التقدير الطيفي لايوني الكوبلت (II) والكروم (( III باستخدام مركب الازو الجديد وتطبيقاتھا

Spectrophotometric Determination of Cobalt (II) and Chromium(III) Ions using the new (Azo) Compound and their Applications.

ABSTRACT

This study encompasses the synthesis and characterization of a novel reagent, namely Ethyl4-(5-acetyl-2,3,4-trihydroxyphenyl) diazenylbenzoate (EATDB). The reagent was synthesized through azo coupling of the imidazole derivative with the diazonium salt of ethyl 4-aminobenzoate (benzocaine). The ensuing compound was subject to extensive analysis, employing sophisticated methods such as gas chromatography-mass spectrometry (G.C. mass), UV-Vis analysis, 1HNMR, 13CNMR, and FT.IR spectroscopy.
Notably, the optimal conditions for the reaction between the two ions (Co(II) and Cr (III) ions ) and the reagent were thoroughly explored. This entailed examining the effect of acidity function, addition sequence, stability duration of the complexes, ligand concentration, temperature influence, and ionic strength impact. The calibration curves for Cobalt (ll) and Chromium (lll) ions were constracted with concentration range from (1-100 µg.mL-1) for both of ions. The Analytical parameters obtained are linearity coefficient (R2)0.9980 and 0.9939,molar opsorpitivity 0.212×102 L.mole,cm-1and 0.935×103 L.mole.cm-1 and Sandall’s sensitivity 0.278 g.cm-2 and 0.556 g.cm-2 for Cobalt (ll) and Chromium (III) ions respectively. To ascertain the equivalency of the complexes, various methods including the Mole ratio method, Job’s method, and Mollard method were utilized. The stability constants (Ksta) for the cobalt (II) and chromium (III) complexes were found to be 5.967×108 and 1.125×1014L.mol-1 respectively. Moreover, the thermodynamic functions (ΔH, ΔG, and ΔS) for both complexes indicated that the reactions Co (II) and Cr (III) complexes were exothermic. Nevertheless, the study noted that there is interference from several cations and anions during the estimation of Cobalt (II) and chromium (III) ions. Consequently, the addition of appropriate masking agents was explored, taking into account the varying degrees of interaction depending on the nature and concentration of interfering ions. Impressively, the analysis of the dissolved complexes indicated that both Cobalt (II) and chromium (III) complexes were uncharged due to the measurement at conductivity.
The precision and accuracy of the analytical method were meticulously evaluated by subjecting it to three distinct ion concentrations, and subsequently computing the relative standard deviation (RSD %) as a measure of variability. Obtained data showcased excellent precision, with RSD% ranging from( 0.479% – 0.874%) for Co (II) and from (0.742% – 0.896%) for Cr (III). Moreover, the relative recovery ranged from 98.43% – 101.764% for Co (II) and from 99.41% – 101.470% for Cr (III).The Limit of Quantification L.O.Q was crucial for determining method’s sensitivity alongside with Limit of Detection L.O.D. For Cobalt (II) ion, the L.O.D and L.O.Q were found to be 0.7410µg.mL-, and 2.4120 µg.mL-1 respectively, while for Chromium (lll) ion are 0.8640 and 2.8510 µg.mL-1 respectively. Additionally, the reagent and the two complexes were investigated for their settling properties and physical characteristics, including melting point and molar conductivity. This analytical method proved effectively in quantifying cobalt (II) and chromium (III) ions present in a pharmaceutical sample, highlighting its utility in sensitive and accurate ion analysis.