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1. (WO1993017321) DISPOSITIF DE PRECONCENTRATION ET D'ABSORPTION ATOMIQUE ELECTROTHERMIQUE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

CLAIMS
1. A method for the analysis of an element that is capable of being electrodeposited onto a graphite surface from a sample which includes the element in low aqueous concentration and a matrix that interferes in the atomic absorption spectrophotometric determination of that element comprising:
a) placing an aliquot of the sample within the inside of a pyrolytic graphite tube disposed in the furnace
assembly of an atomic absorption spectrophotometer using an electrically conductive capillary tube which is maintained in electrical contact with the sample therein;
b) subjecting the sample to electrolysis by applying a potential to the capillary tube as the anode and the pyrolytic graphite tube as the cathode so as to
electrodeposit the element in the sample onto the
inner surface of the pyrolytic graphite tube;
c) removing the electrolysed solution;
d) washing the electrodeposited element to remove the matrix; and
e) subjecting the washed electrodeposited element to
electrothermal atomic absorption spectrophotometric analysis .
2. A method as in claim 1 wherein the aliquot of sample is about 5-100μL.
3. A method as in claim 2 wherein the aliquot of sample is about 50μL.
4. A method as in any one of claims 1 to 3 wherein the sample includes an electrolyte.
5. A method as in claim 4 wherein the electrolyte is in a concentration of at least 0.05M
6. A method as in any one of claims 1 to 5 wherein the sample includes a buffer.

7. A method as in claim 6 wherein the buffer is in a concentration of about 0.02M.
8. A method as in any one of claims 1 to 7 wherein the sample includes a surfactant.
9. A method as in claim 8 wherein the surfactant is in a concentration of about 0.005% w/v.
10. A method as in any one of claims 1 to 9 wherein the potential is about 3-6 volts .
11. A method as in any one of claims 1 to 10 wherein the potential is applied for about 60-240 seconds.
12. A method as in any one of claims 1 to 11 wherein the electrodeposited element is washed with about 100μL of distilled water.
13. A method as in any one of claims 1 to 12 wherein a chemical modifier is applied to the electrodeposited element.
14. A method as in claim 13 wherein about 50μL of
chemical modifier is applied.
15. A method as in any one of claims 1 to 14 wherein the element to be determined is selected from the group consisting of copper, lead, cadmium, zinc, manganese, nickel, chromium, cobalt, silver, gold, mercury,
palladium, platinum, antimony, tin, bismuth, iridium, arsenic, selenium and gallium.
16. An automatic sample loader for use in the analysis of an element that is capable of being electrodeposited onto a graphite surface from a sample which includes the element in low aqueous concentration and a matrix that interferes in the atomic absorption spectrophotometric determination of that element, said sample loader having an electrically conductive capillary tube adapted to hold an aliquot of a sample or other solution, the capillary tube being adapted to be positioned automatically within the opening of a pyrolytic graphite tube, such that a sample discharged into the pyrolytic graphite tube from the capillary tube will remain in electrical contact with said capillary tube and wherein the capillary tube is provided with a means to connect it to a source of
potential to form it into an anode.
17. An apparatus for the analysis of an element that is capable of being electrodeposited onto a graphite surface from a sample which includes the element in low aqueous concentration and a i.f_.trix that interferes in the atomic absorption spectrophotometric determination of that element comprising
an atomic absorption spectrometer incorporating a graphite furnace assembly,
an automatic sample loader as claimed in claim 16;
a pyrolytic graphite tube disposed within the furnace assembly of the atomic absorption spectrophotometer so as to permit the drying, if required, ashing and atomisation of a sample contained therein and having an opening adapted to permit the entry of the capillary tube therein; and
a source of potential connected to the capillary tube so as to form an anode and to the pyrolytic graphite tube so as to form a cathode.
18. An apparatus as in claim 17 or a sample loader as in claim 16, wherein the capillary tube is formed from platinum or platinum/iridium alloy.
19. A method for the analysis of an element that is capable of being determined using electrothermal atomic absorption spectrophotometry comprising
(a) electrodepositing a metal onto the inside of a pyrolytic graphite tube either prior to the introduction of a sample containing the element or concurrently with deposition of the element from the sample into said tube;

(b) either electrodepositing the element from the sample or depositing an aqueous sample and evaporating it to dryness; and (c) subjecting the sample or the element electrodeposited from the sample and the electrodeposited metal to
electrothermal atomic absorption spectrophotometric analysis so as to obtain an analysis for said element. 20. A method as in claim 19 wherein the electrodeposition of step (a) is performed prior to the electrodeposition of step (b) .
21. A method as in claim 19 wherein the electrodeposition of step (a) is performed concurrently with the
electrodeposition of step (b) .
22. A method as in claim 19 wherein the metal is
electrodeposited in step (a) and further metal is
electrodeposited with the element in step (b) .
23. A method as in any one of claims 19 to 22 wherein the element in the sample is electrodeposited.
24. A method as in any one of claims 19 to 23, wherein the electrodeposited metal is selected from the group consisting of palladium, platinum, ruthenium, rhodium, iridium, osmium and gold.
25. A method as in any one of claims 19 to 24 wherein the metal to be electrodeposited is an aqueous solution in a concentration of about 10-lOOppm.
26. A method as in claim 25 wherein about 25-75μL of solution is electrodeposited.
27. A method as in any one of claims 19 to 26 wherein the metal is electrodeposited at a potential of about
3-6 volts with the current in the range of about 15-30mA.

28. A method as in any one of claims 19 to 27 wherein a

* volume of acid is added to the electrodeposited metal and analyte and electrolysed with residual solution being removed following completion of the electrolysis.
29. A method as claimed in claim 28 wherein about 40μL of acid is used for each 25μL of sample.
30. A method as in claim 28 or claim 2'9 wherein
electrolysis is conducted for about 60 seconds.

31. A method as in any one of claims 28 to 30 wherein the acid is about 3% nitric acid solution.
32. A method as in any one of claims 28 to 31 wherein the element to be analysed in the sample is selected from the group consisting of lead, copper, cadmium and manganese.

33. A method as in any one of claims 19 to 32 wherein electrodeposition of the sample is conducted using a method as claimed in any one of claims 1 to 15.
34. A method as in any one of claims 19 to 32 when conducted using an apparatus as claimed in claim 16 or an autosampler as claimed in claim 17.
35. An improvement to the technique of analysis by hydride generation, the improvement comprising
electrodepositing a hydride collecting metal onto the inside surface of a graphite tube prior to introducing the hydride into the tube.
36. A method as in claim 35 wherein the hydride
collecting metal is palladium.
37. A method as in claim 35 or claim 36 wherein the electrodeposition is conducted using a method as claimed in any one of claims 1 to 15 or 19 to 33.
38. A method as in claim 35 or claim 36 wherein following electrodeposition of the hydride collecting metal, a sample is placed in proximity thereto and electrolysed to generate nascent hydrogen to thereby form hydride.