Table 17: Comparision of the results with already reported methods.

Metal ionReagent (nm)pH/mediumAqueous/extractionBeer’s law μg mL−1 L mol−1 cm−1InterferenceReference

Fe(II)Thiocyanate-phenanthroline520Aqueous0–241.87[10]
Fe(II)2-[2-(3,5-Dibromopyridyl-azo]-5-dimethyl amino-benzoic acid6152.0–7.0Extraction0–5.59.36Tl(I), Zn(II), Cr(III), W(VI), Co(II), Cu(II), Ni(II), and Pd(II)[24]
Fe(II)1,10-Phenanthroline and picrate5102.0–9.0Extraction0.1–3.613EDTA, CN-[25]
Fe(II)4-(2-Pyridylazo)resorcinol5056.0–7.5Extraction0–2.06Ni(II), Co(II), Pb(II), and EDTA[26]
Fe(II)1,10-Phenanthroline-tetraphenylborate5154.25Aqueous2.24–37.291.2[27]
Fe(II)1,3-Diphenyl-4-carboethoxy pyrazole-5-one5253.5–4.0Aqueous0.5–101.156Cu(II), Co(II), Zn(II), Mo(VI), EDTA[28]
Fe(II)Dyformyl hydrazine4707.3–9.3Aqueous0.25–130.3258[29]
Fe(II)4,7-Diphenyl-1,10-phenanthroline and tetraphenylborate534Extraction0–20.02[30]
Fe(II)Thiocyanate-acetone480HClO4Aqueous2.1Cu(II), , and [31]
Fe(II)2-Hydroxy-1-naphthaldehyde-p-hydroxybenzoic hydrazone4055Aqueous0.05–1.375.6Sn(II), Co(II) Ni(II) Zn(II) Al(III) Cu(II)Present method
Co(II)Sodium isoamyl xanthate4004.5–9.0Aqueous3.0–351.92[16]
Co(II)2-Pyridine carboxalde hydeisonicotinyl-hydrazine3469Aqueous0.01–2.77.1Au(III), Ag(I), Pt(III)[18]
Co(II)2-Hydroxy-1-naphthalidene salicyloyl hydrazone4308.0–9.0Extraction0–100.16[22]
Co(II)Pyridine-2-acetaldehyde salicyloyl hydrazone4151.0–6.0Extraction0.5–7.01.04[32]
Co(II)Bis-4-phenyl-3-thiosemicarbazone40040.6–6.02.2[33]
Co(II)2-Hydroxy-l-naphthalidene-salicyloylhydrazone4308.0–9.0Extraction0–101.6 × 103[22]
Co(II)2-(2-Quinolynylazo)-5-dimethylamino aniline6255.5Extraction0.01–0.64.3Many cations and anions[34]
Co(II)2-Hydroxy-3-methoxy benzaldehyde thiosemicarbazone3906Aqueous0.06–2.352.74[35]
Co(II)2-Hydroxy-1-naphthaldehyde-p-hydroxybenzoic hydrazone4255Aqueous0.12–3.542.3Ni(II), Zn(II), Sn(II), In(III), and Ga(IIII)Present method