Quality control methods for

Analysis of esters of organophosphorus compounds 
The extraction and the clean-up procedures can be performed as described 
above, but the detection requires a phosphorus flame ionization detector (P-
FID). 
Determination of specific pesticide residues in plant material 
 
General recommendations 
For the total determination, mix thoroughly 1 kg of plant material. 
In order to obtain reliable chromatographic results, do one or more of the 
following: 
- 
repeat the separation using another column;
- 
use a different separation system; 
- 
use a different detector system;
- 
apply a coupling technique;
- 
prepare a derivative; 
- 
perform chromatography with a mixture of the sample and a reference 
substance; 
- 
change the sample preparation; 
- 
use a fractionated elution during the column-chromatography clean-up 
procedure of the plant extract and test every fraction by chromatography; 
and 
- 
compare the distribution coefficient of the material with that of a 
reference substance. 
Prior to the quantitative determination of the material to be tested, check 
whether there is a linear relationship between the values obtained for the 
reference substance and its concentration over the range 0.1-2 times the standard 
concentration. Otherwise, prepare another concentration range or evaluate the 
results using a reference curve. Use any suitable mechanical or manual 
technique for the chromatographic determination. 
Store the reference solutions protected from light to prevent decomposition. Use 
glass vessels closed with glass stoppers and keep them in a container saturated 
with the solvent employed to avoid any increase in concentration due to 
evaporation. Check the loss by evaporation by interim weighing of the vessels. 
Use concentrated reference solutions within 6 months and diluted reference 
solutions within 4 weeks. 

---

Quality control methods for medicinal plant materials