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 (IAP) and detection of trace amounts of TNT was developed on the basis of antibodies (Abs) in a ceramic matrix (sol-gel). The study resulted in: (i) a highly 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 specific to TNT; and (ii) successful entrapment of the Abs that bound free analyte from solution. Binding was found to be highly reproducible, dose dependent, and only slightly (1.2-1,8-fold) lower than that in solution. The entrapped Abs did not leach from the matrix and were tolerant of absolute ethanol, acetone, and acetonitrile. Bound analytes could be easily eluted from the sol-gel matrix at high recoveries. The sol-gel-based IAP method described above introduces a simple one-step procedure that has a high potential to serve as a suitable and convenient immunochromatographic device for cleanup and concentration of TNT from "real field" samples in a manner that complies with both chemical and immunochemical residue analysis methods.