REFERENCES
- Unger , K. 1979 . Porous Silica Amsterdam : Elsevier .
- Mottola , H.A. and Steinmetz , J.R. 1992 . Chemically Modified Surfaces Amsterdam : Elsevier .
- Eiden , R. , Falter , R. , Castro , B.A. and Schöler , H.F. 1997 . Fresenius J. Anal. Chem. , 357 : 439
- Janos , P. , Stutik , K. and Pacakova , V. 1991 . Talanta , 38 : 1445
- Kocjan , R. 1994 . Analyst , 119 : 1863
- Sarkar , A.R. , Datta , P.K. and Sarkar , M. 1996 . Talanta , 43 : 1857
- Kocjan , R. and Przeszlakowski , S. 1992 . Talanta , 39 : 63
- Tong , A. , Akma , Y. and Tanaka , S. 1990 . Analyst , 115 : 947
- Prezeslakowoski , S. and Kocjan , R. 1985 . Analyst , 110 : 1077
- Seshadri , T. and Kettrup , A. 1982 . Fresenius Z. Anal. Chem. , 310 : 1
- Mahmoud , M.E. 1996 . Anal. Lett. , 29 : 1791
- Mahmoud , M.E. and Soliman , E.M. 1997 . Talanta , 44 : 1063
- Soliman , E.M. 1997 . Anal. Lett. , 30 : 1739
- Mahmoud , M.E. 1997 . Talanta , 45 : 309
- Mahmoud , M.E. and Soliman , E.M. 1997 . Talanta , 44 : 15
- Seshadri , T. , Dietz , G. and Haupt , H.J. 1984 . Fresenius Z. Anal. Chem. , 319 : 403
- Becker , N. and Unger , K. 1980 . Fresenius Z. Anal. Chem. , 304 : 374
- Marshall , M.A. and Mottola , H.A. 1985 . Anal. Chem. , 57 : 729
- Mahmoud , M.E. and Al Saadi , M.S.M. 2001 . Anal. Chim. Acts , in press
- Soliman , E.M. , Mahmoud , M.E. and Ahmed , S.A. 2000 . Talanta , 54 : 243
- Mahmoud , M.E. and Gohar , G.A. 2000 . Talanta , 51 : 77
- Mahmoud , M.E. , Osman , M.M. and Amer , M.A. 2000 . Anal. Chim Acts , 413 : 33
- Mahmoud , M.E. 1999 . Anal. Chim. Acta , 398 : 297
- Ma , W.X. , Lin , F. , Li , K.A. , Chen , W. and Tong , S.Y. 2000 . Anal. Chim. Acta , 416 : 191
- Liu , P. , Pu , Q. , Hu , Z. and Su , Z. 2000 . Analyst , 125 : 1205
- Garg , B.S. , Sharma , J.S. , Bist , J.S. , Bhojak , N. and Mittal , S. 1999 . Talanta , 48 : 49
- Volkan , M. , Ataman , O.Y. and Howard , A.G. 1987 . Analyst , 112 : 1409
- Seshadri , T. and Haupt , H.J. 1988 . Anal. Chem. , 60 : 47
- Tong , A. , Akama , Y. and Tanaka , S. 1990 . Anal. Chim. Acta , 230 : 179
- Pyell , U. and Stork , G. 1992 . Fresenius J. Anal. Chem, , 343 : 576
- Soliman , E.M. and Mahmoud , M.E. 1997 . Analusis , 25 : 148
- Soliman , E.M. 1998 . Anal. Lett. , 31 : 299
- Rangnekar , D.M. and Sunthankar , S.V. 1974 . Indian J. Technol. , 12 : 548
- Pearson , R.G. 1963 . J. Am. Chem. Soc. , 85 : 3533
- Myers , R.T. 1978 . Inorg. Chem. , 17 : 952