FAPAS Report Oils and Fats - Mixed Fat Spread. August-September 2012 NOT CONTROLLED WHEN PRINTED. Page 1 of 26

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1 FAPAS Report Oils and Fats - Mixed Fat Spread August-September 2012 Page 1 of 26

2 PARTICIPANT LABORATORY NUMBER Participants can log in to FAPAS SecureWeb at any time to obtain their for this proficiency test. Laboratory numbers are displayed in SecureWeb next to the download link for this report. REPORT INTEGRITY Since 2006 all FAPAS reports have been distributed as Adobe Certified Document Services (CDS) Adobe PDF documents [1]. The use of Adobe CDS allows the PDF files to certify that the author of the report is FAPAS and that the document has not been altered in anyway. A blue ribbon and information bar indicates this validation when the document is opened using Adobe Reader v7 or later. Hard copies of FAPAS reports can never incorporate this level of integrity and consequently when a FAPAS report is printed a watermark, stating that printed copies are not controlled, appears on every page. End users of FAPAS reports should ensure that either the opened PDF file displays a valid FAPAS digital signature or that the content of any hard copy exactly matches the content of a PDF file that displays a valid FAPAS digital signature. QUALITY SYSTEMS FAPAS is accredited by UKAS as complying with the requirements of ISO/IEC 17043:2010 [2]. The Food and Environment Research Agency is an ISO 9001 certified organisation PT Whereas this report has been produced in good faith and in accordance with best industry practice, neither The Food and Environment Research Agency nor the Secretary of State for Environment, Food and Rural Affairs accepts any liability whatsoever as to the application or use of the information contained therein. Crown Copyright 2012 Page 2 of 26

3 SUMMARY 1. The test material for FAPAS proficiency test was dispatched in August Each participant received a mixed fat spread test material to be analysed for total fat, saturates, mono-unsaturates, poly-unsaturates and total trans fatty acids (TFA). 2. An assigned value (x a ) was determined for each analyte and in conjunction with the standard deviation for proficiency (σ p ) was used to calculate a z-score for each result. 3. Results for this proficiency test are summarised as follows: analyte assigned value, x a g/100g number of scores, z 2 total number of scores % z 2 total fat saturates mono-unsaturates poly-unsaturates total TFA Surplus test materials are available for sale, see APPENDIX II. Page 3 of 26

4 CONTENTS 1. INTRODUCTION Proficiency Testing 5 2. TEST MATERIAL Preparation Homogeneity Dispatch 5 3. RESULTS 5 4. STATISTICAL EVALUATION OF RESULTS Calculation of the Assigned Value, x a Standard Deviation for Proficiency, σ p Individual z-scores 6 5. INTERPRETATION OF SCORES 7 6. REFERENCES 7 TABLES Table 1: Results and z-scores 8 Table 2: Assigned Values and Standard Deviations for Proficiency 11 Table 3: Number and Percentage of z-scores where z 2 11 FIGURES Figure 1: z-scores for Total Fat 12 Figure 2: z-scores for Saturates 13 Figure 3: z-scores for Mono-unsaturates 14 Figure 4: z-scores for Poly-unsaturates 15 Figure 5: z-scores for Total TFA 16 APPENDICES APPENDIX I: Analytical Methods Used by Participants 17 APPENDIX II: FAPAS SecureWeb, Protocol and Contact Details 26 Page 4 of 26

5 1. INTRODUCTION 1.1. Proficiency Testing Proficiency testing aims to provide an independent assessment of the competence of participating laboratories. Together with the use of validated methods, proficiency testing is an essential element of laboratory quality assurance. Further details of the FAPAS protocols [3, 4]. 2. TEST MATERIAL proficiency testing scheme are available in our 2.1. Preparation Preparation of the samples for this proficiency test was sub-contracted to a laboratory meeting the quality requirements of the scheme s accreditation [2]. The test materials were prepared from a commercially available mixed fat spread and all analytes were present at natural levels. Samples were stored at -20 C until dispatch Homogeneity To test for homogeneity, randomly selected test materials were analysed in duplicate. Testing was sub-contracted to a laboratory meeting the quality requirements of the scheme s accreditation [2]. These data showed sufficient homogeneity and were not included in the subsequent calculation of the assigned values Dispatch The start date was 14 August Test materials were sent to 54 participants. 3. RESULTS The instructions for reporting results were to determine the level of total fat, saturates, mono-unsaturates, poly-unsaturates and total trans fatty acids, present in the test material, in g/100g. For saturates, mono-unsaturates, poly-unsaturates and total trans fatty acids participants were asked to state the method used to correct results to g/100g. For total trans fatty acids, participants were also asked to report the individual acids included in their result. Results were submitted by 45 participants (83%) before the closing date for this test, 25 September Each participant was given a, assigned in order of receipt of results. The reported analyte concentrations are given in Table 1. The analytical methods used by each participant are summarised in APPENDIX I. Page 5 of 26

6 4. STATISTICAL EVALUATION OF RESULTS The results submitted by participants were statistically analysed in order to provide an assigned value for each analyte. The assigned values were then used in combination with the standard deviation for proficiency, σ p, to calculate a z-score for each result. The procedure follows that recommended in the IUPAC International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories [5]. Further details on the procedure followed can be found in the relevant protocols [3, 4] Calculation of the Assigned Value, x a The assigned value, x a, for each analyte was derived from the consensus of the results submitted by participants. The following results were excluded from the calculation of the assigned value: i) results reported as approximately 10, 100 or 1000 greater or smaller than the majority of submitted results (as these were considered to be reporting errors), ii) iii) non numerical results i.e. qualitative or semi-quantitative results, uncorrected results i.e. results where participants have stated that they have not corrected e.g. triglyceride factor of 0.95, internal standardisation etc. For total fat and total TFA this procedure was straightforward and the robust mean was chosen as the assigned value. For saturates, mono-unsaturates and poly-unsaturates there were a small number of high results reported. Therefore the mode was chosen to set the assigned value for these analytes. The assigned values for all analytes are shown in Table Standard Deviation for Proficiency, σ p The standard deviation for proficiency, σ p, was set at a value that reflects best practice for the analyses in question. For total fat, σ p was derived from the appropriate form of the Horwitz equation [6]. For saturates, mono-unsaturates, and poly-unsaturates, σ p was derived from AOAC data [7]. For total TFA, σ p was derived from collaborative trial data [8]. The values for σ p used to calculate z-scores from the reported results of this test are given in Table Individual z-scores Participants z-scores were calculated as: ( x z = σ p x a ) where x = the participant s reported result, x a = the assigned value and σ p = the standard deviation for proficiency. Participants z-scores for all analytes are given in Table 1 and shown as histograms in Figures 1 5. It is possible for the z-scores published in this report to differ slightly from the Page 6 of 26

7 z-score that can be calculated using the formula given above. These differences arise from the necessary rounding of the actual assigned values and standard deviations for proficiency prior to their publication in Table 2. The number and percentage of z-scores in the range -2 z 2 for all analytes are given in Table INTERPRETATION OF SCORES In normal circumstances, over time, about 95% of z-scores will lie in the range -2 z 2. Occasional scores in the range 2 < z <3 are to be expected, at a rate of 1 in 20. Whether or not such scores are of importance can only be decided by considering them in the context of the other scores obtained by that laboratory. Scores where z >3 are to be expected at a rate of about 1 in 300. Given this rarity, such z-scores very strongly indicate that the result is not fit-for-purpose and almost certainly requires investigation. The consideration of a set or sequence of z-scores over time provides more useful information than a single z-score. Examples of suitable methods of comparison are provided in the IUPAC International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories [5]. 6. REFERENCES 1 Adobe Certified Document Services, accessed 08/05/ ISO/IEC 17043:2010, Conformity assessment General requirements for proficiency testing. 3 FAPAS, 2012, Protocol for Proficiency Testing Schemes, Part 1 Common Principles, Version 3, Issued January FAPAS, 2012, Protocol for Proficiency Testing Schemes, Part 2 FAPAS, Version 2, Issued January Thompson, M., Ellison, S.L.R. and Wood, R., 2006, The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories, Pure Appl. Chem., 78, No. 1, Thompson, M., 2000, Recent trends in inter-laboratory precision at ppb and sub-ppb concentrations in relation to fitness for purpose criteria in proficiency testing, Analyst, 125, Methyl Esters of Fatty Acids in Oils and Fats - Gas Chromatographic Method. AOAC AOAC Official Methods of Analysis, 1995, 16th Edition Ch 41.18D Buchgraber, M. and Ulberth, F., 2002, Determination of Low Level Trans Unsaturation in Physically Refined Vegetable Oils by Capillary GLC-Results of 3 Intercomparison Studies, Eur.J.Lipid Sci. Technol., 104, Page 7 of 26

8 Table 1: Results and z-scores laboratory number analyte total fat saturates mono-unsaturates poly-unsaturates total TFA assigned value assigned value assigned value assigned value assigned value 57.9 g/100g 14.4 g/100g 28.6 g/100g 11.8 g/100g g/100g result z-score result z-score result z-score result z-score result z-score z-scores outside z >2 are shown in bold, see Section 5 Page 8 of 26

9 Table 1 (continued): Results and z-scores laboratory number analyte total fat saturates mono-unsaturates poly-unsaturates total TFA assigned value assigned value assigned value assigned value assigned value 57.9 g/100g 14.4 g/100g 28.6 g/100g 11.8 g/100g g/100g result z-score result z-score result z-score result z-score result z-score z-scores outside z >2 are shown in bold, see Section 5 Page 9 of 26

10 Table 1 (continued): Results and z-scores laboratory number analyte total fat saturates mono-unsaturates poly-unsaturates total TFA assigned value assigned value assigned value assigned value assigned value 57.9 g/100g 14.4 g/100g 28.6 g/100g 11.8 g/100g g/100g result z-score result z-score result z-score result z-score result z-score z-scores outside z >2 are shown in bold, see Section 5 Page 10 of 26

11 Table 2: Assigned Values and Standard Deviations for Proficiency analyte data points, n assigned value, x a, g/100g uncertainty, u standard deviation for proficiency, σ p, g/100g total fat Horwitz [6] saturates AOAC [7] mono-unsaturates AOAC [7] 1.43 poly-unsaturates AOAC [7] total TFA Coll. Trial [8] Coll. Trial = collaborative trial Table 3: Number and Percentage of z-scores where z 2 analyte number of scores where total number % z 2 z 2 of scores total fat saturates mono-unsaturates poly-unsaturates total TFA Page 11 of 26

12 z-score g/100g 57.9 g/100g 56.3 g/100g Laboratory Number Figure 1: z-scores for Total Fat Page 12 of 26

13 z-score Laboratory Number 15.8 g/100g 14.4 g/100g 12.9 g/100g Figure 2: z-scores for Saturates Page 13 of 26

14 z-score Laboratory Number g/100g 28.6 g/100g 25.8 g/100g Figure 3: z-scores for Mono-unsaturates Page 14 of 26

15 z-score Laboratory Number g/100g 11.8 g/100g 10.6 g/100g Figure 4: z-scores for Poly-unsaturates Page 15 of 26

16 z-score Laboratory Number g/100g g/100g g/100g Figure 5: z-scores for Total TFA Page 16 of 26

17 APPENDIX I: Analytical Methods Used by Participants Methods are tabulated according to the information supplied by participants, but some responses may have been combined or edited for clarity. Total Fat Is The Method Used Accredited? yes no What is your method based on? International Standard National Standard In house method Sample Weight (g) < < < < < Acid/Alkaline Hydrolysis Used? acid alkaline none Total Fat Extraction Method Buchi 017 CEM Mojonnier Röse-Gottlieb 027 Soxhlet Page 17 of 26

18 Total Fat Extraction Method (continued) Tecator/Soxtec Weibull-Stoldt 016 Werner Schmidt 042 Acid hydrolysis liquid-liquid extraction 030 DGF-Einheitsmethode Abteilung C-Fette CIII 19(00), nach Caviezel (Pendl et al: J. OF AOAC INTERN. 81, Heft 4, 1998) 002 Gerber 009 ICC 022 solvent extraction 043 Pre-extraction Stage? yes no Pre-extraction Time (hours) < < < Extraction Solvent Components diethyl ether hexane 022 petroleum ether/spirit butanol 002 diethyl ether/petroleum spirit 042 H2SO4 i-buoh 009 n-butanol 017 petroleum ether (50-70) 016 petroleum ether Page 18 of 26

19 Total Extraction Time (Hours) < < < < > Fatty Acids Is The Method Used Accredited? yes no Reference AOAC Official Methods 018 AOAC Official Methods AOAC Official Methods AOAC Official Methods 2002 Chapter 41, p. 20 AOAC Official Methods 2005 Ch 41, pp 20-26, AOAC Official Methods AOCS 018 AOCS 2005 Ch 41, pp 20-26, BS ISO 2.34 & BS ISO DGF C-VI 11d (98) DGF C-VI 11d DGF-Einheitsmethode C-VI 11d Federal Office of Public Health IDF Standard 2002 IDF ISO ISO 1996 ISO ISO IUPAC J. AOAC Int Page 19 of 26

20 Reference (continued) J. AOAC Int Ch 41, pp 20-26, J. Chromatography 011 Korea food code ~47 page 029 korean food code Michael Bokisch Nahrungsfette Pearson's Composition and Anal th edition Sample Weight (g) < < < < Was an Internal Standard Added? yes no Internal Standard Added C11,C C11:0 018 Glyceryl tritridecanoate 043 methyl undecanoate 013 Tritridecanoin, Methyl undecanoate 034 triundecanoin 019 Undecanoic acid 029 Fat Extraction Bligh & Dyer method 003 solvent extraction Weibull-Stoldt none chloroform 001 Page 20 of 26

21 Fat Extraction (continued) DGF-Einheitsmethode Abteilung C-Fette CIII 19(00), nach Caviezel (Pendl et al: J. OF AOAC INTERN. 81, Heft 4, 1998) 002 ICC 022 melting 007 werner schmid 042 Extraction Solvent Components acetone 028 chloroform diethyl ether heptane hexane petroleum ether/spirit ,2,4-trimethylpentane 016 butanol 002 diethyl eher/petroleum spirit 042 GC Pre-Treatment brine clean-up saponification sodium sulphate drying solvent extraction Hydrolysis 043 Esterification BF hydrochloric acid 003 methanol potassium hydroxide sodium methoxide 034 sodium methylate 020 potassium methylate Page 21 of 26

22 Solvent For Derivative heptane hexane iso-octane methanol 020 Toluene 030 Determination GC GC Column Type capillary Capillary Column type highly polar (e.g. CP-sil 88, SP 2340, OV 275, etc) medium polar (e.g. Carbowax, CP-Wax, Stabiliwax, etc) DB non-polar HP SP GC Column Length (capillary) (m) < < < < GC Column Length (packed) (m) <1 029 Page 22 of 26

23 GC Column Film Thickness (µm) < < < GC Injection Mode on-column 001 split splitless GC Injection Technique auto-injection manual injection GC Injection Volume (µl) < < <5 018 GC Injector Temperature ( C) < < < < GC Total Run Time (min) Page 23 of 26

24 GC Total Run Time (min) (continued) GC Oven Temperature ( C) programmed GC Detector FID GC Detector Temperature ( C) < < < Separation Criteria of FAMES (please specify e.g. chromatographic resolution of 1 (from nearest peak)) > N/A 022 nearest peak 018 Page 24 of 26

25 Reporting Limit for Fatty Acids (% of Total Fatty Acids) < < < Page 25 of 26

26 APPENDIX II: FAPAS SecureWeb, Protocol and Contact Details 1. FAPAS SECUREWEB Access to the secure area of our website is only available to participants in our proficiency tests. Please contact us if you require a UserID and Password. FAPAS SecureWeb allows participants to: Obtain their s for the proficiency tests in which they have participated. View the results they submitted in past and current proficiency tests. Submit their results and methods for current tests. Review future tests they have ordered. Order proficiency tests and quality control materials. Freely download copies of reports (PDF file), of proficiency tests in which they have participated. 2. PROTOCOL The Protocols [3, 4] set out how FAPAS is organised. Copies can be downloaded from our website. 3. CONTACT DETAILS This report was prepared and authorised on behalf of FAPAS by Laura Prenton (Round Coordinator). Participants with any comments or concerns about this proficiency test should contact: FAPAS The Food and Environment Research Agency Sand Hutton York YO41 1LZ UK Tel: +44 (0) Fax: +44 (0) info@fapas.com testmaterials@fapas.com Page 26 of 26