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) w ere found suitable for the detection of mercury(II) and lead(II) in ex tremely dilute aqueous solutions. In batch mode of extraction with imm obilized F(2)H(2)Dz-foam as low as 0.05 and 0.15 mu g ml(-1) of mercur y(II) and lead(II), respectively were detected and the colored chelate s were found more stable over 72 h. Lower concentrations of these meta l 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 det ermination of these metals was also possible using a suitable standard color scale. The effect of diverse ions on the detection of 1 mu g me rcury(II) and lead(II) by the proposed F(2)H(2)Dz-foam test was critic ally investigated. The method was satisfactorily applied for the detec tion of mercury(II) or lead(II) in natural water samples. (C) 1997 Els evier Science B.V.