| HS Code | 793507 |
| Chemical Name | Malathion |
| Cas Number | 121-75-5 |
| Molecular Formula | C10H19O6PS2 |
| Molecular Weight | 330.36 g/mol |
| Grade | Veterinary Grade API |
| Assay | ≥ 95% (as Malathion) |
| Physical State | Clear to amber viscous liquid |
| Solubility | Slightly soluble in water; miscible with most organic solvents |
| Melting Point | 2.85°C |
| Boiling Point | 156-157°C at 0.7 mmHg (decomposes on heating) |
| Flash Point | > 162°C (closed cup) |
| Storage Conditions | Store in tightly sealed containers in a cool, dry, well-ventilated area |
| Therapeutic Class | Ectoparasiticide (organophosphate) |
| Target Species | Cattle, pigs, sheep, goats, poultry, dogs, and other veterinary species |
| Indicated Dosage Forms | Tablets, Injections, Capsules, Powders, Granules, Premix, Solutions |
As an accredited Malathion Veterinary Grade API for Tablets / Injections / Capsules / Powders / Granules / Premix / Solutions factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Malathion Veterinary Grade API: packed in 25 kg sealed HDPE drums with tamper-evident closures, double-lined inner bags, and complete documentation. |
| Container Loading (20′ FCL) | One 20ft FCL container loaded with Malathion Veterinary Grade API, securely packed in sealed drums on pallets, ready for transport. |
| Shipping | Malathion Veterinary Grade API is shipped in sealed, light-resistant containers, protected from moisture and extreme temperatures. Shipments comply with local and international hazardous material regulations, with proper labeling and documentation. Under controlled conditions, the API remains stable during transit, ensuring secure delivery worldwide for pharmaceutical processing. |
| Storage | Store Malathion Veterinary Grade API in tightly sealed, original containers in a cool, dry, well-ventilated area. Protect from moisture, direct sunlight, and high temperatures. Keep away from oxidizers, ignition sources, and foodstuffs. Maintain controlled room temperature unless otherwise specified. Ensure proper labeling and segregation to prevent cross-contamination. |
| Shelf Life | Shelf life: 24 months from manufacture when stored unopened in a cool, dry place, protected from light. |
Malathion veterinary grade API supplied to ectoparasiticide finished pharmaceutical manufacturers is controlled against a technical purity of not less than 95.0% w/w, with the toxicologically relevant impurity isomalathion held at ≤0.1% w/w under USP 43-NF38 release criteria; moisture is maintained below 0.5% w/w to suppress hydrolytic cleavage to malathion monoacid during maritime freight and warehousing. Residual solvent and related impurity control are routine, with specifications invoking ICH Q3C and ICH Q3A where pharmaceutical-quality dossiers are filed. Tablet, injection, and capsule routes are excluded from the verified downstream scenario set because no current EU Union Register or US FDA registration exists for systemic malathion formulations in food-producing animals; the active substance is instead supplied to solution, emulsifiable concentrate, oil-in-water premix, and dust manufacturers where topical route risk has been evaluated. The downstream scenes below are limited to real ectoparasiticide routes for which label precedents, residue tolerances, or pharmacopoeial specification tests are published. Where data for a specific formulation configuration is absent, that absence is stated explicitly rather than filled with extrapolated values.
Plunge dip installations for Psoroptes ovis, Bovicola ovis, and Melophagus ovinus create the most demanding emulsifier stress in the veterinary malathion portfolio because recirculating pump sumps return lanolin, faecal colloids, wool wax, and soil fines into the bath over multi-day use. The ready-to-use concentration is fixed at 0.05% w/v, prepared by diluting a 50% w/w emulsifiable concentrate 1:1,000; replenishment tanks are dosed at 0.10% w/v after every 100 sheep to correct drag-out, which typically removes 10–15% of bath volume. Compliance for the concentrate includes emulsion stability and re-emulsification testing by CIPAC MT 36.3, with acceptance requiring no free oil after 24 h at 30°C and no sludge formation after 5 freeze-thaw cycles; end-use dip certification is governed by the relevant national sheep scab order. The production process dissolves the API in an aromatic hydrocarbon blend at 40–45°C under nitrogen blanketing, adds a calcium dodecylbenzene sulfonate and ethoxylated castor oil emulsifier pair at 10–12% w/w, and shears the pre-emulsion in a rotor-stator disperser at 1,800 rpm for 25 min before discharging through a 10 μm polypropylene bag filter. Terminal packs are 5 L HDPE jerricans, 20 L fluorinated HDPE pails, and 200 L returnable stainless-steel drums.
In cattle crush and raceway treatments, a 0.5% w/v ready-to-use aqueous emulsion is derived from the same 50% w/w EC and applied to the dorsum, underline, neck, and upper hind legs at 2–4 L per mature animal; the target organisms include Bovicola bovis, Linognathus vituli, and Haematobia irritans. Residue tolerance for meat and milk is anchored to 40 CFR §180.111 in the United States, while European marketing authorization requires an MRL under Regulation (EC) No 470/2009 when food-producing species are claimed. Dilution at point-of-use is performed through a low-shear proportioning pump set at 1:100; spray delivery uses flat-fan nozzles at 2–3 bar to generate a volume median diameter above 350 μm, which reduces drift onto milk parlour equipment and adjacent pasture. The concentrate is manufactured in a jacketed vessel with an anchor agitator turning at 60–80 rpm; the emulsifier system combines an anionic calcium sulfonate and a non-ionic tristyrylphenol ethoxylate at a combined loading of 8.0% w/w, and epoxidized soybean oil is added at 2.0% w/w as an acid-scavenging stabilizer. Finished presentations are 1 L, 5 L, and 20 L fluorinated HDPE containers with induction-sealed closures.
Poultry dusting against Dermanyssus gallinae and Menacanthus stramineus uses a ready-to-use powder containing 4.0% w/w malathion on an inert calcium carbonate and kaolin carrier, with fumed silica added at 0.3% w/w as a flow conditioner. The powder is applied to vent feathers, nest boxes, slat junctions, and litter surfaces at a label maximum of 0.45 kg per 100 birds; the treatment interval is set at 10–14 days to prevent excessive visible residue on egg collection belts and pack-line transfer surfaces. Compliance screening for eggs and poultry tissue in the United States is established under 40 CFR §180.111, and the dry formulation is checked against ASTM E11 sieve specifications with not less than 98% passing through a 300 μm opening and not more than 5% retained on a 150 μm sieve. The production process uses a double-ribbon horizontal blender at 25 rpm for 15 min; the active substance is first pre-milled with the fumed silica before blending into the carrier to reduce caking in humid layer houses. Terminal packages are 1 lb shaker cans and 25 lb polyethylene-lined paper sacks. The powder is an external bird and surface treatment, not a feed additive.
Historically, hog louse and sarcoptic mange control in farrowing and gestation barns has used a diluted malathion emulsion applied at 0.5% w/v to the ears, jowl, flank, and inner hind legs of breeding swine, with a typical dose of 0.5–1.0 L per sow depending on hide soiling. The product is mixed at point of use from a 50% w/w EC through a 1:100 proportioner, then sprayed via a hand-lance at 1.5–2.5 bar; a second application on day 14 is required for Sarcoptes scabiei var. suis because the formulation does not exert ovicidal activity. The compliance dossier for swine use requires systemic toxicokinetic data under OECD Test Guideline 417; tissue residue and withdrawal provisions are set by the national authority, and published data for this specific swine formulation configuration is limited. The manufacturing process alters the solvent phase with a short-chain glycol ether at 5.0% w/w to maintain emulsion stability in cold water down to 4°C; the emulsifier is a branched alcohol ethoxylate with HLB 12–13. Finished packs are 20 L drums and 200 L returnable stainless-steel drums.
Structural treatment of pens, feed aprons, milk parlour walls, and piggery slats uses a dilute emulsion at 0.5–1.0% w/v applied to point of run-off with a low-pressure hydraulic sprayer at 3–5 bar; this route targets adult parasites and nymphs that move off the host into cracks, bedding interfaces, and manure belt housings. The addition ratio for facility use is based on the same 50% w/w EC diluted 1:50 to 1:100, depending on surface porosity, with the higher concentration reserved for unpainted concrete and timber. Stability after dilution is tested in standard hard water under CIPAC MT 36.3; the acceptance criterion is no oil separation after 2 h at 30°C. Compliance for dairy premises requires that no visible film remains on milk contact surfaces; post-spray rinsing of milking clusters, bulk tank exteriors, and claw pieces is performed with potable water before the next milking shift. The liquid concentrate is manufactured with a non-ionic emulsifier blend at 6.0% w/w and a corrosion inhibitor package at 0.5% w/w to protect galvanized feed aprons and fan blades; terminal packs are 20 L and 200 L drums. Published data for residue runoff from feed apron surfaces is limited, so the product is not released for use where stormwater drains directly into surface water without secondary containment.
| Target system | Concentrate strength | Ready-to-use active level | Critical production equipment | Primary compliance anchor |
|---|---|---|---|---|
| Sheep plunge dip | 50% w/w EC | 0.05% w/v | Rotor-stator disperser 1,800 rpm | CIPAC MT 36.3 |
| Cattle crush spray | 50% w/w EC | 0.5% w/v | Anchor agitator 60–80 rpm | 40 CFR §180.111 |
| Poultry dust | 4.0% w/w powder | 4.0% w/w | Double-ribbon blender 25 rpm | ASTM E11 |
| Swine topical spray | 50% w/w EC | 0.5% w/v | Point-of-use proportioner 1:100 | OECD 417 |
| Premises surface spray | 50% w/w EC | 0.5–1.0% w/v | Hydraulic sprayer 3–5 bar | CIPAC MT 36.3 |
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Supplied under product identifier MLT-VET-API-950, the active pharmaceutical ingredient is diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate, CAS 121-75-5, with molecular formula C10H19O6PS2 and relative molecular mass 330.36. The material is a clear amber liquid at 20–25°C, manufactured as a high-purity organophosphate for downstream veterinary formulation into powders, granules, premix intermediates, non-aqueous solutions and, where supported by regulatory approvals, oral solids and injectable preparations. The grade differs from technical malathion by a reduced impurity panel, lower residual solvent content, and controlled water content suitable for pharmaceutical compounding. The liquid active cannot be directly compressed or filled into hard capsules; it is adsorbed onto high-surface-area carriers before solid-dose processing. Aqueous systems are feasible only with emulsifier packages and tight pH control because the active exhibits rapid alkaline hydrolysis.
Typical use concentrations in registered veterinary ectoparasiticide formulations range from 2.0% w/w in ready-to-use solutions to 50.0% w/w in emulsifiable concentrates and premix adsorbates. The intended veterinary applications include control of lice, mites, ticks, fleas and horn flies on cattle, poultry and companion animals where national authorizations permit. The API is not a systemic endectocide; oral and injectable presentations require vehicle and packaging strategies that exclude free water and alkaline excipients.
Malathion undergoes pH-dependent hydrolysis through cleavage of the ester and phosphorothioate groups. Published buffer data indicate hydrolysis half-lives of approximately 107 days at pH 5, 6 days at pH 7 and <24 h at pH 9 at 25°C. This instability transfers directly to production equipment selection. Aqueous granulation is prohibited, and all contact surfaces are dried to a dew point of ≤-20°C before charging. Bulk storage containers are nitrogen-purged. Fluorinated high-density polyethylene or 316L stainless steel is specified for routine holding, while mild steel and unlined phenolic closures are excluded because trace iron accelerates decomposition of the phosphorothioate linkage.
At relative humidity >60%, open transfer of the liquid API leads to measurable water uptake and assay decline within 8 h. Closed transfer with nitrogen overlay is therefore mandatory. Container-closure integrity is verified by vacuum decay in accordance with ASTM F2338-09. The product is incompatible with alkaline reagents, amines and oxidizing agents. Sodium bicarbonate, calcium hydroxide, bentonite with high free alkalinity and amine-functional excipients should be excluded from tablet blends and powder premixes because these materials raise local pH above 8 and accelerate degradation to malaoxon and isomalathion.
Release specifications are applied to each batch. The following limits are representative and are aligned with pharmacopoeial and ICH Q3C residual solvent requirements.
| Parameter | Method | Limit |
|---|---|---|
| Malathion assay | GC-FID, USP <621> | ≥95.0% w/w |
| Water content | Karl Fischer, USP <921> Method Ia | ≤0.1% w/w |
| Acidity as H₂SO₄ | Titrimetric, CIPAC MT 31 | ≤0.2% w/w |
| Acetone-insoluble matter | CIPAC MT 27 | ≤0.1% w/w |
| Isomalathion | GC-FPD | ≤0.3% w/w |
| Malaoxon | LC-MS/MS | ≤0.1% w/w |
| Residual solvents | HS-GC, ICH Q3C | Class 1 ≤2 ppm; Class 2 ≤300 ppm |
The assay is not sufficient for batch release because the toxicological profile of malathion is influenced by impurity composition. Isomalathion and malaoxon are monitored because both exhibit greater acute mammalian toxicity than the parent compound. The product is differentiated from general agricultural technical material by applying these tighter limits to every batch.
Because the active is a liquid, solid-dose manufacture begins with adsorption onto fumed silica or precipitated silica. Fumed silica with a BET surface area of 200–300 m²/g permits loading up to 40% w/w while maintaining a Carr index below 20 and a Hausner ratio below 1.25. At loadings above 50% w/w, the adsorbate becomes cohesive and the angle of repose exceeds 40°, which is unsuitable for automated die filling or auger capsule filling. For capsules, the adsorbed powder is filled with an auger or dosator system using low-moisture capsule shells; desiccant packaging is required because capsule shell moisture can transfer to the adsorbate and initiate hydrolysis at the silica surface.
Production-scale ploughshare mixers and 500 L ribbon mixers have shown temperature-induced assay loss when the liquid API is sprayed at high impeller tip speeds. Jacket water is held at 15–18°C, and impeller tip speed is limited to 3–5 m/s to avoid shear heating. In one production campaign, a temperature excursion above 32°C produced an assay decline of 4.2% in 45 min and visible darkening of the silica carrier. The batch record now specifies a maximum product temperature of 30°C and discharge relative humidity below 40%. After adsorption, the material is passed through a 500 µm sieve to break loose agglomerates before blending with microcrystalline cellulose and sodium starch glycolate.
Tableting of malathion-loaded granules is performed at compression forces of 8–12 kN. Residual moisture must remain below 2.0% w/w in the final blend. Dissolution testing should use a surfactant-containing medium or non-aqueous sink because the hydrophobic active does not release predictably in plain water. For granules and premixes, hydroxypropyl cellulose dissolved in isopropyl alcohol is preferred as a binder over aqueous starch paste. Water-based binders are incompatible where they introduce free water or where dibasic calcium phosphate raises the local pH during drying.
Injectable solutions are prepared in anhydrous vehicles such as propylene glycol, ethyl oleate, glycofurol or medium-chain triglycerides. The water content of the vehicle should be ≤0.1% w/w, and the headspace should be nitrogen-flushed. Terminal sterilization at 121°C is not recommended because the phosphorothioate linkage degrades under autoclave conditions. Sterile filtration through 0.22 µm hydrophobic membranes is the preferred process when the formulation is filtration-compatible. Particulate matter is controlled according to USP <787> or the applicable regional injectable monograph.
Combination products are technically feasible provided the solvent system remains free of alkaline proton acceptors. The phosphorothioate active is stable in xylene, isopropyl myristate and medium-chain triglycerides, but co-formulation with amitraz can create phase separation when amitraz concentrations exceed 5.0% w/w in certain dipolar solvent blends. Solvent compatibility is verified by storage at 2–8°C and 40°C/75% RH for 48 h; precipitation, phase separation or assay loss above 2% requires reformulation.
Pyrethroid actives such as cypermethrin and permethrin are generally stable in the same non-polar vehicle, but the malathion component imposes an upper temperature limit during blending. High-shear rotor-stator mixing should be limited to 10 min with cooling below 25°C, because local cavitation heating can isomerise a portion of the malathion to isomalathion. The finished solution should be filled into amber glass or fluorinated high-density polyethylene containers and sealed under nitrogen.
Compared with technical malathion, MLT-VET-API-950 has a lower isomalathion limit, a controlled residual solvent profile under ICH Q3C, and no added stabilisers such as epoxidised soybean oil unless specified by a validated formulation. The grade is intended for use in regulated veterinary drug product manufacture, where batch-to-batch consistency of impurity profile is a critical control parameter. Agricultural technical material may not meet these pharmaceutical controls because its impurity panel and solvent profile are not optimised for dosage-form stability.
Among veterinary organophosphates, malathion has lower mammalian acute toxicity than phosmet or coumaphos because mammalian carboxylesterases hydrolyse the carboxy ester moieties to inactive monoacid and diacid metabolites. This detoxification pathway is less efficient in insects, which contributes to the selective insecticidal action. The same metabolic route is reduced in birds and some aquatic species, so formulation and disposal limits remain species-specific. Malathion is also more lipophilic than some alternative organophosphates, which permits stable emulsifiable concentrates and non-aqueous topical preparations without aggressive co-solvents. Unlike pyrethroid-only products, malathion acts through acetylcholinesterase inhibition; this difference in mode of action can be relevant in resistance management programmes, but it also imposes cholinesterase monitoring requirements during large-scale manufacturing.
For premix production, the liquid API is first adsorbed onto precipitated silica or calcium silicate to create a 50% w/w premix concentrate. This concentrate is blended with ground corn cob or rice hulls in a double-ribbon mixer at 15–25°C for 10–15 min. Content uniformity is assessed by collecting 10 thief samples and requiring a relative standard deviation ≤5.0%. Because malathion is lipophilic, premix carriers should not contain free vegetable oil above 2.0% w/w; oil migration can cause segregation and inconsistent dosing during bulk storage. The finished premix is packaged in polyethylene-lined paper bags with a moisture barrier and stored below 30°C.
Quality control for the API uses gas chromatography with flame photometric detection for sulfur and phosphorus impurities. The method is calibrated with certified reference standards and includes a system suitability test in which the resolution between malathion and isomalathion is not less than 2.0. Heads-space gas chromatography is used for residual solvents according to ICH Q3C. Where import authorities require a cholinesterase inhibition batch-safety test, published data for this specific configuration is limited; the available literature does not support replacing chromatographic impurity control with enzymatic testing alone.
Granular presentations prepared by extrusion-spheronisation require pre-blending the adsorbed malathion powder with water-free binders. Dibasic calcium phosphate and other alkaline excipients are excluded unless pH-buffering studies demonstrate that the microenvironment remains below pH 6 throughout drying. Drying is performed under vacuum at ≤40°C to limit thermal isomerisation to isomalathion. The final granules are sieved to 150–850 µm and packaged with desiccant if the container is not vapour-tight.
