UGANDA STANDARD
 
  US ISO 1237
     First Edition
        2009-09-04
 
Reference numbe r
     US ISO 1237:1981
 © UNBS 2009
  
Mustard seed — Specification 
 US ISO 1237:1981 
 
© UNBS  2009 – All rights reserved ii Compliance with this standard does not, of itself confer immunity from legal obligations 
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      US ISO 1237:1981  
© UNBS  2009 - All rights rese rved                iii National foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry  of Tourism, Trade and 
Industry established under Cap 327, of the Laws of U ganda. 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 A limentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agr eements of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a gi ven field or area and consists of representatives of 
consumers, traders, academician s, manufacturers, governme nt and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committ ee 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. 
This Uganda Standard, US ISO 1237, Mustard seed — Specification,  is identical with and has been
reproduced from an International Standard, ISO 1237:1981  Mustard seed — Specification, and  adopted
as a Uganda Standard.  
This standard was developed by the Food and agricu lture Standards Technical Committee (UNBS/TC 2).  
Wherever the words, "International Standard" a ppear, they should be replaced by "Uganda Standard." 
 International Standard 
INTERNATIONAL ORGANIZATION FOR STANDARDlZATlON*MEIKjJYHAPO,QHAR OPTAHM3ALWlR fl0 CTAHJ.JAPTb’l3A~Wl.ORGANlSATlON INTERNATIONALE DE NORMALISATION 
Mustard seed - Specification 
Grahes de moutarde - Spkcifications 
Second edition - 1981-08-01 
UDC 633.844.004.1 Ref. No. IS0 12374981 (E) 
Descriptors : agricultural products, spices, mustard, specifications, tests. 
Price based on 11 pages Foreword 
IS0 (the International Organization for Standardization) is a worldwide federation of 
national standards institutes (IS0 member bodies). The work of developing Inter- 
national Standards is carried out through IS0 technical committees. Every member 
body interested in a subject for which a technical committee has been set up has the 
right to be represented on that committee. International organizations, governmental 
and non-governmental, in liaison with ISO, also take part in the work. 
Draft International Standards adopted by the technical committees are circulated to 
the member bodies for approval before their acceptance as International Standards by 
the IS0 Council. 
International Standard IS0 1237 was developed by Technical Committee ISO/TC 34, 
Agricultural food products. 
This second edition was submitted directly to the IS0 Council, in accordance with 
clause 5.10.1 of part 1 of the Directives for the technical work of ISO. It cancels and 
replaces the first edition (i.e. IS0 1237-19741, which had been approved by the 
member bodies of the following countries : 
Brazil Germany, F. R. 
Bulgaria Hungary 
Czechoslovakia India 
Egypt, Arab Rep. of Iran 
France Israel Netherlands 
Poland 
Romania 
Turkey 
United Kingdom 
This International Standard had also been approved by the Association of Official 
Analytical Chemists (AOACL 
The member body of the following 
ment on technical grounds : country had expressed disapprova I of the docu- 
0 Austria 
International Organization for Standardization, 1981 
Printed in Switzerland INTERNATIONALSTANDARD IS0 12374981 (E) 
Mustard seed - Specification 
1 Scope and field of application 
This International Standard specifies requirements for mustard 
seed. 
- 
Recommendations relating to storage and transport conditions 
are given in annex E. 
2 References 
IS0 927, Spices and condiments - Determination of ex- 
traneous matter content. 
IS0 928, Spices and condiments - Determination of total ash. 
IS0 930, Spices and condiments - Determination of acid- 
insoluble ash. 
IS0 948, Spices and condiments - Sampling. 
IS0 1108, Spices and condiments - Determination of non- 
volatile ether extract. 
IS0 2025, Spices and condiments - Preparation of a ground 
sample for analysis. 
3 Requirements 
3.1 Description 
Mustard seed is the dried clean seed of one or more of the 
following plants : 
- Sinapis alba Linnaeus - White mustard, yellow 
mustard; 
- Brassica nigra 
(Linnaeus) W.D.J Koch - Black mustard; 
- Brassica juncea 
(Linnaeus) Czernajew 
and Cosson in Czernajew - Indian mustard. 
3.2 Odour and flavour 
The odour and flavour of the seeds when ground and moist- 
ened shall be fresh and pungent, and free from rancidity and 
mustiness. 3.3 Freedom from moulds, insects, etc. 
The seeds shall be free from living insects, mites and moulds, 
and shall be practically free from dead insects, insect fragments 
and rodent contamination visible to the naked eye (corrected, if 
necessary, for abnormal vision), using such magnification as 
may be necessary in any particular case. If the magnification 
exceeds X 10, this fact shall be stated in the test report. 
3.4 Extraneous matter, shrivelled and damaged 
seeds 
The seeds shall be whole and mature and shall not contain 
more than 0,7 % (m/m) of extraneous matter or other 
vegetable material, determined by the method specified in 
IS0 927. Extraneous seeds include charlock (Sinapis arvensis 
Linnaeus), rape (Brassica napus Linnaeus), and MeMotus 
species. The proportion of damaged or shrivelled mustard 
seeds shall not exceed 2 % (m/m). 
3.5 Chemical requirementsl) 
The mustard seed shall comply with the requirements given in 
the table. 
Table - Requirements for mustard seed 
Characteristics Requirement Method of test 
Loss in mass at 103 OC, 
% (m/m) max. 10 Annex A 
Total ash, % (m/m) 
on dry basis, max. 65 IS0 928 
-- 
Acid-insoluble ash, 
% (m/m) on dry basis, 18 IS0 930 
max. - 
Non-volatile ether extract, 
% (m/m) on dry basis, min. 28 IS0 1108 
- 
Ally1 isothiocyanate, 
% (m/m) on dry basis 
Annex B 
a) in B. nigra, min. LO 
b) in B. juncea, min. 0,70 
p-hydroxybenzyl 
isothiocyanate, 
% (m/m) on dry basis 23 Annex C or 
in Sin&is alba, min. Annex D 
1) Limits for toxic substances will be included later, in accordance with the recommendations of the FAO/WHO Codex Alimentarius Commission. 
1 IS0 1237-1981 (E) 
4 Sampling 6 Packing and marking 
Sample the mustard seed by the method specified in IS0 948. 6.1 Packing 
The mustard seed shall be packed in clean, hygienic bags of a 
material which does not affect the seed and prevents it from 
absorbing moisture. 5 Methods of test 
5.1 The samples of mustard seed shall be tested for conform- 
ity with the requirements of- this International Standard by the 
methods of test referred to in 3.4 and the table. 6.2 Marking 
The following 
package : particulars shall be or labelled on each 
5.2 For the determination of total ash, use the method 
specified in IS0 928, with the following modifications to sub- _ - 
clause 8.3.2 : a) name of the material (botanical name), and the trade 
name or brand name, if a ny; 
b) name and address of the manufacturer or packer; 
Leach the ash with hot water, filter through a medium-fine, 
ashless filter paper and wash thoroughly. Transfer the filter 
paper and contents to the dish (6.11, dry and heat again in the 
muffle furnace (6.2) for 1 h. Cool and add 5 to 10 drops of 
analytical quality nitric acid, evaporate to dryness on the steam 
bath (6.4) and heat in the muffle furnace for 30 min. Repeat the 
addition of 5 to 10 drops of the nitric acid, again evaporate to 
dryness and heat in the muffle furnace for 1 h. Cool the dish, 
add the filtrate, and evaporate to dryness on the steam bath. 
Heat again in the muffle furnace for 1 h, cool and weigh. 
Repeat these operations until the difference between two suc- 
cessive weighings is less than 0,002 g. Record the lower mass. c) batch or code number; 
d) net mass; 
e) grade of the material (if graded), according 
national standard of the producing country; to the 
f) producing country; 
9) year of harvest, if known; 
h) date of packing; 
The total ash may be retained for the 
insoluble ash and acid-insoluble ash. determinations of water- 
0 any other marking required by the purchaser. IS0 12374981 (E) 
Annex A 
Determination of loss in mass at 103 OC’) 
A.1 Apparatus 
A.l.l Dish, of corrosion-resistant metal, with a suitable 
tight-fitting lid. - 
A.l.2 Constant temperature oven, controlled at 
103 + 2 OC. 
A.1.3 Desiccator, provided with an efficient desiccant. 
A.1.4 Analytical balance. 
A.2 Procedure 
A.2.1 Test portion 
Weigh, to the nearest 0,001 g, about 2 g of the sample in the 
tared dish (A.l.l). 
A.2.2 Determination 
Heat the dish and contents, with the lid alongside the dish, in 
the oven (A.1.2) at 103 + 2 OC for 3 h. Fit the lid, cool in the 
desiccator (A.1.3) and weigh. Heat in the oven for 1 h, cool in 
the desiccator and weigh again. Repeat the operations of 
heating for 1 h in the oven, cooling and weighing, until the 
difference between two successive weighings does not exceed 
0,001 g. A.2.3 Number of determinations 
Carry out two determinations on the same sample. 
A.3 Expression or results 
A.3.1 Method of calculation and formula 
The loss in mass at 103 OC, H, expressed as a percentage by 
mass of the sample, is equal to : 
100 
b-Xl 0- m,) x - 
m0 
where 
m. is the initial mass, in grams, of the test portion; 
ml is the mass, in grams, of the test portion after heating 
in the oven. 
Take as the result the arithmetic mean of the two determina- 
tions (A.2.31, provided that the requirement for repeatability 
(see A.3.2) is satisfied. 
A.3.2 Repeatability 
The difference between the results of the two determinations 
(A.2.31, carried out simultaneously or in rapid succession by 
the same analyst, shall not exceed 1 % of the mean value. 
1) For the purpose of calculating the results of tests on the dry basis, it is assumed that the loss in mass at 103 OC, as determined by the method 
described in annex A, is equal to the moisture content. 
3 IS0 12374981 (E) 
Annex B 
Determination of ally1 isothiocyanate 
B.l Principle 
After two successive soakings of the sample, the first in water 
at a temperature of 70 OC and the second in alcoholic medium, 
distillation of the allyr isothiocyanate liberated into an alcoholic 
ammonium hydroxide solution, addition to the distillate .of a 
standard volumetric silver nitrate solution, and titration of the 
excess silver nitrate with standard volumetric potassium, or 
ammonium, thiocyanate solution in the presence of ammonium 
iron(lll) sulphate. 
B.2 Reagents 
All reagents shall be of recognized analytical quality. The water 
used shall be distilled water or water of at least equivalent 
purity. 
83.21 Ethanol, 95 % (V/I/). 
B.Z.2 Ammonium hydroxide solution, ezo = 0,925 g/ml. 
B.2.3 Nitric acid, ezo = 1,40 g/ml. 
B.2.4 Silver nitrate, standard volumetric solution, 
c(AgN03) = 0,l mol/l. 
B.2.5 Potassium thiocyanate or ammonium thio- 
cyanate, standard volumetric solution, c(KCNS) or 
c(NHJNS) = 0,l mol/l. 
B.2.6 Ammonium iron(W) sulphate solution, saturated 
when cold. 
B.3 Apparatus 
Usual laboratory apparatus, and in particular 
B.3.1 Grinding mill. 
B .3.2 Entrainment distillation 
for a suitable example). apparatus (see the figure 
B.3.3 Burette, graduated at 0,05 ml intervals, complying 
with the requirements of ISO/R 385, class A. 
B .3.4 Analytical balance. B.4 Procedure 
B.4.1 Preparation of the sample 
After very careful mixing of the sample, take 15 to 20 g and 
grind it (see IS0 2825). 
B.4.2 Test portion 
Take about 2 g of the ground sample and weigh it to the 
nearest 0,001 g. 
B.4.3 Determination 
Transfer the test portion to the pear-shaped flask of the distilla- 
tion apparatus, add 80 ml of water previously heated to 
70 & 2 OC, close the flask with its ground glass stopper and 
leave to stand for 15 min. Then add 20 ml of the ethanol (B.2.1) 
and allow to soak for 45 min. 
After the soaking, connect the flask quickly to the distillation 
apparatus. Distil, and collect the distillate in a conical flask con- 
taining a mixture of 5 ml of the ammonium hydroxide solution 
(B.2.2) and 10 ml of the ethanol (B.2.1). (Entrainment distilla- 
tion lasts, on average, for 5 min.) The quantity of the distillate 
should be at least 100 ml. 
Add to the distillate 10 ml of the standard volumetric silver 
nitrate solution (B.2.4) and leave for 12 h at ambient 
temperature (the operation will be faster if the conical flask is 
placed for 1 h in a water bath heated to 70 to 80 OC). 
Filter through a fine filter paper, rinse the flask and residue 
several times with hot water (approximately 90 OC). 
To the bulked filtrate and washings add 10 ml of the nitric acid 
(B.2.3) and then titrate with the standard volumetric 
potassium, or ammonium, thiocyanate solution (B.2.5) using 
the ammonium iron(lll) sulphate solution (B.2.6) as indicator, 
until a persistent pink colour is obtained. 
B.4.4 Number of determinations 
Carry out two determinations on the same prepared sample. 
B.5 Expression of results 
B.5.1 Method of calculation and formula 
The ally1 isothiocyanate content, expressed as a percentage by 
mass on the dry basis, is equal to 
4,95 (10 - I.4 x 100 x 100 
103 m 100 - H IS0 12374981 (E) 
where 
m is the mass, in grams, of the test portion; 
V is the volume, in millilitres, of the standard volumetric 
potassium, or ammonium, thiocyanate solution used in the 
titration; 
H is the moisture content of the sample, expressed as a 
percentage by mass, determined by the method specified in 
annex A. 
NOTE - If the standard-v&metric solutions used are not of the exact 
concentrations indicated in clause B.2, a suitable correction factor 
should be used in calculating the result.. 
Take as the result the arithmetic mean of the two determina- 
tions (B.4.41, provided that the requirement for repeatability 
(see B.5.2) is satisfied. 
B.5.2 Repeatability 
The difference between the results of the two determinations 
(B.4.41, carried out simultaneously or in rapid succession by the 
same analyst, shall not exceed 1 % of the mean value. B.6 Notes on procedure 
B.6.1 During the analysis, all contact with copper or rubber 
shall be avoided, especially in the distillation apparatus. Use 
cork or, preferably, ground glass stoppers. 
B.6.2 The enzymic activity of the mustard seed diminishes 
with age; thus, it may be necessary to modify the analytical 
method in the case of old seed. 
After a preliminary determination giving particularly low figures 
for ally1 isothiocyanate, add to the distillation residue 5 g of 
Si.apis alba (take care to check that sulphur-containing volatile 
substances are not present in it) and then proceed to a second 
determination. 
The addition of the two results will give the real figure of ally1 
isothiocyanate that may be formed in the sample. However, the 
actual quality of the sample should be considered as very 
reduced and it is recommended that the two figures, found 
before and after the addition of Sinapis alba, should be given in 
the test report. 
8.6.3 The enzymic activity of the seeds increases during cer- 
tain periods of the year (particularly in spring); thus, identical 
results are not always found with a given lot of seed, according 
to the season in which the analysis is carried out. IS0 12374981 (E) 
Vapour genera I I 
Ll 
?= 
LJ 
I \ . 4 
l Spherical grow 
glass joint 
Splash head 
\ 
i ’ 
:: ’ \ 1 I 
‘1 ’ t p ’ \ I 
J 
1’ ’ I \ 
\\ : I ’ -Condenser md 
> Pear-shaped flask 
Figure - Entrainment distillation apparatus 
6 IS0 12374981 (E) 
Annex C 
Determination of p-hydroxybenzyl isothiocyanate 
(Calorimetric method) 
C.l Principle C.3.4 Colorimeter, 
wavelength of 450 nm. suitable for measurements at a 
Decomposition, by enzymatic hydrolysis, of the sinalbin 
(glucoside of Sinapis dba) into- glucose, the hydrogen sulphate 
of sinapin and plhydroxybenzyl isothiocyanate, the last- 
mentioned giving p-hydroxybenzyl and thiocyanate. Col- 
orimetric determination of the thiocyanate so formed. C.3.5 Analytical balance. 
C.4 Procedure 
C.2 Reagents C.4.1 Preparation of test sample 
All reagents shall be of recognized analytical quality. The water 
used shall be distilled water or water of at least equivalent 
purity. Carefully render the sample homogeneous, then take a portion 
of 20 to 25 g of the mustard seed and grind it (see IS0 2825). 
C.4.2 Test portion C.2.l Calcium carbonate, pulverized. 
Take approximately 5 g of the ground sample and weigh it to 
the nearest 0,001 g. c.2.2 Mercury(H) chloride, 50 g/l solution. 
C.2.3 Potassium hexacyanoferrate(ll), 106 g/l solution. C.4.3 Hydrolysis 
Transfer the test portion to a 250 ml beaker. C .2.4 Zinc acetate solution. 
Add 100 ml of water at 70 + 2 OC and at least 100 mg of the 
calcium carbonate (C.2.1). Cover the beaker with a watch 
glass. Leave to soak for 15 min at 70 OC, cool, add 20 ml of the 
sodium hydroxide solution (C.2.61, and leave in contact 
for 15 min. Dissolve 21,9 g of zinc acetate [(CH3C00)2Zn] in water, add 
3 ml of glacial acetic acid (CH$OOH) and dilute to 100 ml with 
water. 
C.2.5 Nitric acid, approximately 1 mol/l solution. 
C.4.4 Clarification C.2.6 Sodium hydroxide, approximately 1 mol/l solution. 
Add a sufficient quantity of the nitric acid solution (C.2.51, to 
bring the contents of the beaker to a pH of about 6,0 to 6,5. 
Pour the contents of the beaker into a 250 ml volumetric flask 
and, shaking the flask, add 2 ml of the potassium hexa- 
cyanoferrate(II) solution (C.2.3) and then 2 ml of the zinc 
acetate solution (C.2.4). C.2.7 Ammonium iron(lll) sulphate, 200 g/l solution in 
approximately 0,5 mol/l sulphuric acid solution. 
C.2.8 Potassium thiocyanate or ammonium thio- 
cyanate, standard volumetric solution, c(KCNS) or 
c(NH&NS) = 0,l mol/l, i.e. containing 5,808 g of CNS- per 
Iitre. Dilute to 250 ml with water and add 2 ml of water by pipette 
(C.3.3) (to take into account the volume of the precipitate). 
Shake, and filter through a rapid filter shaded from bright light. 
The filtrate (F) should be clear and colourless. C.3 Apparatus 
Usual laboratory apparatus, and in particular C.4.5 Determination 
Add to a 50 ml volumetric flask : C.3.l Grinding mill. 
- 5 ml of the filtrate (F), 
C.3.2 One-mark volumetric flasks, of capacities 50, 250 
and 1 000 ml, complying with the requirements of IS0 1042, 
class A. - .5 ml of the ammonium iron(lll) sulphate solution 
(C.2.7). 
C.3.3 Pipettes, delivering 2 ml and 5 ml, complying with 
the requirements of IS0 648, class A, or ISO/R 835. Di lute to 50 ml with water, shake, an d measure the absorbance 
at a wavelength of 450 nm by means of the calorimeter (C.3.4). 
7 IS0 12374981 (E) 
. 
C.4.6 Calibration curve 
Transfer, by means of a pipette (C.3.31, 5 ml of the standard 
volumetric potassium, or ammonium, thiocyanate solution 
(C.2.8) to a 1 000 ml volumetric flask and dilute to the mark 
with water. 
Into a series of five 50 ml volumetric flasks, transfer the 
volumes of this diluted potassium, or ammonium, thiocyanate 
solution indicated in the followin-g table : C.5 Expression of results 
C.5.1 Method of calculation and formula 
The p-hydroxybenzyl isothiocyanate content, expressed as a 
percentage by mass on the dry basis, is equal to 
250 loo loo 
2,84%-x--x 
106 5 m. 100 - H 
where 
mo is the mass, in grams, of the test portion; 
ml I I-Q I 
5 14i,2 
10 290,4 
15 435,6 
20 5803 
25 726 
Add to each flask, 5 ml of the ammonium iron(lll) sulphate 
solution (C.2.71, dilute to the mark with water, shake, and 
measure the absorbance as indicated in C.4.5. 
Plot a calibration curve, giving the absorbance as a function of 
the number of micrograms of thiocyanate. 
C.4.7 Matching test 
Carry out a matching test in the same conditions as the actual 
test, but adding 2 drops of the mercury(H) chloride solution 
(C.2.2) to correct for errors due to the reaction of phenols with 
the iron(lll) salts. 
Note on the calibration curve the difference in absorbance be- 
tween the test solution, containing the thiocyanate and 
phenols, and the matching test solution. 
C.4.8 Number of determinations 
Carry out two determinations on the same prepared sample. ml is the mass, in micrograms, of thiocyanate read from 
the calibration curve; 
H is the moisture content of the sample, expressed as a 
percentage by mass, determined by the method specified in 
annex A; 
2,84 is the conversion factor from thiocyanate ion (CNS-1 
to p-hydroxybenzyl isothiocyanate. 
Take as the result the arithmetic mean of the two determina- 
tions (C.4.8), provided that the requirement for repeatability 
(see C.5.2) is satisfied. 
C.5.2 Repeatability 
The difference between the results of the two determinations 
(C.4.8), carried out simultaneously or in rapid succession by the 
same analyst, shall not exceed 2 % of the mean value. 
C.6 Note on procedure 
The enzymic activity of the seeds increases during certain 
periods of the year (particularly in spring); thus, identical results 
are not always found with a given lot of seed, according to the 
season in which the analysis is carried out. 
8 IS0 1237-1981. (E) 
Annex D 
Determination of p-hydroxybenzyl isothiocyanate 1. 
(Argentimetric method) 
D.0 Introduction - 
Laboratories not in possession of a calorimeter may determine 
thiocyanate by argentimetry. In this case it is necessary either 
a) to carry out a preliminary check for the absence of 
Cl- ions in the seed (no reaction with silver nitrate on the 
ash of the mustard seed); or 
b) to provide for correction by carrying out the determina- 
tion of Cl- ions on an aliquot portion of the filtrate. 
This method may be substituted for the calorimetric method by 
agreement between the parties concerned. 
D.l Principle 
Decomposition, by enzymic hydrolysis, of sinalbin (glucoside 
of S;napi” &a) into glucose, the hydrogen sulphate of sinapin 
and p-hydroxybenzyl isothiocyanate, the last-mentioned giving 
p-hydroxybenzyl alcohol and thiocyanate. Determination of the 
thiocyanate thus formed, by argentimetry in nitric acid 
medium; back titration of the excess of silver nitrate using stan- 
dard volumetric potassium thiocyanate solution in the presence 
of ammonium iron(lll) sulphate. 
0.2 Reagents 
All reagents shall be of recognized analytical quality. The water 
used shall be distilled water or water of at least equivalent 
purity. 
The reagents necessary for hydrolysis and clarification (see 
annex C), together with 
D.2.1 Nitric acid, e20 = 1,40 g/ml. 
D.2.2 Silver nitrate, standard volumetric solution, 
c(AgN0,) = 0,l mol/l. 
D.2.3 Potassium thiocyanate, standard volumetric solu- 
tion, c(KCNS) = 0,l mol/l. 
D.2.4 Ammonium iron(W) sulphate solution, saturated 
when cold. 
D .3 Apparatus 
The apparatus necessary for the preparation of the sample, 
hydrolysis and clarification (see annex C), together with D.3.1 One-mark pipettes I of capacities 5 and 
PlYi w with the requ irements of I SO 648, class A 100 ml, com- 
D.3.2 Burette, graduated at every 0,05 ml, complying with 
the requirements of ISO/R 385, class A. 
D.4 Procedure 
D.4.1 Pre paration of test sample, test portion, 
hydro lysis and clarifica tion 
Proceed as specified in C.4.1 to C.4.4 of annex C. 
D.4.2 Titration 
Add to the beaker, shaking after each addition : 
- 100 ml, 
(see C.4.41, 
seed; by means of a pipette (D.3.1) , of the fi ltrate ( I=) 
and approximately equivalent to 2 g of musta rd 
- 1 ml of the nitric acid (D.2.1); 
- 5 ml, by means of a pipette (D.3.11, of the standard 
volumetric silver nitrate solution (D.2.2); 
- 2 ml of the ammonium iron(M) sulphate solution 
(D.2.4). 
Shake the flask to coagulate the precipitate, and titrate with the 
potassium thiocyanate solution (D.2.3) until a persistent faint 
red colour is obtained. 
D.4.3 Number of determinations 
Carry out two determinations on the same prepared sample. 
D.5 Expression of results 
D.5.1 Method of calculation and formula 
The p-hydroxybenzyl isothiocyanate content, 
percentage by mass on the dry basis, is equal expressed 
to 
250 loo 0,016 5 (5 - v) x loo x - x 100 
m 100 - H 
.yn is the 
C.4.2); mass, grams, of the test portion (see annex C, 
9 IS0 12374981 (E) 
Y is the volume, in millilitres, of the standard volumetric 
potassium thiocyanate solution (0.2.3) used in the titration; 
H is the moisture content of the sample, expressed as a 
percentage by mass, determined by the method specified in 
annex A. 
NOTE - If the standard volumetric solutions used are not of the exact 
concentrations specified in clause D.2, a suitable correction factor 
should be used in calculating the result. Take as the result the arithmetic mean of the two determina- 
tions (0.4.31, provided that the requirement for repeatability 
(see 0.5.2) is satisfied. 
0.52 Repeatability 
The difference between the results of the two determinations 
(D.4.31, carried out simultaneously or in rapid succession by 
the same analyst, shall not exceed 0,l g of p-hydroxybenzyl 
isothiocyanate per 100 g of dry matter in the sample. 
10 IS0 12374981 (El 
Annex 
Recommendations relating to storage and transport 
(This annex does not form part of the standard.) 
E.1 The packs of mustard seed should be stored in covered premises well protected from the sun, rain and excessive heat. 
E.2 The store room should be dry, free from objectionable odours and proofed against entry of insects and vermin. The ventilation 
should be controlled- so as to give good ventilation under dry conditions and no ventilation under damp conditions. In a storage 
warehouse, suitable facilities should be available for fumigation. 
E.3 The packs should be so handled and transported that they are protected from the rain, from the sun or other sources of ex- 
cessive heat, from objectionable odours and from cross-infestation, especially in the holds of ships. 
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