DRAFT UGANDA STANDARD  
  DUS 2670  
First  Edition  
yyyy -mm-dd 
 
 
 Reference number  
DUS 2670:2023 
© UNBS 2022   
  
Printing ink for food wrappers, packages and receptacles — 
Specification   
 DUS 26 70:2023 
ii © UNBS 2022  – 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 necessary provisions of a contract. User s are 
responsible for its correct application  
© UNBS 2022  
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, including 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 12 3 
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 26 70:2023 
© UNBS 2022  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ .............................  v 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4. Description of printing inks  ................................ ................................ ................................ ..................  2 
5. Requirements  ................................ ................................ ................................ ................................ .........  2 
5.1 General Requirement  ................................ ................................ ................................ ................................ ... 2 
5.2 Specific requirements  ................................ ................................ ................................ ...........................  2 
5.3 Heavy metal contaminants  ................................ ................................ ................................ ...................  3 
6 Packaging  ................................ ................................ ................................ ................................ ...............  3 
7 Labelling  ................................ ................................ ................................ ................................ .................  3 
Annex A (normative)   Determination of solvent content  ................................ ................................ ...............  4 
A.1 Requirem ents ................................ ................................ ................................ ................................ .........  4 
A.2 Procedure  ................................ ................................ ................................ ................................ ...............  4 
A.3 calculation  ................................ ................................ ................................ ................................ ..............  4 
Annex B  (normative)   Preparation of acid extracts from inks  ................................ ................................ ..... 5 
B.1 Separation of the pigment from the ink  ................................ ................................ ..............................  5 
B.1.1  Preparation of the test sample  ................................ ................................ ................................ .............  5 
B.1.2  Reagents  ................................ ................................ ................................ ................................ ................  5 
B.1.3  Apparatus  ................................ ................................ ................................ ................................ ...............  5 
B.1.4  Procedure  ................................ ................................ ................................ ................................ ...............  5 
B.1.5  Blank test solution  ................................ ................................ ................................ ................................  6 
B.1.6 Treatment of the separated pigment  ................................ ................................ ................................ ....... 6 
B.1.7  Method for the acid extraction of soluble metals  ................................ ................................ ..............  6 
B.1.8  Treatment of the extracted liquid portion  ................................ ................................ ...........................  7 
Annex C  (normative)   Deter mination of lead content by AAS  ................................ ................................ .. 9 
C.1 Principle  ................................ ................................ ................................ ................................ ........................  9 
C.2 Reagents and materials  ................................ ................................ ................................ ........................  9 
C.3 Apparatus  ................................ ................................ ................................ ................................ ...............  9 
C.4 Procedure  ................................ ................................ ................................ ................................ .............  10 
C.4.1  Preparation of the calibration curve  ................................ ................................ ................................ .. 10 
C.4.2  Test solutions  ................................ ................................ ................................ ................................ ...... 11 
C.5 Determination  ................................ ................................ ................................ ................................ ...... 11 
C.6 Expression of results  ................................ ................................ ................................ ..........................  11 
C.6.1  calculations  ................................ ................................ ................................ ................................ ..........  11 
Annex D  (normative)    Determination of antimony by AAS  ................................ ................................ ..... 13 
D.1 Principle  ................................ ................................ ................................ ................................ ...............  13 
D.2 Reagents and materials  ................................ ................................ ................................ ......................  13 
D.3 Apparatus  ................................ ................................ ................................ ................................ .............  13 
D.4 Procedure  ................................ ................................ ................................ ................................ .............  14 
D.4.1  Preparation of the calibration graph  ................................ ................................ ................................ . 14 
D.4.2  Test solutions  ................................ ................................ ................................ ................................ ...... 14 
D.5 Determination  ................................ ................................ ................................ ................................ ...... 15 
D.6 Expression of results  ................................ ................................ ................................ ..........................  15 
D.6.1  Calculations  ................................ ................................ ................................ ................................ .........  15 
Annex E  (normative)   Determination of barium by FAES  ................................ ................................ ...........  17 DUS 26 70:2023 
iv © UNBS 2022  – All rights reserved  
 E.1 Principle  ................................ ................................ ................................ ................................ ...............  17 
E.2 Reagents  ................................ ................................ ................................ ................................ ..............  17 
E.3 Apparatus  ................................ ................................ ................................ ................................ ............  17 
E.4 Procedure  ................................ ................................ ................................ ................................ ............  18 
E.4.1  Preparation of the calibration graph  ................................ ................................ ................................ . 18 
E.5 Test Solution  ................................ ................................ ................................ ................................ ....... 19 
E.5.1 Pigment portion of the liquid ink  ................................ ................................ ................................ ..........  19 
E.5.2 Liquid portion of the ink  ................................ ................................ ................................ ........................  19 
E.6 Determination  ................................ ................................ ................................ ................................ ...... 19 
E.7 Expression of results  ................................ ................................ ................................ .........................  19 
E.7.1  Calculations  ................................ ................................ ................................ ................................ .........  19 
Annex F  (normative)   Determination of cadmium by AAS ................................ ................................ ...... 21 
F.1 Principle  ................................ ................................ ................................ ................................ ...............  21 
F.2 Reagents  ................................ ................................ ................................ ................................ ..............  21 
F.2.5  Cadmium, standard solution containing 10 mg of Cd per litre.  ................................ .....................  21 
F.3 Apparatus  ................................ ................................ ................................ ................................ ............  21 
F.4 Procedure  ................................ ................................ ................................ ................................ ...................  22 
F.4.2  Pigment portion of the liquid ink in powder form  ................................ ................................ ...........  22 
F.4.3  Determination  ................................ ................................ ................................ ................................ ...... 22 
F.5 Expression of results  ................................ ................................ ................................ .........................  23 
F.5.1  Calculations  ................................ ................................ ................................ ................................ .........  23 
Bibliography  ................................ ................................ ................................ ................................ .....................  25 
 DUS 26 70:2023 
© UNBS 2022  – All rights reserved  v 
 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 Organisation 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 prepar ing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or are a and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for com ments. 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 301, Chemistry . 
 
 DUS 26 70:2023 
vi © UNBS 2022  – All rights reserved  
 Introduction  
Food packaging is used to provide information to the final consumer and plays an important role in the 
presentation and advertising of foodstuffs. Some of this information is legally required, such as weight, vendor 
details, information ab out composition, presence of allergens and nutritional details, etc. In addition, printing is 
carried out for decorative and protective purposes. There are exceptional instances where printing inks are 
applied to the inner side of the packaging or on inser ts, e.g. for promotional purposes, and intentionally have 
direct food contact. Direct food contact inks represent a special case and comprise  less than 1% of food 
packaging applications.  
  
   DRAFT UGANDA STANDARD  DUS 2670:2023 
 
© UNBS 2022  – All rights reserved  1 
 Printing ink for food wrappers, packages and receptacles — 
Speci fication  
1 Scope   
This   Draft Uganda Standard specifies the requirements , sampling and test methods for printing inks for food 
wrappers , packages and receptacles .  
This Standard does not cover  non pigment based  printing ink s such as dye -based  and UV pri nting 
inks. 
2 Normative references   
The following referenced documents 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 (including any amendments) applies.  
US ISO 1524, Paints and varnishes — Determination of fineness of grind   
US ISO 8124 -3, Safety of toys — Part 3: Migration of certain elements (3rd Edition)   
 3 Terms  and definitions   
For the purposes of this document, the following terms and definitions apply.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp   
3.1  
Food package  
Any material for concealing food, additional to food wrappers  
 
3.2 
Food Wrapper  
material used to conceal food with which the food is in direct contact.   
2 © UNBS 2022  – All rights reserved  
 3.3 
pigment   
coloured particulate matter suspended in the ink in a carrier liquid  
 
3.4 
soluble metal content of ink  
metal content of the pigment that is soluble in a defined dilute acid plus the total metal content present in the 
liquid portion of the ink.  
 
3.5 
food receptacle  
containment vessel (or container) that is used for storing, holding and carrying food (including water for 
domestic use).  
 4. Description of printing inks  
The inks for food wrappers , packages  and receptacles  shall be of the foll owing categories  
4.1 solvent based pri nting inks - suitable for all the three food packaging materials  
4.2 water based  printing inks - suitable for food packages   
 5. Requirements  
5.1 General Requirement  
5.1.1  The printing ink for food wrappers, packages and receptacles shall be based on pigmen ts that are finely 
dispersed in the ink.  
5.1.2  The ink shall be suitable for the substrate it is printed on.  
5.1.3  The ink shall contain a suitable solvent(s) that is able to dissolve the resins, be stable during printing and 
ensure good drying of the ink.  
5.1.4 The ink shall not contain more than 10 parts by weights of additives - change to 5.1.4 . 
5.1.5  The ink shall meet the requirement s for food safety  
5.2 Specific requirements  
The printing ink for food wra ppers, packages and receptacles  shall meet the specific requirements prescribed 
in table 1  when tested in accordance with the test methods specified therein   
Table 1— Specific requirements for printing ink for food wrappers, packages and receptacles  
Parameter  Requirements   
 Test method  
Fineness of gri nd, µm, max  5   
 US ISO 1524  
Solvent content , %, m/m 
 < 70  
 Annex A  
Pigment content, % m/m, max  20 Annex B 
 DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  3 
 5.3 Heavy metal contaminants  
The print ing ink for food wrappers, packages and receptacles shall comply with the limits for heavy metal 
contami nants given in Table 2 when tested in accordance with the test methods specified therein.  
Table 2 — Limits f or Heavy metal contaminants  
S/No.  Parameter   Maximum limit ,mg/kg  Test method  
i Lead  250  Annex  C 
ii Antimony  250   Annex D 
iii Barium  500   Annex E 
iv Cadmium  100   Annex F 
v Chromium  100   US ISO 8124 -3 
vi Arsenic  100   
6 Pack aging 
The printing ink for food wrappers, packages and receptacles  shall be packaged in suitable containers that 
permits the product’s integrity.  
7 Labelling  
The inks shall be labelled  with the following information:  
a. Manufacturer’s name and the recognized trade -mark, if any;  
b. Name of product as printing ink  
c. Type of ink , as solvent or water based  
d. Lot number or batch number   
e. Country of origin and  
f. Physical address of t he manufacturer  
g. Date of manufacture  
h. Expiry date  
i. Instructions for use, storage and disposal marked on the container or enclosed in t he pack;  
j. The words,  Suitable for use on food wrappers, packages and receptacles . 
k. List of ingredients  
  
4 © UNBS 2022  – All rights reserved  
 Annex A  
(normative)  
 
Determination of solvent content  
 A.1 Requirements  
A.1.1  Weighing scale  
A.1.2  porcelain dish  
A.1.3  Oven  
A.2 Procedure  
A.2.1  weigh  a porcelain dish and record weight  (wo). 
A.2.2 add 1.0 gms of ink and r ecord  as gross weight  (w1). 
A.2.3  transfer the c ontent (A. 2.2) into the oven (100 degree) for 1 hour to evaporate  off the solvent.  
A.2.4   remove the porcelain dish from the oven and cool at room temperature  for 30 minutes.  
A.2.5 weigh the porcelain dish (A.2.4) and  record  the weight (w 2). 
A.3 calculatio n 
Solvent content, expressed in percent by mass, shall be calculated using the formula below  
(w1 – w0) – (w2- w0) × 100%  
 
where  
w0 weight of porcelain dish ; 
w1 weight of both porcelain dish and the ink ; 
w2 weight of both porcelain dish and the ink, after h eating in the oven.  
 
 
 
  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  5 
 Annex B 
 (normative)   
 
Preparation of acid extracts from inks  
 B.1 Separation of the pigment from the ink  
B.1.1 Preparation of the test sample  
Condition the sample for 24 h at 25 ± 2 0C an d relative humidity 65  ± 2 per cent. If any  skin is present, remove 
it as far as possible. Thoroughly stir the sample and if necessary, pass it through a sieve of nominal aperture 
150 µm to remove any remaining skin and othe r extrane ous matter.  
B.1.2 Reagents  
Select a solvent that effects the optim um separation of the pigment. The solvent selected shall be recorded 
and subsequently reported. Examples of suitable solvents or solvent mixtures are as follows:  
a) Toluene/ethanol (4:1 v/v),  
b) XyIene/butan -1-o1 (9:1 v/v),  
c) Toluene,  
d) Butanone (methyl ethyl ketone).  
B.1.3 Apparatus  
Ordinary laboratory a pparatus and glassware and in particular : 
a) Suitable laboratory centrifuge, with tubes of inert material of capacity 50 mL or 100 mL , capable of 
imparting a relative centrifuge acceleration of 100 km s  -2  
b) Air-ventilated oven, capable of being maintained at 105  ± 2 °C,  
c) Stoppered glass container, of at least 2 L capacity.  
B.1.4 Procedure  
Weigh to the nearest 10 mg, a number of centrifuge tubes. Add 10 to 20 g of the prepared sample to each 
tube, taki ng care to avoid contamination of the wal ls and lip of the tube. Immediately weigh the tubes and 
contents to the nearest 10 mg. Approximately half fill the tubes with the selected solvent and stir thoroughly 
using a glass rod. Wash each glass rod thoroughl y with t he solvent, adding all washings to the appropriate 
tube. Balance the opposing centrifuge tubes to within 0 .1 g by adding further solvent, taking care to ensure 
that an adequate working level is not exceeded. Centrifu ge until there is a complete sep aration into a liquor 
and a pigment ca ke. Decant the supernatant liquor from all the tubes comprising a ‘set’ into the container.  
Add further solvent to each tube and mix thoroughly as specified above, taking care to disperse the pigment  
cake completely R epeat the ce ntrifuging and t ransfer t he liquor to the same container. Repeat the addition of 
solvent, centrifuging and transfer of liquor for further three times, taking special care, as before, to thoroughly 
disperse the pigment ca ke. As a final treatment  for the pigment cake and to assist rapid drying, use acetone in 
place of the selected solvent. Add t he acetone and mix, talking special care to disperse the whole pigment 
cake. Centrifuge and transfer the liquor as before to the container. Retain the cont ainer with the combined 
extracts for the procedure described later.   
6 © UNBS 2022  – All rights reserved  
 After ensuring that excess acetone has evaporated, place the centrifuge tubes in the oven, maintained at  105 
± 2 °C, for a minimum period of 3 h . Remove, transfer to a desiccator, al low to  cool to ambient temperature 
and weigh each tube and contents to the nearest 10 mg. Return the tubes and contents to the oven for a 
minimum period of 1 h, allow to cool to ambient temperature in the desiccator and reweigh. Repeat the 
heating, cooling and w eighing operations until the results of two consecutive weighing  do not differ by more 
than 10 mg.  
Calculate the pigment content of the ink as a percentage by mass of the ink sample.  
At the end of the separation procedure, check that the dried pigment cak e can be crumbled easily to indicate 
that the binder has been satisfactorily extracted. If the cake remains cohesive, repeat the whole proce dure on 
the original ink using a more su itable s olvent or solvent mixture.  
B.1.5 Blank test solution  
Prepare a mixtu re of solvent using the same proportions as used in the separation ( B 1.4). Retain the mixture 
for use as the blank in the determinations described later.  
B.1.6 Treatment of the separated pigment  
Take all the drie d pigment from the t ubes i n one set obtaine d by the procedure described in B.1.4. Carefully 
break up the pigment cake by placing it between two sheets of glazed paper and by the application of a 
minimum pressing or ro lling action witho ut and grinding effect disperse it so that all the pigment just passes 
through a 500 µm sieve . Ensure t hat all the pigment passes through the sieve and is collected.  
B.1.7 Method for t he aci d extraction of soluble metals  
B.1.7.1  Reagents  
Only reagents of analytical grade and distilled water sha ll be used:  
a) Dilute Hydrochloric acid , 0.07 M  
b) Hydr ochloric acid strong, dilute 1 part by volume of hydrochloric acid ( S.G1.18) with 1 part by volume of 
water,  
c) Ethanol, minimum 95 per cent (v/v).  
B.1.7.2  Apparatus  
Ordinary laboratory apparatus and glassware and in particul ar 
a) Suitable mechanical stirre r (see Note in B.1.7.3), 
b) pH meter and electrodes,  
c) Membrane filter, pore diameter 0.15 pm or any other suitable filter capable of giving a clear filtrate,  
d) Filtration apparatus, for the membrane filter,  
e) Water -bath,  capable of being maintained at 23  ± 2 °C. 
B.1.7.3  Procedure  
Carry out the extract ion of the prepared pigment B.1.6 in duplicate . Protect the test portion f rom direct sunlig ht 
durin g the extraction and bef ore the analysis.  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  7 
 Weigh 5.0 ± 0.01g of the sample i nto a clean, dry 150 mL beaker. Wet the test portion with 2 mL of the 
ethanol or the minimum larger quantity to wet the test portion, fit the stirrer and add 75 mL of the dilute  
hydrochloric acid previously adjusted at 2 3 ±2 °C by means of the water -bath. Place the beaker in the water -
bath and immediately commence stirring the mixture, insert the electrodes of the pH metre into the mixture 
and, if necessary, adjust the pH to that of the dilute hydrochloric acid, using the strong hydrochloric acid.  
Continue stirring for 15 ± 1 min, checking that the temperature of the mixture is maintained at 23 ± 2 °C 
throughout the t est period. Maintain the pH of the mixture by carefully adding the strong hydrochloric acid. At 
the end of the period of stirri ng, allow the mi xture to stand for a further 5 ± 1 min at 23 ± 2 °C.  T hen decant 
the mixture through the membrane filter using the filtration apparatus and collect the filtrate obtained in the 
first 10 min (which should be a clear solution) in a suitable glass container.  Immediately stopper the container.  
Retain the filtered extract for the determina tion of the various ‘soluble" metals as described in the appropriate 
annexes  of this standard . 
Take appropriate aliquot portions for each determination . 
Carry out the determi nation parts of this standard, of the ‘soluble ’ metal content of the filtrate as soon as 
possible and within 4 h of the preparation of the extract.  
NOTE : During t he whole  period of extract, the speed of th e stirrer should be ad justed so that the pigment is  kept in 
continuous suspension whilst taking care to avoid splashing.  
B.1.8 Treatment of the extracted liquid portion  
B.1.8.1  Reagents  
Only rea gents of analytical grade and distilled  water shall be used. 
a) Nitric acid — Dilute 1 part by volum e of nitric a cid, 65 % ( m/m), (S.G=1.40) with 1 part by volume of 
water,  
b) Dilute Hydrochloric acid, 0 07 M.  
B.1.8.2  Apparatus  
a) Water -bath,  
b) Hot-plate,  
c) Muffle furnace, capable of being maintained at 475 ± 25 °C, 
d) One-mark volumetric f lask of capacity 100 mL  
B.1.8.3  Procedure  
Carry out the following procedure in duplicate on the extracted liquid portion.  
Carry out the same procedure on the blank test solution B.1.5 using the same quantities of all reagents.  
Transfer the contents of the stoppered glass container , obtained according to B.1.4, into a suitable graduated 
vessel and dilute to a specific volume with the solvent or solvent mixture. Transfer an aliquot portion to a 
porcelain or silica dish of suitable capacity.  
Evaporate the main portion of the solvent, using the water-bath.   
8 © UNBS 2022  – All rights reserved  
 Place the dish on the hot -plate and slowly increase the temperature in order to remove all residual solvent. 
Gradually increase the temperature of the hot -plate until the material begins to char. Then transfer the dish to 
the muf fle furnace, maintained at 475 ± 25 °C, and ash . When the ashing is co mplete, remove the dish from 
the muffle furnace and allow it to cool to ambient temperature. Break up the ash into fine particles with a g lass 
rod and leave the road in t he dish during the fo llowing filtration step.  
Taking care to avoid loss of material if the ash reacts vigorously , slowly add 10 mL of the nitric acid. Heat  
carefully on the hot -plate until 2 to 3 mL of solution remain. Add an additional 10 mL of the nitric ac id and 
continue he ating on the h ot-plate unti l less than 5 mL of solu tion remain. Add 20 to 25 mL of water and filter 
the solution through a medium porosity f ilter paper into the 100 mL one -mark volumetric flask. If the filtrate is 
not clear, re filter through a fine porosi ty filter paper.  
Wash the dish and the filter paper several times with water and add the washings to the flask. Dilute to the 
mark with the hydrochloric acid and mix well . 
Retain the extract for the determination of the various "soluble" metals as described  in the appropriate 
annexes of this standard. Take appropriate aliquot portions for each determination.  
NOTE 1 If the ink sample cont ains cellulose nitrate, add 2 g liquid paraffin to the liquid portion of the ink before removing  
the volatile solvents.  
NOT E 2 If desired, the bu lk of the solvent may be removed by distillation from a flas k. This latter method is preferred 
when, for example, the Solvents include butanol or xylene  
NOTE 3 If the ink sample contains chlorinated compounds , acidic products will be formed during ashing.  Therefore, 
before ash ing, the residue obtained on evaporatio n to dryness of th e extract of the liq uid portion should be covered with 
anhydrous sodium carbonate to neutralize these products. Approximately 1 g of sodium carbonate shoul d be added for 
each 1 g of residue. I f it should be necessary to a dd a relatively large quantity of sodium carbonate, it is desirable to take 
an appropriate li quot portion of the combined extract.  
The same procedure sh ould also be applied to the blank solution. 
B.1.8.4  Blan k solution  
Take 75 or 500 mL , as app ropriate, of the di lute hydrochloric aci d and if necessary  add 2 mL of the ethanol. 
Retai n this solution for the blank deter minations on the pigmen t portion of the ink as described later in  the 
standard . DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  9 
  Annex C  
(normative)  
 
 Determination of lead content by AAS  
C.1 Principle  
Aspiration of the test solution in to an acetylene/air flame. Measurement of the absorption of the se lected 
spectral line, emitted by a lead hollow -cathode or lead discharge lamp, in the region of 283.3 nm.  
C.2 Reagents and materials  
Only analytical grade and disti lled water shall be used:  
a) Dilute Hydrochloric acid, 0.07 M,  
b) Acetylene, commercial grade, in a steel cylinder,  
c) Compressed air,  
d) Lead, standard stock  solution con taining 1 g of Pb per litre.  
Procedure  
either,  
Transfer the contents of an ampoule of standard lead solution containing exactly 1 g of Pb into a 1000 mL 
one-mark volumetric flask, dilute to t he mark with dilute  hydrochloric acid and mix well,  
Or 
Weigh, to  the nearest 1 mg, 1.598 g of lead nitrate (P b(N0 3)2) (previously dried for 2 h at 105  °C), dissolve in 
dilute hydrochloric acid in a 1 000 mL one -mark volume tric flask, dilute to the mark with the same hydrochloric 
acid and mix well.   
Note: 1 mL of this s tandard stock solution  contains  1 mg of Pb per litre  
 e) Lead, standard solution containing 100 mg of Pb per litre.  
Note: Prepare this solution on the day of use.  
Pipette 100 mL of the standard stock solution into a 1 000 mL one -mark volumetric flask, dilu te to the mark 
with dilute  hydrochloric acid and mix well.  
Note: 1 mL of this standard solution contains 100 µg of Pb.  
C.3 Apparatus  
Ordinary laboratory apparatus and  
a) Flame atomic absorption spectromete r, suitable for measurements at a wavelength of 283 .3 nm and fitted 
with a burner fed with acetylene and air,   
10 © UNBS 2022  – All rights reserved  
 b) Lead hollow -cathode lamp or lead discharge lamp,  
c) Burette, of capacity 50 mL,  
d) One-mark volumetric flasks, of capacity 100 mL  
Concentration, dilute the test solution appropriately (dilution factor F)  with a known volume of the hydroch loric 
acid ( B.5.2.1 , Table E below ). 
C.4 Procedure  
C.4.1 Preparation of the calibration curve  
C.4.1.1  Preparation of the standard matching solutions  
Prepare these solutions on the day of use into a se ries of six 100 mL one -mark volumetric flasks . Introduce 
from the burette, respectively , the volumes of the standard lead solution given in Table C below, dilute each to 
the mar k with the hydrochloric acid an d mix well . 
Table C — Concentration of lead in standard matc hing solution  
Standard matching solution No.  Volume of the standard lead 
solution, mL  Corresponding concentration  of 
lead in the standard matching 
solution, µg/mL  
0a 0 0 
1 2.5 2.5 
2 5 5 
3 10 10 
4 20 20 
5 30 30 
aBlank matching solution  
 
C.4.1.2  Spectromet ric measurements  
Install the cadmium spectral source in t he spectrometer and optimize the conditions for the determination of 
lead. Adjust the instrument in accordance with the manufacturer’s instructions and adjust the mon ochromator 
to the region o f 283.8 nm in order to obtain the maximum absorbance.  
Adjust the flow of the acetylene and of the air according to the characteristics of the aspirator -burner, and 
ignite the flame. Set the scale expansion, if fitted, so that the standard matching solution  No. 5 (see Table B) 
gives almost a full -scale deflection.  
Aspirate into the flame each of the standard matching solutions in ascending order of concentration, and  
repeat with the standard matching solution No 4 to verify that the instrument has achieved s tability. Aspirate 
water through the burner between each measurement, taking care to keep the rate of aspiration uniform  
C.4.1.3  Calibration graph  
Plot a graph having the masses, in micrograms,  of Pb contained in 1 mL of the standard matching solutions as 
abscissae and the corresponding values of the absorbances, reduced by the reading for the bla nk matching 
solution, as ordinat es. DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  11 
 C.4.2 Test solutions  
C.4.2.1  Pigment portion of the liq uid ink  
Use the solution obtained  by the procedure described in B.1.7.3.  
C.4.2.2  Liquid portion of the in k 
Use the solutions obtained by the procedure described in B.1.8.3.  
C.5 Determination  
Measure first the absor bance of the hydrochloric acid in the  spectrometer after having adjusted it as described 
in C.4.1.2. Then measure the absorbance of each  test solution three times and, afterwards, that of the 
hydrochloric acid again Finally, determine the absorbance of standard matching solution No. 4 in order to 
verify that the response of the apparatus has not changed. If the absorb ance of a test solution is higher than 
that of the standard matchin g solution with the highest Iead  concentration, dilute the test solution appropriately 
(dilution  factor F) wit h a k nown volume of the hydrochloric  acid.  
C.6 Expression  of results 
C.6.1 calculations  
C.6.1.1  Pigment portion of the liquid in k 
Calculate the mass o f ‘soluble ’ lead in the hydrochloric acid extract obtained by the method described in  
B.1.7.3 using the equation:  
mo = [(a1 – a0) ÷10] × V1 × F1  
Where,  
a0, is the lead concentration, in micrograms per millilitre , of the blank tes t solution prepared by the method 
described in B.1.8.4;  
a1, is the lead concentration, in micrograms per millilitre , of the test solution obtained from the calibration 
graph;  
F1, is the dilution fact or, 
mo, is the mass, in grams, of "soluble" lead in t he hydrochloric acid extract;  
V1 is the volume, in mL, of the hydrochloric acid plus ethanol used for the ex traction described in B.1.7.3 
(assumed to be 77 mL o r 502 mL respectively).  
Calculate the ’soluble’ lead c ontent of the pigment portion of the ink using the equation:  
cPb1 = m o x 102/m1 x p/102 = (m o x p)/m 1  
Where,  
 cPb1, is the ‘ soluble ’ lead content, of the pigment portion of the paint, expressed as a percentage by mass of 
the ink,  
 m1, is the mass, in gra ms, of the test portion ta ken to prepare the solution described in B.1.7.3;   
12 © UNBS 2022  – All rights reserved  
 p, is the pigment content of the liquid in k, expressed as a percentage by mass, obtai ned by the met hod 
described in B.1.4. 
C.6.1.2  Liquid portion of the in k  
Calculate the mass of l ead in the solution (ex tract), obtained by the method described in B.1.8 3  
M2 = (b 1 – bo)/106 x V2 x F2 
Where,  
bo, is the lead concentration, in mic rograms per mL, of the blank test solution prepared by the method 
described in B.1.5; 
b1, is the lead concen tration, in micrograms per mL, of the test solution obtained from the calibration graph;  
F2, is the dilution factor;  
M2, is the mass, in g, of lead in the liquid portion of the ink;  
V2, is the volume, in mL, of the solution obtained by the method described  in B.1.8 3. (= 100 mL).  
Calculate the lead content of the liquid portion of the in k using the equation.  
cPb2 = m2/m3 x 102 
Where,  
cPb2, is the lead content of the liquid portion of the ink, expressed as a percentage by mass of ink;  
m3,  is the total mass,  in grams  of ink comprising a ’set’ as described in C 4. 
C.6.1.3  Liquid ink  
Calculate the total “soluble" lead content of the liquid in k as the sum of the results obtained according to  
C.6.1.1 and C.6.1.2 thus,  
cPb3 = cPb1 + cPb2 
where,  
cPb3, is the total ’soluble’  lead content of the ink, expressed as a percentage by mass.  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  13 
 Annex D  
(normative)  
  
Determination of antimony by AAS  
D.1 Principle  
Aspiration of the test solution into an acetylene/air flame. Measure ment of the absorption of the selected 
spectral  line, emitted by an antimony hollow -cathode or antimony discharge lamp, in the region of 217.6 nm.  
D.2 Reagents and materials  
During the analysis, use only reagents of recognized analytical grade and distilled water . 
a) Concentrated  Hydrochloric acid, app roximately 37% ( v/v and S.G=  1.18), 
b) Hydrochloric acid, c(HCL) — 1 M, 
c) Compress ed air,  
d) Antimony, standard stoc k solution conta ining 1 g of Sb per litre,  
Weigh, to the nearest 0.1 mg, 119.7 mg of dried antimony trioxide, dissolve in 40 mL of the hydroc hloric acid 
in a 100 mL one -mark volumetric flask, dilute to the ark with water and mix well. 
Note: 1 mL of this standard stock solution contains 1 mg of Sb.  
e) Antimony, standard solution containing 100 mg of Sb per litre.  
Note: Prepare this solution on t he day of use.  
Pipette 10 mL of the standard stock solutio n into a 100 mL one -mark volumetric flask, dilute to the mark with  
the hy drochloric acid and mix well . 
Note: 1 mL of this standard solution contains 1 00 mg of Sb.  
D.3 Apparatus  
a) Flame atomic abso rption spectromete r, suitable and, measurements at a wavelength of 217.6 nm  and 
fitted 'with a burner fed with acetylene and air,  
b) Antimony hollow -cathode lamp or antimony discharge lamp,  
c) Burette, of capacity 50 mL,  
d) One-mark volumetric flasks , of c apacity 100 mL   
14 © UNBS 2022  – All rights reserved  
 D.4 Procedure  
D.4.1 Preparation of the calibration graph  
D.4.1.1  Preparation of the standard matching solution  
Note: Prepare this solution on the day of use:  
Into a series of fi ve 100 mL one -mark volumetric flasks, introduce from the burette , respectively, the volumes 
of the standard antimony solution given in Table D below, dilute each to the mark with the hydrochloric acid 
and mix well . 
Table D — Concentration of antimony in st andard matching solution  
Standard matching solution No.  Volume o f the standard Antimony 
solution, mL  Corresponding concentration  of Sb 
in the standard matching solution, 
µg/mL  
0a 0 0 
1 5 5 
2 10 10 
3 20 20 
4 40 40 
aBlank matching solution  
 
D.4.1.2  Spectrometric measurements  
Install the antimony spectral in the s pectrometer and optimize the conditions for the determination of 
antimony . Adjust the instrument i n accordance with the manufacturer’s instructions and adjust the 
monochromator to the region of 217.6 nm in order to obtain the maximum absorbance.  
Adjust the  flow of the acetylene and of the air according to the characteristics of the aspirator -burner, and 
ignite the flame. “Set the scale expansion, if fitted, so that the standard matching solution No. 4 (see Table D) 
gives almost a full -scale deflection.  
Aspirate into the flame each of the standard matching solutions in ascending order of concentration, and 
repeat with the standard matching solution No 3 to verify that the instrument has achieved stability. Aspirate 
water through the burner between each measur ement, taking care to keep the rate of aspiration uniform.  
D.4.1.3 Calibration grap h  
Plot a graph having the masses, in micrograms, of S b contained in 1 mL of the standard matching solutions as 
abscissae and the corresponding values of the absorbances, re duced by the reading for the blank matching 
solution, as ordinates.  
D.4.2 Test solutions  
D.4.2.1 Pigment portion of the liquid ink  
Mix thoroughly 9 parts by volume of each of the solution obtained by the procedure described in B.1.7.3 with 1  
part by volume  of the hydrochloric acid  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  15 
 D.4.2.2 Liquid portion of the ink  
Mix thoroughly 9 parts by volume of each of the solutions obtained by the procedure described in B.1.8.3 with 
1 part by volume of the h ydrochl oric acid 
D.5 Determination  
Spectral interference occu rs in the presence of lead, calcium or copper on the resonance line at 217.6 nm. In 
the presence of lead, use the antim ony resonance line at 206.8 nm or 231.1 nm. I n the presence of calcium, 
measure the absorbance at 217.0 nm and subtract the result from t he absorbance at 217.6 nm. In the 
presence of copper, use the antimony resonance line at 231 1 nm.  
Use a deuterium background corrector to correct for background absorption . Alternatively, the solutions can 
be reaspirated using a neighbouring non absor bing line for the background correction [see Note below).  
NOTE  Some hollow -cathode la mps for an timony have a non -absorbing line at 216.9 nm.  
D.6 Expression of resul ts  
D.6.1 Calculations   
D.6.1.1  Pigment portion of the liq uid ink  
Calculate the mass of "solubl e" antimony in the hydrochloric acid extract obtained by the method  described in 
B.1.7.3, using the equation : 
mo = [(a 1 – a0)/106] × V 1 × (10/9) × F1  
 Where,  
a0, is the antimony concentration, in micrograms per millilitre, of the blank test solution prepa red by the 
method described in B.1.8.4;  
a1, is the antimony concentration, in micrograms per millilitre, of the test solution obtained from the calibration 
graph;  
F1, is the dilution factor,  
mo, is the mass, in grams, of "soluble" antimony in the hydrochlo ric acid extract;  
V1, is the volume, in mL, of the hydro chloric acid plus ethanol used f or the extraction described in B.1.7.3 
(assumed to be 77 mL).  
Calculate the ’solu ble’ antimony content of the pigment portion of the ink, using the equation:  
cSb1 = m o × 102/m1 × p/102 × (mo × P)/m 1 
Where,  
cSb1, is the soluble antimony content of the pigment portion of the ink, expressed as a percentage by mass of 
the ink  
m1, is the mass, in grams , of the test portion taken to prepare the solution described in B.1.7.3; 
P, is the pigme nt content o f the liq uid ink , expressed as a percentage by mass.   
16 © UNBS 2022  – All rights reserved  
  
D.6.1.2  Liquid portion of the ink  
Calculate the mass of antimony in the solution (extract), obtained by the method described in B.1.8.3, using 
the equation:  
m2= (b 1 - bo)/106 x V2 x 10/9 x F2 
Where,  
bo, is the anti mony concentration, in micrograms per mL, of the b lank test solution prepared by the meth od 
described in B.1.5; 
b1, is the antimony concentration, in micrograms per mL, of the test solution obtained from the calibratio n 
graph;  
F2, is the dilution factor;  
m2, is the mass, in g, of antimony in the liquid portion of the ink , 
V2, is the volume, in mL, of the solution obtained by the method described in B.1.8.3 (=100 mL) 
Calculate the antimony content of like liquid portion of the ink, using the equation:  
cSb2 = m 2/m3 × 102 
cSb2, is the antimony content of the liquid portion of the ink, expressed as a percentage by mass of the ink;  
m3, is the total mass, in g rams  of ink comprising a 'set’ as des cribed in B.1.4. 
D.6.1.3  Liquid  ink 
Calculate t he total ‘soluble ’ antimony con tent of the liquid in k as the sum of the results obtained according to  
D.6.1.1 and D.6.1.2 thus,  
cSb3 = cSb1 + cSb2 
Where,  
cSb3, is the total soluble antimony co ntent of the ink expres sed as a percentage by ma ss. 
 DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  17 
 Annex E  
(normative)  
  
Determination of barium  by FAES  
E.1 Principle  
Aspiration of the solution int o a dinitrogen mon oxide/acetylene flame. Measurement of the radiation emitted by 
barium at a wavelength of 553 .5 nm. The ionization of the barium atoms in the flame is suppressed by 
addition of potassium chloride.  
E.2 Reagents  
During the analysis, use only reagents or recog nized a nalytical grade and distilled water only  
a) Potassium chloride, 50 g/L solution,  
b) Hydrochloric acid, c (HCL) = 0 07 M,  
c) Dinitrogen mon oxide, commercial grade, in a steel cylinder,  
d) Acetylene, commercial grade, in a steel cylinder,  
e) Barium, standard stock solution containing 1 g of Ba per litre  
Either,  
Transfer the contents of an ampoule of standard barium solution containi ng exactly 1 g of Ba rium into a 1000 
mL one -mark volumetric flask, dilute Io the mark with the hydrochloric acid and mix well.  
Or 
Weigh, to the nearest 1 mg, 1.779 g of barium chloride dihydrate  (BaCl 2.2H 20), dissolve in the hydrochloric  
acid in a 1000 mL one-mark volumetric flask, dilute to the mark with the same hydrochloric acid and mix well.  
Note: 1 mL of this standard stock solution contains 1 m g of Ba.  
f) Barium, standard solution containing 20 mg of Ba per litre .  
Note: Prepare this solution on the d ay of use.  
Pipette 20 mL of the standard stock solution into a 1000 mL one -mark volumetric flask,  dilute to the mark with 
the hydrochloric acid and mix well.  
Note: 1 mL of this standard solution contains 20 µg of Ba  
E.3 Apparatus  
For this test, the laborat ory glassware shall be barium free.  
Ordinary laboratory apparatus and   
18 © UNBS 2022  – All rights reserved  
 a) Flame atomic emission spectrometer, suitable for measurements at a wavelength of 553.5 nm and fitted  
with a burner fed wit h dinitrogen monoxide and acetylene,  
b) Pipettes, of suitable  volume , 
c) Burettes, of capacity 10 and 50 mL,  
d) One-mark volumetric flasks, of capacity 50 mL,  
e) Recordin g apparatus, a compensating record is recommended.  
E.4 Procedure  
E.4.1 Preparation of the calibration graph  
E.4.1.1  Preparation o f the standard mat ching solutions  
Prepare these solutions on the day of use int o a series of six 50 mL one -mark  volumetric flasks , introduce 
from the burette, respectively, the volumes of the standard barium s olution given in Table  E, add 5 mL of the 
potassium chloride solu tion, dilute each to the mark with the hydrochloric acid and mix well.  
Table E — Concentration of barium in standard matching solution  
Standard matching solution No.  Volume of the standard barium 
solution, mL  Corresponding conce ntration of 
barium in the st andard matching 
solution, µg/mL  
0a 0 0 
1 2 0.8 
2 5 2 
3 10 4 
4 20 8 
5 40 16 
aBlank matching solution  
 
E.4.1.2  Spectrometric measurements  
Measure the emission of the standard matching solutions in the spectrometer, using the operating conditions 
specified by the manufacturers of the instrument.  
In order to determine and correct for the constant background emission, due to the presence of calcium, the 
barium line or record the emission over a wavelength range f rom 553.0  nm to 554.0 nm.  
E.4.1.3  Calibra tion graph  
Plot a graph having the masses, in micrograms, Ba contained in 1 mL of the stand ard matching solutions as 
abscissae and the corresponding values of the emission, corrected for background emission, as ordinates.  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  19 
 E.5 Test Solution  
E.5.1 Pigment po rtion of the liquid ink  
Pipette a suitable volume (V 3) of each of the solutions obtained by the procedure described in  solutions 
obtained by the  procedure described in B.1.7.3 of 50 mL one -mark volumetric flasks so that the barium 
concentration of each tes t solution will be within the Calibration range. Add 5 mL of the potassium chloride 
solution, dilute to the mark with the hydrochloric acid and mix well  
E.5.2 Liquid portion of the ink  
Pipette a suitable volume ( V4) of each of the solutions obtained by the  procedure described in  B.1.8.3 of 50 
mL one -mark volumetric flas ks so that the barium concentration of each test solution will be within the 
calibration range. Add 5 ml. of the potassium chloride solution, dilute to the mark with the Hydrochloric acid 
and mix well . 
E.6 Determination  
Measure first the emission of the hydrochloric acid in the spectrometer after having adjusted it as described in 
E.4.1.2. Then measure the emission of each test solution E.5 three times and, afterwards, that of the 
hydrochloric  acid again. Finally , re-determine the emission of the standard matching solution No. ( E.4.1.1) in 
order to verify that the respo nse of the apparatus has not changed. I f the emission of a test solution is higher 
than that of the standard matching solution with the highest barium concentration, dilute the test solution 
approximately (dilution factor F1) with a known volume of the hydrochloric acid.  
E.7 Expression of results  
E.7.1 Calculations  
E.7.1.1  Pigment portion of the liquid ink  
Calculate the mass ‘soluble’ barium in the h ydroch loric acid extract, ob tained by the method described in 
B.1.7.3, using the equation:  
mo = (a 1 – ao)/106 (V1/V3) x 50 F 1 
Where,  
ao, is the barium concentration, in micrograms per mL, of the bank test solution prepared by the method  
described in B.1.8.4;  
a1, is the barium concentration, in micrograms per mL, of the test solution obtained from the calibration;  
F1 is the dilution factor;  
mo, is the mass, in g rams , of "soluble" barium in the hydrochloric acid extract;  
V1, is the volume,  in mL, of the hydrochloric acid  plus ethanol used for the extr action described in B.1.7.3 
(assumed to be 77 mL);  
V3, is the volume, in mL, of the aliquot portion of the hydrochloric acid plus ethanol extract taken for the test 
(E.5.1).  
Calculate the "solu ble" barium content of the pigment portion of the ink, using the equation:   
20 © UNBS 2022  – All rights reserved  
 cBa1 = m o × 102/m1 × p/102  
Where,  
cBa1, is the  ‘soluble’ barium content, of the pigment portion of the ink, expressed as a percentage by mass of 
the ink  
m1, is the mass, in g rams , of the test portion taken to prepare the solution described in B.1.7.3;  
P, is the pigment content of the liquid ink, expressed as a percentage by mass, obtained by the appropriate 
method described in B.1.4. 
E.7.1.2  Liquid portion of the ink  
Calculate the m ass of barium in the solution (extract), obtained by the method described in B.1.8.3, using the 
equation:  
m2 = (b 1 – bo)/106 (V2/V4) x 50 x F2 
Where,  
bo, is the barium concentration, in micrograms per mL, of the blank test solution prepared by the method 
described in B.1.5; 
b1 is the barium concentration, in micrograms per mL of t he test solution obtained from the calibration graph;  
F2, is the dilution factor;  
m2, is the mass, in g rams , of barium in the liquid portion of the ink;  
V2, is the volume, in mL, o f the solution obtained b y the method described in B.1.8.3 (= 100 mL);  
V4, is the volume, mL, of the aliquot portion of the solution taken for the test.  
Calculate the barium content of the liquid portion of the ink, using the equation:  
CBa2 = (m2/m3) × 102  
Where,  
CBa2, is the barium content, of the liquid portion of the ink, expressed as a percentage by mass of the ink;  
m3, is the total mass, in g of ink comprising a ‘set” as described in B.1.4. 
E.7.1.3  Liquid in k  
Calculate the total “soluble" barium cont ent of the liquid ink as the sum of the results obtained according to 
E.7.1.1 and E.7.1.2 thus,  
cBa3 = cBa1 + cBa2 
where,  
cBa3, is the total 'soluble" barium content of the ink expressed as a percentage by mass.  
 DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  21 
 Annex F  
(normative)  
  
Determination of cad mium  by AAS  
F.1 Principle  
Aspiration of the test solution into an acetylene/air flame. Measurement of the absorption of the selected  
spectraI line emitted by a cadmium hollow -cathode or cadmium discharge lamp, in the region of 228 . 8 nm.  
F.2 Reagents  
F.2.1 Hydrochloric acid, (HCL) = 0.07  M. 
F.2.2 Acetylene, commercial grade, in a steel cylinder.  
F.2.3 Compressed air.  
F.2.4 Cadmium, standard stock solution containing 1 g of Cd per litre.  
Either,  
a) transfer the contents of an ampoule of standard cadmium solu tion containing 1 g of Cd into a 1 000 mL 
one-mark volumetric flask, dilute to the mark with the hydrochloric acid ( F.2.1) and mix well;  
b) weigh, to the nearest 1 mg, a mass of a water soluble cadmium salt of defined purity containing exactly 1 
g of Cd, d issolve in the hydrochloric acid ( F.2.1) in a 1 000 mL one -mark  volumetric flask, dilute to the mark 
with the same hydrochloric acid and mix well.  
Or 
c) weigh, to the nearest 1 mg, exactly 1 g of cadmium meta l dissolve it in the minimum of concentrated 
hydrochloric acid ( e.g. appro ximately 1 .18g/mL) in a 1000 mL one -mark with the hydrochloric acid ( F.2.1) and 
mix well  
Note: 1 mL of this standard stock sol ution contains  1mg of Cd.  
F.2.5 Cadmium, standard solution containing 10 mg of Cd per litre.  
Note: Prepa re this solution on the day of use.  
Pipette 10 m L of the standard stock solution ( F.2.4) into a 1 000 mL one -mark volumetric flask, dilute to the 
mark with the hydrochloric acid ( F.2.1) and mix we ll. 
Note: 1 mL of this  standard solution contains 10 µg of C d. 
F.3 Apparatus  
Ordinary laboratory apparatus and   
22 © UNBS 2022  – All rights reserved  
 F.3.1 Flame atomic absorption spectrometer, suitable for measurement at a wavelength of 228.8 nm and 
fitted with a burner fed with acetylene and air.  
F.3.2 Cadmium hollow -cathode lamp or cadmium discharge lamp.  
F.3.3 Burette, of capacity 10 mL  
F.3.4  One mark volumetric flasks, of capacity 100 mL  
F.4 Procedure  
F.4.1 Preparation of the calibration graph  
F.4.1.1  Prepare these solutions on the day of use  
Aspirate into the flame each of the standard matching s olutions in ascending order of concentration, and 
repeat with the standard matching solution No. 3 to verify that the instrument has achieved stability. Aspirate 
water through the burner between each measurement, taking care to keep the rate of aspiration uniform.  
F.4.1.2  Spectrometric measurements  
Install the cadmium spectral source ( F.3.2) in the spectrometer ( F.3.1) and optimize the conditions for the 
determination of cadmium. Adjust the instrument in accordance with the manufacturer’s instructions and 
adjust the mon ochromator to the region of 228.8 nm in order to obtain the maximum absorbance.  
Adjust the flow of the acetylene ( F.2.2) and of t he air ( F.2.3) according to the characteristics of the aspirator -
burner, and ignite the flame. Set the scale expan sion, if fitted, so that the stand ard matching solution No. 4 
(see Table F) gives almost a full scale deflection.  
F.4.2 Pigment portion of the liquid ink in powder form  
Use the solutions obtained by the procedure described in B.1.8.3. 
F.4.3 Determination  
Measure first the absorption of the hydrochloric acid (F.2.1) in the spectrometer ( F.3.1) after having adjusted it 
as described in ( F.4.1.2). Then measure the absorbance of each te st solution three times and, afterwards, that 
of the hydrochloric acid again.  Finally, re -determine the absorbance of standard matching solution No.3 in 
order to verify that the response of the apparatus has not changed. If the absorbance of a test solution is 
higher than that of the standard matching solution with the highest cadm ium, put it into a series of five 100 mL 
one mark volumetric flasks ( F.3.4), introduce from the burette ( F.3.3) respectively, the volumes of the standard 
cadmium solution ( F.2.5) given in Table F below and mix well  
Table F — Concentration of cadm ium in sta ndard matching solution  
Standard matching solution No.  Volume of the standard cadmium 
solution  (A.5.2.5) , mL Corresponding concentration of 
cadmium in the standard matching 
solution, µg/mL  
0a 0 0 
1 0.5 0.05 
2 1 0.1 
3 2 0.2 
4 4 0.4 
aBlank matching sol ution  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  23 
 F.5 Expression of results  
F.5.1 Calculations  
F.5.1.1 Pigment portion of the liquid ink  
Calculate the mass of ‘soluble ’ cadmium  in the hydrochloric acid extract obtained by the method described in  
B.1.7.3 using the equation:  
mo = [(a 1 – ao)/106] x V1 x F 1 
Where,  
ao, is the cadmium concentration, in micrograms per millilitre , of the blank test solution prepared by the 
method described in B.1.8.4;  
a1, is the cadmium concentration, in micrograms per millilitre , of the test solution obtained from the calibration 
graph;  
F1, is the dilution factor referred to in F.4.3 
mo,  is the mass, in grams, o f ‘soluble ’ cadmi um in the hydrochloric acid extract;  
V1, is the volume, in mL, at the hydrochloric acid plus ethanol used for the extraction described in B.1.7.3 
(assumed to be 77 mL or 502 mL respectively).  
Calculate the ’soluble' cadmium content of the pigment portion of the ink using the equation:  
cCd1 = (mo x P)/m 1 
Where,  
cCd1, is the 'soluble’ cadmium content of the pigment portion of the ink, expressed as a p ercentage by mass of 
the ink;  
m1, is the mass, in grams of the test portion taken to prepare the solutions described in B.1.7.3;  
P, is the pigment content of the liquid ink, expressed as a percentage by mass, obtained by the method 
described in B.1.4. 
F.5.1.2 Liquid portion of the in k  
Calculate the mass of cadmium in the solution (e xtract) obtained b y the method described in ( B.1.8.3). 
M2 = [(b 1 – bo)/106] x V2 x F 2 
Where,  
bo, is the cadmium concentration, in micrograms per mL, of the blank test solution p repared by the method in 
B.1.5; 
b1, is the cadmium concentration, in micrograms per mL, of the test solution obtained from the calibration 
graph;  
F2 is the dilution factor referred to in F.4.3; 
m2, is the mass, in g of cadmium in the liquid portion of the ink;  
24 © UNBS 2022  – All rights reserved  
 V2, is the volume, in mL, of the solution obtained by the met hod described in B.1.8.3 (= 100  mL). 
Calculate the cadmium content of the liquid portion of the ink, using the equation,  
cCd2 = (m 2/m3) x 102 
Where,  
cCd2, is the cadmium conten t, of the liqu id portion of the in k, expressed as a percentage by mass  of the ink,  
m3, is the total mass, in g rams , of ink comprising a ‘set’ as described in B.1. 4.  
F.5.1.3  Liquid ink  
Calculate the total ‘ soluble ’ cadmium cont ent of the liquid ink as the sum  of the results obtained according to  
F.5.1.1 and F.5.1.2. 
cCd3 = cCd2 + cCd1 
Where,  
cCd3, is the total ’soluble’ cadmium content of the ink, expressed as a percentage by mass.  
  DUS 26 70:2023 
© UNBS 2022  – All rights  reserved  25 
 Bibliography  
[1] KS 810:2013, Printing inks for use on food wrappers, packages and recep tacles — Specification , 2nd 
edition  
[2] International Life Sciences Institute (ILSI) Europe Report Series  on Packaging Materials  - Printing I nks for 
Food  Packaging  Composition and  Properties of Printing Inks , December 2011  
[3] IS 15495: 2020, P rinting ink for food packaging — code of practice  
 
 DUS 2670: 2023 
© UNBS 2022  – All rights reserved  27 
 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 Standards and in conjunction with the relevant Uganda Standard. T he 
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 in 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 2670 :2023   
 
ICS 8 7.080 
Price based on nn pages  
© UNBS 2022 – All rights reserved