th PT 11 th PT 1 1 Round on Milk 11 Round on Milk Preparation - PowerPoint PPT Presentation

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

Liquid milk CRL-ISS Annual Workshop, 19 October 2007

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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

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

CRL-ISS Annual Workshop, 19 October 2007

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

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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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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