Quality control methods for

Determination by gas chromatography 
Perform the determination as described in Volume 1 of The international 
pharmacopoeia (5). 
Apparatus 
The equipment consists of: 
- 
a glass column 1.2 m long, internal diameter 2 mm; 
- 
a suitable stationary liquid phase; 
- 
a suitable diatomaceous support. 
Use nitrogen R as the carrier gas with a flow rate of 30.0 ml/min. The sample 
injection block should be maintained at 230°C, the column at 190°C and the 
detector, which should be nitrogen-selective, at 300°C. In addition: 
- 
volume of sample solution to be injected: 2.0 µl; 
- 
separation characteristics: h ≤ 1.2 x 10
-3
for desmetryn R; R
S
≥ 1.2 for 
prometryn R and simazine R; 
- 
relative standard deviation (precision of chromatographic system): s
r
≤ 
0.05 for desmetryn R, prometryn R and simazine R. 
Method 
Chromatogram T. To determine the separation characteristics, inject solution S
2
(for the preparation of solution S
2
see "Determination of the rate of recovery" 
above). Chromatograms A
1
-A
5
. To determine the relative standard deviation, 
inject solution S
2
and repeat the determination 5 times. 

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Quality control methods for medicinal plant materials 
Chromatogram S
2
. Inject 1.0 ml of solution S
2
for the determination of the rate of 
recovery. Dilute 1.0 ml of solution S
2
to 10.0 ml with acetone R and inject it for 
the chromatographic determination. On the chromatogram the peaks occur in 
the following sequence: prometryn, simazine, desmetryn. 
Chromatogram P
2
. Inject the purified extract or the especially purified extract. 
Determine using an external standard: a = 0.0005To convert the values obtained 
to percentage by weight, multiply the concentration in mg/kg by 10
4
. 
The total maximum permissible amount of residues due to desmetryn, 
prometryn and simazine is 2 mg per kg of plant material. 

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Quality control methods for medicinal plant materials