TECHNICAL (RS)-METHOPRENE

WHO/IS/TC/414/2001 METHOPRENE
TECHNICAL
1. Specification
1.1 Description
TECHNICAL (RS)-METHOPRENE
Interim specification WHO/IS/TC/414/2001
The material shall consist of (RS)-methoprene together with some related
manufacturing impurities. It shall be in the form of an oily, transparent, pale yellow or
amber brown liquid with sweetish aromatic (fruity) odour, and shall be free from
visible extraneous matter and added modifying agents.
1.2 Chemical and physical requirements
The material, sampled from any part of the consignment (see method WHO/M/1.R1)
shall comply with the requirements of section 1.1 and with the following requirements.
1.2.1 Identity test
When the identity of the active ingredient is in doubt, then it shall be comply with at
least one additional test.
1.2.2 (RS)-methoprene content (g/kg basis)
The (RS)-methoprene content shall be declared (not less than 920 g/kg) and, when
determined by the method described in section 2.1, the mean measured content
obtained shall not be lower than the declared content. The minimum content of the
highly active trans (E) isomer is 900 g/kg, and the maximum content of cis (Z) isomer
is 20 g/kg.
1.2.3 Heat stability
The technical product, after treatment as described in section 2.2, shall comply with
the requirements of sections 1.2.1 and 1.2.2, but a decrease of the (RS)-methoprene
content of maximum 0.2% is acceptable.

WHO/IS/TC/414/2001 METHOPRENE
TECHNICAL
1.3 Packing and marking of packages
The technical (RS)-methoprene shall be packed in suitable clean containers as
specified in the order.
All packages shall bear, durably and legibly marked on the container the following:
Manufacturer’s name
Technical (RS)-methoprene (920 g/kg)
Batch or reference number and date of test
Net weight of contents
Date of manufacture
and the following minimum cautionary notice:
(RS)-methoprene is an insect growth regulator, a juvenile hormone analogue (juvenoid)
preventing insect metamorphosis to viable adults when applied to larval stages. Not known to
cause adverse effect by ingestion, inhalation and contact of skin but may irritate eyes.
Keep the material out of reach of children and away from foodstuffs and animal feed and their
containers.
First aid measures:
Ingestion: Do not induce vomiting, get medical attention.
Eye contact: Flush with large amounts of water.
Skin contact: Wash with soap and water.
2. Methods of determining chemical and physical properties
2.1 Methoprene content
2.1.1 Outline of method
The determination of the active ingredient content in (RS)-methoprene technical is
carried out by gas chromatography ( GC ), using the total area method.
The constituents are separated by GC on a methyl siloxane capillary column and
detected by flame ionization.
2.1.2 Apparatus
1. Gas-liquid chromatograph. Hewlett Packard 6890 GC with a HP 3398 GC
Chemstation software or equivalent
2. Chromatographic column. Capillary column 30 m long, 0.25 mm internal
diameter, 0.25 µm film thickness, filled with methyl siloxane (Type: HP-1) or
equivalent
Before use, condition a new column by purging with nitrogen overnight at about
280 °C. During this operation the column must not be connected to the detector
to avoid contamination by " initial bleed " of the stationary phase.
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WHO/IS/TC/414/2001 METHOPRENE
TECHNICAL
2.1.3 Operating conditions for gas chromatography
The conditions given below are typical values and may have to be adjusted to obtain
optimum results from a given apparatus.
Temperatures
Column oven 170°C 10°C/min. 240 °C (10 min.)
Injector 250 °C
Detector: 300 °C
Gas flow rates
Carrier gas: N 2 : 1.7 mL/min.
Hydrogen and air: H 2 : 30 mL/min.
Air: 400 mL/min.
Make-up: N2 25 mL/min.
Septum purge: 3.0 mL/min.
Split ratio: 1:100
Typical retention times:
cis-methoprene: ~5,6 min.
trans-methoprene: ~6.1 min.
Injected volume: 1 µL
2.1.4 Sample preparation and analysis
Sample solution. Prepare a 1% solution with ethanol. Weigh approximately 0.5 g of
sample in a 5 mL volumetric flask, dissolve in ethyl alcohol and fill to volume.
2.1.5 Chromatographic method
Inject 1 µL of the sample solution three times in succession. The differences between
the peak areas for the three injections must not exceed 2%. If not repeat the sequence.
2.1.6 Calculation
The percentage composition of each peak is determined by GC software using the total
area method.
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WHO/IS/TC/414/2001 METHOPRENE
TECHNICAL
2.2. Heat stability treatment
54°C ± 2°C for 14 days ( CIPAC method MT 46.1, CIPAC Handbook F, p.149) unless
other temperatures and times are requested ( FAO Manual on the development and
use of FAO specifications for plant protection products, n°149, p.33).
After completion of the heat stability treatment, the samples should not be exposed to
heat, bright sunshine or atmospheric humidity.
If required the test should de conducted in the commercial type pack.
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WHO/IS/EC/414/2001 ( RS ) METHOPRENE
EMULSIFIABLE CONCENTRATE
1. Specification
1.1 Description
(RS)-METHOPRENE
EMULSIFIABLE CONCENTRATE
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Interim specification WHO/IC/EC/414/2001
The material shall consist of technical (RS)-methoprene, complying with the
requirements of the WHO specification WHO/IS/TC/414/2001, dissolved in suitable
solvents, together with other necessary formulants. It shall be in the form of a stable,
homogeneous liquid with slight petroleum odour, free from visible suspended matter
and sediment, to be applied as an emulsion after dilution in water.
1.2 Chemical and physical requirements
The material sampled from any part of the consignment (see method WHO/M/1.R1),
shall comply with the requirements of section 1.1 and with the following requirements.
1.2.1 (RS)-methoprene content (g/kg basis)
The content of (RS)-methoprene determined by the method described in section 2.1
shall not differ from the declared content by more than the following amounts:
Declared content Tolerance permitted
Up to 25 g/kg + 15 % of the declared content
Above 25 up to 100 g/kg + 10 % of the declared content
Above 100 up to 250 g/kg + 6 % of the declared content
The average content of all samples taken shall not be lower than the declared content.
1.2.2 Water content
The water content determined by the method WHO/M/7.R1, shall not be higher than
1.6 g/kg.
1.2.3 Acidity
The acidity determined by the CIPAC method MT 31 (CIPAC Handbook F, p. 96)
shall not be higher than 0.1 g/kg calculated as H2SO4.

WHO/IS/EC/414/2001 ( RS ) METHOPRENE
EMULSIFIABLE CONCENTRATE
1.2.4 Cold test
No separation of solid or oily material shall occur when the concentrate is tested as
described in CIPAC method MT 39 ( CIPAC Handbook F, p.128 ).
1.2.5 Flash point
The flash point of the product, determined by the CIPAC method MT 12 ( CIPAC
Handbook F, p.31) shall not be lower than 66 o C and shall comply with all national
and/or international transport regulations.
1.2.6 Stability of the emulsion
In WHO standard soft water. Any separation, including creaming/oiling at the top and
oiling/sedimentation at the bottom, of 100 mL of emulsion prepared in WHO standard
soft water (WHO/M/29) with 5 mL of concentrate shall not be present when tested as
described in WHO/M/13.R4.
In WHO standard hard water. Any separation including creaming/oiling at the top and
oiling/sedimentation at the bottom, of 100 mL of emulsion prepared in WHO standard
hard water (WHO/M/29) with 5 mL of concentrate shall not exceed 2 mL when tested as
described in WHO/M/13.R4.
1.2.7 Persistent foam
In WHO standard soft water: When tested by the CIPAC method MT 47.2 (CIPAC
Handbook F, p.152 ) a maximum of 60 mL of foam shall be observed after 1 minute.
1.2.8 Heat stability
The concentrate, after treatment as described in section 3.1, shall comply with the
requirements of sections 1.2.1, 1.2.3 and 1.2.6 of this specification.
1.3 Packing and marking of packages
The (RS)-methoprene emulsifiable concentrate shall be packed in suitable clean
containers, as specified in the order.
All packages shall bear, durably and legibly marked on the container the following:
Manufacturer’s name
(RS)-methoprene emulsifiable concentrate
(RS)-methoprene (....g/kg)
Batch or reference number and date of test
Net weight of contents
Instructions for use
Date of manufacture
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WHO/IS/EC/414/2001 ( RS ) METHOPRENE
EMULSIFIABLE CONCENTRATE
and the following minimum cautionary notice:
(RS)-methoprene is an insect growth regulator, a juvenile hormone analogue (juvenoid)
preventing insect metamorphosis to viable adults when applied to larval stages. Not known to
cause adverse effect by ingestion, inhalation and contact of skin but may irritate eyes.
Keep the material out of reach of children and away from foodstuffs and animal feed and their
container.
First aid measures:
Ingestion: Do not induce vomiting, get medical attention.
Eye contact: Flush with large amounts of water.
Skin contact: Wash with soap and water.
2. Methods of determining chemical and physical properties
2.1 Methoprene content
2.1.1 Outline of method
The determination of the active ingredient content in (RS)-methoprene EC formulations
is carried out by gas chromatographic method, using an internal standard solution
containing eicosane.
The formulation is separated by GC on a methyl siloxane capillary column and detected
by flame ionization..
2.1.2 Apparatus
1. Gas-liquid Chromatograph. Hewlett Packard 6890 GC with a HP 3398 GC
Chemstation software or equivalent
2. Chromatographic Column. Capillary column 30 m long, 0.25 mm internal
diameter, 0.25 µm film thickness, filled with methyl siloxane (Type: HP-1) or
equivalent
Before use condition a new column by purging with nitrogen overnight at about
280 °C. During this operation the column must not be connected to the detector
to avoid contamination by " initial bleed " of the stationary phase.
2.1.3 Reagents
Methoprene standard. Analytical grade, of known purity stored under 10 °C.
Internal standard. Eicosane, free from components which should co-elute with
methoprene under the chromatographic conditions given in section 2.1.5.
2.1.4 Preparation of standard solutions
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WHO/IS/EC/414/2001 ( RS ) METHOPRENE
EMULSIFIABLE CONCENTRATE
Internal standard solution. Weigh 1.0 g of eicosane, dissolve in ethyl alcohol and make
up to 250 mL in a volumetric flask.
Methoprene standard solution. Weigh approx. 50 mg standard methoprene in a 25 mL
volumetric flask, dissolve in ethyl alcohol, then add 5 mL of internal standard solution by
pipette and fill to volume.
2.1.5 Operating conditions for gas chromatography
The conditions given below are typical values and may have to be adjusted to obtain
optimum results from a given apparatus.
Temperatures
Oven 170°C 10°C/min. 240 °C (10 min.)
Injection port 250 °C
Detector: 300 °C
Gas flow rates
Carrier gas: N 2 : 1.7 mL/min.
Hydrogen and air: H 2 : 30.0 mL/min.
Air: 400.0 mL/min.
Make-up: N2 25.0 mL/min.
Septum purge: 3.0 mL/min.
Split ratio: 1:100
Approximate retention times:
Eicosane: ~5.5 min.
Methoprene: ~6.1 min.
Injected volume 1 µL
2.1.6 Sample preparation.
Sample solutions. Ensure that samples are homogeneous by equilibrating to room
temperature and mixing thoroughly. Weigh approximately 0.5 g of sample in a 25 mL
volumetric flask, dissolve in ethyl alcohol, then add 5 mL of the internal standard
solution by pipette and fill to volume.
2.1.7 Chromatographic method
Inject 1 µL of the standard solution three times in succession, then calculate the
proportion of peak area of methoprene and eicosane.
The differences between the proportions of peak area received for the three injections
must not exceed 2 %. Afterward, inject three times of the sample solution, and proceed
as for the standard.
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WHO/IS/EC/414/2001 ( RS ) METHOPRENE
EMULSIFIABLE CONCENTRATE
2.1.8 Calculation
Active ingredient % =
Am x Mstd x T
Astd x Mm
Am = ratio of the under-peak area of methoprene and eicosane in the sample
Astd = ratio of the under-peak area of methoprene and eicosane in the standard
Mm = mass of the sample (in grams)
Mstd = mass of the standard (in grams)
T = purity of the standard (in %)
3.1 Heat stability treatment
54°C ± 2°C for 14 days ( CIPAC method MT 46.1, CIPAC Handbook F, p.149 ),
unless other temperatures and times are requested ( FAO Manual on the development
and use of FAO specifications for plant protection products, n° 149, p.33 ).
After completion of the heat stability treatment, the samples should not be exposed to
heat, bright sunshine , or atmospheric humidity.
If required the test should be conducted in the commercial type pack.
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