ICS 65.100.10  
 
Reference number  
DRS 465 -1: 2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
465-1 
 
First edition  
Approved by RSB 2021 -mm-dd 
 
Pyrethr um-based insecticides — 
Specification  —  
Part 1:  
Dusting powder s (DP) 
 
   
DRS 465 -1: 2021  
©RSB 2021  - All rights reserved                  ii 
 In order to match with technological development and to keep continuous progress in industries, 
standards are subject to periodic review. Users shall ascertain that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
© RSB 2021  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
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ePortal: www.portal.rsb.gov.rw   DRS 465 -1: 2021  
iii                ©RSB 2021  - All rights reserved  
 Contents  Page 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  2 
4.1 General requirements  ................................ ................................ ................................ ...........................  2 
4.2 Specific requirements  ................................ ................................ ................................ ...........................  2 
5 Packaging and labelling ................................ ................................ ................................ ........................  3 
5.1 Pack aging  ................................ ................................ ................................ ................................ ...............  3 
5.2 Labelling  ................................ ................................ ................................ ................................ .................  3 
6 Sampling  ................................ ................................ ................................ ................................ ................  3 
Annex  A (normative)  Determination of total pyrethrins  ................................ ................................ ................  4 
A.1 General  ................................ ................................ ................................ ................................ ...................  4 
A.2 Reagents  ................................ ................................ ................................ ................................ ................  4 
A.3 Apparatus  ................................ ................................ ................................ ................................ ...............  4 
A.4 Operating conditions  ................................ ................................ ................................ ............................  4 
A.5 Preparation of the standard  ................................ ................................ ................................ .................  5 
A.6 Sample preparation  ................................ ................................ ................................ ...............................  5 
A.7 Procedur e ................................ ................................ ................................ ................................ ...............  5 
A.8 Calculation  ................................ ................................ ................................ ................................ .............  5 
Annex  B (normative)  Test sieves  ................................ ................................ ................................ .....................  6 
B.1 Apparatus  ................................ ................................ ................................ ................................ ...............  6 
B.2 Procedure  ................................ ................................ ................................ ................................ ...............  6 
B.3 Calculation  ................................ ................................ ................................ ................................ .............  6 
Annex  C (normative)  Determination of bulk density after compacting  ................................ .......................  7 
C.1 Apparatus  ................................ ................................ ................................ ................................ ...............  7 
C.2 Procedure  ................................ ................................ ................................ ................................ ...............  7 
C.3 Test evaluation  ................................ ................................ ................................ ................................ ...... 7 
Annex  D (normative)  Determination of acidity or alkalinity  ................................ ................................ ..........  8 
D.1 Qualitative test  ................................ ................................ ................................ ................................ ....... 8 
D.2 Determination of acidity ................................ ................................ ................................ ........................  8 
D.3 Determination of alkalinity  ................................ ................................ ................................ ...................  9 
Annex  E (normative)  Determination of pH value  ................................ ................................ ..........................  11 
E.1 Outline of method  ................................ ................................ ................................ ................................  11 
E.2 Reagents  ................................ ................................ ................................ ................................ ..............  11 
E.3 Apparatus  ................................ ................................ ................................ ................................ .............  11 
E.4 Procedure  ................................ ................................ ................................ ................................ .............  11 
E.5 pH of aqueous dispersion  ................................ ................................ ................................ ..................  11 
 DRS 465 -1: 2021  
©RSB 2021  - All rights reserved                  iv 
 Foreword   
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board (RSB) 
Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT 
agreement on the preparation, adoption and application of standards.  
The ma in task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified  by me mbers of RSB Board of Director s for publication and 
gazettment as Rwanda Standards.  
DRS 465 -1 was prepared by T echnical Committee RSB/TC 007, Agrochemicals.  
In the preparation of this standard, reference was made to the following standard:  
IS 6178 : Specification for pyrethrum dusting powders  
The assistance de rived from the above source is hereby acknowledged with thanks.  
DRS  465 consists of the following parts, under the general title Pyrethrums -based insecticides — 
Specification : 
 Part 1: Dusting powders (DP)  
 Part 2: Grease (GS)  
Part 3: Emulsions (Oil in water, EW)  
Committee membership  
The following organizations  were represented on the Technical Committee on Agrochemicals  (RSB/TC 007) in 
the preparation of this standard.  
University of Rwanda/College of Sciences and Technology (UR/CST)  
University of Rwanda/College of Education (UR/CE)  
Rwanda Forensic Laboratory (RFL)  
Ministry of Environment (MoE)  
Standards for Sustainability (SfS)  
AGROPY Ltd  DRS 465 -1: 2021  
v                ©RSB 2021  - All rights reserved  
 Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
Rwanda Agriculture and Animal Resources Development Board  (RAB)   
Rwanda  Standards Board  (RSB) – Secretariat  DRS 465 -1: 2021  
©RSB 2021  - All rights reserved                  vi 
 Introduction  
Pyrethrum  owes its insecticidal properties to esters which are reportedly produced by a number of different 
cell types (oil glands, resin ducts and mesophyll cells). Pyrethrin I, jasmolin I and cinerin I are esters of 
chrysanthem ic acid (chrysanthemum monocarboxylic acid), while pyrethrin II, jasmolin II and cinerin II are 
esters of pyrethric acid (monomethyl ester of chrysanthemum dicarboxylic acid). The biosynthesis of pyrethrin 
I in seedlings of C. cinerariifolium  has been stud ied using [1 -C]-d-glucose as a precursor; the acid portion of 
the molecule is derived from d -glucose and the alcohol moiety possibly from linoleic acid . 
Pyrethrum Extract contains 20-50% of total pyrethrins; it may be prepared extemporaneously from the flo wer-
heads and is used for the preparation of the dusting powder and spray. The dusting powder (pyrethrum 
extract, diatomite, talc) has a pyrethrin content of 0. 10–0.50%, of which not less than half consists of pyrethrin 
I. It is assayed by titrimetry for b oth pyrethrin I and II. Extracts containing 50% more active material compared 
with commercial extracts can be obtained by extraction of the plant material with liqu ified carbon dioxide (100 
bar). 
 
 
 DRS 465 -1: 2021  
1                ©RSB 2021  - All rights reserved  
 Pyrethrum -based  insecticide s — Specification  — Part 1: Dusting 
powder s (DP)  
1 Scope   
This Draft  Rwanda Standard  prescribes the requirements, sampling and test methods for pyrethr um-based  
dusting powders  used in the control of insect pests of agricultural importance, especially in grain storage . 
2 Normative references   
The following documents are referred to in the te xt in such a way that some or all of  their content constitutes 
requirements of this document.  For dated references, only the edition  cited applies. For undated references, 
the latest edition of the referenced document (including any amendments) applies.  
RS 406, Pesticides  — Terminology  
RS 191 , Refined pyrethrum concentrate — Specification  
RS 40 5, Pesticides  — Sampling  
3 Terms and definitions   
For the purposes of this standard, the terms and definitions given in RS 406 and the following apply.  
3.1 
pyrethrum  
genus of several Old World plants now classified as Chrysanthemum or Tanacetum (e.g., C. coccineum ) 
which are cultivated as ornamentals for their showy flowers heads  
3.2 
pyrethrum extracts  
extract of the flowers of the plant, Chrysanthemum cinerariaefolium  
3.3 
pyrethrins  
the six naturally occurring isomers that are esters of pyrethric acid and chrysenthemic acid viz: pyrethrin -I, 
pyrethrin -II, cinerin -I, cinerin -II, jasmolin -I, jasmolin -II; having insecticidal property and are extracted from the 
flower of Chrysanthemum cinerariaefolium.   
©RSB 2021  - All rights reserved                  2 
 3.4 
dusting powder (DP)  
a free -flowing powder suitable for dusting  
4 Requirements  
4.1 General requirements  
4.1.1  The product shall consist of a homogeneous mixture of pyrethrum extract s, complying with the 
requirements of RS 191, together with carriers and any other necessary formulant.  
4.1.2  The product may contain one or more synthetic pyrethroid, but the formulation shall be approved by 
the Competent Authority.  
4.1.3  The product shall be in form of a fine,  free-flowing powder, free from visible extraneous matter and 
hard lumps . 
4.1.4  The product , when dusted through a hand rotary  duster shall issue freely with out clogging or 
bridging.  
4.1.5  The product shall be whitish to brown in colour.  
 
4.2 Specific requirements  
4.2.1  The product shall comply with the requirements given in Table 1 when tested in accordance with the 
test methods prescribed therein.  
Table 1 — Specific requirements for pyrethr um-based dusting powder  insecticide s 
S/N Parameters  Requirements  Test methods  
i.  Total pyrethrins content , % by mass  0.10 — 5.0 Annex A  
ii.  Material passing through 75 µm, % by 
mass, min.  90 Annex B  
iii.  Bulk density after compacting  Not exceed the value 
obtained before 
compacting by more than 
60% Annex C  
iv.  Acidity (as H 2SO 4), % by mass, max.  0.25 Annex D  v.  Alkalinity (as NaOH), % by mass, max.  0.05 
vi.  pH range  5 — 7 Annex E  
4.2.2  Storage stability — After storage at 54 ± 2°C for 14 days, the product shall remain stable without 
any changes on quality and performance properties.  DRS 465 -1: 2021  
3                ©RSB 2021  - All rights reserved  
 5 Packaging and labelling  
5.1 Packaging  
5.1.1  The product shall be packaged in a well closed container that will preserve its original characteristics.  
5.1.2  The packaging material shall protect the contents from adventitious contamination under handling 
and storage condi tions.  
5.2 Labelling  
The containers shall be closed and shall bear legibly and indelibly the following information  in any of the three 
languages officially accepted in the Republic of Rwanda namely : Kinyarwanda, English and French.  
a) Name of the product;  
b) Name an d address of the manufacturer;  
c) Manufacture and expiry dates;  
d) Batch number;  
e) Active ingredient (s) contents;  
f) Storage conditions;  
g) Instructions for use;  
h) Precautions and warnings; and  
i) Country of origin.  
6 Sampling  
Representative samples of the product shall be drawn as prescribed in RS 405.  
  
©RSB 2021  - All rights reserved                  4 
 Annex  A 
(normative)  
 
Determination of total pyrethrins  
A.1 General  
The active ingredients in pyrethrum extract may be determined using a HPLC system first by injecting a 
solution of the analyte  into the chromatograph, followed by the separation and comparison of peaks areas of 
the analytes in the sample with that of an external standard containing a known amount of the analytes. The 
peaks are eluted in the following order: Cinerin II, Pyrethrin II, Jasmolin II (total Pyrethrins II) and Cinerin I, 
Pyrethrin I, Jasmolin I (total Pyrethrins I).  
A.2 Reagents  
World pyrethrum standard, 50%  
Acetonitrile, HPLC grade  
Water, HPLC grade  
A.3 Apparatus  
Ww A liquid chromatography System equipped with an auto -sampler, a Variable Wavelength Detector (or 
equivalent) and a Column {Phenomenex, 250 x 4.6 mm Luna Phenyl -Hexyl 5μ Reverse Phase (or 
equivalent)}.  
A.4 Operating conditions  
Flow rate:    1.5 ml/min  
Composition:    40:60 (%, v/v water/acetonitrile  
Elution:     isocratic  
Column temperature:  40 °C 
Wavelength:    240 nm  
Injection volume:   15 µl 
Stop time:    22 min  
Post time:    1 min  DRS 465 -1: 2021  
5                ©RSB 2021  - All rights reserved  
 A.5 Preparation of the standard  
Weigh 20 mg of the pyrethrum standard to the nearest 0.0001 g in a 100 mL volumetric flask and dilute to 
volume with Ac etonitrile and label it. Transfer a small portion to a sample vial and label it accordingly.  
A.6 Sample preparation  
In a 100 ml volumetric flask, weigh 20 mg to the nearest 0.0001 g of the sample to be analysed and dilute to 
volume with Acetonitrile. Sample this solution using a vial and label it accordingly.  
A.7 Procedure  
After the chromatograph is stable, make a minimum of three injections for the standard solution as well as for 
the analyte and average the area counts. The relative Standard Deviation between i njections should be within 
2 %. 
A.8 Calculation  
The total pyrethrins is calculated as follow:  
 total  pyrethrins ,% m/m=𝐴𝑣𝑒𝑟𝑎𝑔𝑒  𝑠𝑎𝑚𝑝𝑙𝑒  𝑎𝑟𝑒𝑎  𝑋 𝑤𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 ∗𝑃𝑢𝑟𝑖𝑡𝑦  𝑜𝑓 𝑡ℎ𝑒 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑  (𝑖𝑛 %)
𝐴𝑣𝑒𝑟𝑎𝑔𝑒  𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑  𝑎𝑟𝑒𝑎 ∗𝑊𝑒𝑖𝑔 ℎ𝑡 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒 
 
 
   
©RSB 2021  - All rights reserved                  6 
 Annex  B 
(normative)  
 
Test sieves  
B.1 Apparatus  
Test sieve , 75 µm. 
B.2 Procedure  
Weigh accurately 10.0 g of the material and transfer it to the test sieve. Cover the sieve and screen the 
material  in a Ro -Tap or a simi lar machine for 20 minutes. Two small square rubber cubes are introduced 
along with the material on the sieve to facilitate the breaking up of any soft lumps of the caked material.er 20 
minutes stop the machine and brush the residue on the sieve into a tar ed weighing dish. Weigh the dish and 
determine the mass of the residue.  
B.3 Calculation  
Material passing through test sieve, 75 µm: 
        =100  (1− 𝑚
𝑀) 
Where,  
  m = mass in g of the material retained on the test sieve, and  
  M = mass in g of the material ta ken for the test  DRS 465 -1: 2021  
7                ©RSB 2021  - All rights reserved  
 Annex  C 
(normative)  
 
Determination of bulk density after compacting  
C.1 Apparatus  
C.1.1  Graduated cylinder  – of 100 ml capacity with internal diameter of 27 t0 29 mm.  
C.1.2  Funnel  – wide and short -stemmed.  
C.2 Procedure  
C.2.1  Bulk density before compacting  – Rest the funnel over the top edge of the tared graduated 
cylinder. Fill the cylinder to the 100 -ml mark by pouring the material through the funnel, without tapping, and 
level the powder with the minimum of disturbance. Leave the cylinder untou ched for 5 minutes and add more 
powder if necessary, to bring the contents to the 100 -ml mark, level again with the minimum of disturbance. 
Weigh the filled cylinder and calculate the bulk density before compacting (mass of the material/volume 
occupied by the material).  
C.2.2  Bulk density after compacting  – Stopper the filled cylinder, and drop it 20 time through a height of 
15 cm on to a felt pad resting on a hard surface. Note the volume of the material after compacting.  Calculate 
the bulk density of the material after compacting (mass of the material/volume occupied by the material after 
compacting).  
C.3 Test evaluation  
The value obtained in C.2 shall not exceed the value obtained in C.1 by more than 60%.   
©RSB 2021  - All rights reserved                  8 
 Annex  D 
(normative)  
 
Determination of acidity or alkalinity  
D.1 Qualitative test  
Procedure  – Take about 0.5 g of the material in a test -tube and mix with about 1 ml of water. Test the mixture 
for acidity or alkalinity with a litmus paper. Determine the acidity or alkalinity, as the case may be.  
D.2 Determination of acidity  
D.2.1  Reagents  
D.2.1.1  Methyl red indicator solution -aqueous – one percent (m/v)  
D.2.1.2  Bromocresol purple indicator solution – one perc ent (m/v) in ethyl alcohol  
D.2.1.3  Standard sodium hydroxide solution – 0.05N  
D.2.1.4  Standard hydrochloric acid – 0.05N 
D.2.2  Procedure  
Weigh accurately 10.0 g of the material into a dry conical flask, add 25 ml of acetone and mix. Warm the flask 
gently to effect the solution of the active ingredient present. Add 75 ml of water and let it stand for an hour. 
Filter the sup ernatant aqueous extract and take 50 ml filtrate. Titrate immediately with the standard sodium 
hydroxide solution using methyl red or bromocresol purple as the indicator. Alternatively, the end point may be 
determine d electrometr ically.  
Carry out a blank d etermination on an aliquot of 50 ml made from 25 ml acetone and 75 ml water.  
D.2.3  Calculation  
Acidity (as H 2SO 4), % m/m =4.9 𝑥 2(𝑉−𝑣)𝑁
𝑀 
Where;  
 V  = volume in ml of the standard sodium hydroxide solution required for the test with the material , 
 v = volume in ml of the standard sodium hydroxide solution required for the blank determination,  
 N = normality of the standard sodium hydroxide solution, and  DRS 465 -1: 2021  
9                ©RSB 2021  - All rights reserved  
 M = mass in g of the material taken for the test.  
In case the blank shows alkaline reaction, neutralize  with the standard hydrochloric acid and calculate the 
acidity as follows:  
 Acidity (as H 2SO 4), % m/m =4.9 𝑥 2(𝑉𝑁1−𝑣𝑁2)
𝑀 
Where;  
 V  = volume in ml of the standard sodium hydroxide solution required for the test with the material,  
 N1 = normality of the  standard sodium hydroxide solution,  
 v = volume in ml of the standard sodium hydroxide solution required for the blank determination,  
 N2 = normality of the standard hydrochloric acid , and  
M = mass in g of the material taken for the test.  
D.3 Determination of  alkalinity  
D.3.1  Reagents  
D.3.1.1  Methyl red indicator solution -aqueous – one percent (m/v)  
D.3.1.2  Bromocresol purple indicator solution – one percent (m/v) in ethyl alcohol  
D.3.1.3  Standard hydrochloric acid – 0.05N  
D.3.1.4  Standard sodium hydroxide sol ution – 0.05N  
D.3.2  Procedure  
Weigh accurately 10.0 g of the material into a dry conical flask, add 25 ml of acetone and mix. Warm the flask 
gently to effect the solution of the active ingredient present. Add 75 ml of water and let it stand for an hour. 
Filter the supernatant aqueous extract and take 50 ml of folterate. Titrate immediately with the standard 
hydrochloric acid using methyl red or bromocresol indicator as the indicator. Alternatively, the end point may 
be determined electrometrically.  
Carry ou t a blank determination on 50 ml aliquot made from 25 ml acetone and 75 ml water.  
D.2.3  Calculation  
Alkalinity (as NaOH), % m/m =4.0 𝑥 2(𝑉−𝑣)𝑁
𝑀  
©RSB 2021  - All rights reserved                  10 
 Where;  
 V  = volume in ml of the standard hydrochloric acid required for the test with the material,  
 v = volume in ml of the standard hydrochloric acid required for the blank determination,  
 N = normality of the standard hydrochloric acid, and  
M = mass in g of the material taken for the test.  
In case the blank shows acid reaction, neutralize with the standard  sodium hydroxide solution and calculate 
the alkalinity as follows:  
 Alkalinity (as NaOH), % m/m =4.0 𝑥 2(𝑉𝑁1−𝑣𝑁2)
𝑀 
Where;  
 V  = volume in ml of the standard hydrochloric acid required for the test with the material,  
 N1 = normality of the standard hyd rochloric acid,  
 v = volume in ml of the standard sodium hydroxide solution required for the blank determination,  
 N2 = normality of the standard sodium hydroxide solution, and  
M = mass in g of the material taken for the test.  DRS 465 -1: 2021  
11                ©RSB 2021  - All rights reserved  
 Annex  E 
(normative)  
 
Determination of pH value  
E.1 Outline of method  
The pH value of a liquid is determined by means of pH meter and a glass electrode.  
E.2 Reagents  
E.2.1 Potassium hydrogen phthalate (COOH -C6H4-COOK) 0.05 mol/l (0.05M) – Dissolve 10.21 g in 
freshly boiled distilled water and make u p to 1000 ml. do no keep the solution for longer than one month.  
E.2.2 Disodium tetraborate (Na 2B4O7.10H 2O 0.05M  – Dissolve 19.07 g in freshly boiled distilled water 
and make up to 1000 ml. do no keep the solution for longer than one month.  
E.2.3 Water  – Freshly boiled and cooled distilled water of pH 5.5 to 7.0  
E.3 Apparatus  
E.3.1 pH meter  
E.3.2 Glass electrode and reference electrode  
E.4 Procedure  
Operate the pH meter and electrode system in accordance with the manufacturer’s instructions. Standardize 
the meter and electrodes with the 0.05M phthalate (pH 4.00) when an acid solution is being measured or 
0.05M borate when an alkaline solution is being measured (see Table B1). The reading should not differ by 
more than 0.02 pH units from the original value at which the apparatus was standardized. If the difference is 
greater than 0.05, then repeat the measurements.  
Table B1 – pH values of 
0.05M disodium 
tetraborateTemperature, 
°C 10 15 20 25 30 
pH 9.32 9.28 9.22 9.18 9.14 
E.5 pH of aqueous dispersion  
Weigh 1 g of sample, transfer to the measuring cylinder containing water (about 50 ml), make up to 100 ml 
with water, and shake vigorously for 1 min. allow any suspension to settle for 1 min and then measure the pH 
of the supernatant liquid.   
©RSB 2021  - All rights reserved                  12 
 Bibliography  
[1] IS 6940 , Methods of test for pesticides and their formulations , 2012  
[2] ES 757, Pesticides  — Determination of pH values , 2002  
[3] ES 750, Pesticides — Determination of free acidity or alkalinity, 2002  
 
 DRS 465 -1: 2021  
 
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