The ratio of hapten to bovine serum albumin in an antigen conjugate was determined by matrix-assisted laser desorption/ionization mass spectrometry. A hybridoma secreting monoclonal antibodies (MAbs) was produced by fusing splenocytes immunized with an antigen-bovine serum albumin (BSA) conjugate with HAT-sensitive mouse myeloma cells. The cross-reaction of anti-forskolin antibodies with 7- deacetyl forskolin was 5.6%. A very small cross-reaction appeared with other derivatives. The full measuring range of the assay extends from 6 ng to 200 ng of forskolin. Immunoaffinity column chromatography using anti-forskolin MAbs appears to be far superior to previously published separation methods based on crystallization and chromatography. The capacity of the immunoaffinity column as determined by ELISA is 9 μg/ml. Forskolin has been isolated directly from the crude extracts of tuberous roots and the callus culture of Coleus forskohlii. A MAb against Δ¹-tetrahydrocannabinolic acid (THCA) was produced. The cross-reaction of anit Δ¹-THCA antibody against other cannabinoids was very wide. Many cannabinoids and a spiro-compound were reactive, but did not react with other phenolics. It became evident that this ELISA was able to be applied to the biotransformation experiments of cannabinoids in plant tissue culture system. Anti-solamargine MAbs were produced. A method of determination for solasodine glycosides by using TLC immunostaining was inverstigated. Solasodine glycosides separated by silica gel TLC were transferred to a polyvinylidene difluoride membrane. The membrane was treated with sodium periodate solution followed by BSA, resulting in a solasodine glycoside-BSA conjugate. Immunostaining of solasodine glycosides were more sensitive compared to other staining.