Spectrophotometric determination of iron in sugarcane leaves and sugar house products with two common comlexing agents

الملخص EN

Sensitive spectrophotometric methods for the determination of iron as iron (III) in sugarcane leaves and sugarhouse products were described.

The proposed methods involve the complexation of iron (III) in weakly acidic conditions with 5-sulphosalicylic acid and tiron having respective maximum absorbances at 490 nm and 670 nm.

Both the systems obey Lambert and Beer’s law in the concentration range 0.5–23 µg / ml.

Molar absorptivity, correlation coefficient and Sandell sensitivity values were found to be of 1.7141 x 103mol-1 cm-1 dm3, 0.9998 and 32.5845 ng / cm2 respectively for iron (III)-5-sulphosalicylic acid.

Whereas the corresponding values were found to be 1.870 × 103 mol-1 cm-1 dm3, 0.99903, 29.8553 ng / cm2 for iron (III)-tiron system.

Iron present in sugarcane leaves, sugarcane juice, pressmud, bagasse and also iron in pharmaceutical sample, plant leaves of Murrya coyingi and Moringaoliera was determined as iron (III) by both the methods following the principles of calibration graph method.

The results obtained from iron (III)-5-sulphosalicylic acid were reproducible with acceptable standard deviation 0.021-0.0319 and coefficient of variation 0.2414-1.5978%.

Whereas the results of iron (III)-tiron system were also reproducible with standard deviation 0.0192-0.033 and coefficient of variation 0.351-1.756 %.

For comparison iron present in all the seven samples were also determined separately as iron (II) following the ICUMSA iron (II)–1, 10-phenanthroline official method.

The results of total iron as iron (III) obtained by the proposed methods were comparable with those of the official method.

Therefore, the proposed spectrophptometric methods for the determination of iron (III) could be either complimentary or alternative to the ICUMSA official method.

Stoichiometry, iron (III) to complexing agents were determined by Job’s method and were found to be 1 : 2 for both the complexes.

The stability constant values determined by Job’s modified method were found to be 3.2 × 105 mol-1 dm3 and 0.84 × 105 mol-1 dm3 respectively for Iron (III)-5-sulphosalicylic acid and iron (III)-tiron.