Method for determining iron ions in lubricating compositions, comprising the following steps: a) Taking a sample of the lubricating compositing to be analysed that is introduced 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 of the lubricating composition to an aqueous phase, the water coming from the composition CR1; ∘ a second aqueous reactive composition CR2 comprising at least one reducing agent of ferric ions Fe 3+ to ferrous ions Fe 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, characterized in that this agent changes colour when complexing with ferrous ions; and mixing thereof of the first, second, third and fourth reactive compositions; d) optionally, photochemical measurement of the absorbance of the mixture obtained at step c); e) Taking drops of the supernatant of the lubricating composition contained in the first container, held in position on the magnet, and adding 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 sample of the lubricating composition from the measurements obtained at step g) or from the difference between absorbance obtained at step g) and the one obtained at step d) if this last one is measured. a) Taking a sample of the lubricating compositing to be analysed that is introduced 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 of the lubricating composition to an aqueous phase, the water coming from the composition CR1; ∘ a second aqueous reactive composition CR2 comprising at least one reducing agent of ferric ions Fe 3+ to ferrous ions Fe 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, characterized in that this agent changes colour when complexing with ferrous ions; and mixing thereof of the first, second, third and fourth reactive compositions; ∘ 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 to an aqueous phase, the water coming from the composition CR1; ∘ a second aqueous reactive composition CR2 comprising at least one reducing agent of ferric ions Fe 3+ to ferrous ions Fe 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, characterized in that this agent changes colour when complexing with ferrous ions; d) optionally, photochemical measurement of the absorbance of the mixture obtained at step c); e) Taking drops of the supernatant of the lubricating composition contained in the first container, held in position on the magnet, and adding 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 sample of the lubricating composition from the measurements obtained at step g) or from the difference between absorbance obtained at step g) and the one obtained at step d) if this last one is measured.