METHOD AND KIT FOR DOSING IRON IONS IN LUBRICATING COMPOSITIONS

Abstract

Disclosed is a method for dosing iron ions, by spectrophotometry, especially ferric and ferrous ions, contained in a used lubricating composition, especially a lubricating composition of a marine engine. The invention also relates to a kit for implementing the method.

Claims

1-11. (canceled)

12. Method for determining iron ions, in particular ferric and ferrous ions, in lubricating compositions, comprising the following steps: a) Taking a sample of the lubricating compositing to be analysed in a first container; b) Placing said first container containing the sample to be analysed on a magnet; c) Adding to a second container: a first aqueous reactive composition (CR1) comprising at least one extracting agent of ferric and ferrous ions from the oil phase towards the aqueous phase; a second aqueous reactive composition (CR2) comprising at least one reducing agent of ferric ions (Fe.sup.3+) to ferrous ions (Fe.sup.2+); a third reactive composition (CR3) comprising at least one emulsion destabilising agent; and a fourth reactive composition (CR4) in an aqueous solution comprising a complexing agent of ferrous ions, wherein this agent changes colour when complexing with ferrous ions; and mixing thereof; d) optionally, photochemical measurement of the absorbance of the mixture obtained at step c); e) Taking a few drops of the lubricating composition contained in the first container, held in position on the magnet, and adding these few drops to the second container comprising the mixture of the first, second, third and fourth reactive compositions obtained at step c); f) Agitating the mixture obtained at step e); g) Conducting photochemical measurement of the absorbance of the mixture obtained at step f); h) Determining the quantity of ferrous ions in the lubricating composition from the measurements obtained at steps d) and g).

13. The method according to claim 12, wherein the extracting agent is selected from among agents solubilising ferric and ferrous ions and being immiscible in the lubricating composition.

14. The method according to claim 12 wherein the extracting agent is selected from among sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, alone or in a mixture.

15. The method according to claim 14, wherein the extracting agent is sulfuric acid.

16. The method according to claim 12, wherein the reducing agent of ferric ions to ferrous ions is selected from among hydroquinone, hydroxylamine hydrochloride, hydrazine, dithionite, alone or in a mixture.

17. The method according to claim 16, wherein the reducing agent of ferric ions to ferrous ions is hydroxylamine hydrochloride.

18. The method according to claim 12, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

19. The method according to claim 18, wherein the destabilising agent is isoamyl alcohol, octan-1-ol, octan-2-ol, 1-heptanol, 2-ethyl-hexanol, 2-ethyl-butanol.

20. The method according to claim 19, wherein the complexing agent is selected from among ferrous ion complexing agents and for which complexing is the cause of a change of colour able to be detected by spectrophotometric measurement of the absorbance of the solution obtained.

21. The method according to claim 12, wherein the complexing agent is selected from among ferrozine, ferene, phenantroline and derivatives thereof, bipyridine, thioglycolic acid, nitroso-R salt (sodium salt of 3-hydroxy-4-nitroso-2,7-naphthalenedisulfonic acid), potassium ferricyanide (potassium hexacyanoferrate(III)), 2,4,6-tripirydyl-s-triazine (TPTZ).

22. The method according to claim 20, wherein the complexing agent is nitroso-R salt.

23. The method according to claim 12, wherein the first and second reactive compositions are included in an aqueous reactive composition CR1′.

24. Kit to implement the method according to claim 12, comprising: a first aqueous reactive composition (CR1) comprising at least one extracting agent of ferric and ferrous ions from the oil phase of the lubricating composition towards the aqueous phase; a second aqueous reactive composition (CR2) comprising at least one reducing agent of ferric ions (Fe3+) to ferrous ions (Fe2+); a third reactive composition (CR3) comprising at least one emulsion destabilising agent; a fourth reactive composition (CR4) in an aqueous solution comprising a ferrous ion complexing agent, wherein this agent changes colour when complexing with ferrous ions; a spectrophotometer; at least one second container; a device (D2) to take up each of the first, second, third and fourth reactive compositions; a magnetised support; at least one device (D3) to take up a few drops of lubricating composition to be analysed at step e).

25. The method according to claim 13, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

26. The method according to claim 14, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

27. The method according to claim 15, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

28. The method according to claim 16, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

29. The method according to claim 17, wherein the destabilising agent is selected from among primary or secondary alcohols (C4 to C10) non-miscible in water, alone or in a mixture.

30. The kit of claim 24, further comprising at least one first container.

31. The kit of claim 30, further comprising at least one device (D1) to take a sample of lubricating composition to be analysed.

Description

[0096] FIG. 1) illustrates a kit of the invention.

[0097] FIG. 2) illustrates a magnetised support of the invention.

[0098] The kit in FIG. 1) comprises: [0099] a magnetised support 1 comprising positions 2 each having a magnet and intended to receive first containers 3, and positions 4 intended to receive second containers 5; [0100] first containers 3; [0101] second containers 5; [0102] a reactive composition 6 (CR1′); [0103] a reactive composition 7 (CR3); [0104] a reactive composition 8 (CR4); [0105] an electronic spectrophotometer 9 comprising a receiving area 10 to receive second containers, preferably this receiving area forms an angle of 35 to 75°, preferably 50 to 70° e.g. 60° with the body of the spectrophotometer; [0106] at least one device 11 (D3); and [0107] at least three devices 12 (D2).

[0108] FIG. 2 illustrates a magnetised support 1 comprising positions 2 each having a magnet and intended to receive first containers 3, and positions 4 intended to receive second containers 5.

[0109] The present invention will now be described with the aid of a non-limiting example of embodiment of the method and kit of the invention.

EXAMPLE

[0110] The operator sets the spectrophotometer in operation.

[0111] a) The operator collects the lubricating compositions to be analysed in first containers 3, and places these containers in positions 2 comprising magnets of the magnetised support 1, after which any particulate iron contained in the lubricating composition to be analysed is drawn downwards to the bottom of the container close to the magnet.

[0112] b) The operator then uses three separate devices 12 (D2) to place each of the reactive compositions 6 (CR1′), 7 (CR3) and 8 (CR4) in as many second containers 5 as there are oils to be analysed. The content of the second containers is mixed by upturning the second containers 5. All the second containers 5 are arranged at positions 4 of the magnetised support 1.

[0113] c) The operator then places one of the second containers 5 in the receiving area 10 of the spectrophotometer 9 and measures the absorbance of the solution contained in the second container 5.

[0114] d) This second container 5 is then replaced in one of the positions 4 of the magnetised support 1 and the operator, using a device 11 (D3), then adds thereto three drops of one of the lubricating compositions to be analysed contained in one of the first containers 3. To do so, the operator must take care not to insert the device D3 into the bottom of the container 3 to avoid taking up any particulate iron which may be present at the bottom of the container 3. After adding the lubricating composition, the operator records any change in colour resulting from the reaction between the iron ions and the complexing agent of the reactive composition CR4.

[0115] e) The container 5 is then agitated by turning it over 10 times, after which it is placed in the receiving area 10 of the spectrophotometer 9.

[0116] f) The container 5 is left 5 minutes in the receiving area 10 of the spectrophotometer 9 before initiating measurement of the absorbance of the solution contained in said second container 5.

[0117] g) The spectrophotometer calculates the difference between the absorbance measurement when container 5 only contains the reactive compositions CR1′, CR3 and CR4, and the absorbance measurement when the lubricating composition is added to the container 5.

[0118] h) From the measurement obtained at g), the spectrophotometer determines the quantity of iron ions contained in the lubricating composition to be analysed.

[0119] Steps c) to h) are then repeated for each of the lubricating compositions to be analysed.