DRAFT UGANDA STANDARD  
  DUS 756 
Second  Edition  
2017 -mm-dd 
 
 
 Reference number  
DUS 756  
© UNBS 2017   
  
Urea fertilizer grade — Specification  
 DUS 756 
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 necessary provisions of a contract. Users are 
responsible for its correct ap plication  
© UNBS 2017  
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Web: www.unbs.go.ug  DUS 756 
© UNBS 2017 – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements  ................................ ................................ ................................ ................................ .........  1 
4.1 General requirements  ................................ ................................ ................................ ...........................  1 
4.2 Specific requirements  ................................ ................................ ................................ ...........................  2 
4.3 Heavy metal contamination  ................................ ................................ ................................ ..................  2 
5 Packaging  ................................ ................................ ................................ ................................ ...............  2 
6 Weights and Measures regulations  ................................ ................................ ................................ ..... 2 
7 Labelling  ................................ ................................ ................................ ................................ .................  2 
8 Sampling  ................................ ................................ ................................ ................................ ................  3 
Annex  A (normative)  DETERMINATION  OF MOISTURE  ................................ ................................ ................  4 
A.1 KARL  FISCHER  METHOD  ................................ ................................ ................................ .....................  4 
A.2 APPARATUS ................................ ................................ ................................ ................................ ..........  4 
A.3 REAGENTS  ................................ ................................ ................................ ................................ .............  4 
A.4 PROCEDURE  ................................ ................................ ................................ ................................ ..........  4 
A.4.1  Standardization  of KF reagent  ................................ ................................ ................................ ..............  4 
A.4.2  Determination of moisture of sample  ................................ ................................ ................................ .. 4 
A.5 CALCULATION  ................................ ................................ ................................ ................................ ....... 5 
Bibliography  ................................ ................................ ................................ ................................ ........................  6 
 DUS 756 
iv © UNBS 2017  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a paras tatal 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 preparing Uganda Standards is carried out through Technical Committe es. 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 Uganda Standards adopted by t he 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 2, Food and agriculture , 
Subcommittee SC 2 0, Agrochemicals and veterinary drugs . 
This second  edition cancels and replaces the first edition (US 759: 2007), which has been technicall y revised.  
 DRAFT UGANDA STANDARD  DUS 756 
 
© UNBS 2017  – All rights reserved  1 
 Urea fertilizer grade — Specification  
1 Scope  
This Draft Uganda  Standard specifies  the requirements , sampling and test methods for urea fertilizer  grade.  
2 Normative references   
The following  documents  are referred to in the text in such a wa y 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.  
AOAC 976.01 Biure t in fertilizers. Atomic absorption spectrophotometric method  
ISO 5315, Fertilizers — Determination of total nitrogen content — Titrimetric method after distillation  
ISO 8157 , Fertilizers and soil conditioners — Vocabulary  
ISO 8397,  Solid fertilizers and so il conditioners — Test sieving  
ISO 8633, Solid fertilizers — Simple sampling method for small lots  
ISO 8634, Solid fertilizers — Sampling plan for the evaluation of a large delivery  
ISO 17318,  Fertilizers and soil conditioners — Determination of arsenic, c admium, chromium, lead and 
mercury contents  
ISO 18643,  Fertilizers and soil conditioners — Determination of biuret content of urea -based fertilizers — 
HPLC method  
3 Terms and definitions   
For the purposes of this document, the terms and definitions given i n ISO 8157, Fertilizers and soil 
conditioners  — Vocabulary 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  
4 Requirements  
4.1 Gene ral requirements  
a) The fertilizer  shall be in the form of a free-flowing  crystal , powder,  granules  or prills,  generally 
white in colour and free from any visible  impurities.   
2 © UNBS 2017 – All rights  reserved  
 b) Particle size: Not less than 90 % of the material shall pass through 4 mm IS sieve a nd be retained on 
1 mm IS sieve. Not more than 5 % shall be below 1 mm size  when tested in accordance with ISO 
8397 . 
4.2 Specific requirements  
The fertilizer shall conform to the requirements given in Table 1 when tested in accordance with the methods 
spec ified therein.  
Table  1 — Chemical composition  requirements  for urea  
SN Characteristic  Requirement  Method  of test 
(i) Total  nitrogen, percent by  mass, min  46 
45 - 46 ISO 5315  
(ii) Biuret,  percent  by mass,  max.  1.5 
1.5 ISO 18643 /AOAC 976.01 . 
(iii) Moistur e, percent by  mass,  max 1.0 
1.0 Annex A  
 
4.3 Heavy metal contamination  
When tested in accordance with the methods specified therein, the heavy metal contaminants shall not 
exceed those indicated in Table 2  
Table 2 — Limits for heavy metal contaminants  
Metal Maximum limits,  
mg/kg  Test methods  
Arsenic  20 
ISO 17318  Cadmium  7 
Mercury  0.1 
Lead  30 
Chromium  500 
 
5 Packaging  
Urea  fertilizer shall be packaged in materials that ensure the product integrity and quality and protect it against 
physical damag e, chemical and moisture contamination.  
6 Weights and Measures regulations  
The fill of the package shall comply with the weight s and measures act  
7 Labelling  
The following information shall be clearly and indelibly marked  in English  on each package or co ntainer : 
a) name of the fertilizer as  “Calcium ammonium nitrate”;  DUS 756 
© UNBS 2017 – All rights reserved  3 
 b) name, address and physical location of manufacturer/packer/importer ; 
c) chemical composition of the fertilizer;  
d) nitrogen content of the material as a percentage by weight ; 
e) date of manufacture;  
f) expiry date ;  
g) batch/lot number ; 
h) the net weight of the fertilizer in the package; in metric units ; 
i) storage and h andling instructions ; 
j) risk warning;  
k) instructions  for use ; 
l) disposal instructions  and; 
m) country of origin.  
8 Sampling  
Sampling shal l be done in accorda nce with ISO 8633 and ISO 8634  
  
4 © UNBS 2017 – All rights  reserved  
 Annex  A 
(normative)  
 
DETERMINATION  OF MOISTURE  
A.1 KARL  FISCHER  METHOD  
This method  is applicable to fertilizers  like CAN, Urea and urea based  complexes.  This method  is not suitable  
for phosphate  rock based  fertilizers  and fertilizers  containing  monocalcium  phosphate,  calcium  sulphate,  
alkali  carbonates  as well as aldehydes  and ketone  groups.  
A.2 APPARATUS 
Karl Fischer  titrator  
A.3 REAGENTS  
A.3.1  Karl Fischer  reagent (KF)  – Karl Fischer  solution  (pyridine  free) (single  solutio n) 
A.3.2  Di-sodium  tartarate  dihydrate  (Na 2C4O62H2O) analytical  grade  
A.3.2  Methanol -KF grade/spectroscopy  grade  containing  less than 0.05 % water  
A.4 PROCEDURE  
A.4.1  Standardization  of KF reagent  
a) Set up the instrument  as per manufacturer’s  manual.  
b) Add methanol  to the titration  vessel  until the electrodes  are dipped  and titrate  with Karl- Fischer  
reagent  to a pre-set end point  persists  for 30 seconds.  
c) Add 100mg of the  disodium tartarate dehydrate to  the titration  vessel  carefully  and titrate  with Karl 
Fisch er reagent  to a pre-set end point  (the pre-set end point  should  persist  for 30 seconds).  
Note  the volume  of KF reagent  used  as V1 mL. 
A.4.2  Determination of moisture of sample  
a) Weigh  accurately  1 g of the prepared  sample  and transfer  to the titration  vessel  carefully  and stir until 
dispersed.  
b) Titrate  with KF reagent  to the same  pre-set end point  as above  and note the volume  of KF reagent  
used  as V2 mL. DUS 756 
© UNBS 2017 – All rights reserved  5 
 A.5 CALCULATION  
1added dihydrate tartarate sodiumof milligrams 0.1566
V
 reagentKFofmlO/12(mgH actor(F)F
 
1000 (grams) sampleof Weight100
w eightbycentper Moisture

2VF
  
6 © UNBS 2017 – All rights  reserved  
 Bibliography  
[1] US 756: 2007,  Urea fertili zer grade  — Specification   
[2] FAO Mineral  fertilizer Specifications 2010  
[4] Agricultural Chemicals (Control) Act, 2006 (Act No.1 of 2007)  
[5] The Fertilizer Control Regulations, 2010  
[6] AFDC 10 (4467) P3, Fertilizer — Urea — Specification  
 DUS 756 
© UNBS 2017  – All rights reserved  7 
 Certificatio n 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 ma de 
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. 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 in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS marked products a re 
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 756   
 
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© UNBS 2017 – All rights reserved