CAS Number: 121-75-5


pK Chemicals manufactures Malathion in accordance with current Good Manufacturing Practice (cGMP).

Purified Malathion

    •   is used as an API in lice shampoo
    •   is highly effective, safe, and has been used for decades all over the world
    •   is approved by FDA and EMEA for treatment of head lice infestation

Malathion, an organophosphate, is both pediculicidal (kills live lice) and partially ovicidal (kills lice eggs). Organophosphates acts by inhibiting the enzyme acethylcholine esterase, which breaks down the neurotransmitter acetylcholine, the primary neurotransmitter in muscle tissue. The accumulation of acetylcholine causes muscle spasms and death of the lice and bugs by suffocation.

The compendial specification for Malathion exists in the European Pharmacopoeia.



Test/Characteristic Limit Test Method
Appearance Colourless to pale yellow liquid Visual (Ph.Eur.)
Identification As Malathion CRS IR (2.2.24)
Relative Density 1.220 to 1.240 Relative Density (2.2.5)
Optical Rotation - 0.1 to + 0.1 º Polarimetry (2.2.7)
Water NMT 0.1 w/w % Karl Fischer (2.5.12)
Assay 98.0 - 102.0 % HPLC (2.2.29)
Impurity A (Isomalathion) NMT 0.3 w/w % HPLC (2.2.29)
Impurity B (Maloxon) NMT 0.1 w/w % HPLC (2.2.29)
Impurity C NMT 0.25 % HPLC (2.2.29)
Any single unspecified impurity NMT 0.1 % HPLC (2.2.29)
Total impurities NMT 1 % HPLC (2.2.29)
Ethanol NMT 5000 ppm GC (Ph.Eur)
TAMC NMT 1000 Cfu/g (2.6.12)
TYMC NMT 100 Cfu/g (2.6.12)