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th PT 11 th PT 1 1 Round on Milk 11 Round on Milk Preparation of material and of material and results results Preparation Laura Ciaralli Laura Ciaralli Community Reference Reference Laboratory Laboratory for for Chemical

  1. th PT 11 th PT– – 1° 1° Round on Milk 11 Round on Milk Preparation of material and of material and results results Preparation Laura Ciaralli Laura Ciaralli Community Reference Reference Laboratory Laboratory for for Chemical Chemical Elements Elements Community in Food of Animal in Food of Animal Origin Origin CRL- CRL -ISS ISS CRL-ISS Annual Workshop, 19 October 2007

  2. Liquid milk CRL-ISS Annual Workshop, 19 October 2007

  3. ������������������������������������������� �� �������� ����� ���� �������� � ������ ����� ���� ��������� ��� ���������� ��� ������ ��� ������ ���� ������������� ��� ������ ������ ������������������������������� CRL-ISS Annual Workshop, 19 October 2007

  4. Sample Preparation • Purchasing of commercial partially skimmed milk • Partition into two aliquots • Spiking of As, Cd, Pb at two concentration levels • Homogenization by a peristaltic pump • Sampling by a peristaltic pump • Closing of bottles • Sterilization process in autoclave • Labelling • Shipping CRL-ISS Annual Workshop, 19 October 2007

  5. CHARACTERISTICS of TEST TUBES � ��������� !"�#� � �$%&�'�(�)*$"+)$*+�)#� � ��%+%*$)*��*��*,��%*��+ +-$*+�)����(�%%�+)� $!*�( $��#� � �$%&��,$)' +).�'!�+).�*,��/+*,'�$/$ ��0�*,�� %$"� �# � $1%�)(���0�*�$)%0���$)'2���$'%���*+�)��0� � �"�)*%�0��"�*,��/$ �$)'�*,��($� CRL-ISS Annual Workshop, 19 October 2007

  6. GLASS TEST TUBES CRL-ISS Annual Workshop, 19 October 2007

  7. CRL-ISS Annual Workshop, 19 October 2007

  8. Sterilisation process Autoclave 3 minutes, 120 ° C CRL-ISS Annual Workshop, 19 October 2007

  9. ������������������������� CRL-ISS Annual Workshop, 19 October 2007

  10. Arsenic Level A � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 45.1 45.9 45.7 SD 2.07 2.67 1.82 CV% 4.6 5.8 4.0 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.742 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  11. Arsenic Level B � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 92.8 92.5 94.2 SD 3.96 1.53 3.14 CV% 4.3 1.7 3.3 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.443 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  12. Cadmium Cadmium Level A � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 7.5 7.6 7.6 SD 0.25 0.33 0.35 CV% 3.3 4.3 4.6 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.765 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  13. Cadmium Level B � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 2.64 2.47 2.50 SD 0.18 0.12 0.12 CV% 7.0 4.9 4.8 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.661 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  14. Lead Level A � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 11.8 11.4 11.5 SD 0.5 0.7 0.59 CV% 4.0 6.0 5.2 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.377 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  15. Lead Level B � g/l Time 0(t 0 ) 1 month (t 1 ) 2.5 months (t 2 ) Media (n=10) 23.6 22.0 23.2 SD 0.61 0.83 1.08 CV% 2.6 3.8 4.7 Statistical Tests ANOVA T test t 0 vs t 1 N.S. t 0 vs t 2 N.S. P= 0.002 t 2 vs t 1 N.S. CRL-ISS Annual Workshop, 19 October 2007

  16. Sample Preparation • Purchasing of commercial partially skimmed milk • Partition into two aliquots • Spiking of As, Cd, Pb at two concentration levels • Homogenization by a peristaltic pump • Sampling by a peristaltic pump • Closing of bottles • Sterilization process in autoclave • Samples immersion in chilled water • Labelling • Shipping CRL-ISS Annual Workshop, 19 October 2007

  17. Procedure adopted for the evaluation of the material homogeneity The adopted procedure was that of Thompson and Fearn (1), which is an improvement of the process described in the International Harmonised Protocol (2). (1) Fearn, T. and Thompson, M, A new test for ‘sufficient homogeneity’, Analyst, 2001, 126, 1414-1417. (2) M. Thompson and R. Wood, The International Harmonised Protocol for the Proficiency Testing of (Chemical) Analytical Laboratories, Pure & Applied Chemistry , 1993, 65 (9),2123-2144. CRL-ISS Annual Workshop, 19 October 2007

  18. Selection of the bottles for the test of homogeneity The selection was performed by a table of records generated by a computer package. The number of the bottles was obtained through this formula ( √ n - 1) Two equally sized portions were taken from the same bottle and analysed CRL-ISS Annual Workshop, 19 October 2007

  19. The analytical determinations were performed on aliquots of milk, previously mineralized with an acid digestion through Micro-Wave oven, by Inductively Coupled Plasma with Mass Detector (ICP-MS) CRL-ISS Annual Workshop, 19 October 2007

  20. Arsenic Level A Level B 105.0 55.0 C (µg kg-1) C (µg kg-1) Replicate A Replicate A Replicate B Replicate B 45.0 35.0 80.0 18 31 43 53 57 62 84 89 100 126 18 31 43 53 57 62 84 89 100 126 bottle n° bottle n° CRL-ISS Annual Workshop, 19 October 2007

  21. Cadmium Level B Level A Replicate A Replicate A Replicate B Replicate B 4.0 8.5 3.5 8.0 C (µg kg-1) C (µg kg-1) 7.5 3.0 7.0 2.5 6.5 2.0 18 31 43 53 57 62 84 89 100 126 18 31 43 53 57 62 84 89 100 126 bottle n° bottle n° CRL-ISS Annual Workshop, 19 October 2007

  22. Lead Level A Level B 20.0 30.0 28.0 17.5 C (µg kg-1) C (µg kg-1) 26.0 Replicate A Replicate A 15.0 Replicate B Replicate B 24.0 12.5 22.0 10.0 20.0 18 31 43 53 57 62 84 89 100 126 18 31 43 53 57 62 84 89 100 126 bottle n° bottle n° CRL-ISS Annual Workshop, 19 October 2007

  23. STATISTICAL EVALUATION OF PERFORMANCE CRL-ISS Annual Workshop, 19 October 2007

  24. Summary Level A As Cd Pb (mg kg -1 ) (mg kg -1 ) (mg kg -1 ) N. of Results 17 23 23 min 0,0370 0,0050 0,0080 0,0740 0,0100 0,0240 max 0,0522 0,0074 0,0145 Mean SD 0,0086 0,0012 0,0044 0,0516 0,0077 0,0130 Median 0,0511 0,0074 0,0144 Robust Mean Robust SD 0,0012 0,0047 0,0047 σ p σ σ σ 0,0112 0,0016 0,0044 CRL-ISS Annual Workshop, 19 October 2007

  25. Summary Level B As Cd Pb (mg kg -1 ) (mg kg -1 ) (mg kg -1 ) N. of Results 17 23 23 min 0,0700 0,0020 0,0150 0,1610 0,0050 0,0420 max Mean 0,1062 0,0030 0,0254 SD 0,0209 0,0006 0,0057 0,1026 0,0030 0,0250 Median 0,1037 0,0029 0,0247 Robust Mean Robust SD 0,0137 0,0004 0,0037 σ p σ σ σ 0,0228 0,0006 0,0069 CRL-ISS Annual Workshop, 19 October 2007

  26. z-scores 0,3 -0,1 0,0 0,2 0,1 -0,5 -0,6 As Cd Pb Level A Level B Level A Level B Level A Level B -0,5 -0,2 0,4 0,1 0,6 0,0 - - -0,8 -1,3 -0,8 -0,5 2,0 2,5 -0,8 -1,4 1,1 -0,4 - - 0,3 0,7 -0,3 0,1 -0,7 -0,9 -0,2 0,1 -1,5 -0,5 0,3 0,0 1,0 0,1 -0,3 0,0 - - -1,1 -0,9 -1,2 -1,4 -0,1 -0,2 -0,2 0,1 1,3 0,8 - - 1,6 3,2 1,8 2,5 - - -0,5 -0,7 -0,3 -0,4 - - 0,2 0,1 -1,4 -0,6 -0,1 -0,2 0,2 -0,2 -0,2 0,0 -0,1 -0,2 -0,2 1,1 2,2 1,5 0,0 0,0 1,0 1,7 0,6 1,5 0,1 -0,1 0,4 0,1 -0,3 -0,1 1,6 1,6 -0,2 0,1 -0,5 0,0 0,3 0,4 0,4 0,1 -0,8 0,0 0,2 1,0 -1,5 0,1 -0,8 0,3 0,2 0,1 0,4 0,1 -0,3 0,0 -1,3 -1,5 0,4 -1,4 -0,5 -0,4 0,0 0,0 -0,8 -0,2 1,2 -0,4 0,2 0,1 0,0 0,0 1,3 0,0 CRL-ISS Annual Workshop, 19 October 2007

  27. Arsenic Arsenic Percentage of of z z- -scores scores Percentage Level A Level B 6% 12% 6% lzl ≤ 1 lzl ≤ 1 1< lzl ≤ 2 1< lzl ≤ 2 2< lzl ≤ 3 88% 88% CRL-ISS Annual Workshop, 19 October 2007

  28. Cadmium Cadmium z - of z Percentage of -scores scores Percentage Level A Level B 4% 4% 13% lzl ≤ 1 lzl ≤ 1 1< lzl ≤ 2 1< lzl ≤ 2 2< lzl ≤ 3 83% 96% CRL-ISS Annual Workshop, 19 October 2007

  29. Lead Lead z - of z Percentage of -scores scores Percentage Level A Level B 14.4 µg/kg 24.7 µg/kg 4% 4% 13% 25% lzl ≤ 1 lzl ≤ 1 1< lzl ≤ 2 1< lzl ≤ 2 2< lzl ≤ 3 2< lzl ≤ 3 71% 83% CRL-ISS Annual Workshop, 19 October 2007

  30. Pb z z- -scores scores Pb vs 11thPT 10th PT vs 11thPT 10th PT Level A Level B 14.4 µg/kg 24.7 µg/kg 4% 4% 13% 25% lzl ≤ 1 lzl ≤ 1 1< lzl ≤ 2 1< lzl ≤ 2 2< lzl ≤ 3 2< lzl ≤ 3 71% 83% Level A Level B 17.3 µg/kg 39.7 µg/kg 10% 14% 10% 5% 76% 85% 0< lzl ≤ 1 1< lzl ≤ 2 lzl > 3 0< lzl ≤ 1 1< lzl ≤ 2 2< lzl ≤ 3 CRL-ISS Annual Workshop, 19 October 2007

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