Immunochemical approaches for purification and detection of TNT traces by antibodies entrapped in a sol-gel matrix

A highly sensitive immunochemical method for immunoaffinity purification (I AP) and detection of trace amounts of TNT was developed on the basis of ant ibodies (Abs) in a ceramic matrix (sol-gel). The study resulted in: (i) a h ighly sensitive and reproducible TNT ELISA (I-50 and I-20 values of 0.4 +/- 0.09 ppb and 0.12 +/- 0.03 ppb, respectively; n = 12), which is highly spe cific to TNT; and (ii) successful entrapment of the Abs that bound free ana lyte from solution. Binding was found to be highly reproducible, dose depen dent, and only slightly (1.2-1,8-fold) lower than that in solution. The ent rapped Abs did not leach from the matrix and were tolerant of absolute etha nol, acetone, and acetonitrile. Bound analytes could be easily eluted from the sol-gel matrix at high recoveries. The sol-gel-based IAP method describ ed above introduces a simple one-step procedure that has a high potential t o serve as a suitable and convenient immunochromatographic device for clean up and concentration of TNT from "real field" samples in a manner that comp lies with both chemical and immunochemical residue analysis methods.