Fapas Food Chemistry Proficiency Test Report Quality Indicators in Olive Oil. July-August Page 1 of 32

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1 Fapas Food Chemistry Proficiency Test Report Quality Indicators in Olive Oil N O T C O N TR O LL ED W H EN PR IN TE D July-August 2017 Page 1 of 32

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 Fapas reports are distributed as digitally signed Adobe PDF files. When these files are opened with Adobe Reader v9 or later, a blue ribbon and information bar indicates that the certificate has been valid. This confirms that the author of the report is Fapas and that the document has not been altered since it was signed [1, 2]. The integrity of hard copies of Fapas reports cannot be assured in this way, i.e. printed copies are not controlled. A watermark stating this appears on every page when a Fapas report is printed. End users of Fapas reports should ensure that either the PDF file they are viewing displays a valid Fapas digital signature or that the content of their hard copy exactly matches the content of a PDF file that displays a valid Fapas digital signature. QUALITY SYSTEMS Fapas Food Chemistry is accredited by UKAS as complying with the requirements of ISO/IEC 17043:2010 [3]. Fera is an ISO 9001 certified organisation. Fera hereby excludes all liability for any claim, loss, demands or damages of any kind whatsoever (whether such claims, loss, demands or damages were foreseeable, known or otherwise) arising out of or in connection with the preparation of any technical or scientific report, including without limitation, indirect or consequential loss or damage; loss of actual or anticipated profits (including loss of profits on contracts); loss of revenue; loss of business; loss of opportunity; loss of anticipated savings; loss of goodwill; loss of reputation; loss or damage to or corruption of data; loss of use of money or otherwise, and whether or not advised of the possibility of such claim, loss demand or damages and whether arising in tort (including negligence), contract or otherwise. This statement does not affect your statutory rights. Nothing in this disclaimer excludes or limits Fera liability for: (a) death or personal injury caused by Fera negligence (or that of its employees, agents or directors); or (b) the tort of deceit; [or (c) any breach of the obligations implied by Sale of Goods Act 1979 or Supply of Goods and Services Act 1982 (including those relating to the title, fitness for purpose and satisfactory quality of goods);] or (d) any liability which may not be limited or excluded by law (e) fraud or fraudulent misrepresentation. The parties agree that any matters are governed by English law and irrevocably submit to the non-exclusive jurisdiction of the English courts. Copyright Fera Science Ltd (Fera) All rights reserved Page 2 of 32

3 SUMMARY 1. The test material for Fapas Food Chemistry proficiency test was dispatched in July Each participant received an olive oil test material to be analysed for Peroxide Value, Acidity, Anisidine Value and Iodine Value. 2. An assigned value (xa) was determined for each analyte and in conjunction with the standard deviation for proficiency (σp) was used to calculate a z-score for each result. 3. Results for this proficiency test are summarised as follows: analyte assigned value, xₐ units number of scores, z 2 total number of scores % z 2 Peroxide Value 4.65 meq O2/kg sample Acidity % w/w as oleic acid Anisidine Value 7.18 AV Iodine Value 92.5 % iodine absorbed Page 3 of 32

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 7 5. INTERPRETATION OF SCORES 7 6. REFERENCES 8 TABLES Table 1: Results and z-scores 9 Table 2: Assigned Values and Standard Deviations for Proficiency 17 Table 3: Number and Percentage of z-scores where z 2 17 FIGURES Figure 1: z-scores for Peroxide Value 18 Figure 2: z-scores for Acidity 19 Figure 3: z-scores for Anisidine Value 20 Figure 4: z-scores for Iodine Value 21 APPENDICES APPENDIX I: Analytical Methods Used by Participants 22 APPENDIX II: Fapas SecureWeb, Protocol and Contact Details 32 Page 4 of 32

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 valid methods, proficiency testing is an essential element of laboratory quality assurance. Further details of the Fapas Food Chemistry proficiency testing scheme are available in our protocols [4, 5]. 2. TEST MATERIAL 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 [3]. The test material was prepared from olive oil blended with a lesser amount of sunflower oil. An anti-oxidant was added. All analytes were present at natural levels. Samples were stored at ambient temperature 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 [3]. These data showed sufficient homogeneity and were not included in the subsequent calculation of the assigned values. Samples were also tested to confirm that the level of peroxide value was stable during the period of the proficiency test Dispatch The start was 31 July Test materials were sent to 113 participants. 3. RESULTS The instructions for reporting results were as follows: Store the sample in a cool (4 15 C) dark environment. The sample has been packed under an atmosphere of nitrogen. Do not open the bottle until you are ready to undertake the analysis of all analytes because once the oil is exposed to the atmosphere the peroxide value, acidity, anisidine value and iodine value could change. Ensure the sample is mixed thoroughly before analysis. 2) Determine the level of peroxide value, acidity, anisidine value and iodine value present in the test material, PLEASE NOTE: Page 5 of 32

6 Determination of all four analytes should be undertaken on the day as the bottle is opened. Please confirm this when submitting your results. For peroxide value the results should be expressed as meq O2/kg (milliequivalents peroxide per kilogram of sample). For acidity the results should be expressed as % w/w as oleic acid. For anisidine value the results should be expressed as anisidine value units (AV). For iodine value the results should be expressed as centigrams of iodine absorbed per gram of sample (% iodine absorbed). For each analyte, report the analysed. It is important that you report the results in this way so that we can include as many results as possible in the statistical analysis. Results were submitted by 111 participants (98%) before the closing for this test, 31 August Each participant was given a, assigned in order of receipt of results. The reported analyte concentrations are given in Table 1. There were no participants comments submitted in this test. The analytical methods used by each participant are summarised in APPENDIX I. 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, σp, to calculate a z-score [6] for each result. The procedure is detailed in the relevant protocols [4, 5]. Further background on the procedure followed can be found in the IUPAC International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories [7] Calculation of the Assigned Value, xa The assigned value, xa, 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) semi-quantitative results, <0.25, ii) iii) 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), results not produced on the day that the sample bottle was opened. For Peroxide Value, Acidity and Iodine Value, this procedure was straightforward and the robust mean was chosen as the assigned value. For Anisidine Value, the median was chosen as the assigned value because it was considered to be the best measure of the consensus. The assigned values for all analytes are shown in Table 2. Page 6 of 32

7 4.2. Standard Deviation for Proficiency, σp The standard deviation for proficiency, σp, was set at a value that reflects best practice for the analyses in question. For Peroxide Value, σp was derived from the appropriate form of the Horwitz equation [8]. For Acidity and Anisidine Value, σp was calculated using fitness-for-purpose criteria based on expert advice. For Iodine Value, σp was derived from collaborative trial data [9]. The values for σp 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, xa = the assigned value and σp = the standard deviation for proficiency. Participants z-scores for all analytes are given in Table 1 and shown as histograms in Figures 1 4. It is possible for the z-scores published in this report to differ slightly from the 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 [7]. Page 7 of 32

8 6. REFERENCES 1 Adobe Approved Trust List, accessed 01/06/ GlobalSign PDF Signing Tool, accessed 01/06/ ISO/IEC 17043:2010, Conformity assessment General requirements for proficiency testing. 4 Fapas, 2017, Protocol for Proficiency Testing Schemes, Version 6, April 2017, Part 1 Common Principles. 5 Fapas, 2017, Protocol for Proficiency Testing Schemes, Version 5, April 2017, Part 2 Fapas Food Chemistry scheme (FAPAS). 6 AMC Tech Brief No. 74, z-scores and other scores in chemical proficiency testing their meanings, and some common misconceptions, Anal. Methods, 2016, 8, 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, AOCS, 1987, Official Methods and Recommended Practices of the AOCS, Iodine Value of Fats and Oils Cyclohexane Acetic Acid Method Cd 1d-92. Page 8 of 32

9 Table 1: Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis Yes Yes YES YES Yes Yes Yes Yes Yes Yes Y N /08/2017 Yes /08/2017 Yes /08/17 Yes /08/17 Yes yes yes yes yes yes yes no Yes Yes Yes Yes Yes -2.7 z-score Yes yes yes no no z-scores outside z >2 are shown in bold, see Section 5 Page 9 of 32

10 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis /08/2017 yes /08/2017 yes /08/2017 Yes /08/2017 Yes /08/2017 No: /08/2017 Yes /08/2017 Yes /08/ /08/2017 Yes /08/17 No /08/17 YES /08/17 YES /08/17 YES /08/17 yes /08/17 yes /08/17 yes /08/17 yes Yes Yes /11/17 Yes /11/17 Yes /11/17 Yes No No yes yes yes yes yes yes Yes Yes -1.0 z-score Yes Yes yes yes -4.7 z-scores outside z >2 are shown in bold, see Section 5 Page 10 of 32

11 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis /08/2017 Yes /08/2017 Yes yes yes /08/2017 yes /08/2017 yes yes yes yes yes no no Yes Yes Yes Yes /08/2017 Yes /08/2017 Yes /08/2017 Yes /08/2017 Yes /08/2017 yes /08/2017 yes /08/2017 yes Yes Yes Yes Yes Yes Yes Yes Yes Yes 0.5 z-score Yes Yes /08/2017 Yes /08/2017 No /08/2017 No -1.2 z-scores outside z >2 are shown in bold, see Section 5 Page 11 of 32

12 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis Yes Yes /08/2017 Y /08/2017 Y yes yes yes /08/2017 yes /08/2017 yes Y Y yes yes /08/2017 Yes /08/2017 Yes /08/2017 Yes /08/2017 Yes -0.8 < /08/2017 Yes /9/2017 Yes /9/2017 Yes Yes Yes Yes yes yes yes yes yes 0.4 z-score yes yes yes yes Yes Yes -0.6 z-scores outside z >2 are shown in bold, see Section 5 Page 12 of 32

13 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis Yes -1.1 < Yes 5.6 y Yes Yes /08/2017 yes /08/2017 no /08/2017 yes y y yes yes YES YES Yes yes yes yes No No No yes yes No Y Y Yes Yes /08/14 Yes /08/14 Yes /08/14 Yes -0.3 z-score /08/14 Yes /08/14 Yes /08/14 Yes Yes Yes Yes -1.5 z-scores outside z >2 are shown in bold, see Section 5 Page 13 of 32

14 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis no yes no /08/2017 yes /08/2017 yes /08/2017 yes /08/2017 yes /08/17 yes Yes No Yes Yes /08/17 Yes Yes No No No Yes yes yes /08/2017 yes /08/2017 yes /08/2017 yes Yes Yes Yes yes yes no / no no no z-score YES YES YES NO Y Y Y 0.7 z-scores outside z >2 are shown in bold, see Section 5 Page 14 of 32

15 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis YES YES YES YES yes No No No Yes Yes No /08/2017 YES /08/2017 YES /08/2017 YES /08/2017 YES No No Yes Yes Yes Yes Yes Yes Yes Yes yes yes no /08/2017 yes /08/2017 yes /08/17 Yes /08/17 Yes /08/17 Yes /08/17 Yes /01/ /01/ z-score yes yes yes /01/2017 Y /01/2017 y /01/2017 y 0.4 z-scores outside z >2 are shown in bold, see Section 5 Page 15 of 32

16 Table 1 (continued): Results and z-scores laboratory number analyte Peroxide Value Acidity Anisidine Value Iodine Value assigned value: 4.65 meq O2/kg sample assigned value: % w /w as oleic acid assigned value: 7.18 AV assigned value: 92.5 % iodine absorbed result analysis /31/2017 y /31/2017 y /31/2017 y /31/2017 y /08/17 No /08/17 No y y Yes Yes Yes Yes Yes 2.1 z-scores outside z >2 are shown in bold, see Section 5 z-score Page 16 of 32

17 Table 2: Assigned Values and Standard Deviations for Proficiency analyte data points, n assigned value, xₐ units uncertainty, u standard deviation for proficiency, σ p Peroxide Value meq O2/kg sample 0.10 Horwitz [8] Acidity % w /w as oleic acid ffp Anisidine Value AV 0.18 ffp 1.36 Iodine Value % iodine absorbed 0.2 Coll. Trial [9] ffp = fitness-for-purpose criteria Table 3: Number and Percentage of z-scores where z 2 analyte number of scores total number of % z 2 where z 2 scores Peroxide Value Acidity Anisidine Value Iodine Value Page 17 of 32

18 z-score Laboratory Number meq O2/kg sample 4.65 meq O2/kg sample 3.47 meq O2/kg sample Figure 1: z-scores for Peroxide Value Page 18 of 32

19 z-score Laboratory Number % w/w as oleic acid % w/w as oleic acid % w/w as oleic acid Figure 2: z-scores for Acidity Page 19 of 32

20 AV z-score AV 4.45 AV Laboratory Number Figure 3: z-scores for Anisidine Value Page 20 of 32

21 % iodine absorbed z-score Laboratory Number % iodine absorbed 90.8 % iodine absorbed Figure 4: z-scores for Iodine Value Page 21 of 32

22 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. Peroxide Value Is The Method Used Accredited? yes no What is Your Method Based On? International Standard National Standard Manufacturer/Kit Instructions/Technical Note 093 In house method Sample Weight (g) < < < < Page 22 of 32

23 Titration Reagents ethanoic acid (acetic acid) chloroform saturated potassium iodide solution ,2,4-trimethylpentane dichloromethane 038 iso-octane sodium thiosulfate Titration Method add water mix sample and reagents place sample in dark peroxide (add water,mix sample reagents and 054 placed in the dark). sodium dodecyl sulfate 020 Page 23 of 32

24 Titration of Liberated Iodine sodium thiosulphate solution starch solution (as indicator) Other Method AOCS Cd Auto titration 038 OMA AOAC Acidity Is The Method Used Accredited? yes no What is Your Method Based On? International Standard National Standard In house method Page 24 of 32

25 Sample Weight (g) 1 - < < < < < Titration Reagents bromothymol blue 026 diethyl ether ethanol hexane petroleum ether/spirit phenolphthalein sodium hydroxide propanol 109 chloroform 037 isopropyl alcohol 087 Titration Method add water mix sample and reagents place sample in dark sodium hydroxide and phenolphthalein 054 Page 25 of 32

26 Titration of Free Fatty Acids phenolphthalein potassium hydroxide sodium hydroxide Other Method AOAC method, Incorporated Heating of 2-propanol solution, ensured early endpoint detection Anisidine Value Is The Method Used Accredited? 109 yes no What is Your Method Based On? International Standard National Standard In house method 082 Sample Preparation filtration 015 sodium sulphate drying 035 none Sample Weight (g) < < < Page 26 of 32

27 Solvent Added? 2,2,4-trimethylpentane glacial acetic acid iso-octane Total Reaction Time (mins) Determination spectrophotometry UV/Vis Wavelength (absorbance)(nm) Iodine Value Is The Method Used Accredited? yes no Page 27 of 32

28 What is Your Method Based On? International Standard National Standard Manufacturer/Kit Instructions/Technical Note 045 In house method Sample Weight (g) < < Filtration? no Filtration Performed in Air Oven? no Sample Allowed to Cool to C After Filtration no Sample Weight Taken yes no Page 28 of 32

29 Reagent Added to Dissolve the Oil carbon tetrachloride chloroform cyclohexane glacial acetic acid no reagents used 045 Wijs Solution Added? yes no Sample Stored in Dark? yes no Page 29 of 32

30 Storage Time 3 min minutes hour hours hours 067 Temperature of Stored Sample ( C) ambient/room temperature Reagent Added potassium iodide solution starch solution (as indicator) water Titration sodium thiosulphate solution sodium thiosulphate solution and starch solution (as indicator) 044 How Many Blank Determinations Were Carried Out? Page 30 of 32

31 Other Method (give brief outline) Used Wij's Method (AOAC), 2017 Testing - Used Hanus Method (AOAC), used Hanus Solution and sample mixed with chloroform 109 FT-NIR 045 Page 31 of 32

32 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, reference materials and quality control materials. Freely download copies of reports (PDF file), of proficiency tests in which they have participated. View charts of their z-scores obtained in previous Fapas Food Chemistry proficiency tests. 2. PROTOCOL The Protocols [4, 5] set out how Fapas Food Chemistry is organised. Copies can be downloaded from our website. 3. CONTACT DETAILS This report was prepared and authorised on behalf of Fapas by Michael Knaggs (Round Coordinator). Participants with any comments or concerns about this proficiency test should contact: Fapas Fera Science Ltd (Fera) National Agri-Food Innovation Campus Sand Hutton York YO41 1LZ UK Tel: +44 (0) Fax: +44 (0) info@fapas.com Page 32 of 32