WO1991001487A1 - Process and device for element determinations - Google Patents

Process and device for element determinations Download PDF

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Publication number
WO1991001487A1
WO1991001487A1 PCT/EP1990/001146 EP9001146W WO9101487A1 WO 1991001487 A1 WO1991001487 A1 WO 1991001487A1 EP 9001146 W EP9001146 W EP 9001146W WO 9101487 A1 WO9101487 A1 WO 9101487A1
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WIPO (PCT)
Prior art keywords
filter
induction furnace
atomic absorption
elements
furnace
Prior art date
Application number
PCT/EP1990/001146
Other languages
French (fr)
Inventor
Hermann R. Trabert
Cvetko Krajina
Original Assignee
Trabert Hermann R
Cvetko Krajina
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
Application filed by Trabert Hermann R, Cvetko Krajina filed Critical Trabert Hermann R
Publication of WO1991001487A1 publication Critical patent/WO1991001487A1/en

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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N1/00—Sampling; Preparing specimens for investigation
    • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
    • G01N1/44—Sample treatment involving radiation, e.g. heat
    • 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
    • G01N2021/745—Control of temperature, heating, ashing

Definitions

  • This invention relates to a process and a device for the determination of elements by means of atomic absorption, ICP or other analytical methods.
  • the atomic absorption methods hitherto known have determined elements in complex materials by atomizing samples in a flame or in an electrothermal atomizer. These methods have substantial disadvantages.
  • the detection limit is too low when the directly analyzed elements are not concentrated first. Matrix and interference effects of other elements result in a low precision of the measuring results.
  • a new concentration method is therefore used in connection with atomic absorption, ICP and other analytical methods (e.g X-ray analyzer, emission spectrophotometry) to increase the detection limit and to improve measuring precision.
  • the process according to our invention can be applied to elements or their oxides whose volatility at high temperatures is higher than that of the matrix.
  • Fig. 1 shows a sectional view of the induction furnace according to the invention.
  • Fig. 2 shows a flow chart of the process steps.
  • Fig. 1 shows a sectional view of the induction furnace, which is already known in its basic elements.
  • the ceramic crucible 16 in which the sample to be analyzed is placed, is put on the base 18 within the quartz tube 12.
  • the crucible 16 is surrounded by a heating device 14, which may act inductively or in some other way.
  • the quartz tube is covered by the cylinder 24 and at the bottom respectively a ground plate 20 with seals 34 between the quartz tube 12 and the cylinder 24 and the ground plate 20 respectively ensuring a tight seal.
  • the combustion tube may also consist of one piece made of quartz or some other material.
  • a carrier gas is passed into the interior of the induction furnace 10 via a tube 22 arranged in the ground plate 20.
  • Oxygen (0 2 ) is used as a reaction gas and passed into the interior of the induction furnace 10 via a tube 26 according to our invention, which, through an opening in the cylinder 24, projects into the interior >f the induction furnace 10 above the ceramic crucible.
  • the upper section of the cylinder 24 contains a filter 30 according to this invention, which can be taken out and replaced by means of the changing device 28.
  • the filter 30 serves to collect the combustion products resulting from the combustion process.
  • An exhaust duct 32 in the cover area of the cylinder 24 serves to carry off the carrier and reaction gases.
  • Fig.2 shows a flow chart of the individual steps of the process according to our invention for element determinations by means of atomic absorption, X-ray fluorescent analysis and emission spectrophotometry.
  • a few grammes of the sample to be analysed are placed in the ceramic crucible 16. 0.8-1.2g tungsten powder are added.
  • the crucible 16 is placed on the base 18 and put into the interior of the quartz tube 12.
  • the gas pipes for the carrier gas and the reaction gas are connected.
  • the next step is switching on the induction furnace and burning the sample at ca. 2.100° Kelvin.
  • the elements are carried off in the form of volatile oxides by the carrier gas. They are collected in the form of solid particles in the ashless paper filter 30, a ceramic filter, a metallic filter or some other filter.
  • the filter 30 is taken out of the cylinder 24 and is now - as a whole or in part - available for analysis.
  • Table 1 shows the optimum ratio 1/d (Fig. 1), i.e. the ratio between the distance of the filter to the combustion area (1) and the quartz tube diameter (d) limiting the combustion space. The results shown in table 1 have been obtained in experiments.
  • ceramic filter can be used
  • the filter matrix of the filter aliquot is burnt during the ashing process in the graphite furnace of an atomic absorption spectrophotometer and carried off. This results in a substantial reduction or even total exclusion of the non- selective absorption of light during the atomizing phase.
  • Ashing Detection limit (%mass)/ Nonselective tempera- relative error (%) absorption ture (°K)

Abstract

This invention relates to a process and a device for the determination of elements by means of atomic absorption and X-ray fluorescent analysis. The process according to this invention comprises the three steps evaporization of the sample with concurrent oxidation, collection of the oxides in a filter and measurement of the element concentrations by ashing the filter in an atomic absorption spectrophotometer or analysis of the filter in an X-ray spectrometer or an optical emission spectrophotometer. The induction furnace has been especially adapted.

Description

Process and Device for Element Determinations
This invention relates to a process and a device for the determination of elements by means of atomic absorption, ICP or other analytical methods.
The atomic absorption methods hitherto known have determined elements in complex materials by atomizing samples in a flame or in an electrothermal atomizer. These methods have substantial disadvantages. The detection limit is too low when the directly analyzed elements are not concentrated first. Matrix and interference effects of other elements result in a low precision of the measuring results. According to our invention, a new concentration method is therefore used in connection with atomic absorption, ICP and other analytical methods (e.g X-ray analyzer, emission spectrophotometry) to increase the detection limit and to improve measuring precision.
An atomic absorption method without chemical sample preparation is known from the DE-32 23 334. In this process, samples are pressed and placed into a sealed graphite con¬ tainer. The container is placed into the flame of a plasma burner and the sample burnt at high temperatures. During this step, partially fractional evaporisation of the elements occurs in the gas phase.
It is the object of the process and device according to this invention to offer a remedy for the disadvantages described above.
The process according to our invention can be applied to elements or their oxides whose volatility at high temperatures is higher than that of the matrix.
This is case with the following elements: Al, Ag, As, B, Ba, Bi, Ca, Cd, Ce, Ga, Ge, Hg, In, K, Li, Mg, Mn, Na, Nb, Os, P, Pb, Rb, Re, Ru, Se, Si, Sn, Sr, Ta, Te, Zn.
The induction furnace required for the process according to our invention is known from the state of the art and has been especially adapted to suit the process. The details can be seen from the description of the figures and the claims.
The process according to our invention consists of the following steps:
- evaporization of the samples with concurrent oxidation
- collection of the oxides in a filter and
- measurement of the element concentration by ashing the filter/filter aliquot in an atomic absorption spectropho- tometer or direct measurement on a X-ray spectrometer or measurement on an optical emission spectrophotometer. The individual steps are described in detail in the claims and the description of the figures.
Further advantages of the invention can be seen from the description of the figures, which shall be taken as purely descriptive and not as limiting in any way.
The figures show the following:
Fig. 1 shows a sectional view of the induction furnace according to the invention.
Fig. 2 shows a flow chart of the process steps.
Fig. 1 shows a sectional view of the induction furnace, which is already known in its basic elements. The ceramic crucible 16, in which the sample to be analyzed is placed, is put on the base 18 within the quartz tube 12. The crucible 16 is surrounded by a heating device 14, which may act inductively or in some other way. At the top, the quartz tube is covered by the cylinder 24 and at the bottom respectively a ground plate 20 with seals 34 between the quartz tube 12 and the cylinder 24 and the ground plate 20 respectively ensuring a tight seal. Alternatively, the combustion tube may also consist of one piece made of quartz or some other material. A carrier gas is passed into the interior of the induction furnace 10 via a tube 22 arranged in the ground plate 20. Oxygen (02) is used as a reaction gas and passed into the interior of the induction furnace 10 via a tube 26 according to our invention, which, through an opening in the cylinder 24, projects into the interior >f the induction furnace 10 above the ceramic crucible. The upper section of the cylinder 24 contains a filter 30 according to this invention, which can be taken out and replaced by means of the changing device 28. The filter 30 serves to collect the combustion products resulting from the combustion process. An exhaust duct 32 in the cover area of the cylinder 24 serves to carry off the carrier and reaction gases.
Fig.2 shows a flow chart of the individual steps of the process according to our invention for element determinations by means of atomic absorption, X-ray fluorescent analysis and emission spectrophotometry.
According to our invention, a few grammes of the sample to be analysed are placed in the ceramic crucible 16. 0.8-1.2g tungsten powder are added. The crucible 16 is placed on the base 18 and put into the interior of the quartz tube 12.
Then the gas pipes for the carrier gas and the reaction gas are connected. The next step is switching on the induction furnace and burning the sample at ca. 2.100° Kelvin. As a result of the combustion in the reaction gas flow (0,) , the elements are carried off in the form of volatile oxides by the carrier gas. They are collected in the form of solid particles in the ashless paper filter 30, a ceramic filter, a metallic filter or some other filter. When the combustion process is completed, the filter 30 is taken out of the cylinder 24 and is now - as a whole or in part - available for analysis.
An aliquot of the filter or the filter as a whole is then placed into the graphite crucible of an atomic absorption spectrophometer and analysed as known. It may also be analysed on an X-ray spectrometer or an optical emission spectrophotometer. As an example, optimum analytical conditions and results are described for the elements As, Sn, Sb and Pb in tables 1 and 2.
Table 1 shows the optimum ratio 1/d (Fig. 1), i.e. the ratio between the distance of the filter to the combustion area (1) and the quartz tube diameter (d) limiting the combustion space. The results shown in table 1 have been obtained in experiments.
Table It 1/d ratios obtained in experiments
Detection limit (% mass.)/relative error (%)
1/d As Sn Sb Pb
2.0 Paper filter burns, ceramic filter can be used
3.0 Paper filter burns, ceramic filter can be used
3.5 10"5/10
4.5 10"5/10
5.5
Figure imgf000007_0001
10"4/20
The filter matrix of the filter aliquot is burnt during the ashing process in the graphite furnace of an atomic absorption spectrophotometer and carried off. This results in a substantial reduction or even total exclusion of the non- selective absorption of light during the atomizing phase.
The nonseleσtive absorption of light is increased at low ashing temperature. With excessively high temperatures, element loss due to evaporisation has been observed. The optimum ashing temperature in the graphite furnace of an atomic absorption spectrophotometer determined in experiments, can be seen in table 2.
Table 2: Ashing temperatures determined in experiments
Ashing Detection limit (%mass)/ Nonselective tempera- relative error (%) absorption ture (°K)
As Sn Sb Pb
Figure imgf000008_0001
In table 3, the analytical results of the process according to our invention are compared with the results of the nearest prior art process.
Table 3: Comparison between the process according to our invention and the nearest prior art process
Element Detection Limit (10~3%mass) Standard deviation
Prior art Invention Prior art Invention
7
8
5
10
Figure imgf000009_0001
Figure imgf000009_0002
10

Claims

Process and Device for Element DeterminationsW h a t i s c l a i m e d is:
1. Process for the determination of elements by means of atomic absorption, X-ray fluorescent analysis or optical emission spectophotometry comprising the following steps:
- Placing the sample into a ceramic crucible and adding tungsten powder;
- burning the sample in an induction furnace at ca. 2100° K; collecting the element oxides in a filter;
- dividing the filter into aliquot parts;
- ashing the filter in the graphite furnace of an atomic absorption spectrophotometer;
- analyzing the filter using a X-ray fluorescent analyzer or an optical emission spectrophotometer and
- element analysis
2. Process according to claim 1, c h a r a c t e r i z e d in t h a t oxygen is passed into the induction furnace to oxidize the elements.
3. Process according to claim 1, c h a r a c t e r i z e d i n t h a t a carrier gas is used and passed into the induction furnace to carry the oxidized elements to the filter.
4. Process according to claim 1, c h a r a c t e r i z e d i n t h a t the preferred ashing temperature in the graphite furnace of the atomic absorption spectrophotometer is 1100-1300° Kelvin.
5. Device for the determination of elements by means of atomic absorption or X-ray fluorescent methods using an induction furnace and an atomic absorption spectrophotometer, c h a r a c t e r i z e d in t h a t the induction furnace (10) comprises a tube (22) for passing a carrier gas as well as a tube (26) for passing the t>2 reaction gas, and that in the upper part of the induction furnace (10) a cylinder (24)-is arranged containing a changing deviced (28) for the paper, ceramic, metallic or other filter (30) as well as an exhaust duct (32) for the gases in the interior of the induction furnace.
6. Device according to claim 5, c h a r a c t e r i z e d i n t h a t the filter (30) consists of ashless paper.
7. Device according to claim 5, c h a r a c t e r i z e d i n t h a t the filter (30) consists of ceramic or some other material.
8. Device according to claim 5, c h a r a c t e r i z e d i n t h a t the filter (30) consists of metal or any comparable material.
9. Device according to claim 5, c h a r a c t e r i z e d i n t h a t the preferred ratio between the distance of the filter to the combustion area (1) and the quartz tube diameter (d) lies between 3 .5 and 5.
PCT/EP1990/001146 1989-07-20 1990-07-12 Process and device for element determinations WO1991001487A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19893923983 DE3923983C2 (en) 1989-07-20 1989-07-20 Device for preparing a sample for a device for determining elements by means of atomic absorption methods or X-ray fluorescence methods
DEP3923983.7 1989-07-20

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WO1991001487A1 true WO1991001487A1 (en) 1991-02-07

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WO (1) WO1991001487A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1509067A2 (en) * 2003-08-20 2005-02-23 Shin-Etsu Chemical Co., Ltd. Vessel for pretreatment of elementary analysis, method for analysing elements, inductively coupled plasme torch and apparatus for elementary analysis
WO2006138375A2 (en) * 2005-06-17 2006-12-28 The Government Of The United States Of America As Represented By The Secretary Of The Department Of Health And Human Services, Centers For Disease Control And Prevention Monitor and methods for characterizing airborne particulates
WO2014075385A1 (en) * 2012-11-13 2014-05-22 北京吉天仪器有限公司 Method and instrument for simultaneously measuring mercury and cadmium by direct sample injection
EP2594921A4 (en) * 2010-07-15 2016-01-13 Beijing Titan Instr Co Ltd Electrothermal vaporization atomic fluorescence spectral method and spectrometer for determining cadmium
RU199394U1 (en) * 2020-05-26 2020-08-31 Федеральный исследовательский центр "Пущинский научный центр биологических исследований Российской академии наук" (ФИЦ ПНЦБИ РАН) ELECTROTHERMAL TWO-STAGE ATOMIZER FOR ANALYTICAL SPECTROMETRY

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JP2008111840A (en) * 2007-11-06 2008-05-15 Shin Etsu Chem Co Ltd Container for element analysis pretreatment, and element analysis method
EA014588B1 (en) * 2008-06-19 2010-12-30 Борис Арсентьевич Ревазов Method for determining metals in mineral raw material
CN106041037A (en) * 2016-05-31 2016-10-26 安泰科技股份有限公司 Preparation method for test sample for alloy powder performance analysis and special compound crucible
CN107213932B (en) * 2017-04-20 2019-05-28 东莞中子科学中心 A kind of Multi-example thermostat for small-angle scattering experiment

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US4008963A (en) * 1974-03-07 1977-02-22 Bodenseewerk Perkin-Elmer & Co. Gmbh Method of and device for the analysis of samples by means of flameless atomic absorption spectroscopy
DE2735467A1 (en) * 1977-08-05 1979-02-08 Beckman Instruments Gmbh METHOD OF AUTOMATIC SAMPLING IN THE FLAMELESS ATOMIC ABSORPTION SPECTRALPHOTOMETRY
US4407582A (en) * 1981-01-12 1983-10-04 The Research And Development Institute, Inc. At Montana State University Method and apparatus for reduction of matric interference in electrothermal atomizer for atomic absorption spectroscopy
US4548497A (en) * 1981-11-25 1985-10-22 Bodenseewerk Perkin-Elmer & Co., Gmbh Method and device for introducing a sample into a graphite tube

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DE2949460A1 (en) * 1979-12-08 1981-06-11 Ringsdorff-Werke GmbH, 5300 Bonn Emission spectral analysis sample holder of graphite - has bowl with perforated cap and leg fitting in base
DE3223334C2 (en) * 1982-06-23 1986-03-06 Peter Dr. 6296 Waldernbach Wirz Atomization unit for use in a Zeeman atomic absorption spectrometer, a forward scattering spectrometer or an atomic fluorescence spectrometer
DE3233130A1 (en) * 1982-09-07 1984-03-08 Harald Dipl.-Chem. Dr. 4600 Dortmund Berndt Process for introducing a finely-divided sample substance into an excitation source for spectroscopic purposes

Patent Citations (5)

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Publication number Priority date Publication date Assignee Title
US3824016A (en) * 1972-06-16 1974-07-16 R Woodriff Combined sample collection and vaporization system for spectro-chemical analysis
US4008963A (en) * 1974-03-07 1977-02-22 Bodenseewerk Perkin-Elmer & Co. Gmbh Method of and device for the analysis of samples by means of flameless atomic absorption spectroscopy
DE2735467A1 (en) * 1977-08-05 1979-02-08 Beckman Instruments Gmbh METHOD OF AUTOMATIC SAMPLING IN THE FLAMELESS ATOMIC ABSORPTION SPECTRALPHOTOMETRY
US4407582A (en) * 1981-01-12 1983-10-04 The Research And Development Institute, Inc. At Montana State University Method and apparatus for reduction of matric interference in electrothermal atomizer for atomic absorption spectroscopy
US4548497A (en) * 1981-11-25 1985-10-22 Bodenseewerk Perkin-Elmer & Co., Gmbh Method and device for introducing a sample into a graphite tube

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1509067A2 (en) * 2003-08-20 2005-02-23 Shin-Etsu Chemical Co., Ltd. Vessel for pretreatment of elementary analysis, method for analysing elements, inductively coupled plasme torch and apparatus for elementary analysis
EP1509067A3 (en) * 2003-08-20 2010-02-03 Shin-Etsu Chemical Co., Ltd. Vessel for pretreatment of elementary analysis, method for analysing elements, inductively coupled plasme torch and apparatus for elementary analysis
WO2006138375A2 (en) * 2005-06-17 2006-12-28 The Government Of The United States Of America As Represented By The Secretary Of The Department Of Health And Human Services, Centers For Disease Control And Prevention Monitor and methods for characterizing airborne particulates
WO2006138375A3 (en) * 2005-06-17 2007-03-22 Us Gov Health & Human Serv Monitor and methods for characterizing airborne particulates
US7947503B2 (en) 2005-06-17 2011-05-24 The United States Of America As Represented By The Department Of Health And Human Services Monitor and methods for characterizing airborne particulates
EP2594921A4 (en) * 2010-07-15 2016-01-13 Beijing Titan Instr Co Ltd Electrothermal vaporization atomic fluorescence spectral method and spectrometer for determining cadmium
WO2014075385A1 (en) * 2012-11-13 2014-05-22 北京吉天仪器有限公司 Method and instrument for simultaneously measuring mercury and cadmium by direct sample injection
RU199394U1 (en) * 2020-05-26 2020-08-31 Федеральный исследовательский центр "Пущинский научный центр биологических исследований Российской академии наук" (ФИЦ ПНЦБИ РАН) ELECTROTHERMAL TWO-STAGE ATOMIZER FOR ANALYTICAL SPECTROMETRY

Also Published As

Publication number Publication date
JPH04503412A (en) 1992-06-18
DE3923983C2 (en) 1999-02-25
EP0436008A1 (en) 1991-07-10
DE3923983A1 (en) 1991-01-31

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