ICS 71.100.70 
 
 
Reference number  
DRS  453: 202 1 
© RSB 2021 
  
 RWANDA 
STANDARD  DRS 
453 
First  edition  
Approved by RSB 2021-mm-dd 
Mouthwash — Specification  
 
  
DRS 453: 2021  
ii        ©RSB 2021 - All rights reserved  
 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 RSB.  
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Rwanda Standards Board  
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E-mail: info@rsb.gov.rw  
Website: www.rsb.gov.rw  
ePortal:  www.portal.rsb.gov.rw   DRS 453: 2021  
iii        ©RSB 2021 - All rights reserved  
  
Contents  
1 Scope  ................................ ................................ ................................ ................................ .............  2 
2 Normative references  ................................ ................................ ................................ ...................  2 
3 Terms and definitions  ................................ ................................ ................................ ..................  2 
4 Classification  ................................ ................................ ................................ ................................  2 
5 Requirement  ................................ ................................ ................................ ................................ .. 3 
5.1 General requirem ents ................................ ................................ ................................ ..................  3 
5.2 Specific requirements  ................................ ................................ ................................ ..................  3 
6 Sampling  ................................ ................................ ................................ ................................ ....... 4 
7 Packaging and labellin g................................ ................................ ................................ ...............  4 
7.1 Packaging  ................................ ................................ ................................ ................................ ...... 4 
7.2 Labelling  ................................ ................................ ................................ ................................ ........  4 
Annex  A (normative)  Determination of stability against ageing ................................ ..........................  6 
A.1 Test ................................ ................................ ................................ ................................ ................  6 
A.2 Compliance  ................................ ................................ ................................ ................................ ... 6 
Annex  B ................................ ................................ ................................ ................................ ......................  7 
(normative)  ................................ ................................ ................................ ................................ .................  7 
Determination of fluoride in mouthwash containing ionic fluoride compounds  ................................  7 
B.1 Principle  ................................ ................................ ................................ ................................ ........  7 
B.2 Reagents and/or materials  ................................ ................................ ................................ ..........  7 
B.3 Apparatus  ................................ ................................ ................................ ................................ ...... 7 
B.4 Preparation of s olutions and calibration curve  ................................ ................................ .........  8 
B.5 Sample analysis  ................................ ................................ ................................ ............................  9 
B.6 Expression of results  ................................ ................................ ................................ ...................  9 
 DRS 453: 2021  
iv        ©RSB 2021 - All rights reserved  
 Foreword  
Rwanda Standards are prepared by Technical Committees and approved by Rwanda 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 Standards adopted 
by Technical committees are ratified by members of RSB Board of Directors for publication and gazettment as 
Rwanda Standards.  
DRS  453 was prepared by Tec hnical Committee RSB/TC 011, Cosmetics and related products.  
In the preparation of this standard, reference was made to the following standard:  
ISO 16408 Dentistry — Oral care products — Oral rinses   
The assistance derived from the above source is hereby acknowledged with thanks.  
Committee membership  
The following organizations were represented on the Technical Committee on Cosmetics and related products 
of TC  (RSB/TC 011) in the preparation of this standard.  
Paragraph of participants  
University of Rwanda/  College of Sciences and Technology (UR/CST)  
Rwanda Forensic Laboratory (RFL)  
SULFO industries Ltd  
Rwanda Inspectorate, Competition and Consumer Protection Authority ( RICA)  
MORI JA Cosmetics Ltd  
Better Home Ltd  
UBURANGA Products Ltd  
BARANYUZWE Cosmetics Lt d 
Better Home Ltd  
ORIBUT Company Ltd  DRS 453: 2021  
ii        ©RSB 2021 - All rights reserved  
 Rwanda Standards Board (RSB) – SecretariatDRS  453: 2021  
1        ©RSB 2021 - All rights reserved  
 Introduction  
A mouthwash (mouth rinse or  oral rinse) is a liquid solution that you swish around your entire mouth, teeth, 
gums and tongue to help promote oral hygiene, reduce oral discomfort, provide moisture to oral tissues or help 
with bad breath. Oral rinses may be purchased over -the-counter (OTC) or via prescription, and can be 
categorized as cosmetic, therapeutic or a combination of the two.  
While not a replacement for daily brushing and flossing, use of mouthwash (mouth rinse) may be a helpful 
addition to the daily oral hygiene routine for some people because mouthwash offers the benefit of reaching 
areas not easily accessed by a toothbrush.  
Cosmetic mouthwashes may temporarily control or reduce bad breath (halitosis), rinse away oral debris, 
diminish bacteria in your mouth and leave it with  a pleasant, refreshing taste. Cosmetic mouthwashes mask 
rather than eliminate bad breath. Their odor -masking effects typically last no more than three hours. Some 
mouthwashes also contain whiteners to help whiten the teeth.  
Cosmetic mouthwashes that cont ain some of the active ingredients found in rinses designed to treat oral health 
conditions (i.e. fluoride to help strengthen teeth and prevent cavities) also double as therapeutic rinses  
Therapeutic mouthwashes available in non -prescription and prescripti on formulations contain added active 
ingredients to help prevent or treat various oral health conditions and diseases. Therapeutic mouthwashes are 
either anti -plaque/anti -gingivitis, anti -cavity, anti -tartar or antibacterial.  
 
 
 
 
 
 DRS  453: 2021  
2        ©RSB 2021 - All rights reserved  
 Mouthwash — Specificatio n 
1 Scope  
This Draft Rwanda standards specifies physical and chemical requirements , sampling  and test methods for 
liquid mouthwash.  
This Draft Rwanda standards is not applicable to other delivery systems (e.g. mouth sprays, foams, powders). 
It is not appli cable to mouthwash for prescription only.  
2 Normative references  
The following documents 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 appl ies. For undated references, the 
latest edition of the referenced document (including any amendments) applies.  
ISO 1942, Dentistry — Vocabulary  
RS ISO 3696, Water for analytical laboratory use — Specification and test methods  
RS EAS 847 -16, Cosmetics  — Analytical methods  — Part 16: Determination of lead, mercury and arsenic 
content  
RS EAS 847 -17, Cosmetics — Analytical methods  — Part 17: Determination of pH  
3 Terms and definitions  
For the purposes of this standard, the terms and definitions given in ISO 1 942 and the following apply.  
3.1 
mouthwash  
mouth  rinse  
oral rinse  
liquid formulation used by the public for oral care purposes  
4 Classification  
Mouthwash shall be classified according to their application by the user as follows:  
— Type 1: ready -for-use solutions;  
— Type 2: concentrated solutions for use after dilution with water;  DRS  453: 2021  
3        ©RSB 2021 - All rights reserved  
 — Type 3: solutions for use after mixing. 
5 Requirement  
5.1 General requirements  
5.1.1  Compatibility with oral tissues  
Mouthwash shall not cause irritation or damage to the oral hard and/or  soft tissue, when used in accordance 
with the manufacturer’s recommendation for frequency and duration of use and experience with known side 
effects.  
5.1.2  Stability against ageing  
Mouthwash shall show no signs of deterioration, such as agglomeration or change in clarity, after being 
subjected to the determination of stability to ageing procedure specified in Annex A.  
5.1.3  Container and/or dispensing system  
The container and/or dispensing system shall neither contaminate nor permit contamination of the mouthwash 
after being subjected to the determination of stability to ageing described in Annex A.  
5.1.4  Readily fermentable carbohydrates  
Mouthwash shall not contain readily fermentable carbohydrates.  
5.1.5  Visual inspection  
Before and after agitation, examine the mouthwash under a bright light with normal visual acuity without 
magnification.  
5.2  Specific requirements  
The  product shall also comply with the requirements given in  table when tested in accordance with the methods 
indicated therein.  
Table 1: Specific requirements for mouthwash  
S/N Characteristics    
Requirements  Test method  
  
i) Stability against ageing  Pass the test  Annex A  
ii) Total fluoride concentration, max. mass 
fraction %  0.15 Annex B  DRS  453: 2021  
4        ©RSB 2021 - All rights reserved  
 iii) pH 3.0-10.5 RS EAS 847 -17 
iv) Unintended heavy metals, mg/kg  20 RS EAS 847 -16 
v) Microbial contamination, CFU(Colony -
Forming Units), per gram  100  
 
6 Sampling  
The mouthwashes used for testing shall be representative of actual manufactured mouthwash and shall not be 
altered in any way.  
Eight containers of mouthwash from the same manufacturing tracking code (e.g. batch code, lot number) shall 
be tested before the determination of stability to ageing (see Annex A).  
7 Packaging and labelling  
7.1 Packaging  
Packaging should ensure the integrity of the contents of the container during storage and transportation. The 
packaging system for mouthwash is left to the discretion of the manufacturer.  
7.2 Labelling  
The following information, where appropriate, shall be given on the primary container, and also on the secondary 
container, if it exists:  
a) name of the product  
b) the manufacturer’s name and address;  
c) trade name;  
d) the wording “mouthwash” or equivalent, as defined in Clause 3;  
e) the manufacturer’s tracking code (e.g. batch code, lot number);  
f) country of origin  
g) a list of ingredients  
h) net volume, in millilitres;  
i) if the mouthwash contains alcohol, the declaration of alcohol content, as volume fraction;  DRS  453: 2021  
5        ©RSB 2021 - All rights reserved  
 j) if the mouthwash contains fluoride, the concentration of fluoride, in milligrams per kilogram (mg/kg)  
or ppm (parts p er million; 10−6) by mass of fluoride ion;  
k) instructions and warning for proper use with children;  
l) the statement: Not suitable for children under 6 years of age unless medically recommended;  
m) for mouthwash of Type 2, the statement: “Dilute according to the m anufacturer’s instructions for use”;  
n) for mouthwash of Type 3, the statement: “Mix according to the manufacturer’s instructions for use”;  
o) the warning: “Do not swallow”;  
p) information on common side - effects,  
q) manufacture date and best before date,  
r) recommended  storage conditions.  
 
 
 
 
 
 DRS  453: 2021  
6        ©RSB 2021 - All rights reserved  
 Annex  A 
(normative)  
 
Determination of stability against ageing  
A.1 Test  
One of the following two tests shall be performed:  
a) Accelerated test  
Store the mouthwash at (40 ± 2) °C for 3 months at (75 ± 5) % relative humidity or under such conditions of 
time and temperature as will simulate storage at room temperature for 30 months.  
b) Real time test  
Store the mouthwash at (23 ± 2) °C at (60 ± 15) °C relative humidity for 30 months or for the period indicated 
by the expiry date listed on the pr oduct label.  
A.2 Compliance  
Examine by visual inspection (5.1.5) of the mouthwash if requirement 5.1.2 is fulfilled.  
 
 
 
 
 
 
 
 
 DRS  453: 2021  
7        ©RSB 2021 - All rights reserved  
 Annex  B 
                                                                (normative)  
Determination of fluoride in mouthwash containing ionic fluoride 
compounds  
B.1 Principle  
This test method is used for the determination of fluoride in mouthwash containing ionic fluoride compounds.  
B.2 Reagents and/or materials  
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade . 
B.2.1  Deionized water,     in accordance with ISO 3696, grade 2 . 
B.2.2  Fluoride standard solution,  commercially available or prepared with sodium fluoride (NaF).  
B.2.3   Total Ionic Strength Adjustment Buffer (TISAB) solution , with cyclohexanediamine tetra-
acetate (CD TA). Other buffer solutions such as ammonium acetate buffer, applicable to fluoride analysis, may 
also be used.  
Ammonium acetate buffer (pH 5.3) is prepared by dispersing of 16 g of ammonium chloride, 23 g of ammonium 
acetate and 0,4 g of trans -1,2-cyclohe xanediamine -N,N,N’,N’ -tetraacetate monohydrate in about 80 ml of water 
and by dissolving this solution after mixing and heating. The pH value of this buffer is adjusted to 5,3 with acetic 
acid, and the buffer is diluted with deionized water to 100 ml.  
B.3 Apparatus  
The following apparatus shall be used.  
B.3.1  Laboratory balance, with a reading accuracy of 0.01g.  
B.3.2  Flask, of capacity 20mL  
B.3.3  Fluoride ion selective electrode (F -ISE), with reference electrode or combination F -
ISE/reference electrode pair  
B.3.4  Graduated cylind er, of capacity 15 ml to 50 ml.  
B.3.5  Magnetic stirring apparatus, with PTFE -coated magnetic stirring bar and magnetic stir plate.  
 DRS  453: 2021  
8        ©RSB 2021 - All rights reserved  
 B.3.6  pH/mV -electrometer (pH meter), with an accuracy of ±0,05 pH units (±0,1 mV), calibrated . 
B.3.7  Pipette, of capacity (1,0 ± 0,1) ml.  
B.3.8  Plastic vial , or any small beaker or container, 10 ml or more capacity.  
B.3.9   Washing bottle.  
B.4 Preparation od solutions and calibration curve  
B.4.1  Preparation of standard solution for calibration  
Make successive dilutions of the fluoride standard solution ( B.2.2 ) to obtain a set of working standards which 
includes 5 mg/kg, 10 mg/kg (10−5 mol/l), 50 mg/kg, 100 mg/kg (10−4 mol/l), and 150 mg/kg of fluoride.  
 
B.4.2  Preparation of calibration curve  
Use the following procedure to prepare the calibration curve.  
a) Pipette 1,0 m l of each standard solution (B.4.1) into a plastic vial (B.3.8).  
b)  Add 1,0 ml of TISAB solution (B.2.3), and add a magnetic stirring bar (B.3.5) to each plastic vial. Mix 
thoroughly.  
c) Insert the fluoride ion selective electrode (B.3.3) and reference electrodes into the liquid in the plastic vial 
containing the first standard solution. Make sure no air bubbles have been trapped under the electrode.  
d) Record the millivolt reading to 0,1 mV at the steady potential difference with the mV electrometer (B.3.6 ). 
e) Conduct at least two measurements for millivolt readings, until the difference between the two millivolt 
readings is less than 0,2 mV.  
f) Repeat steps c) to e) for each of the other standard solutions.  
g) Construct a calibration curve of millivolts versus the  log of the fluoride ion concentration of the standard, 
expressed in milligrams per kilogram.  
NOTE  The slope of the calibration curve should be linear.  
B.4.3  Preparation of sample solution  
In duplicate, pipette (1,0 ± 0, 1) g of each sample into a 20 ml flask (B .3.2).  
Add (9,0 ± 0,1) ml of deionized water (B.2.1) to the flask and mix thoroughly. This is the sample solution.  DRS  453: 2021  
9        ©RSB 2021 - All rights reserved  
 B.5 Sample analysis  
Determine the fluoride ion concentration in the sample solution as follows.  
a) Pipette accurately an equal amount of sample solu tion (B.4.3) and TISAB solution (B.2.3) into a plastic vial 
(B.3.8) and mix thoroughly.  
b) Insert the fluoride ion selective electrode (B.3.3) and reference electrodes into liquid that contains the 
sample and buffer solution, in the plastic vial (B.3.8). Make  sure no air bubbles are trapped under the 
electrode.  
c) Record the millivolt reading to the nearest 0,1 mV at the steady potential difference with the mV 
electrometer.  
d) Use the calibration curve of standard solutions to determine the fluoride ion concentratio n in the sample 
solution, in milligrams per kilogram . 
B.6 Expression of results  
B.6.1  Expression  
The fluoride ion concentration shall be expressed in milligrams per kilogram of the oral rinse solution unless 
otherwise required.  
NOTE   Regulatory requirements in some regions require the expression of fluoride ion concentration in ppm = 
parts per million (10−6). 
 
B.6.2  Calculation of fluoride ion concentration  
Calculate the fluoride ion concentration of one container of oral rinse using Formula (B.1) (units see 
B.6.1):  
C OR =CS*10 
where  
cOR is the fluoride ion concentration of mouthwash, in milligram per kilogram (10 −6); 
cS is the fluoride ion concentration of sample solution, in milligram per kilogram (10 −6). 
B.6.3  Calculation of mass of ionic fluoride  
Calculate the mass of ionic fluoride per single container of oral rinse using Formula (B.2) (units see 
B.6.1):  DRS  453: 2021  
10        ©RSB 2021 - All rights reserved  
 mOR = cOR * m 
Where  
mOR   is the mass of ionic fluoride of mouthwash, in milligram;  
cOR is the fluoride ion concentration of mouthwash, in milligram per kilogram (10−6); 
m  is the mass of the solution in one container of mouthwash, in kilogram.  
 
cOR is the fluoride ion concentration of mouthwash, in milligram per kilogram (10−6); 
cS is the fluoride ion concentration of sample so lution, in milligram per kilogram (10−6). 
B.6.4  Calculation of mass of ionic fluoride  
Calculate the mass of ionic fluoride per single container of oral rinse using Formula (B.2) (units see 
B.6.1):  
mOR = cOR * m 
Where  
mOR   is the mass of ionic fluoride of mouthwash, in milligram;  
cOR is the fluoride ion concentration of mouthwash, in milligram per kilogram (10−6); 
m  is the mass of the solution in one container of mouthwash, in kilogram.  
 
 
 
 
. DRS  453: 2021  
 
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