Thin-layer chromatographic method of estimation of individual meliacins such as azadirachtin,
salannin etc. could at best be considered as semi-quantitative, its main limitation being poor
resolution of meliacins. With the result, one cannot estimate quite confidently azadirachtin co-
occurring with its closely related analogues in crude extracts. HPLC analysis is the only reliable
method reported. Warthen et al160 developed a method and demonstrated its utility in the
analysis of azadirachtin in neem extracts and formulations. They employed a l0μ- Radial-pack. μ
--Bondapak C-18 column in a Z module Radial compression separation system using methanol
¬water (1:1) with a flow rate of 2 ml/min and detection at 214 nm. Klocke161 employed two
methods, one employing Phenomenex column, a solvent mixture consisting of MeCN-H2O (3:7)
isocratically with a flow rate of Iml min-I and detector set at 218 nm and the other employing
Alltech silica gel, isopropanol-hexane (1:3, I ml min-I) isocratically. Devakumar36 used MeOH -
H2O (1:1, I ml min-') and ODS chromosorb column for the analysis of nimbin, desacetylnimbin
and azadirachtin. Govindachari employed both MeOH-H2O and MeCN -H2O eluants with RP-18
column54.55.56. Analysis by super critical fluid chromatography is also reported61. Schneider
and Ermel123 have employed RP-8 column and a mobile phase containing a mixture of MeCN -
H2O in graded proportions with a flow rate of I ml min-I and UV detector set at 210 nm. This
procedure enabled them to survey different eco-types for azadirachtin content and the
dissipation behaviour of azadirachtin (112) and salannin (85) in the environment44
salannin etc. could at best be considered as semi-quantitative, its main limitation being poor
resolution of meliacins. With the result, one cannot estimate quite confidently azadirachtin co-
occurring with its closely related analogues in crude extracts. HPLC analysis is the only reliable
method reported. Warthen et al160 developed a method and demonstrated its utility in the
analysis of azadirachtin in neem extracts and formulations. They employed a l0μ- Radial-pack. μ
--Bondapak C-18 column in a Z module Radial compression separation system using methanol
¬water (1:1) with a flow rate of 2 ml/min and detection at 214 nm. Klocke161 employed two
methods, one employing Phenomenex column, a solvent mixture consisting of MeCN-H2O (3:7)
isocratically with a flow rate of Iml min-I and detector set at 218 nm and the other employing
Alltech silica gel, isopropanol-hexane (1:3, I ml min-I) isocratically. Devakumar36 used MeOH -
H2O (1:1, I ml min-') and ODS chromosorb column for the analysis of nimbin, desacetylnimbin
and azadirachtin. Govindachari employed both MeOH-H2O and MeCN -H2O eluants with RP-18
column54.55.56. Analysis by super critical fluid chromatography is also reported61. Schneider
and Ermel123 have employed RP-8 column and a mobile phase containing a mixture of MeCN -
H2O in graded proportions with a flow rate of I ml min-I and UV detector set at 210 nm. This
procedure enabled them to survey different eco-types for azadirachtin content and the
dissipation behaviour of azadirachtin (112) and salannin (85) in the environment44
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