Sensitive detection and semiquantitative determination of mercury(II) and lead(II) in aqueous media using polyurethane foam immobilized 1,5-di-(2-fluorophenyl)-3-mercaptoformazan

1,5-Di-(2-fluorophenyl)-3-mercaptoformaza (F(2)H(2)Dz) immobilized and plasticized with tri-n-butylphosphate (TBP) polyurethane foam (PUF) were found suitable for the detection of mercury(II) and lead(II) in extremely dilute aqueous solutions. In batch mode of extraction with immobilized F(2)H(2)Dz-foam as low as 0.05 and 0.15 mu g ml(-1) of mercury(II) and lead(II), respectively were detected and the colored chelates were found more stable over 72 h. Lower concentrations of these metal ions (less than or equal to 1 ppb) were detected by plasticized F(2)H(2)Dz-TBP foam packed in column extraction mode. Semiquantitative determination of these metals was also possible using a suitable standard color scale. The effect of diverse ions on the detection of 1 mu g mercury(II) and lead(II) by the proposed F(2)H(2)Dz-foam test was critically investigated. The method was satisfactorily applied for the detection of mercury(II) or lead(II) in natural water samples. (C) 1997 Elsevier Science B.V.