DEAS 90 8:2018  
 
© EAS 201 8                                                                                                               First Edition 201 8 
 
 
DRAFT EAST AFRICAN STANDARD  
Fertilizer ― Potassium chloride (muriate of potash) ― 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 services 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 objectiv e, 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 sectors 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 with 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 th e standards 
they are implementing.   
© EAC 2018 – All rights reserved   
Fertilizer ― Potassium chloride (muriate of potash) ― 
Specification  
1 Scope  
This Draft East African  Standard specifies  requirements and methods of sampling and test for potassium 
chloride (muriate of potash) 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 a mendments) applies.  
ISO 8157 , Fertilizers and Soil Conditioners ― Vocabulary  
DEAS 913 , Fertilizers ― Methods of sampling   
ISO 17318 , Fertilizers and soil conditioners — Determination of arsenic, cadmium, chromium, lead and 
mercury contents  
ISO 8397 , Solid fertilizers and soil conditioners ― Test sieving   
3 Terms and De finitions  
For the purpose of this standard, terms and definitions given in ISO 8157  shall apply.  
4 Requirements  
4.1 Physical  
Potassium chloride fertilizer shall be in the form of free -flowing granules or pow der, uniform colour and free 
from foreign matter.  The particle size of granules when tested by ISO 8397 , the material shall not be less than 
90 % by mass of particles in the size range of 1 mm to 4 mm for crystals and 2mm to 5mm for granules.  
4.2 Chemical  
The potassium chloride fertilizer shall comply wi th the requirements given in Table 1.   
   
Table 1 ― Requirements for potassium chloride fertilizer  
Characteristic  Requirement  Method of Test  
Potash content (as K 2O), % by mass, min. 60.0 Annex A  
Sodium content (as NaCI), % by mass, max.  3.5 Annex B  
Moistu re, % by mass, max. 0.5 Annex C  
 
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 metal contaminants  
Heavy metal  Requirement  Method of test  
Arsenic , mg/kg, max . 20 
ISO 17318  Cadmium , mg/kg, max.  7 
Mercury , mg/kg, max . 0.1 
Lead , mg/kg, max.  30 
Chromium , mg/kg, max.  500 
6 Sampling  
Sampling of fertilizer shall be carried out in accordance with DEAS 913 . 
7 Packaging and labelling  
7 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).  
7.2 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. "potassium chloride (“muriate of potash” fertilizer;  
b) the potash content (as K 2O), percentage by  mass;  
c) name and address of the manufacturer and importer;  
d) net content by mass in kg;  
e) handling instructions – including the words “Use No hooks”;  
f) production date and expiry date;   
© EAC 2018 – All rights reserved  g) country of origin ; 
h) batch number ; and  
i) storage conditions .  
  Annex A  
(normative)  
 
Determination of potash content (flame photometric method)  
A.1 Reagents  
Potassium nitrate (KNO 3) or potassium chloride (KCI) . Recrystallise reagent grade salt twice from water 
and dry for 5 hours at 105 ºC.  
A.2 Preparation of solution  
Dissolve 1.5058 g of  sample in water (H 20) and dilute to 500 ml.  
A.3 Preparation of standard curve  
Dissolve 1.2931 g of KNO 3 (or 0.9535 g KCI) in water and dilute to 500 ml (1 000 ppm K). Prepare standard 
solutions by dilution to cover a range of 0 ppm –80 ppm K at intervals o f 10 ppm, adding appropriate amounts 
of lithium nitrate (LiNO 3) if internal standard is to be used. Prepare standard curve of emission against 
concentration, adjusting instrument so that 50 ppm K gives reading near mid -scale. Atomize portions of 
standard s olutions until readings for the series are reproducible.  
A.4 Procedure  
A.4.1  Transfer 10 ml aliquot of sample solution to 250 ml beaker. Dilute to 100 ml volume and mix (if 
internal standard instrument is used, add required LiNO 3 before diluting to volume) . Atomize portions of 
sample several times to obtain reliable average reading for each solution.  
A.4.2  Determine ppm K from standard curve (temperature of standard and sample solutions must not differ 
by more than 2 ºC).  
A.4.3  Calculate % K 2O as follows:  
0% – 30%, ppm K/2 = % K 2O  
> 30%. ppm K/1 = % K 2O  
© EAC 2018 – All rights reserved  Annex B  
(normative)  
 
Determination of sodium content  
B.1 Reagents  
B.1.1  Concentrated hydrochloric acid , analytical grade.  
B.1.2  Barium chloride solution , 12%. 
B.1.3  Ammonium carbonate solution , 1 M.  
B.1.4  Perchloric acid  
B.1.5  Ethanol,  96 %. 
B.1 6  Washing alcoho l, prepared by mixing ethanol with 0.2 % (v/v) of perchloric acid.  
B.1.7  Ammonium hydroxide , 2 M.  
B.1.8  Magnesium uranyl acetate solution  – Dissolve 90.0 g of crystallized uranyl acetate in 60 ml of 
glacial acetic acid and sufficient water by stirring and warming it to 70  ºC. Dilute the solution to 1 litre. Dissolve 
600 g of crystallized magnesium acetate in 60 ml of glacial acetic acid and sufficient water by stirring and 
warming to 70  ºC.Dilute the s olution to 1 litre. Mix the two solutions. Allow to stand for several hours. Filter off 
any residue. The final solution should be kept at 20  ºC in flasks made of glass with very low sodium content. 
The solution should also be used at 20  ºC. 
B.2 Procedure  
Weigh accurately about 10 g of the prepared sample, add a few milliliters of concentrated hydrochloric acid 
and 100 ml of water and heat to boiling in a beaker. To the boiling solution, add slowly in small quantities 
barium chloride solution. Heat for somet imes and then cool. Transfer to a 250-ml volumetric flask and dilute to 
the mark with water, stir the solution and filter. Reject the first few milliliters of filtrate. Take exactly 10 ml of the 
filtrate and add a few milliliters of ammonium carbonate solu tion. Filter off the precipitated carbonates and 
wash the precipitate with water, the washings being added to the filtrate. Evaporate the filtrate and washings 
to dryness in a porcelain dish of 10 cm diameter and calcine gently. Add to the residue a small quantity of 
water and 6 ml of perchloric acid and evaporate almost to dryness in a water bath. Repeat the evaporation 
with perchloric acid twice again.  
Cool the residue, add a few millilitres  of ethanol and crush the moist mass to a fine state by using a g lass 
pestle. Decant off the liquid. Repeat the crushing of the residue and decantation with further additions of 
washing alcohol, collecting all the decanted liquid. Transfer the precipitate to a small filter and wash 
thoroughly with ethanol adding these w ashings also to the decanted liquid. Neutralize the filtrate and washings 
with ammonium hydroxide and heat to dryness. Trans fer the residue to a beaker with about 5 ml of water and 
add an excess of magnesium uranyl acetate, maintaining the temperature at 2 0 ºC. Stir the precipitation and 
allow it to stand for half an hour at 20  ºC. 
Decant off the clear solution through a sintered glass crucible which has been previously washed with ethanol, 
dried at 120  °C ± 5  ºC and weighed. Again,  add a small quantity of ethanol and repeat the decantation twice. 
Finally wash the precipitate with ethanol on the filter. Dry the crucible with the precipitate for half an hour at 
120°C ± 5  ºC, cool in desiccator and weigh.   
  B.3 Calculation  
Sodium (as NaCI), % by mass (on dry bas is) = 
MM1 97.05  
where , 
M1 is the  mass in g rams  of the precipitate ; and 
M is the  mass in g rams  of the prepared sample taken for the test.   
© EAC 2018 – All rights reserved  Annex C  
(normative)  
 
Determination of Moisture Content  
C.1 Oven dry method  
C.1.1  General  
The method does not apply to fertilizers that yield volatile substances other than water at drying temperature.  
C.1.2  Procedure  
C.1.2.1  Weigh accurately 2 g of the prepared sample in a pre -weighed, clean and dry weighing bottle or 
petridish.  
C.1.2.2  Heat in an oven for ab out 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.  
C.1.3  Calculation  
Moisture per cent by weight (%) = 
ABCB

100  
where,  
A is the weight in gram of  the empty bottle ; 
B is the weight of the bottle plus the material in gram, before drying ; 
C is the weight of the bottle plus the material in gram, after drying . 
C.2 Vacuum desiccator method  
C.2.1  General  
The method is applicable to Ammonium Chloride, Calc ium Ammonium Nitrate (CAN), Di -Ammonium 
Phosphate (DAP) and all types of complex and mixtures of NPK fertilizers.  
C.2.2  Procedure  
Weigh accurately in duplicate 5  g of prepared sample 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 from the 
desiccator and weigh.  
C.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 ; 
W2is the weight in gram of porcelain dish with sample before putting the sample for 24 hours in the 
desiccator ; 
W3 is the weight in gram of porcelain dish with sample after p utting the sample for 24 hours in the 
desiccator . 
C.3 Karl Fischer method  
C.3.1  General  
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 conta ining monocalcium phosphate, calcium sulphate, alkali 
carbonates as well as aldehydes and ketone groups.  
C.3.2  Apparatus  
Karl Fischer titrator  
C.3.3  Reagents  
C.3.3.1  Karl Fischer reagent(KF) – Karl Fischer solution (pyridine free) (single solution)  
C.3.3.2  Di-sodium tartarate dihydrate (Na 2C4O62H2O) analytical grade  
C.3.3.3  Methanol -KF grade/spectroscopy grade containing less than 0.05 % water  
C.3.4  Procedure  
C.3.4.1  Standardization of KF reagent.  
C.3.4.1.1  Set up the instrument as per manufactur er’s manual.  
C.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.  
C.3.4.1.3  Add 100  mg of the disodium tartarate dehydrate to the titration vess el 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. 
C.3.4.2  Determination of moisture of sample  
C.3.4.2.1  Weigh accurately 1 g of the prepared sample and transfer to the titration vessel carefully and stir 
until dispersed.  
C.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 V 2 ml. 
C.3.5  Calculation  
Factor (F)(mgH2O/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 2018 – All rights reserved