The CAMAG Automated Multiple Development procedure allows thin-layer chromatography to be utilized for tasks that could not be performed by TLC in the past.
Only the AMD 2 procedure can be successfully employed for reproducible gradient elution with silica gel as the stationary phase. In column liquid chromatography, gradient elution is common on reversed phases only because a silica gel column would call for a time consuming reconditioning or be irreversibly degraded, which is not acceptable in a technique depending on multiple use of the stationary phase. In Thin-Layer chromatography this is not relevant.
The principle of the CAMAG AMD procudure
- The HPTLC plate is developed repeatedly in the same direction.
- Each successive run extends over a longer solvent migration distance than the one before.
- Between runs, the solvent is completely removed from the developing chamber and the layer is dried under vacuum.
- Each successive run uses a solvent of lower elution strength than that of the one used before. In this way, a stepwise elution gradient is formed.
- The combination of focusing effect and gradient elution results in extremely narrow bands. Their typical peak width is about 1 mm. This means that, with the available separation distance of 80 mm, up to 40 components can be completely resolved, i.e. with base line separation.
The AMD 2 with winCATS is compliant with the requirements of GMP/GLP and can be IQ/OQ qualified. If you want to use the instrument in a 21 CFR Part 11 environment, the option 21 CFR Part 11«compliance ready» is required for each winCATS workstation.
The AMD 2, like other computer controlled CAMAG instruments, communicates with winCATS. The gradient, made from up to 5 solvent bottles, is defined by input into a table in winCATS. Gradient and developing distance for each run can be shown graphically for verification. Then all individual runs of the developing program are performed fully automatic and monitored by winCATS.
- Multiple development gradient elution
- Separation power improved over regular HPTLC by a factor 3
- Data input and monitoring through winCATS
- Utilizing time also after working hours
Separation of various rhubarb samples by AMD
Detection: UV 366 nm
Mobile phase: gradient in 10 steps: methanol – dichloromethane (40:60) to (10:90) in 9 steps, 40 mm developing distance, then one isocratic step methanol – dichloromethane (10:90) over 70 mm developing distance
Note: for operating the AMD system, an external supply of compressed nitrogen or air (4 bars) is required; consumption: about 10 L/h.
If the AMD system is to be operated with a different type vacuum pump, note that a minimum average pumping speed of 3 m3/h according to PNEUROP is required and an ultimate partial pressure of < 10 mbar is reached.
CAMAG® AMD 2 System Automated Multiple Development
Oil-sealed rotary vane vacuum pump RV3 (Edwards);
Fields marked with an '*' are mandatory fields.