A colorimetric method was developed to determine the quantity of total azadirachtin related limonoids (AZRL) in neem extracts. A mathematical model was also developed to aid in the multivariate calibration technique for the analysis of the spectra. With this model and the multivariate calibration technique, the colorimetric method can be used directly to analyse the purified neem seed kernel extracts and to eliminate interferences from other absorbing species. The AZRL and simple terpenoids (ST) content in the neem seed kernel, the seed shell, the leaf and the leaf stem was determined with conventional extraction method and the newly developed quantification technique. The results showed that the AZRL content in these parts of neem decreases in the order of seed kernel > leaf > seed shell > leaf stem. With the HPLC quantification technique, the content of azadirachtin in the neem seed kernel was determined, and the comparison of the azadirachtin content and the AZRL content suggested that azadirachtin accounts for around 58% of the total AZRL. Microwave-assisted extraction (MAE) of AZRL and ST from various parts of neem was also investigated. Various parameters affecting the extraction such as the power and the microwave irradiation time were studied. The comparison of the MAE with two conventional extraction methods, viz., room temperature extraction (RTE) and reflux temperature extraction (RFX) revealed that the property of sample matrix affected the special accelerating effect of the MAE. The study on the influence of solvents on the MAE showed that the solubility of the solvent to the target components and the ability of the solvent to absorb microwave energy played an important role in MAE.

No description available.