The research resulted in the development of a new method for selective extraction of iron and complex formation of 5-(pyridilazo)-2- (mono ethylamine paracresol) (PAAC) directly in the organic phase. The experience has shown that iron (III) from a highly acidic environment in the presence of chloride ions and dimethylformamide (DMF) is well extracted by chloroform. In the absence of DMF, iron (III) is not extracted. The study of iron (III) extraction by chloroform as H⁺ ion, Cl- ion function and DMF concentrations has shown that the optimum conditions for iron (III) extraction are: 5.55 m and above in hydrogen ions, 6.55 m and above in chloride ions, 30-45 vol % DMF and shaking phases for 10-15 seconds. If the volumes of the aqueous and organic phases are equal, iron (III) extraction at single extraction is 99.9% and does not change to a 3:1 ratio.

The extractable iron chloride complex (III) composition was determined by the balance shift method. The data obtained shows a straight-line relationship with the tangent angles of straight lines equal to 1, 4 and 3, respectively.

Consequently, iron (III) is extracted by chloroform as Н[FeCl₄]. The solvate number in the extract is 3. The number of water molecules associated with Н[FeCl₄] in the extract determined by spectrophotometry [8] is 4. Thus, the iron chloride complex (III) from a highly acidic medium in the presence of DMF is extracted by the chloroform hydro-solvate mechanism.

Once iron (III) is extracted with chloroform under optimal conditions, the aqueous phase is separated, the PAAC chloroform solution, the acetate-ammonia buffer solution is added to the extract and the phases are shaken, iron (III) is complexed with PAAC in the organic phase.

Studies of iron complex (III) with PAAC depending on the optical density of the pH buffer solution have shown that the practical complete complexation of iron (III) with PAAC in chloroform occurs in the pH range of the buffer solution 3-7.

Iron complex (III) with PAAC in the extract is stable for over three days. The maximum light absorption of iron complex (III) with PAAC is at 540 nm. The apparent molar yield at 540 nm is 3.36∙10⁴.

The Ber law is observed in the range of 0.5-150 µg iron in 10 ml of the extract. The reproducibility of definitions is in the range of 1-5%.

The developed method of iron extraction and photometric determination makes it possible to determine the microgram content of iron in the presence of large amounts of foreign elements. The iron extraction method has been tested on model solutions, silicate rocks and ores.

The developed method of extraction and photometric determination of iron can be recommended for the analysis of production solutions, waste water, ores, rocks and other materials with complex chemical composition without separating the associated elements.