ICS 65.100.10  
 
Reference number  
DRS 465 -3: 2021  
© RSB 2021  
  
 RWANDA 
STANDARD  DRS  
465-3 
 
First edition  
2021-mm-dd 
 
Pyrethrum -based insecticides — 
Specification  — 
Part 3: 
Emulsion (Oil in water, EW)  
 
   
DRS 465 -3: 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 
in any form or by any means, electronic or mechanical, including photocopying and microfilm, without 
prior written permission from R SB. 
Requests for permission to reprodu ce this document should be addressed to : 
Rwanda Standards  Board  
P.O Box 7099 Kigali -Rwanda  
KK 15 Rd, 49  
Tel. +250 788303492  
Toll Free: 3250  
E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal: www.portal.rsb.gov.rw   DRS 465 -3: 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 ................................ ................................ ................................ ...............  2 
5.1 Pack aging  ................................ ................................ ................................ ................................ ...... 2 
5.2 Labelling  ................................ ................................ ................................ ................................ ........  3 
6 Sampling  ................................ ................................ ................................ ................................ ....... 3 
Annex  A (normative)  Det ermination of total pyrethrins  ................................ ................................ ....... 4 
A.1 General  ................................ ................................ ................................ ................................ ..........  4 
A.2 Reagents  ................................ ................................ ................................ ................................ ....... 4 
A.3 Apparatus  ................................ ................................ ................................ ................................ ...... 4 
A.4 Operating condit ions ................................ ................................ ................................ ...................  4 
A.5 Preparation of the standard  ................................ ................................ ................................ ........  5 
A.6 Sample preparation  ................................ ................................ ................................ ......................  5 
A.7 Procedure  ................................ ................................ ................................ ................................ ...... 5 
A.8 Calculation  ................................ ................................ ................................ ................................ .... 5 
Annex  B (normative)  Determination of pourability  ................................ ................................ ...............  6 
B.1 Outline of the method  ................................ ................................ ................................ ..................  6 
B.2 Apparatus  ................................ ................................ ................................ ................................ ...... 6 
B.3 Procedure  ................................ ................................ ................................ ................................ ...... 6 
Annex  C (normative)  Determination of characteristics of emulsion (EW) insecticides  ....................  8 
C.1 Outline of method  ................................ ................................ ................................ .........................  8 
C.2 Methods of determination  ................................ ................................ ................................ ...........  8 
Annex  D (normative)  Determination of persistent foaming  ................................ ...............................  13 
D.1 Apparatus  ................................ ................................ ................................ ................................ .... 13 
D.2 Procedure  ................................ ................................ ................................ ................................ .... 13 
Annex  E (normative)  Determination of flash point  ................................ ................................ .............  14 
E.1 General  ................................ ................................ ................................ ................................ ........  14 
E.2 Apparatus  ................................ ................................ ................................ ................................ .... 14 
E.3 Reagents  ................................ ................................ ................................ ................................ ..... 15 
E.4 Procedure  ................................ ................................ ................................ ................................ .... 15 
E.5 Results  ................................ ................................ ................................ ................................ .........  16 
Annex  F (normative)  Determination of acidity or alkalinity  ................................ ...............................  17 
F.1 Qualitative test  ................................ ................................ ................................ ............................  17 
F.2 Determin ation of acidity ................................ ................................ ................................ .............  17 
F.3 Determination of alkalinity  ................................ ................................ ................................ ........  18 
Annex  G (normative)  Determination of pH value  ................................ ................................ ................  20 
G.1 Outline of the method  ................................ ................................ ................................ ................  20 
G.2 Reag ents ................................ ................................ ................................ ................................ ..... 20 DRS 465 -3: 2021  
©RSB 2021  - All rights reserved                  iv 
 G.3 Apparatus  ................................ ................................ ................................ ................................ ... 20 
G.4 Procedure  ................................ ................................ ................................ ................................ ... 20 
G.5 pH of aqueous dispersion  ................................ ................................ ................................ .........  20 
Anne x H (normative)  Determination of  stability of liquid formulations at 0 °C ..............................  21 
H.1 Outline of the method  ................................ ................................ ................................ ................  21 
H.2 Emulsifiable concentrates and solutions  ................................ ................................ ................  21 
H.2.1  Apparatus  ................................ ................................ ................................ ................................ ... 21 
H.2.2  Procedure  ................................ ................................ ................................ ................................ ... 21 
H.3 Aqueous solutions ................................ ................................ ................................ .....................  22 
H.3.1  Apparatus  ................................ ................................ ................................ ................................ ... 22 
H.3.2  Procedure  ................................ ................................ ................................ ................................ ... 22 
Annex  I (normative)  Determination of  accelerated storage stability  ................................ ...............  23 
I.1 Outline of the method  ................................ ................................ ................................ ................  23 
I.2 General method  ................................ ................................ ................................ ..........................  23 
I.3 Apparatus  ................................ ................................ ................................ ................................ ... 23 
I.4 Procedure  ................................ ................................ ................................ ................................ ... 23 
 DRS 465 -3: 2021  
v                ©RSB 2021  - All rights reserved  
 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 sta ndards.  
The main 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 -3 was prepared by Technical Committee RSB/TC 007, Agrochemicals.  
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  
Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)  
Rwanda Agriculture and Animal Resourc es Development Board (RAB)  
Rwanda  Standards Board  (RSB) – Secretariat  DRS 465 -3: 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). Pyret hrin I, jasmolin I and cinerin I are esters of 
chrysanthemic 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 py rethrin I in 
seedlings of C. cinerariifolium  has been studied 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 . 
 
 DRS 465 -3: 2021  
1                ©RSB 2021  - All rights reserved  
 Pyrethrum -based insecticide s — Specification  — Part 3: Emulsions (oil 
in water, EW)  
1 Scope   
This Draft Rwanda Standard prescribes the requirements, sampling and test methods for pyrethrum -based 
emulsion (oil in water , EW ) insecticides for direct application  or after dilution,  used in animal and crop protection 
to control insect pests . 
2 Normative references   
The following do cuments are referred to in the text 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 (incl uding 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 concentrate  
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 
  
4 Requirements  
4.1 General requirements  
4.1.1  The product shall consist of pyrethrum extracts, complying with the requirements of RS 191, in an 
aqueous phase toget her with suitable formulants.  
4.1.2  If synthetic pyrethroid s are added , the product shall be approved by the Competent Authority.  
4.1.3  After agitation,  the product shall be homogeneous liquid  and suitable for dilution in water , free from 
sediment and/or suspended matter.  
4.2 Specific requirements  
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 pyrethrum -based emulsi on insecticides  
S/N Parame ters Requirements  Test methods  
i.  Total pyrethrins 
content, % by mass  Ready to use  0.10 — 0.50 Annex A  Dilutable  0.50 — 5.0 
ii.  Pourability % m/v, max.  0.5 Annex B 
iii.  Emulsion stability and re -emulsification , at 
30 ± 2°C. Pass the test  Annex C  
iv.  Persistent foam, after 1minute, volume, 
max.  Nil  Annex D  
v.  Flash point , °C, min.  32 Annex E  
vi.  Acidity (as H 2SO 4), g/kg, max.  3.0 Annex F  vii.  Alkalinity (as NaOH), g/kg , max.  0.10 
viii.  pH range  5 — 7 Annex G 
ix.  Storage stability  At 0 ± 2°C for 7 
days , ml, max.  Pass to iii)  Annex H  
At 54  ± 2°C for 14 
days , percentage of 
declared total 
pyrethrins ( % m/m ), 
min. 98 Annex I  
 
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.  DRS 465 -3: 2021  
3                ©RSB 2021  - All rights reserved  
 5.1.2  The packaging material shall protect the contents from adventitious contamination under handling and 
storage conditions.  
5.2 Labelling  
The containers shall be closed and shall bear legibly and indelibly the following information in any o f the three 
languages officially accepted in the Republic of Rwanda namely: Kinyarwanda, English and French.  
a) Name of the product;  
b) Name and address of the manufacturer;  
c) Manufacture and expiry dates;  
d) Batch number;  
e) Active ingredient (s) contents;  
f) Indicate: “r eady to use” or “dilutable”  
g) Storage conditions;  
h) Instructions for use;  
i) Precautions and warnings; and  
j) 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 pyrethru m standard, 50%  
Acetonitrile, HPLC grade  
Water, HPLC grade  
A.3 Apparatus  
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 -3: 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 Acetonitrile 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 inje ctions for the standard solution as well as for 
the analyte and average the area counts. The relative Standard Deviation between injections should be within 
2 %. 
A.8 Calculation  
The total pyrethrins is calculated as follow:  
 total  pyrethrins ,% m/m=𝐴𝑣𝑒𝑟𝑎 𝑔𝑒 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)  
 
Determination of pourability  
B.1 Outline of the method  
The pro duct is allowed to stand for a definite time and the amount remaining in the container after a standardized 
pouring procedure is determined. The container is rinsed and the amount then remaining is determined.  
B.2 Apparatus  
Container  – A 500 -ml stoppered measu ring cylinder.  
Volume equivalent to 1 subdivision of the scale   = 5 ml.  
Capacity corresponding to lowest graduation mark  = 50 ml  
Capacity corresponding to highest graduation mark  = 50 ml  
Length of scale          = 250 ml  
Overall height          = 39 cm  
Diame ter of base          = 10 cm  
Stopper            = B34  
NOTE  High density polyethylene bottles, 100 ml volume and kilner jars, 700ml volume, can be used but this must be 
recorded with the result.  
B.3 Procedure  
Weigh the empty container and stopper (w 0 g) and add e nough of the sample taken from a recently mixed bulk 
sample to leave approximately 20% of the volume of the container as ullage. Replace the stopper and reweigh 
the container (w 1 g). allow the container to stand undisturbed for 24 hours and then pour out t he product (Note 
1) for 60 s at an angle of 45 °C and then finally invert the container for 60 s (Note 2). Reweigh the container and 
stopper (w 2 g). 
Add distilled water at 20 °C (a volume of 80% of that of the container) and replace the stopper. Invert the  
container 10 times (note 3) and empty the container as before and reweigh the container and stopper (w 3 g). 
Calculate the residue (R) and the rinsed residue ( R’). 
         𝑅 (%)=(𝑤2 −𝑤0)
(𝑤1−𝑤0)𝑋 100 DRS 465 -3: 2021  
7                ©RSB 2021  - All rights reserved  
          𝑅′ (%)=(𝑤3 −𝑤0)
(𝑤1−𝑤0)𝑋 100 
NOTE 1  The length of the standing period and the temperature should be agreed previously.  
NOTE 2  A square -sided container should be held so that a flat side is underneath.  
NOTE 3  The term ‘invert the container’ means that the container’s vertical axis is turned throu gh 180 degrees and then 
brought back to its original position, the whole operation taking about 2 s.   
©RSB 2021  - All rights reserved                  8 
 Annex  C 
(normative)  
 
Determination of characte ristics of emulsion (EW) insecticides  
C.1 Outline of method  
Five ml of the product are mixed with a standard water to gi ve 100 ml of aqueous emulsion. The stability of this 
emulsion is then assessed in terms of the amounts of free ‘oil’ or ‘cream’ which separates while the emulsion is 
allow to stand undisturbed for 24 h. The ability of the system to re -emulsify at the end o f 24 h period is also 
determined. If required, the test is repeated on a fresh sample of the emulsion.  
C.2 Methods of determination  
C.2.1  Five percent v/v oil phase  
C.2.1.1  Hand shaking  
C.2.1.1.1  Apparatus  
Measuring cylinders  – A 100 -ml glass stoppered, the volume between the 100 ml graduated mark and the 
bottom of the stopper should be not more than 40 ml and not less than 35 ml. The apparatus must be clean and 
free from grease.  
Constant temperature bath  – Large enough to all ow several 100 ml measuring cylinders to be immersed in 
an upright position in the water to the neck; maintained at 30 ± 1 °C (Note).  
NOTE  1 Any vibration can alter the properties of the dilute emulsion in the cylinder. The cylinder should, therefore, be 
supported or clamped in such a way that it is not in contact with the body of the water bath. The stirrer assembly should 
preferably be clamped independently of the water bath.  
Adjustable lamp  – Fitted with a 60 -watt bulb.  
Measuring cylinders , 5 ml.  
C.2.1.1 .2 Procedure  
a) Initial emulsification  
Fill a 100 ml  measuring cylinder to the 95 ml mark with standard water at 30 ± 1 °C unless otherwise specified. 
The sample (5 ml at the same temperature as the standard water) is gently poured on to the surface of the 
water; the stopper is replaced and the cylinder is inverted once (Note).  
After 30 sec observe whether the mixture has emulsified spontaneously giving 100 ml of an emulsion which 
appears, on visual examination, to be uniform. Note any froth produced.  DRS 465 -3: 2021  
9                ©RSB 2021  - All rights reserved  
 NOTE  2 The expression ‘invert the cylinder’ implies that the stoppered cylinder is tipped by hand through 180 degrees, 
and is then brought back to its original position, the whole operation being completed in approximately 2 sec.  
b) Emulsion stability on standing  
Invert the cylinder 10 times (Note 2), and allow the cylinder and its contents of stand undisturbed in the constant 
temperature bath at 30 ± 1 °C for 24 h. Record the volume (Note 3), if any of free oil (Note 4), froth and ‘cream’ 
formed either at the top or the bottom of the emulsion, after standing for 30 min, 2 h and 24 h.  
NOTE 3  An adjustable lamp, fitted with a 60 -watt pearl bulb, should be used to illuminate the cylinder. The position and 
angle of the light should be adjusted for optimum viewing of the phase boundary. It is often easier to see this by reflected, 
rather than by transmitted light.  
NOTE 4  If, initially, difficulty is experienced in distinguishing between oil and cream, a dye soluble in the oil phase may 
be used, but the final tests should b e carried out without the addition of dye. It has been found that dyes which give a deep 
blue solution in aromatic hydrocarbon solvents, e.g. oil Blue SWS, 1,4 - is (isopropylamine) anth raquinone (CI 61551), are 
most suitable for this purpose. The dye (0.1g /100ml) should be added to the emulsion before carrying out the test. If oil is 
present  then the dye will colour it deep blue; if extensive creaming has occurred, the dye will give a pale blue layer; if little 
or no creaming has occurred then no definite c olour band will be produced.  
c) Emulsion stability on standing  
At the end of the 24 h period invert the cylinder 10 times (Note 2). Allow to stand for 30 sec, then observe whether 
any free oil, froth, ‘cream’ or solid matter found after standing for 24 h is re -emulsified, giving 100 ml of an 
emulsion which appears, on visual examination (Note 3), to be uniform.  
d) Final emulsion stability  
Allow the cylinder to remain undisturbed for a further period of 30 min.  
Record the volume, if any, of free oil, froth, ‘cream’, or solid matter present at the end of the 30 min period.  
C.2.1. 2 Mechanical  shaking   
C.2.1. 2.1 Apparatus  
As for C.2.1.1.1  together with shaking apparatus; the plate should not rotate at 30 rpm.  
C.2.1. 2.1 Procedure  
a) Initial emulsification  
Fill a 100 -ml measuring cylinder to the 95 ml mark with standard at 30 ± 1 °C. pour the emulsion, which should 
be at the same temperature as the standard water, gently (5 ml from a measuring cylinder) on the surface of 
water, replace the stopper and invert the cylin der once (Note 2).  
After 30 sec observe whether the mixture has emulsified spontaneously giving 100 ml of an emulsion which 
appears, on visual examination, to be uniform. Note any froth produced.   
©RSB 2021  - All rights reserved                  10 
 b) Emulsion stability on standing  
Shake the cylinder for 20 sec  in the shaking machine (i.e. 10 inversions) and allow the cylinder and its contents 
to stand undisturbed in the constant temperature bath at 30 ± 1 °C for 24 h. record the volume (Note 3), if any, 
of free oil, froth and the total volume of ‘cream’ formed either at the top or the bottom of the emulsion, after 
standing for 30 min, 2 h and 24 h.  
c) Re-emulsification after standing for 24 h  
At the end of the 24 h period shake the cylinder for 20 sec as before.   
Record whether any free oil, froth, ‘cream’ or solid  matter, found after standing for 24 h is re -emulsified, giving 
100 ml of an emulsion which appears, on visual examination (Note 3), to be uniform.  
Final emulsion stability  – Allow the cylinder to remain undisturbed for a further period of 30 min. Observe the 
volume, if any, of free oil, froth, ‘cream’, or solid matter present at the end of the 30 min period.  
C.2.2  1% v/v oil phase (Note 6)  
NOTE 6  The method is not suitable for formulations intended for low volume spraying and/or aerial application; it may 
not be suitable for ‘invert’ formulations.  
C.2.2.1  Preliminary examination  
Prepare a 5% v/v dilution of the emulsion in water and allow to stand in a 100 ml measuring cylinder. Allow to 
remain undisturbed at room temperature to determine whether top or bottom creaming occurs.  
In the sample does not separate, no further testing is required.  
If it does separate after 24 h, continue the test by the appropriate section of clause C.2.1.2.1 . 
C.2.2.2  Dispersion stability  
C.2.2.2.1  Apparatus  
Measuring cylinder  – A 250 -ml fitted with stopper, and with dimensions of between 20 and 21.5 cm from 
the bottom, i.e. the 0 -ml mark to the 250 -ml mark.  
Water bath – At 30 ± 1 °C unless otherwise specified.  
Sampling tube – A piece of a small bore tubing 2 mm internal diameter , about 30 cm long, fitted at one 
end with a two -way stopcock. One of the arms of the stopcock is connected to a Drechsel bottle with 
nylon tubing; the outlet from the bottle is connected to a vacuum source via a second stopcock. The 
tube is fitted with a bung to act as a stop.  
Pipette , 2 ml  DRS 465 -3: 2021  
11                ©RSB 2021  - All rights reserved  
 C.2.2.2.2  Procedure  
a) Active ingredient in initial dispersion  
Determine the content of active ingredient in 100 m of the initial dispersion (Note 7). Express the result in grams 
(x g) per 100 ml of the dilute emulsion.  
NOTE 7  The content of active ingredient in the initial dispersion must be determined by the same method as is used for 
determination of the active ingredient in the dilute emulsion after estimation of dispersion stability.  
b) Top creaming  
Removal of 100 ml of e mulsion from the bottom of the cylinder, i.e. between 0 and 100 ml marks. Adjust the 
stop on the glass tube so that the tip of the tube is below the 10 ml graduation mark near the bottom of the 
cylinder. Remove the tube and fill the cylinder to the 100 ml mark with water. Fill the sampling tube to the top 
with water and close the two -way stopcock. Calibrate the cylinder by inserting the tube into the cylinder (i.e. 
near the bottom) and mark the new l evel of water on the side of the cylinder.  
Pour the standa rd water (198 ml at 30 °C unless otherwise specified) into the cylinder and add the emulsion (2 
ml). Insert the stopper, invert the cylinder 30 times (Note 2), and put the cylinder in the water bath at 30 ± 1 °C 
(note 1).  
At the end of the specified time p lace the sample tube, filled with water, in position in the cylinder, open the 
stopcocks, and remove the dilute emulsion until the surface of the liquid reaches the calibration mark of the 
cylinder. Close the stopcock on the tube, remove the tube from the cylinder, and wash any material adhering to 
the outside of the tube directly into the cylinder. Open the stopcock, cuck the remainder of the liquid into the 
bottle, and wash the tube and leads to the bottle by inserting the tube in distilled water, and app lying suction.  
Determine the insecticide  conte nt (y g)  of the dilute emulsion remaining in the cylinder (Note 8).  
NOTE 8  The insecticide  content of the emulsion drawn into the Drechsel bottle may also be determined (z g) to check 
the recoveries of the acti ve ingredient, since y + z should equal 2x.  
c) Bottom creaming  
(Removal of 100 ml of emulsion from the top of the cylinder i.e. between the 100 and 200 ml graduations). Pour 
standard water (198 ml at 30 °C unless otherwise specified) into the cylinder and add the emulsion (2.0 ml). 
Insert the stopper, invert the cylinder 30 times, and place in the water bath at 30 ± 1 °C. At the end of the 
specified time insert the sampling tube into the cylinder and draw the dilute emulsion over into the Drechsel 
bottle, until the surface of the liquid in the cylinder reaches the 100 ml mark, maintaining the tip of the tube just 
below the sinking level of the liquid. Withdraw the sampling tube and wash the tube and leads t o the bottle by 
inserting the tube into distilled water and applying suction.  
Determine the insecticide content  (y g) of the dilute emulsion remaining in the cylinder (Note 8).  
C.2.2.2. 3 Dispersion stability  
   𝐷𝑖𝑠𝑝𝑒𝑟𝑠𝑖𝑜𝑛  𝑠𝑡𝑎𝑏𝑖𝑙𝑖𝑡𝑦 ,% 𝑚/𝑚=100 (2𝑋−𝑦)
𝑋  
©RSB 2021  - All rights reserved                  12 
 C.2.3  Results  
After testing, the formulation shall comply with the following:  
Time after dilution  Limits of stability  
0 h Initial emulsification: complete  
0.5 h  “Cream”, maximum: 0 ml  
2.0 h  “Cream”, maximum: 0 ml  
 “Free oil”, maximum:  0 ml 
24 h Re-emulsification: complete  
24.5 h  “Cream”, maximum: 0 ml  
 “Free oil”, maximum: 0 ml  DRS 465 -3: 2021  
13                ©RSB 2021  - All rights reserved  
 Annex  D 
(normative)  
 
Determination of persistent foaming  
D.1 Apparatus  
D.1.1  Stoppered measuring cylinder , 100 ml – If possible select one whose volume between 100 ml 
graduation mark and the bottom of the stopper is, not more than 40 ml and not less than 35 ml (Note 1).  
NOTE 1  The cylinder should be clean and free from grease.  
D.1.2  Weighing bottle . 
D.1.3  Graduated cylinder  – Glass stoppered, 250 ml capacity with 2 ml graduations, the distance between 
the 0 mark and the 250 ml mark being 20 – 21.5 cm, and between the 250 ml mark and the bottom of the 
stopper, 4 – 6 cm.  
D.1.4  Stopwatch . 
D.2 Procedure  
D.2.1  Weigh out the specified  amount of the material and add it to standard water (95 ml) in the measuring 
cylinder and make up to the mark. Stopper the cylinder and invert 30 times (Note 2). Stand the cylinder on the 
bench and leave undisturbed for the specified time. Note the volume  of foam (Note 3).  
NOTE 2  The expression ‘invert the cylinder’ means that the stoppered cylinder in held by two hands, one at each end of 
the cylinder, which are insulated from the cylinder by means of a cloth. The upright cylinder in turned through 180 de grees 
and back to its original position without any ‘bounce’ occurring, this operation taking approximately 2 sec. It is convenient  to 
observe a stop -clock equipped with a second hand which sweeps once every 60 sec. while doing this.  
NOTE 3  A few bubbles round the periphery are not significant. Any volumes above the 100 ml mark or the 250 ml mark 
should be marked on the outside and the volume of foam thus determined.  
D.2.2  The mass of sample to be taken is that mass required to make 200 ml of a suspension with a 
concentration recommended in the directions for use supplied with the product. Where several concentrations 
are recommended, the maximum concentration shall be used.  
D.2.3 Put about 180 ml of standard water into 250 ml measuring cylinder standing on  a top pan balance and 
weigh in the required amount of the sample. Top up with standard water until the distance between the 
suspension surface and the bottom of the ground glass joint is 9 ± 0.1 cm. stopper the cylinder and invert 30 
times. Place the stop pered cylinder upright on the bench and immediately start the stopwatch. Read the volume 
of foam produced and remaining after 10 ± 1 sec, 1, 3 and 12 min ± 10 sec.   
©RSB 2021  - All rights reserved                  14 
 Annex  E 
(normative)  
 
Determination of flash point  
E.1 General  
This test method is similar to the Contin uously Closed Cup Flash Point Test method. It utilizes a closed but 
unsealed cup with air injected into the test chamber.  
E.2 Apparatus  
The Continuously Closed Cup Flash Point tester shall essentially consist of:  
E.2.1  A lid of solid brass : The temperature of which is controlled electrically. Two temperature sensors for 
the specimen and the lid temperatures, respectively, two electrically insulated pins for a high voltage arc, and a 
connecting tube for the pressure monitoring.  
E.2.2 Sample cup : Made of nickel -plated aluminium with an overall volume of 4 mL and capable of 
containing 1 ± 0.1 mL of sample.  
E.2.3 Test Chamber : Formed by sample cup and the temperature controlled lid and shall have an overall 
volume of 4 ± 0.2 mL  
E.2.4 Specimen Temperature Sensor : A thermocouple (Ni -Cr-Ni or similar) in stainless steel of 1 mm 
diameter with a response time of t(90) = 3 sec. It shall be immersed to a depth of at least 2 mm into the specimen. 
It shall have a resolution of 0.1 °C and a minimum accuracy of ± 0.2 °C, w ith a digital readout.  
E.2.5 Magnetic Stirring : A rotating magnet outside the sample cup that can drive a small stirring magnet, 
which is inserted into the sample cup after sample introduction. It should have a diameter of 3 ± 0.2 mm and a 
length of 12 ± 1  mm. The rotation speed of the driving magnet shall be between 250 and 270 revolution/minute.  
E.2.6 Air Introduction Provision : For introduction of 1.5 ± 0.5 mL of air immediately after each test. The air 
shall be introduced by a short air pulse from a sma ll membrane compressor by means of a T -inlet in the 
connecting tube to the pressure transducer.  
E.2.7 Arrangement Electrical heating and thermoelectric cooling of the lid : used to regulate the 
temperature of the test chamber during the test. The temperatur e regulation shall have a minimum accuracy of 
± 0.2 °C.  
E.2.8 A high voltage electric arc : Used for the ignition of the flammable vapour. The energy of the arc 
should be 3± 0.5 mJ per arc and it shall be applied within 43 ± 3 ms.  
E.2.9 The pressure transdu cer (for flash point detection): connected to the connecting tube in the lid; 
should have a minimum operational range from 80 to 177 kPa with a minimum resolution of 0.1 kPa and a DRS 465 -3: 2021  
15                ©RSB 2021  - All rights reserved  
 minimum accuracy of ± 0.5 kPa. It shall be capable of detecting an instantan eous pressure increase above 
barometric pressure of a minimum of 20 kPa within 100 ms.  
E.3 Reagents  
The reagents should be of analytical quality and of sufficient purity to guarantee the accuracy of the test results.  
Anisole  
Dodecane  
Acetone (or toluene)  
E.4 Procedure  
E.4.1 Thoroughly clean and dry the lid together with the arc pins and the sample cup before starting the test. 
Remove any solvent used to clean the apparatus. If the expected flash point of a sample is more than 15 °C 
higher than the flash point of the previous sample, heat the lid together with an empty, dry sample cup to a 
temperature 30 °C higher than the expected flash point of the new sample.  
E.4.2  Set the initial temperature to at least 18 °C below the expected flash point. Set the final temper ature 
to a value beyond the expected flash point.  
E.4.3  Set the pressure threshold for the flash detection to 20 kPa.  
E.4.4  Initiate the test procedure to regulate the lid to the initial temperature. When the initial temperature is 
reached as indicated by the instrument, prepare to introduce 1± 0.1 mL specimen of the sample.  
E.4.5  Ensure that the sealed sample and the sample cup are at least 18 °C below the expected flash point 
temperature, cool if necessary. Shake the sample thoroughly before opening the s ample container. Extract 1 
mL of sample with a pipette or syringe, and close the container. Transfer 1± 0.1 mL of the sample to be tested 
into the sample cup.  
E.4.6  Insert a stirring magnet into the sample cup to ensure a consistent sample mixing. Put the sample cup 
onto the sample cup support of the tester, and start the procedure. Raise and press the sample cup onto the 
lid, which is at the initial temperature and thus at a higher temperature than the sample cup.  
E.4.7  While the temperature of the sample cup and the lid are equalizing, apply a precautionary arc at 10 °C 
intervals. If a flash is detected at one of these precautionary arcs, discontinue the test, and discard the result. 
Repeat the test with a fresh specimen and with a lower initial temperatur e of at least 18 °C below the temperature 
at which the flash was detected.  
E.4.8  After the temperature between the temperatures regulated lid and the specimen have equalized to 
within 1 °C, start the actual test for the flash point. Heat the lid with the p rogrammed heating rate, and apply the 
arc ignition in equidistant temperature steps of 1 °C. Monitor the instantaneous pressure increase within 100 
ms after the arc. Stop the test when a flash is detected or when the final temperature is reached in the cas e of 
no flash point. The flash point temperature is the specimen temperature at which the instantaneous pressure 
increase, due to the presence of the flash, exceeds 20 kPa.   
©RSB 2021  - All rights reserved                  16 
 E.4.9  When a flash is detected at a temperature that is higher than 26 °C above the  initial temperature, or 
when a flash is detected at a temperature that is less than 10 °C above the initial temperature, consider the 
result approximate and repeat the test with a fresh test specimen. Adjust the expected flash point for this next 
test to the temperature of the approximate result. The initial temperature for this fresh test specimen shall be 
18 °C below the temperature of the previous approximate result.  
E.4.10  Record the specimen temperature reading at the detected flash point as the uncor rected flash point 
temperature. If no flash point was detected within the tested temperature range, record “ flash point is higher 
than the final temperature”.  
E.4.11  At the conclusion of the test, cool the sample cup below 50 °C to withdraw it safely.  
E.5 Resu lts 
E.5.1  Observe and record the ambient barometric pressure at the time of the test; when the pressure differs 
from 101.3 kPa, correct the flash point as follows:  
  Corrected flash point = C + 0.25 (101.3 – p) 
Where,  
  C = observed flash point in °C, and  
  p = ambient barometric pressure in kPa.  
Round up the corrected value to the nearest 0.5 °C. 
E.5.2  The barometric pressure used in this calculation must be the absolute ambient pressure for the 
laboratory at the time of the test. Aneroid barometers, such as those used at weather stations and airports, are 
corrected to give sea level readings; these shall not be used.  DRS 465 -3: 2021  
17                ©RSB 2021  - All rights reserved  
 Annex  F 
(normative)  
 
Determination of acidity or alkalinity  
F.1 Qualitative test  
Procedure  – Take about 0.5 g of the material in a test -tube and mix wit h 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.  
F.2 Determination of acidity  
F.2.1  Reagents  
F.2.1.1  Methyl red indicator solution -aqueous – one percent (m/v)  
F.2.1. 2 Bromocresol purple indicator solution – one percent (m/v) in ethyl alcohol  
F.2.1.3  Standard sodium hydroxide solution – 0.05N  
F.2.1.4  Standard hydrochloric acid – 0.05N  
F.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 supernatant aqueous e xtract 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 determined 
electrometrically.  
Carry out a blank determination on an  aliquot of 50 ml made from 25 ml acetone and 75 ml water.  
F.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   
©RSB 2021  - All rights reserved                  18 
 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 h ydroxide 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.  
F.3 Determination of alkalinity  
F.3.1 Reagents  
F.3.1.1  Methyl red indicator solution -aqueous – one percent (m/v)  
F.3.1.2  Bromocresol purple indicator solution – one percent (m/v) in ethyl alcohol  
F.3.1.3  Standard hydrochloric acid – 0.05N  
F.3.1.4  Standard sodium hydroxide solution – 0.05N  
F.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 supern atant 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 out a blank deter mination on 50 ml aliquot made from 25 ml acetone and 75 ml water.  
F.2.3  Calculation  
Alkalinity (as NaOH), % m/m =4.0 𝑥 2(𝑉−𝑣)𝑁
𝑀 DRS 465 -3: 2021  
19                ©RSB 2021  - All rights reserved  
 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 hydroxid e 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 hydrochloric 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.   
©RSB 2021  - All rights reserved                  20 
 Annex  G 
(normative)  
 
Determination of pH value  
G.1 Outli ne of the method  
The pH value of a liquid is determined by means of pH meter and a glass electrode.  
G.2 Reagents  
G.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 up to 1000 ml.  do no keep the solution for longer than one month.  
G.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.  
G.2.3  Water  – Freshly boiled and cooled distilled water of pH 5.5 to 7.0  
G.3 Apparatus  
G.3.1  pH meter  
G.3.2  Glass electrode and reference electrode  
G.4 Procedure  
Operate the pH meter and electrode system in accordance with the manufacturer’s instructions. Standardize 
the met er 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 whi ch 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 
G.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.  DRS 465 -3: 2021  
21                ©RSB 2021  - All rights reserved  
 Annex  H 
(normative)  
 
Determination  of  stability of liquid formulations at 0 °C 
H.1 Outline of the method  
A sample is maintained at 0 °C for 1 h and the volume of any separated solid or oily matter is then recorded. 
Storage at 0 °C is continued for 7 days, any solid matter is settled by centrifuging and its volume recorded.  
H.2 Emulsifiable concentrates and solutions  
H.2.1  Apparatus  
H.2.1 .1 Refrigerator – Capable of maintaining a temperature at 0 ± 1 °C (Note 1)  
H.2.1.2 Cone shaped centrifuge tubes, 100 ml.  
H.2.1.3 Centrifuge – equipped with buckets capable of holding the specified tubes.  
H.2.1.4 Pipette, 100 ml.  
NOTE 1  A domestic refrigerator is often unsuitable because the on/off cycle covers a range greater than 2 °C. 
H.2.2  Procedure  
Transfer 100 ± 1.0 ml of a sample of the product to a centrifug e tube. Cool the tube and its content to (0 ± 1) °C 
in the refrigerator. Allow the tube and its contents to remain at (0 ± 1) °C for 1 h, and during this time stir the 
contents of the tube at intervals of approximately 15 min, each time for approximately 3 0 s. After this period 
examine the tube and record whether any solid or oily matter is present. Replace the tube in the refrigerator and 
allow it to remain at (0 ± 1) °C for a total period of 7 days.  
At the end of 7 days, remove the tube from the refrigera tor, and allow it to remain undisturbed at room 
temperature for 3h. invert the centrifuge tube once, and centrifuge for 15 min at such a speed that the relative 
centrifugal force (RCF) at the tips of the tubes is about 550 x G (the acceleration due to grav ity = 981 cm/s-2, 
Note 2).  
Record the volume of any separated material at the bottom of the tube to the nearest 0.005 ml.  
NOTE 2  : RCF = (𝑟𝑝𝑚 )2𝑑
179000  and  rpm = √98.45 𝑋 𝑑−1 𝑋 103 
Where:   
©RSB 2021  - All rights reserved                  22 
  RCF is relative centrifuge force;  
 d is diameter of swing (i n cm) measured from the tips of the opposite tubes when in the position occupied 
during the centrifuging.  
NOTE 3  If the liquid phase is not homogenous, record the volume of each layer.  
H.3 Aqueous solutions  
H.3.1  Apparatus  
H.3.1.1  Measuring cylinder , 100ml.  
H.3.1.2  Refrigerator , at 0 ± 1 °C 
H.3.2  Procedure  
Put 100 m of the product in the measuring cylinder and then put it in the refrigerator for 48 h at 0 ± 1 °C. At the 
end of this time, note the amount of separated material, if any, then allow the cylinder to reach room t emperature 
and again note the amount of separated material.  DRS 465 -3: 2021  
23                ©RSB 2021  - All rights reserved  
 Annex  I 
(normative)  
 
Determination of  accelerated storage stability   
I.1 Outline of the method  
Representative sample is stored in a screw -capped bottle in an oven at a specified temperature and time.  
I.2 General method  
As this is intended as a model procedure, temperature and times specified are examples only since the 
parameters will normally be given for individual pesticide formulations.  
I.3 Apparatus  
I.3.1  Beaker  – 250-ml, 6 to 6.5 internal diameter.  
I.3.2  Metal disc  – Plastic coated; a loose fit in the beaker, and of such dimensions that an even pressure 
of 25 g/cm2 can be produced on the surface of the sample in the beaker.  
NOTE 1  Alternatively, a close fitting cylinder with a flat bottom, containing le ad shot, can be used, the lead shot may be 
sealed in with molten wax so as ti give the correct weight, and prevent the shot from being lost.  
I.3.3  Oven  – Thermostatically controlled to the specified temperature ( ± 2 °C) 
I.3.4  Desiccator without desiccant  
I.4 Procedure  
Put the sample into the beaker and spread it, without using any pressure, in a smooth even layer of constant 
thickness. Place the disc on the surface of  the solution in the beaker, and put in the oven (Note 2). After the 
specified time remove th e beaker, take out the disc, and allow the beaker to cool in the desiccator.  
NOTE 2  Use the specified temperature and time given in the specification of method of analysis. If no temperature of 
time is specified, store the sample at 54 ± 0.2 °C for 14 days . 
Ensure that each sample taken is truly representative of that left in the beaker. Sampling of a hard cake may be 
carried out conveniently by removing several cores with a small diameter (6 mm) cork borer.  
 
  
©RSB 2021  - All rights reserved                  24 
 Bibliography  
[1] ES 758 , Pesticides — Determina tion of pourability of suspension concentrates , 2000  
[2] ES 756 , Pesticides  — Determination of characteristics of emulsifiable concentrates , 2002  
[3] ES 756, Pesticides — Determination of persistent foaming , 2002  
[4] ES 750, Pesticides — Determination of free acidity or alkalinity, 2002  
[5] ES 757, Pesticides — Determination of pH values, 2002  
[6]      ES 752, Pesticides — Determination of stability of liquid formulations at 5 °C, 2002  
[7]      ES 753, Pesticides — Determination of accelerated storage stability, 2002  DRS 465 -3: 2021  
 
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©RSB 2021  - All right s reserved