FOSFA Technical Manual - Oils and Fats

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

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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.

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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

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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

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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

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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

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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

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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

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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

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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

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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.

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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.

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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.

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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)

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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)

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3.2