Field Detection and Sensitive Determination of Copper in Soil and Airborne Dust Particulates with1-[Pyridyl-(2)-azo]-naphthol-(2), N-Phenyl-N′-(4-methylphenyl)benzamidine, and Triton X-100

Abstract

Abstract A rapid field detection and spectrophotometric method for determining copper is described. The method is based on extraction of the red Cu(II)-1-[pyridyl-(2)-azo]naphthol-(2) (PAN) complex with N-Phenyl-N'-(4-methylphenyl)benzamidine (PMPBA) in the presence of a nonionic surfactant, Triton X-100 (TX-100) at pH 8.0–9.3. The molar absorptivity of the red Cu(II)-PAN–TX-100–PMPBA complex is 1.90 × 10s L/mol/cm at 550 nm, the wavelength of maximum absorption. The detection limit is 1 ng Cu/mL aqueous solution. The system obeys Beer’s law up to a concentration of 0.4 μg Cu(II)/mL or 4 μg/10 mL in organic solution. Precision was checked by finding the relative standard deviation (RSD) for N = 10 at a level of 2.0 μg/10 mL Cu(II), which was 1.5%. The validity was tested by determining total Cu in soil and airborne dust particulate samples. Six soil and 24 dust fallout samples were analyzed. Cu concentrations in soil ranged from 2.88 ± 0.05 ppm to 9.34 ± 0.16 ppm, with RSD values ranging from 1.6 to 2.1 % (N = 5). Cu concentrations in dust fallout ranged from 33 ± 01 ppb to 557 ±10 ppb with, RSD values ranging from 1.6 to 3.0%. These data agreed very closely with results of analyses by atomic absorption spectrophotometry.