DEAS 90 6:2018  
 
© EAS 201 8                                                                                                               First Edition 201 8 
 
 
DRAFT EAST AFRICAN STANDARD  
Fertilizer ― Triple Superphosphate ― Specification  
EAST AFRICAN COMMUNITY     
 
 
  
 Foreword  
Development of the East African Standards has been necessitated by the need for harmonizing requirements 
governing quality of products and serv ices in the East African Community. It is envisaged that through 
harmonized standardization, trade barriers that are encountered when goods and services are exchanged 
within the Community will be removed.  
In order to achieve this objective, the Community established an East African Standards Committee mandated 
to develop and issue East African Standards.   
The Committee is composed of representatives of the National Standards Bodies in Partner States, together 
with the representatives from the private secto rs and consumer organizations. Draft East African Standards 
are circulated to stakeholders through the National Standards Bodies in the Partner States. The comments 
received are discussed and incorporated before finalization of standards, in accordance wit h the procedures 
of the Community.  
East African Standards are subject to review, to keep pace with technological advances. Users of the East 
African Standards are therefore expected to ensure that they always have the latest versions of the standards 
they are implementing .   
© EAC 2017  – All rights reserved  Fertilizer ― Triple Superphosphate ― Specification  
1 Scope  
This Draft East African  stand ard specifies  requirements, methods of sampling and test for Triple 
Superphosphate (TSP) fertilizer.  
2 Normative References  
The following referenced  documents are indispensable for the application 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 8157 , Fertilizers and Soi l Conditioners – Vocabulary   
DEAS 913,  Fertilizers – Methods of Sampling   
ISO 17318 , Fertilizers and soil conditioners -- Determination of arsenic, cadmium, chromium, lead and 
mercury contents.  
ISO 5316, Fertilizers – Extraction of Water -Soluble Phosphate  
ISO 6598 , Fertilizers - Determination of Phosphorous Content - Quinolinephosphomolybdate - Gravimetric 
method  
ISO 8397  Solid Fertilizers and Soil Conditioners – Test sieving  
3 Terms and Definitions  
For the purpose of this standard, terms and definitions given in ISO 8157  shall apply.  
4.0  Requirements  
4.1 Physical  
4.1.1  The fertilizer shall be in granular or prilled forms free flowing, uniform  in colour  and free from foreign 
matter . 
4.1.2 The particle size of the granular material, shall be such that not les s than 90 % by mass of fertilizer, 
shall be of particles size range of 2 mm – 5 mm and for prilled material shall be of particles size range of 1mm 
- 4mm when tested in accordance with  ISO 8397  
4.2 Chemical  
The Triple Superphosphate fertilizer shall comply  with the requirements given in Table 1  
Table 1 ― Requirements for Triple Superphosphate fertilizer  
Characteristic  Requirement  Method of test  
Total phosphates, as P 2O5, % by mass, 
min 46 ISO 6598  
Water soluble phosphates, as P 2O5, % 
by mass, min 42.5 ISO 5316  
Free phosphoric acid as P 2O5, % by 
mass  max. 3.0 Annex B   
  Moisture, % by mass, max.  5.0 Annex A  
 
5 Heavy metal contaminants  
Heavy metal contaminants in the fertilizers shall conform to the limits given in Table 2 when tested with the 
method specified therein.  
Table 2 – Requirements for heavy met al contaminants  
Heavy metal  Requirement  Method of test  
Arsenic , mg/kg, max . 20 
ISO 17318  Cadmium , mg/kg  P2O5, max.  60 
Mercury , mg/kg, max . 0.1 
Lead , mg/kg, max.  30 
Chromium , mg/kg, max.  500 
 
7 Sampling   
Sampling of fertilizer shall be carr ied out in accordance with  DEAS 913 . 
8 Packaging and labelling  
8.1 Packaging  
The fertilizer shall be packaged in materials that are clean and non -defective that protect s the product from 
physical, chemical and moisture contamination and withstand multiple stages  of handling (transportation and 
storage).  
8.2 Labelling  
Each package shall be indelibly labeled in English and/or any other language with the following information:  
a) name of the fertilizer i.e. "Triple Superphosphate (TSP) fertilizer;  
b) name and address of t he manufacturer and importer;  
c) nutrient content;  
d) net content by mass in kg;  
e) handling instructions – including the words “Use No hooks”;  
f) production date and expiry date;  
g) country of origin ;  
h) batch number ; and 
i) storage conditions .  
© EAC 2017  – All rights reserved  Annex A  
(normative)  
 
Determina tion of moisture content  
A.1 Oven dry method  
A.1.1  General  
The method does not apply to fertilizers that yield volatile substances other than water at drying temperature.  
A.1.2  Procedure  
A.1.2.1  Weigh accurately 2 g of the prepared sample in a pre -weighed,  clean and dry weighing bottle or 
petridish.  
A.1.2.2  Heat in an oven for about 5 hours at 105  C + 2  C to constant weight. Cool in a desiccator and 
weigh. For urea, heat at 70  C + 5  C  for five hours to constant weight.  
A.1.3  Calculation  
Moisture per ce nt by weight (%) =  
ABCB

100  
where,  
A is the w eight in gram of the empty bottle ; 
B is the w eight of the bottle plus the material in gram, before drying ; 
C is the w eight of the bottle plus the material in gram, after drying . 
A.2 Vacuum desicca tor method  
A.2.1  General  
The method is applicable to Ammonium Chloride, Calcium Ammonium Nitrate (CAN), Di -Ammonium 
Phosphate (DAP) and all types of complex and mixtures of NPK fertilizers.  
A.2.2 Procedure  
Weigh accurately in duplicate 5g of prepared sampl e in a weighed shallow porcelain dish. Put the sample in a 
desiccator over concentrated sulphuric acid, close and introduce vacuum for about 10 minutes, then stop the 
vacuum pump and leave the sample for 24 hours, then release vacuum, remove the sample fro m the 
desiccator and weigh.  
A.2.3 Calculation  
Moisture per cent by weight = 
) () (
100
1 23 2
W WW W

  
where,   
  W1 is the Weight in gram of empty porcelain dish ; 
W2 is the Weight in gram of porcelain dish with sample before putting the sample for 24 hours in th e 
desiccator ; 
W3 is the Weight in gram of porcelain dish with sample after putting the sample for 24 hours in the 
desiccator . 
A.3 Karl Fischer method  
A.3.1  General  
This method is applicable to fertilizers like CAN, Urea and urea based complexes. This metho d 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.3.2  Apparatus  
Karl Fischer titrator  
A.3.3  Reagents  
A.3.3.1  Karl Fischer r eagent(KF) – Karl Fischer solution (pyridine free) (single solution) . 
A.3.3.2  Di-sodium tartarate dihydrate (Na2C4O62H2O) analytical grade  
A.3.3.3  Methanol -KF grade/spectroscopy grade containing less than 0.05 % water . 
A.3.4  Procedure  
A.3.4.1  Standardizat ion of KF reagent.  
A.3.4.1.1  Set up the instrument as per manufacturer’s manual.  
A.3.4.1.2  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.  
A.3.4.1.3  Add 100mg of the disodium tartarate dehydrate to the titration vessel carefully and titrate with Karl 
Fischer 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 V 1 ml. 
A.3.4.2  Determi nation of moisture of sample  
A.3.4.2.1  Weigh accurately 1 g of the prepared sample and transfer to the titration vessel carefully and stir 
until dispersed.  
A.3.4.2.2  Titrate with KF reagent to the same pre -set end point as above and note the volume of KF 
reagent used as V2 ml. 
A.3.5  Calculation  
Factor (F)(mgH 2O/1 ml of KF reagent ) = 
1added dihy drate tartarate sodiumofmg 0.1566
V  
Moisture per cent by weight = 
0001 (gram) sampleof Weight100 2
VF   
© EAC 2017  – All rights reserved  Annex B  
(normative)  
 
Determination of free acidity  
B.1 Part 1 : Determination of free acidity as H 2SO4 
B.1.1  Reagent  
B.1.1.1  Standard sodium hydroxide solution – 0.02 N  
B.1.1.2  Methyl red -methylene blue mixed indicator solution – prepared by mixing equal volumes of 0.2  % 
solution in rectified spirit of methyl red and 0.1  % solution in rectified spirit of  methylene blue.  
B.1.2  Procedure  
B.1.2.1  Dissolve 20  g of the sample in about 50  ml of cold neutral water.  
B.1.2.2  Filter and make up the volume to about 200  ml. The filtering media shall be neutral and shall not 
contain any alkaline material which would  neutralize the free acidity.  
B.1.2.3  Titrate the solution with standard NaOH solution using one or two drops of methyl red -methylene 
blue mixed indicator and a microburette.  
B.1.3  Calculation  
Free sulphuric acid (as H 2SO 4) % by mass  = 
WVN 4.904  
where . 
N is the normality of standard NaOH solution;  
V is the volume in milliliter (m l) of standard NaOH solution;  
W is the weight in gram (g) of sample taken for the test.  
B.2 Part 2  :Determination of free acidity as HNO 3 
B.2.1  Reagent  
B.2.1.1  Standar d sodium hydroxide solution – 0.02 N  
B.2.1.2  Methyl red -methylene blue indicator solution – prepared by mixing equal volumes of 0.2  % methyl 
red solution in alcohol and 0.1  % methyl blue solution in alcohol  
B.2.2  Procedure  
B.2.2.1  Dissolve 10  g of the samp le in 100  ml of neutral water at room temperature in a beaker or conical 
flask.  
B.2.2.2  Filter and add 2 -3 drops of indicator solution   
  B.2.2.3  Titrate the solution with standard NaOH solution until the colour changes from violet to green  
B.2.3  Calculatio n 
Free Nitric acid (as H)(HNO 3) % by mass  = 
WVN 4.904  
where;  
N is the normality of standard NaOH solution ; 
V is the volume in milliliter (m l) of standard NaOH solution ; 
W is the weight in gram (g) of sample taken for the test . 
B.3 Part 3:Dete rmination of free acidity as P 2O5 
B.3.1  Reagents  
B.3.1.1  Acetone  
B.3.1.2  Standard sodium hydroxide solution – 0.1 N  
B.3.1.3  Bromo cresol green indicator solution – Dissolve 0.1  g bromocresol green in 100mL of rectified 
spirit  
B.3.2  Procedure  
B.3.2.1  Weigh  accurately about 2.5  g of the prepared sample in a 250mL Erlenmeyer flask  
B.3.2.2  Add 100  ml neutral acetone. Shake for one hour.  
B.3.2.3  Filter rapidly through whatman filter paper No.1 in to 250  ml Erlenmeyer flask. Wash four times 
with 10mL portion of acetone  
B.3.2.4  Evaporate acetone as far as possible  
B.3.2.5  Add about 50  ml water and drops of bromocresol green indicator  
B.3.2.6  Titrate with standard NaOH solution, until the colour changes from yellow to blue  
B.3.3  Calculation  
Free phosphoric acid (as P 2O5) % by mass  = 
WVN1.7  
where;  
N is the normality of standard NaOH solution;  
V is the volume in milliliter (mL) of standard NaOH solution;  
W is the mass in gram (g) of sample taken for the test.