fumigation of food products

1. Phosphine Fumigation Work Book III
Aluminium Phosphide (Phosphine)
Formulations Properties & Use

2. Aluminium Phosphide (15% to 77.5%) Formulations
56% 3g Tablets,
56% 34g Powder
For various stored products
15% 12g Tablets,
56% 10g Pouches
For farm storages
77.5% 125 to 4400g
Granules
On-site phosphine generators
Magnesium Phosphide (56% minimum) Formulation
56% 117g Plates For tobacco and various stored products

3. ALP formulations consist of
1. Active ingredient: Aluminium phosphide (56 % w/w)
2. Others: (Chemical fire retardant & Binding materials 44 % w/w maximum)

4. Formulation Gross weight (g) PH3 released (g)
AlP Tablets, 56% 3 1
AlP powder, 56%
10
34
3
11
77.5% 125 – 4.400 56 – 2000
MgP plates, 56% 117 33

5. ALP Formulation
1. Composition
• Aluminium Phosphide (a.i) 56 % w/w
• Other Ingredients 44%w/w
Total 100% w/w
2. Shelf life 3 years
5

6. Magnesium Phosphide Plate Formulation
1. Composition
• Magnasium Phosphide (Tech.) 56 % w/w
• Other Ingredients 44%w/w
Total 100% w/w
2. Shelf Life :2 years
6

7. Solid Tablets, Pellets Powder-in-sachet

8. 8
• Sachet, net wt 34 g, is equivalent to 11
tablets
• Spent powder is retained in the bag itself
• Hygienic Application

9. Tablet application involves more labour & time when
compared to Sachet

10. MgP impregnated Plate Formulation
• Releases phosphine at a faster
rate
• Suitable for temperate climatic
conditions
• Readily used for fumigation of
freight containers

11. Release of Phosphine from ALP/MgP Formulation
1. Ammonium carbamate releases Ammonia and CO2.
2. ALP reacts with atmospheric moisture producing Aluminum hydroxide and Phosphine.
ONH4
2 O=C + 2H2O --- (NH4)2 CO3 + 2NH3 + CO2 + H2O
NH2
AlP + 3H20 --- Al (OH)3 + PH3
3Mg P2 + 6H2O -- 3 Mg (OH)2 + 2 PH3

12. Rate of Phosphine release in ALP preparations
depends on
•Moisture content of commodity (>9%)
•Ambient humidity (>50%)
•Ambient temperature (>20°C)

13. Lowest Molecular Weight
Fumigant Molecular weight
PHOSPHINE 34
Ethane dinitrile 52
Ethyl formate 74
Methyl bromide 95
Sulfuryl fluoride 102

14. Highest Vapour Pressure
PHOSPHINE 29,260 mm of Hg
Sulfuryl fluoride 13,442
Ethane dinitrile 3,876
Methyl bromide 1,824
Ethyl formate 200

15. PHOSPHINE IS VERY PENETRATIVE
PH3 Vapor Pressure 29,260 mm of Hg
x 16 of MBr
x 2.2 of SF
x 146 of EF at 25°C
Hence, high standards of sheeting & floor sealing are required

16. Lowest gas density
Fumigant Gas/vapour density
PHOSPHINE 1.2
Ethane dinitrile 1.8
Methyl bromide 3.4
Sulfuryl fluoride 3.5
Ethyl formate 2.56
• Equilibrium is achieved
rapidly in phosphine
fumigations
• No stratification or
pocketing of phosphine gas
occurs

17. Lowest Water Solubility
Fumigant Water solubility
PHOSPHINE 0.35 g/L
Sulfuryl fluoride 0.75
Methyl bromide 13.4
Ethane dinitrile 1%
Ethyl formate 14.5%

18. 18
Flammability (Explosion) limit of Phosphine 1.79 %
v/v or 25 g/m3
Hence, prevent the formation of
“gas pockets” reaching the
concentration at which phosphine
is flammable

19. Do not Heap Tablets/Sachet
Dr. S. Rajendran

20. Leaky roof?
Rectify

21. Prevent Entry of rain water from doorways

22. Check weather conditions before fumigation
•High wind may damage the fumigation
sheets or dilute gas concentrations
•Heavy lightning storm/rain may lead to
water leakage into the warehouse/inside
fumigation stack resulting in fire

23. AlP (Phosphine): Merits
• Economical
• Easy to Store, handle and apply
• Environmentally safe (degrades in 5-28 hr)
• Airs off easily after treatment; fan not required

24. AlP (Phosphine): Merits
• Nearly residue-free
• No tainting or off-odour
• No adverse effect on:
Commodity quality,
Organoleptic property,
Germination &
End-use parameters

25. Phosphine is safe for seed materials; phosphine affects seed
germination only when:
• Seed moisture exceeds 15%
• At exaggerated dosages
(>10 g/m3)

26. • Long exposure period essential
• Lesser penetration in egg and pupal stages
• Corrodes copper & its alloys
Drawbacks

27. Phosphine and Corrosion
• Due to oxidation process,
phosphoric acid (a corrosive
substance) accumulates on metal
surfaces
• Copper salts will form with time
on the product being affected
• The corrosion appears as a
grayish coating

28. How Phosphine Works in Insects?
Entry through respiratory system :
1. Spiracle-Trachea-Tracheoles-Gas-exchange sites
2. Cuticle/integument/Aeropyles
Once entered phosphine affects mitochondrial respiration at cellular level

29. 8/22/2023 29
Active adults & larvae with higher respiratory rate
are susceptible
Eggs, pupae, diapausing Khapra larvae with low
respiratory rate are tolerant
Phosphine is Fast Acting even at low concentrations
to man and animals
But much Slower in toxic effect on insects– days
rather than hours
Fumigant toxicity is related to insect respiration

30. Inhalation Exposure Limits
Gas TLV-TWA (ppm) TLV-STEL (ppm)
Phosphine 0.3 1.0
Ammonia 25 35
CO2 5,000 30,000

31. Relatively tolerant species – High Concentration & Longer Exposure Period
Trogoderma granarium Khapra beetle
Lasioderma serricorne Cigarette beetle
Sitophilus oryzae Rice weevil
Cayedon serratus Peanut bruchid
Crytolestes ferrugineus Flat grain beetle
Susceptible species
Tribolium castaneum Rust red flour beetle
Rhyzopertha dominica Lesser grain borer
Oryzaephilus surinamensis Saw-toothed grain beetle

32. Trogoderma granarium The Khapra Beetle
Notoriously tolerant to fumigants
due to diapause

33. Cryptolestes
ferrugineus,
Flat Grain Beetle

34. Highly tolerant Psocids, Booklice (Liposcelis sp.,)

35. • Store preferably at < 30°C under lock & key in a dry well-ventilated area & out of
reach of unauthorized persons & children
• Do not store in buildings inhabited by humans or domestic animals & where
fertilizers, seed, food and feedstuffs are held
• Do not allow water or other liquids to contact AlP formulations
• The storage area must be declared as “Pesticide Storage Area” & must be labeled
Storage of ALP Formulations

36. Open Discussion