SAMPLING METHODS OILS, FATS, TECHNICAL TALLOWS, GREASES AND ACID OILS
Sampling
ISO 5555:2001
Preparation of laboratory samples
ISO 5555:2001 5555:2001 Section 6.9
Labelling of laboratory laborator y samples
ISO 5555:2001 Section 7.2
Preparation of test sample
ISO 661:2003
Packaging Packaging and and storage storage of oils and and fats samples samples
FOSFA FOSFA Internatio International nal Official Official Method Method
17 FOSFA
International Copyright 2010
April 2010
FOSFA INTERNATIONAL OFFICIAL METHOD PACKAGING AND STORAGE OF OILS AND FATS SAMPLES 1
Scope
This FOSFA method for the labelling, packaging, transport and storage of samples is applicable to all samples drawn under the terms of FOSFA International contracts for analysis, arbitration or standards purposes.
2
Label design
2.1 Labels must comply with ISO 5555:2001 Section 7.2. 2.2 Labels should be completed in legible handwriting, preferably in capital letters, or typed. Labels should be securely attached to the samples they represent.
3
Sample labelling, sealing and distribution
The label is to be affixed to the sample bottle and sealed to the bottle (jointly where appropriate) and to clearly indicate the appropriate FOSFA International contract number. Sealing wax, if used, should not contain copper. If a sealing wax does contain copper or the composition is unknown, the sample container shall be placed in a tight-fitting plastic bag and labelled and sealed therein. Samples shall be distributed in accordance with the relevant FOSFA International contract requirements.
4
Packaging of oils and fats samples for analysis
The samples shall be packed in accordance with ISO 5555:2001. For contractual analysis a sample of 250 ml is sufficient. Where special analyses are needed, a sample of 500 ml or more will be required.
5
Storage of samples after analysis
Samples should be clearly marked and stored with an in-house reference number in cool, dry conditions, away from strong light. The sample area should be insect and rodent free and hygienic. In normal circumstances, it has been the experience that contractual samples should be stored for a minimum of three months and longer if circumstances so dictate.
18 FOSFA
International Copyright 2010
April 2010
FULL ANALYST MEMBERS Mandatory Contractual Analysis Methods: Oils, Fats, Technical Tallows and Greases (except Acid Oils, Palm and Palm Kernel Oil Products traded on FOSFA Contract No 81) The tests shown below are mandatory for all Full Analyst Members in the Oils and Fats Section.
TEST NO
METHOD OF ANALYSIS
DETERMINATION
1
Determination of Lovibond colour
ISO 15305:1998
2
Flashpoint limit test using Pensky-Martens closed cup flash tester
ISO 15267:1998
3
Determination of free fatty acid content
ISO 660:2009
4
Determination of insoluble impurities content
ISO 663:2007
5
Determination of iodine value
ISO 3961:2009
6
Determination of conventional mass per volume (litre weight in air)
ISO 6883:2007
7
Determination of melting point in open capillary tubes (slip point)
ISO 6321:2002
8
Determination of moisture and volatile matter content
ISO 662:1998
9
Determination of peroxide value ─ Iodometric (visual) endpoint determination
ISO 3960:2007
10
Determination of acid value and acidity
ISO 660:2009
11
Determination of ash
ISO 6884:2008
12
Determination of carotene in vegetable oils
BS 684-2.20:1977
13
Cold Test
14
Determination of sea water contamination in oils
AOCS Cc 11-53 2009 FOSFA Method:2010
15
Determination of copper. Colorimetric method (Reference method)
BS 684-2.16:1976
16
Determination of erucic acid content (Total C22 monoenes)
ISO 5508:1990
17
Determination of visible foots in crude fats and oils
ISO 19219:2002
18
Preparation of methyl esters of fatty acids
ISO 5509:2000
19
Analysis by gas chromatography of methyl esters of fatty acids
ISO 5508:1990
20
Determination of iron. Colorimetric method (Reference method)
BS 684-2.17:1976
19 FOSFA
International Copyright 2010
April 2010
21
Determination of Chlorophyll Pigments in Crude Vegetable Oils
AOCS Cc 13i-96 2009 ISO 10540-1:2003
22
Determination of phosphorus content ─ Part 1: Colorimetric method (Reference method)
23
Determination of refractive index
ISO 6320:2000/ Cor 1:2006
24
Determination of saponification value
ISO 3657:2002
25
Determination of alkalinity
ISO 10539:2002
26
Determination of ultraviolet absorbance expressed as specific UV extinction
ISO 3656:2002
27
Calculation of total fatty matter
BS 684-2.4:1976
28
Determination of unsaponifiable matter ─ Method using diethyl ether extraction (Reference method)
ISO 3596:2000
29
Determination of water content ─ Entrainment method
ISO 934:1980
30
Determination of water content ─ Karl Fischer method (pyridine free)
ISO 8534:2008
20 FOSFA
International Copyright 2010
April 2010
FULL ANALYST MEMBERS Optional Contractual Analysis Methods: Oils, Fats, Technical Tallows and Greases (except Acid Oils, Palm and Palm Kernel Oil Products traded on FOSFA Contract No 81) The tests shown below are optional for all Full Analyst Members in the Oils and Fats Section.
TEST NO
METHOD OF ANALYSIS
DETERMINATION
31
Determination of bleachability a. General Case
BS 684-2.27:1987
32
Determination of bleachability b. Bleach Test for Palm Oil
BS 684-2.27:1987
33
Determination of cadmium content by direct graphite furnace atomic absorption spectrometry
ISO 15774:2000
34
Determination of cloud point
35
Color - FAC Standard Color
BS 684-1.5:1987/ Amd:1989 AOCS Cc 13a-43 2009
36
Color - Wesson Method Using Color Glasses Calibrated in Accordance with the AOCS-Tintometer Color Scale
AOCS Cc 13b-45 2009
37
Color - Gardner 1963 (Glass Standards)
AOCS Td 1a-64 2009
38
Determination of copper, iron and nickel contents ─ Graphite furnace atomic absorption method
ISO 8294:1994
39
Evaluation of technical tallows and animal greases
BS 3919:1987/ Amd:1989
40
Determination of oxidized fatty acids
BS 684-2.12:1984
41
Determination of oxidative stability (accelerated oxidation test) Rancimat or equivalent
ISO 6886:2006
42
Determination of phosphorus content ─ Part 2: Method using graphite furnace atomic absorption spectrometry
ISO 10540-2:2003
43
Determination of phosphorus content ─ Part 3: Method using inductively coupled plasma (ICP) optical emission spectroscopy
ISO 10540-3:2002
44
Determination of content of polar compounds
ISO 8420:2002/ Cor 1:2004
45
Phosphoric acid test
ISO 150:2006
46
Determination of polyethylene-type polymers
ISO 6656:2002
47
Refined and Bleached Colour
AOCS Cc 8d-55 2009
48
Determination of smoke point
BS 684-1.8:1976
21 FOSFA
International Copyright 2010
April 2010
49
Determination of solid fat content by pulsed NMR ─ Part 1: Direct method
ISO 8292-1:2008
50
Determination of solid fat content by pulsed NMR ─ Part 2: Indirect method
ISO 8292-2:2008
51
Determination of individual and total sterols contents ─ Gas chromatographic method
ISO 12228:1999
52
Determination of titre
ISO 935:1988
53
Determination of lead by direct graphite furnace atomic absorption spectroscopy
ISO 12193:2004
54
Determination of unsaponifiable matter ─ Method using hexane extraction (for Sheanut Oil only)
ISO 18609:2000
55
Determination of sediment in crude fats and oils ─ Centrifuge method
ISO 15301:2001/ Cor 1:2007
56
Determination of benzo[a]pyrene ─ Reverse-phase high performance liquid chromatography method
ISO 15302:2007
57
Determination of the deterioration of bleachability index (DOBI)
ISO 17932:2005
58
Determination of anisidine value
ISO 6885:2006
59
Determination of the composition of fatty acids in the 2-position of the triglyceride molecules
ISO 6800:1997
60
Determination of residual technical hexane content
ISO 9832:2002
61
Determination of mineral acidity
BS 684-2.48:1998
62
Determination of water-insoluble solvents
BS 684-1.9:1976
63
Detection and identification of a volatile organic contaminant by GC/MS
ISO 15303:2001
64
Determination of stigmastadienes in vegetable oils ─ Part 1: Method using capillary-column gas chromatography (Reference method)
ISO 15788-1:1999
22 FOSFA
International Copyright 2010
April 2010
ASSOCIATE ANALYST MEMBERS Mandatory Contractual Analysis Methods: Oils, Fats, Technical Tallows and Greases (except Acid Oils, Palm and Palm Kernel Oil Products traded on FOSFA Contract No 81) The tests shown below are mandatory for all Associate Analyst Members in the Oils and Fats Section.
TEST NO
METHOD OF ANALYSIS
DETERMINATION
1
Determination of Lovibond colour
ISO 15305:1998
2
Flashpoint limit test using Pensky-Martens closed cup flash tester
ISO 15267:1998
3
Determination of free fatty acid content
ISO 660:2009
4
Determination of insoluble impurities content
ISO 663:2007
5
Determination of iodine value
ISO 3961:2009
6
Determination of conventional mass per volume (litre weight in air)
ISO 6883:2007
7
Determination of melting point in open capillary tubes (slip point)
ISO 6321:2002
8
Determination of moisture and volatile matter content
ISO 662:1998
9
Determination of peroxide value ─ Iodometric (visual) endpoint determination
ISO 3960:2007
23 FOSFA
International Copyright 2010
April 2010
ANALYSIS METHODS ACID OILS TEST NO
DETERMINATION
METHOD OF ANALYSIS
1
Determination of ash
ISO 6884:2008
2
Determination of insoluble impurities content
ISO 663:2007
3
Determination of iodine value
ISO 3961:2009
4
Determination of mineral acidity
BS 684-2.48:1998
5
Determination of soap content
FOSFA Method:2010
6
Determination of unsaponifiable matter ─ Method using diethyl ether extraction (Reference method)
ISO 3596:2000
7
Determination of water content ─ Entrainment method
ISO 934:1980
8
Determination of water content ─ Karl Fischer method (pyridine free)
ISO 8534:2008
9
Determination of free fatty acid content
ISO 660:2009
10
Total saponifiable matter shall be equivalent to:
Determined by the Standard Contractual Methods as per this List
100 – (W + I + U + S) where: W is water content I is insoluble impurities U is unsaponifiable matter S = soap content 11
Total fatty matter shall be equivalent to:
Determined by the Standard Contractual Methods as per this List
100 – (W + A + I) where: W A I
is water content is ash is insoluble impurities
24 FOSFA
International Copyright 2010
April 2010
FOSFA INTERNATIONAL/PORAM STANDARD CONTRACTUAL METHODS LIST PALM OIL AND PALM KERNEL OIL PRODUCTS IN BULK CIF FOR USE WITH FOSFA INTERNATIONAL CONTRACT NO 81
DETERMINATION
METHODS OF ANALYSIS
FFA % (as Palmitic for palm oil products and as Lauric for palm kernel oil products)
ISO 660:2009 AOCS Ca 5a-40 2009 MPOB Method p2.5:2004
Moisture and Volatile Matter (Palm Oil/Palm Stearin/Palm Olein)
ISO 662:1998 AOCS Ca 2c-25 2009 MPOB Method p2.1:2004
Moisture and Volatile Matter (Processed Palm Kernel Oil products)
ISO 662:1998 AOCS Ca 2c-25 2009 MPOB Method k1.4:2004
Iodine Value (Wijs)
ISO 3961:2009 AOCS Cd 1d-92 2009 MPOB Method p3.2:2004
Insoluble Impurities
ISO 663:2007 (Warm solvent may be used) AOCS Ca 3a-46 2009 MPOB Method p2.2:2004
Colour
ISO 15305:1998 AOCS Cc 13e-92 2009 (Without the use of black sheath) MPOB Method p4.1:2004
Melting Point (Slip Point)
ISO 6321:2002 AOCS Cc 3-25 2009 MPOB Method p4.2:2004
25 FOSFA
International Copyright 2010
April 2010
FOSFA INTERNATIONAL/PORAM STANDARD CONTRACTUAL METHODS LIST PALM ACID OIL/PFAD/FLAKED STEARIC ACID
DETERMINATION
METHODS OF ANALYSIS
Free Fatty Acid (FFA) (as Palmitic)
AOCS Ca 5a-40 2009 MPOB Method p2.5:2004
Saponification Value
AOCS Cd 3-25 2009
Moisture and Volatile Matter
AOCS Ca 2b-38 2009 AOCS Ca 2c-25 2009 MPOB Method p2.1:2004
Unsaponifiable Matter
AOCS Ca 6a-40 2009
Total Fatty Matter
100 - (M + I ) *
Saponifiable Matter
100 - (M + I + U) *
Soap
FOSFA Method 2010
Impurities
ISO 663:2007 MPOB Method p2.2:2004
*Where: M
is Moisture as per AOCS Ca 2b-38 2009
I
is Impurities as per ISO 663:2007/MPOB Method p2.2:2004
U
is Unsaponifiable Matter as per AOCS Ca 6a-40 2009
26 FOSFA
International Copyright 2010
April 2010
FOSFA INTERNATIONAL OFFICIAL METHOD DETERMINATION OF SEA WATER CONTAMINATION IN OILS 1
Scope
The method is applicable to all oils, with the exception of those (such as acid oils) which are known to have been treated with hydrochloric acid.
2
Principle
The oil is examined for the presence of chloride ions in the aqueous contaminant. If chloride ions are detected and the amount of aqueous phase permits, quantitative determinations of chloride and other ions may be carried out.
3
References
3.1 Official, Standardised and Recommended Methods of Analysis. The Society for Analytical Chemistry, London, 1973. 3.2 Analysis of Raw, Potable and Waste Waters. HMSO, 1972. 3.3 Methods for the examination of Water and Associated Materials. The National Water Council, Department of the Environment. 3.4 Official Methods of Analysis of the Association of Official Analytical Chemists. 13th edition, Washington, 1980.
4
Reagents
4.1 Silver nitrate solution, approximately 0.1 M. 4.2 Nitric acid, concentrated, AR.
5
Procedure
5.1 Sample preparation 5.1.1 If the nature of the sample permits, separate the aqueous and oil components by centrifugation, or by allowing the sample to stand. Determine the volume of aqueous contaminant in the oil. 5.1.2 If the amount of the contaminant is small, extract it by shaking the oil with water. Dilution of the oil with petroleum ether may assist the separation of the aqueous layer. If this procedure is unsatisfactory the oil should ashed at a temperature of not more than 450 C and the tests carried out on an aqueous solution of the ash.
5.2 Qualitative test Acidify a portion of the aqueous phase with a few drops of concentrated nitric acid, and add a few drops of silver nitrate solution. A white precipitate which darkens upon exposure to light, especially sunlight, (or turbidity if the sample solution is very dilute) indicates the presence of chloride and suggests that the sample may have been contaminated with sea water.
27 FOSFA
International Copyright 2010
April 2010
6
Further examination
If a more detailed examination of the aqueous contaminant is required, quantitative determination of chloride and sodium should first be carried out. Determinations of other major constituents of sea water, such as sulphate, magnesium, potassium and calcium may then be carried out as further confirmatory tests. The principal inorganic constituents of typical sea water are:
Chloride Sodium (as Na) Sulphate Magnesium (as Mg) Calcium (as Ca) Potassium (as K) Bicarbonate Bromide
% m/m 1.90 1.06 0.26 0.13 0.04 0.01 0.01 0.007
The methods of analysis will depend on the quantity of the aqueous contaminant available. Some sources of suitable analytical methods are given in Section 3 (References).
7
Test report
The Analyst's report shall indicate the method(s) of analysis employed.
28 FOSFA
International Copyright 2010
April 2010
FOSFA INTERNATIONAL OFFICIAL METHOD DETERMINATION OF SOAP IN ACID OILS 1
Scope
A non-aqueous titration method is described for the determination of soap in all types of acid oils.
2
Definition
The soap content is expressed as sodium oleate as a percentage by mass calculated from the total alkalinity of the oil.
3
Principle
The total alkalinity is determined by titration in neutral solvent solution of the oil using standard ethanolic hydrochloric acid and bromophenol blue indicator solution. For dark coloured and/or very low expected soap contents (less than 0.01 % by mass) the end-point is measured electrometrically.
4
Reagents
Use only reagents of recognised analytical quality.
4.1 Ethanolic hydrochloric acid solution 0.01N and/or 0.1N accurately standardised. 4.2 Bromophenol blue indicator. Solution of 49 g per litre of 95 % (m/m) ethanol. 4.3 Solvent mixture. 1 volume ethanol/2 volumes acetone neutralised by adding a few drops of indicator solution (4.2) and titrating with hydrochloric acid solution (4.1) or with ethanolic potassium hydroxide solution until just yellow.
5
Apparatus
Use laboratory apparatus and in particular the following.
5.1 Burette 10 ml graduated in 0.02 ml. 5.2 pH meter fitted with automatic temperature compensation and equipped with a suitable electrode system. The electrode assembly should be washed with neutral solvent (4.3) before use. NOTE It is essential that the pH equipment be very carefully checked for both repeatability and reproducibility at the required operational temperatures. Some equipment has been found to give variations in excess of 0.6 pH units in day-to-say measurements on the same solvent mixture and to require several minutes to give a constant reading after agitation has ceased.
5.3 pH electrode suitable for work in non-aqueous solvent mixture is recommended. 5.4 Suitable means of heating the solvent mixture and oil solution such as a water bath thermostatically controlled at about 46 C.
5.5 Conical Erlenmeyer flasks (250 ml) having no alkaline reaction.
6
Preparation of sample
Melt the oil sample and mix thoroughly.
29 FOSFA
International Copyright 2010
April 2010
7
Procedure
7.1 Oils which yield a clear colourless solution in the solvent mixture (4.3) 7.1.1
Test solution
Accurately weigh a suitable mass of sample (6) directly into a 250 ml conical (Erlenmeyer) flask then add 100 ml of solvent mixture (4.3) and dissolve at 40 C to 45 C.
7.1.2
Titration
Add a few drops of indicator solution (4.2). The formation of a green colour indicates the presence of soap. Titrate the test solution (7.1.1) with ethanolic hydrochloric acid (4.1) until the solution is just yellow at its initial temperature (40 C to 45 C). Allow adequate time (5 min) for reaction of calcium soaps etc.
7.2 Oils which yield a dark solution in the solvent mixture (4.3) and/or are expected to have a very low (less than 0.01 % by mass) soap content 7.2.1
pH of solvent mixture
Warm 100 ml solvent mixture (4.3) to 40 C to 45 C, Measure the temperature accurately and adjust the pH meter (5.2) for operation at this temperature and measure the pH. Determine end-point by reference to a calibration curve.
NOTE Choose the vessel to contain the solvent mixture which will subsequently permit the insertion of the pH electrodes (5), such as a beaker or wide-necked conical flask.
8
Expression of results
8.1 Method of calculation Calculate the soap content, expressed as a percentage (mass/mass) of sodium oleate in the original sample (6) from the formula. % Soap content (as sodium oleate)
= V x N x 30.4 W
Where: V N W
is volume in ml of ethanolic hydrochloric acid used (7.1.2 or 7.2.2) to reach equivalence is normality of ethanolic hydrochloric acid (4.1) is mass of sample used to prepare test solution (7.1.1 or 7.2.2)
30 FOSFA
International Copyright 2010
April 2010
DETERMINATION OF SOAP IN ACID OILS
Figure 1: Curve of change in scale reading per unit volume of acid added against volume of acid added and from this measure the equivalence volume corresponding to the curve maximum.
700
600
500
400
300
200
100
0 0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
1.9 1.95 2.0
2.1
2.4
2.6
2.8
3.1
Volume of HCL (ml)
31 FOSFA
International Copyright 2010
April 2010
3.2
