DRAFT UGANDA STANDARD  
  DUS 1666  
First Edition  
2017 -01-02 
 
 
 Reference number  
DUS 1666: 2017  
© UNBS 2017   
  
Polystyrene for its safe use in contact with foodstuffs, 
pharmaceuticals and drinking water — Specification  
 DUS 1666 : 2017  
ii © UNBS 2017  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necess ary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2017   
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, i ncluding photocopying and microfilm, without prior written 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 1666: 2017  
© UNBS 2017  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  2 
4.1 Basic resin  ................................ ................................ ................................ ................................ .............  2 
4.1.1  Residual monomer  ................................ ................................ ................................ ................................  2 
4.1.2  Material  ................................ ................................ ................................ ................................ ...................  2 
4.1.3  Pigments and colorants  ................................ ................................ ................................ ........................  2 
4.2 Overall migration  ................................ ................................ ................................ ................................ ... 2 
4.3 Storage and control  ................................ ................................ ................................ ...............................  2 
4.3.1  Storage  ................................ ................................ ................................ ................................ ...................  2 
4.3.2  Control  ................................ ................................ ................................ ................................ ....................  2 
5 Packing and marking  ................................ ................................ ................................ ............................  2 
5.1 Packing  ................................ ................................ ................................ ................................ ...................  2 
5.2 Marking  ................................ ................................ ................................ ................................ ...................  3 
6 Sampling  ................................ ................................ ................................ ................................ ................  3 
6.1 Preparation of test samples  ................................ ................................ ................................ .................  3 
Annex  A (normative)  Analytical metho d for determination of total residual styrene monomer 
content  ................................ ................................ ................................ ................................ ....................  4 
A.1 General  ................................ ................................ ................................ ................................ ...................  4 
A.2 Principle  ................................ ................................ ................................ ................................ .................  4 
A.3 Apparatus  ................................ ................................ ................................ ................................ ...............  4 
A.3.1  Gas chromatograph  ................................ ................................ ................................ ..............................  4 
A.3.2  Chromatograph column  ................................ ................................ ................................ ........................  4 
A.3.3  Recorder  ................................ ................................ ................................ ................................ .................  4 
A.4 Reagents  ................................ ................................ ................................ ................................ ................  4 
A.5 Operating conditions for the gas chromatograph  ................................ ................................ .............  4 
A.6 Standardisation  ................................ ................................ ................................ ................................ ..... 5 
A.7 Procedure  ................................ ................................ ................................ ................................ ...............  5 
A.8 Calculation  ................................ ................................ ................................ ................................ .............  5 
Annex B (normative) Sampling of Polystyrene  ................................ ................................ ...............................  6 
B.1 General  ................................ ................................ ................................ ................................ ...................  6 
B.2 Scale of sampl ing ................................ ................................ ................................ ................................ .. 6 
B.2.1  Lot ................................ ................................ ................................ ................................ ...........................  6 
B.2.2  Sample size  ................................ ................................ ................................ ................................ ............  6 
B.3 Preparation of test sa mples  ................................ ................................ ................................ .................  7 
B.4 Number of tests  ................................ ................................ ................................ ................................ ..... 7 
B.5 Criteria for conformity ................................ ................................ ................................ ...........................  7 
 DUS 1666 : 2017  
iv © UNBS 2017  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisati on for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out  through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Ug anda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS/TC 19, Packaging and 
Packaging products   
 DRAFT UGANDA STANDARD  DUS 1666: 2017  
 
© UNBS 2017  – All rights reserved  1 
 Polystyrene for its safe use in contact with foodstuffs, 
pharmaceuticals and drinking water — Specification  
1 Scope 
This Draft Uganda Standard specifies requirements, sampling and test methods for polystyrene (crystal and 
high impact) materials for the manufacture of plastic items used in contact with foodstuffs, pharmaceuticals 
and drinking water.  
This standard does  not cover requirements of a packaging media for a particular foodstuff and drinking water 
other than toxicological considerations   
2 Normative references  
The following referenced documents referred to in the text in such a way that some or all of their co ntent 
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.  
ISO 24153 , Random sampling and randomisation  
US 1659 , Packaging materials for food contact use – General requirements  
US 1675 , Determination of overall migration of constituents of plastics materials and articles intended to come 
in contact with foodstuffs – Method of analysis  
DUS 1667   Positive list of constituents of polyvinyl chloride (PVC) and its copolymers in contact with food 
stuffs, pharmaceuticals and drinking water.  
3 Terms and definitions  
For the purposes of this standard, the following term s and definition s apply  
3.1  
polystyrene  
shall mea n: 
a) homo polymers of styrene produced by the polymerisation of styrene, and  
b) rubber modified polystyrene consisting of basic polymers produced by combining styrene butadiene 
copolymers and/or polybutadiene ‘with polystyrene either during or after polymerisat ion of the 
polystyrene such that the finished basic polymers contain not less than 75 percent by mass of total 
polymer units derived from styrene monomer  DUS 1666: 2017  
2 © UNBS 2017  – All rights reserved  
 4 Requirements  
4.1 Basic resin  
To comply with this standard, the styrene polymers defined in 3 shall b e made in such a way that they contain 
no ingredients or residuals of ingredients other than those listed in 4.1.1, 4.1.2 and 4.1.3.  
4.1.1  Residual monomer  
The total -residual styrene monomer, when present, shall not exceed 0.1 percent by mass of the polym er 
when tested according to the method prescribed in Annex A. 
4.1.2  Material  
The material shall comply with the threshold limits of the catalyst, emulsifying agents, suspension agents, 
miscellaneous polymerisation additives and other additives as prescribe d in US 1667.  
4.1.3  Pigments and colorants  
In case the coloured material is used for food packaging applications , it shall comply with the list and limits of 
the pigments and colorants prescribed in US 1659 . 
4.2 Overall migration  
The material shall also co mply with the overall migration limits of 60 mg/l, Max of the simulant and 10 mg/dm2, 
Max of the surface of the material or article, when tested by the method prescribed in US 1675 . 
NOTE  The requirements of this draft standard are considered fully met when  the two requirements mentioned in 4 
are met, that is, basic resin characteristics at 4.1 and overall migration at 4.2.  
4.3 Storage and control  
4.3.1  Storage  
Plastics materials intended for food contact use shall be stored separately from other materials i n closed, 
properly identified containers.  
4.3.2  Control  
An authorised person shall supervise and control the issue of plastics materials to the process or 
manufacturing area and shall maintain appropriate written records of the issue of such materials.  
GMP  shall be maintained at all times and plant operators and storemen shall be trained in proper hygiene 
practices  
5 Packing and marking  
5.1 Packing  
The material shall be suitably packed in Paper/Polythene/Plastic bags (with or without liner), as agreed 
betwe en the purchaser and the supplier, in a manner so as to ensure that the items do not become 
contaminated during storage.  DUS 1666: 2017  
© UNBS 2017  – All rights reserved  3 
 5.2 Marking  
5.2.1  Each package shall be clearly marked with the name and type of the material, month and year of 
manufacture of the mat erial, name of the manufacturer and manufacturer’s trade mark, if any.  
5.2.2  The packages shall also carry the symbol (Fig. 1) clearly embossed/printed on it  
 
Figure 1 — Symbol  
6 Sampling  
6.1 Preparation of test samples  
The method  of drawing representative samples of the material and the criteria for conformity s hall be as 
prescribed in Annex B . DUS 1666: 2017  
4 © UNBS 2017  – All rights reserved  
 Annex  A 
(normative)  
 
Analytical method for determination of total residual styrene monom er 
content  
A.1 General  
This method is suitable for the determination of residual styrene monomer in all types of styrene polymers.  
A.2 Principle  
The sample is dissolved in methylene chloride. An aliquot of the solution is injected into a gas chromatograph.  
The amount of styrene monomer present is determined from the area of the resulting peak.  
A.3 Apparatus  
A.3.1  Gas chromatograph  
Gas chromatograph with hydrogen flame detector or apparatus of equivalent sensitivity.  
A.3.2  Chromatograph column  
6.35 mm outsid e diameter, stainless steel tubing (0.71 mm wall thickness), 1.2 m in length, packed with 20 
percent polyethylene glycol (20 000 molecular weight) on alkaline treated 60 -80 mesh firebrick.  
A.3.3  Recorder  
Millivolt range of 0 to 1, chart speed of 12.7 mm/mi n. 
A.4 Reagents  
Compressed air, purified; helium gas; hydrogen gas; methylene chloride, redistilled; and styrene monomer, 
redistilled  
A.5 Operating conditions for the gas chromatograph  
A.5.1  The column is operated at a temperature of 100°C with a helium fl ow rate of 82 mm/min.  
A.5.2  The hydrogen burner is operated with 1.1 kg/cm2 of air pressure and 0.5 kg/cm2 of hydrogen 
pressure.  
A.5.3  The attenuation of the hydrogen flame detector is set at 2 x102 DUS 1666: 2017  
© UNBS 2017  – All rights reserved  5 
 A.6 Standardisation  
A.6.1  Prepare a standard solution by weighing accurately 15 mg to 20 mg of styrene monomer into a 0.06 
kg bottle containing 25.0 mm of methylene chloride. Cap the bottle tightly and shake to thoroughly mix the 
solution.  
A.6.2  By means of a microliter syringe, inject 1 µm of the standard solut ion into the gas chromatograph. 
Measure the area of the styrene monomer peak which emerges after approximately 12 min  
A.7 Procedure  
A.7.1  Transfer 1 g of sample (accurately weighed to the nearest 0.001 g) to a 0.06 kg bottle and add several 
glass beads. Pi pette 25.0 ml of methylene chloride into the bottle. Cap the bottle tightly and place on a 
mechanical shaker. Shake until the polymer is completely dissolved. If any insoluble residue remains, allow 
the bottle to stand (or centrifuge at a low speed) until a clear supernatant layer appears.  
A.7.2  By means of a microliter syringe, inject 3 microliters of the clear supernatant liquid into the gas 
chromatograph.  
A.7.3  Measure the area of the resulting styrene monomer peak. Compare the sample peak area with the 
area produced by the sta ndard styrene monomer solution.  
A.8 Calculation  
30

gin w eight samplemonomer standardof area peaksampleof area peakmg  in monomer standardof mass
monomer styreneresidual percentage
 DUS 1666: 2017  
6 © UNBS 2017  – All rights reserved  
 Annex B  
(normative)  
Sampling of Polystyrene  
B.1 General  
B.1.1  In drawing, preparing, storing and handling samples,  the following precautions and directions shall be 
observed.  
B.1.2  Samples shall not be taken in an exposed place.  
B.1.3  The sampling instrument, wherever applicable, shall be made of stainless steel or any other suitable 
material on which the material sha ll have no action. The instrument shall be clean and dry.  
B.1.4  Precautions shall be taken to protect the samples, the material being sampled, the sampling 
instrument and the containers for samples from adventitious contamination.  
B.1.5  The samples shall b e placed in a suitable, clean, dry, air -tight metal or glass containers on which the 
material has no action. The sample containers shall be of such a size that they are almost completely filled by 
the sample.  
B.1.6  Each sample container shall be sealed air -tight with a stopper after filling and marked with full details 
of sampling, such as the date of sampling, the month and year of manufacture of the material, etc.  
B.1.7  Samples shall be stored in such a manner that the temperature of the material does not  vary unduly 
from the normal temperature.  
B.2 Scale of sampling  
B.2.1  Lot 
In a single consignment all the packages of the same class, same type, same form and belonging to the same 
batch of manufacture shall ‘be grouped together to constitute a lot. If a c onsignment is known to consist of 
packages belonging to different batches of manufacture or different forms, the packages belonging to the 
same batch of manufacture and same form shall be grouped together and each such group shall constitute a 
lot 
The pack ages may consist of containers of polystyrene materials, rolls, films, vials, etc.  
B.2.2  Sample size  
For ascertaining the conformity of the material to the requirements of this specification, samples shall be 
tested from each lot separately. The number of packages to be sampled shall depend on the size of the lot 
and shall be in accordance with Table B 1. DUS 1666: 2017  
© UNBS 2017  – All rights reserved  7 
  
Table B 1 — scale of sampling  
Number of 
packages in the 
lot Sample size  
Up to 15  2 
16 to 50  3 
51 to 100  4 
101 to 300  5 
301 t o 500  6 
501 to 1000  8 
1001 and above  10 
 
NOTE  When the number of packages in the lot is less than three, all the packages shall be sampled.  
B.2.2.1  These packages shall be selected at random from the lot and in order to ensure the randomness 
of selectio n, procedures given in ISO 24153  may be followed.  
B.3 Preparation of test samples  
B.3.1  From each of the packages of material selected, small portions of material shall be drawn with the 
help of a suitable sampling instrument. The total quantity of materia l collected from each package shall be 
sufficient to test all the requirements given in 4.  
B.3.2  In the case of packages consisting of containers, vials, rolls or films, the number of items to be 
selected from a package, for testing each of the requirement s given in 4, shall be one.  
B.4 Number of tests  
Tests for determining all the requirements given in 4 shall be carried out on the individual test samples.  
B.5 Criteria for conformity  
The lot shall be declared as conforming to the requirements of this speci fication if all the test results on 
individual samples meet the relevant specification requirements  
 DUS 1666: 2017  
© UNBS 2017  – All rights reserved  9 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Stan dards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing i n accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 1666: 2017    
 
ICS 71.100.01  
Price based on nn pages  
© UNBS 2017 – All rights reserved