven.
  • the interior of the pin can have a cavity, for example as a circular or oval-shaped cutout.
  • the size of the cavity and thus the effective cross-sectional area of the pin allow the heat conduction to be adjusted with regard to an optimal time delay and to minimize the overall mass of the sample carrier.
  • the location for this connecting web for longitudinally and transversely heated furnaces is also in the relatively coldest area of the inner wall of the atomizing furnace during the heating process, as published studies by Falk and co-workers ("Spectrochimica Acta", Vol. 40B, pp 533 to 542, 1985) for longitudinally heated ovens and own
  • the selected arrangement principle thus also ensures that the desired time-delayed heating of the sample is carried out almost exclusively by radiation energy which is only radiated from the inner wall of the respective tubular atomizing furnace part.
  • Fig. La a longitudinal section through an atomizing furnace according to the invention.
  • Fig. Lb a cross section through an atomizing furnace according to Fig. La along the sectional area A-A.
  • FIG. 2 an exploded view of a cross-heated atomizing furnace according to the invention.
  • Fig. 3 the view of a sample carrier according to the invention. 4, recordings and diagrams of the temperature-time -
  • Fig. 5a a longitudinal section through an atomizing furnace for longitudinal or for transverse heating with additional longitudinal groove on the bottom of the sample carrier.
  • FIG. 5b a cross section through an atomizing furnace according to FIG. 5a for the longitudinally heated embodiment.
  • FIG. 5c a cross section through an atomizing furnace according to FIG. 5a for the cross-heated embodiment.
  • FIG. 7a and 7b spatial, cut representations of atomizing furnace according to Fig. 5b with views of the bowl-shaped platform of the sample holder (Fig. 7a) and on the pin and the bottom of the sample holder (Fig. 7b).
  • FIGS. 8a and 8b representations corresponding to FIGS. 7a and 7b, but for cross-heated atomizing furnaces.
  • Fig. 9 measurement diagrams of test analyzes, which were obtained with different types of sample carriers in an atomizing furnace.
  • Fig. La shows a longitudinal section through a tubular atomizing furnace 1 made of pyrocarbon-coated electrographite.
  • a sample carrier 2 which is opposite a sample input opening 3 in the tubular furnace part 17 by means of a support foot or pin 4 in a recess in the tubular furnace part 17.
  • the sample holder 2 like the tube furnace part 17, is made of electrographite and, after being inserted into the tube furnace part 17, was coated with pyrocarbon together with the latter.
  • the sample carrier 2 has in its platform 16 a bowl-shaped recess 5 for receiving a sample.
  • the recess 5 is machined less deep at its ends 10, so that edges are formed which form obstacles to the flow of the sample liquid.
  • the pin 4 is step-shaped, so that an intermediate stage 6 ensures that the required constant distance from the inner wall of the tube furnace part 17 is ensured.
  • FIG. 1 b shows a cross section through the atomizing furnace 1 shown in FIG. 1 a along a section line A-A, contact pieces 7 and 8 being shown for the transverse heating.
  • the sample carrier 2 has straight side surfaces 9 which are technically simple to manufacture.
  • FIG. 2 shows an exploded view of a complete, cross-heated atomizing furnace 1 with the sample carrier 2.
  • FIG. 3 shows a spatial representation of an embodiment of the sample carrier 2 from FIG. 2.
  • the pin or support foot 4 has a cross-section deviating from the circular shape, so that when the sample carrier 2 is installed in the tube furnace part 17, a cross-section is mutual
  • Fig. 4 shows the temperature distribution T (t) of a cross-heated atomizing furnace in the embodiment according to the invention as a function of time (t) during one rapid heating process to a predetermined atomization temperature in stages tl, t2 and t3. It can be seen that the central zone of the tube furnace is advantageously heated last to the desired final temperature.
  • FIG. 5a shows a longitudinal section through a tube furnace part 17 - sample holder 2 - arrangement for longitudinally and transversely heated furnaces with a further embodiment of a sample holder 2 according to the invention.
  • a sample holder 2 For a safe holding of the analysis sample, there is an additional one in the bottom of the dish-shaped sample holder 2
  • Much of the length of the sample carrier 2 extending, preferably milled groove 11 with substantially vertical side walls 12.
  • the bottom of the groove 11 is preferably flat for reasons of ease of manufacture.
  • the pin 4 of the sample holder 2 has a preferably drilled or milled and preferably extending in the axial direction 18 recess 13 in order to further reduce its heat conduction and to minimize the mass of the sample holder 2. It is particularly advantageous that all wall thicknesses 14 do not go beyond an essurg of 0.5 mm, whereby the total mass of the sample carrier 2 is kept very small.
  • FIG. 5b shows a cross section through the center of the furnace arrangement according to FIG. 5a for the case of a longitudinally heated furnace
  • FIG. 5c is a corresponding cross-sectional representation for a cross-heated atomizing furnace.
  • 6a and 6b each show a spatial representation of the sample carrier 2 of FIGS. 5a to 5c in an oblique view from above and an oblique view from below.
  • 7a and 7b show the sample carrier designs 2 according to FIGS. 5a and 5b and FIGS. 6a, b in a longitudinally heated tube furnace part 17 as spatial, cut-open representations.
  • FIGS. 8a and 8b show partially cut-away spatial representations of a cross-heated atomizing furnace 1 with sample carriers 2 according to FIGS. 5a, 5c, 6a and 6b.
  • Curve 2 was obtained in a measurement with a sample carrier of the "fork platform” type made of solid pyrographite material according to EP 0 442 009 A.
  • Curve 3 was created using a sample holder according to DD 233 190 A (DE-OS 35 45 635) i.e. with a sample holder made of glassy carbon, which is detachably held in a hole in the wall of the tube furnace by means of a pin located on its underside.
  • Curve 4 was created using a "fork platform” type sample carrier that was coated with pyrocarbon.
  • Curve 1 clearly shows the most sensitive signal and decays to the zero line within 10 seconds as desired. So there are no residues left in the oven. The ratio of signal level to noise level is very high and is therefore extremely favorable. This ensures a high degree of reproducibility of the measurements.
  • Curves 2 and 3 show that the atomization signal practically does not decay.
  • Large quantities of the substance to be analyzed remain in the analysis arrangement consisting of sample holder and tube furnace, which are gradually evaporated and atomized only after the time available for the analysis. Both the constructive design of the sample holder and the material from which the analysis arrangement is made are responsible for such behavior. Measurement results of this type cannot be used for analysis purposes, since the analysis process takes too long and the result of the subsequent measurement cycle is falsified by analyte residues which have not completely evaporated ("memory effect").
  • Curve 4 was obtained with an analysis arrangement in which both the sample carrier and the atomizing furnace were included

Abstract

L'invention concerne un four d'atomisation (1) chauffé transversalement ou longitudinalement, constitué d'un matériau carboné, destiné à la spectrométrie d'absorption atomique et comprenant un four tubulaire (17) dans lequel se trouve un porte-échantillon (2). Le perfectionnement consiste dans le fait que le porte-échantillon possède sur sa face inférieure, en vue de sa fixation dans le four, un tourillon ou un pied central (4) qui est fixé dans un évidement correspondant sensiblement à la forme du tourillon et se trouvant au centre de la paroi intérieure du four et sensiblement en regard de l'ouverture d'introduction des échantillons. Le porte-échantillon et le four sont constitués d'électrographite. La surface accessible au gaz du porte-échantillon et du four est revêtue de pyrocarbone. Les deux parties précitées sont métallisées par cette couche de pyrocarbone de manière définie. Le porte-échantillon s'étend de préférence sur la plus grande partie possible de la longueur du four. La face supérieure du porte-échantillon présente un évidement en forme d'auge (5) pouvant contenir jusqu'à 50 νl de solution d'analyte. Le poids du porte-échantillon est réduit grâce à des dispositions structurales. Lors de son fonctionnement, le four d'atomisation présente une bonne stabilité à long terme de la sensibilité et de la reproductibilité, ainsi qu'une plage d'énergie de concentration linéaire élargie sur le plan de l'extinction intégrée dans le temps.
EP97930496A 1996-07-11 1997-07-03 Four d'atomisation tubulaire chauffe longitudinalement ou transversalement Withdrawn EP0877928A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
DE29612065U DE29612065U1 (de) 1996-07-11 1996-07-11 Querbeheizter rohrförmiger Atomisierofen
DE29612065U 1996-07-11
DE19716492 1997-04-19
DE19716492A DE19716492A1 (de) 1996-07-11 1997-04-19 Längs- oder quergeheizter rohrförmiger Atomisierofen
PCT/EP1997/003500 WO1998002733A1 (fr) 1996-07-11 1997-07-03 Four d'atomisation tubulaire chauffe longitudinalement ou transversalement

Publications (1)

Publication Number Publication Date
EP0877928A1 true EP0877928A1 (fr) 1998-11-18

Family

ID=26035921

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97930496A Withdrawn EP0877928A1 (fr) 1996-07-11 1997-07-03 Four d'atomisation tubulaire chauffe longitudinalement ou transversalement

Country Status (4)

Country Link
EP (1) EP0877928A1 (fr)
AU (1) AU734744B2 (fr)
CA (1) CA2231548A1 (fr)
WO (1) WO1998002733A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19932874C2 (de) * 1999-07-16 2002-11-14 Schunk Kohlenstofftechnik Gmbh Atomisierofen
DE102016219492A1 (de) * 2016-10-07 2018-04-12 Schunk Kohlenstofftechnik Gmbh Probenträgereinrichtung für einen Atomisierofen und Verfahren zur Herstellung
CN112080619A (zh) * 2020-08-14 2020-12-15 中国石油天然气集团有限公司 一种冷速可调的管式炉及其工作方法

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3416421A1 (de) * 1984-05-04 1985-11-07 Philips Patentverwaltung Gmbh, 2000 Hamburg Probentraeger fuer die flammenlose atomabsorptions- und -emissionsspektroskopie und verfahren zu dessen herstellung
DD233190A1 (de) * 1984-09-28 1986-02-19 Adw Der Ddr Zi F Optik U Spekt Atomisator fuer probentraeger
DE3743286A1 (de) * 1987-12-19 1989-06-29 Bodenseewerk Perkin Elmer Co Ofen zur thermoelektrischen atomisierung
DE3726533A1 (de) * 1987-08-10 1989-02-23 Bodenseewerk Perkin Elmer Co Kontaktanordnung fuer die stromzufuhr zu einem ofen bei der atomabsorptions-spektroskopie
DE8803144U1 (fr) * 1988-03-09 1988-04-21 Ringsdorff-Werke Gmbh, 5300 Bonn, De
DE3823346C2 (de) * 1988-07-09 1994-03-24 Ringsdorff Werke Gmbh Graphitrohrofen mit einem Probenträger für die Atomabsorptionsspektroskopie
DE3923822C2 (de) * 1989-07-19 1998-08-20 Bodenseewerk Perkin Elmer Co Ofen zur elektrothermischen Atomisierung von Proben für spektroskopische Zwecke und Verfahren zu seiner Herstellung

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9802733A1 *

Also Published As

Publication number Publication date
AU734744B2 (en) 2001-06-21
AU3442697A (en) 1998-02-09
WO1998002733A1 (fr) 1998-01-22
CA2231548A1 (fr) 1998-01-22

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