Quality control methods for

Determination of total chlorine and phosphorus 
Most pesticides contain organically bound chlorine or phosphorus. 
Recommended procedure 
 
Preparation of samples 
Reduce the plant material to a fine powder, and extract with a mixture of water 
and acetonitrile R. Most pesticides are soluble in this mixture, while most 
cellular constituents (e.g. cellulose, proteins, amino acids, starch, fats and related 
compounds) are sparingly soluble and are thus removed. A number of polar and 
moderately polar compounds may also be dissolved; it is therefore necessary to 
transfer the pesticides to light petroleum R. For pesticides containing chlorine, 
further purification is seldom required, but for those containing phosphorus, 
further purification by column chromatography may be necessary, eluting with 
mixtures of light petroleum R and ether R. 
Preparation of the column 
Use Florisil R grade 60/100 PR (or equivalent), activated at 650°C, as the 
support. If this material is obtained in bulk, transfer it immediately after opening 
to a 500-ml glass jar or bottle with a glass stopper or foil-lined, screw-top lid. 
Store in the dark. Before use, heat at not less than 130°C, cool in a desiccator to 
room temperature and heat once again to 130°C after 2 days. 
Prepare a Florisil column (external diameter, 22 mm) which contains, after set-
tling, 10 cm of activated Florisil topped with about 1 cm of anhydrous sodium 
sulfate R. Pre-wet the column with 40-50 ml of light petroleum R. Place a 
graduated flask under the column to receive the eluate. 
Method 
Grind the material to pass through a sieve no. 710 or 840 and mix thoroughly. 
Place 20-50 g of the ground sample into a blender, add 350 ml of acetonitrile R 
with a water content of 35% (to 350 ml of water add sufficient acetonitrile R to 
produce 1000 ml). Blend for 5 minutes at a high speed. Filter under vacuum 

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Quality control methods for medicinal plant materials 
through an appropriate funnel, diameter 12 cm, fitted with filter-paper, into a 
500-ml suction flask. 
Transfer the filtrate to a 250-ml measuring cylinder and record the volume. 
Transfer the measured filtrate to a 1-litre separating funnel and carefully add 
100ml of light petroleum R. Shake vigorously for 1-2 minutes, add 10 ml of 
sodium chloride (400 g/l) TS and 600 ml of water. Hold the separating funnel in 
a horizontal position and mix vigorously for 30-45 seconds. Allow to separate, 
discard the aqueous layer and gently wash the solvent layer with two 100-ml 
portions of water. Discard the washings, transfer the solvent layer to a 100-ml 
glass-stoppered cylinder, and record the volume. Add about 15 g of anhydrous 
sodium sulfate R and shake vigorously. The extract must not remain in contact 
with this reagent for longer than 1 hour. Transfer the extract directly to a Florisil 
column; if necessary, reduce the volume first to 5-10 ml. Allow it to pass through 
the column at a rate of not more than 5 ml per minute. Carefully rinse the 
cylinder with two portions, each of 5 ml, of light petroleum R, transfer them to 
the column, rinse with further small portions of light petroleum R if necessary, 
and then elute at the same rate with 200 ml of ether/light petroleum TS1. 
Change the receiver and elute with 200 ml of ether/light petroleum TS2. Again 
change the receiver and elute with 200 ml of ether/light petroleum TS3. 
Evaporate each eluate to a suitable volume, as required, for further testing. 
• The first eluate contains chlorinated pesticides (aldrin, DDE, TDE (DDD), 
o,p'-and p,p'-DDT, HCH, heptachlor, heptachlor epoxide, lindane, 
methoxychlor), polychlorinated biphenyls (PCB), and phosphated 
pesticides (carbophenothion, ethion, and fenchlorphos). 
• The second eluate contains chlorinated pesticides (dieldrin and endrin) 
and phosphated pesticides (methyl parathion and parathion). 
• The third eluate contains phosphated pesticide (malathion).