Presentation on theme: "1 Programa MERCOSUR de Comparaciones Interlaboratorios."— Presentation transcript:
1 Programa MERCOSUR de Comparaciones Interlaboratorios
2 Hola, buenas dias soy Miguel Scheutwinkel
3 Hallo, thank you for coming.
4 Programa – Presentación del desempeño del proyecto de los ensayos interlaboratorios por el OA nacional – Introducción a la segunda ronda (Dr. Scheutwinkel), Criterios de evaluación, metódos de referencia, estadística, valores de orientación – Pausa de café – Fechas y organización del PT (Dr. Scheutwinkel) Discusión – Pausa de almuerzo – Presentación y evaluación de los resultados de la ronda intermedia de suero de leche en polvo (experto nacional a designar por los OAs)
5 Secunda Ronda in Alimentos
Proyecto: PT-ILC MERCOSUR BMZ PTB - LATU ONACGCREOUA Luis Mussio PT- Provider / Resp. de Evaluación OAA Material de ReferenciaLaboratorio de Referencia MUESTRA Alimentos LABORATORIOS CLIENTE / INDUSTRIA Rol de NMI Chile
7 Muva Dr. Leist and his team Changes in organization of PT Rounds Before Now
Statistical evaluation of results Basis ISO-Guide 43-1 Statistical analysis Reference value Standard deviation of PT Consensus valueDefined by provider Condition: 3x greater than variation from material! Limits for successful participation successful not successfulquestionable ISO ISO 5725 ISO ISO 5725
9 After long discussions it was decided to follow the European Approach in addition with South American results. Means: The best estimate of the true value is based on the value, obtained by those laboratories applying the reference method. And in addition only South American results, same as was applied in the intermediate round. 80 Labs
10 Uncertainty of reference value: The higher value of the reference method´s confidence interval (Europe) or of the material´s uncertainty will be attributed to the reference value. Range of variation of best estimate of the true value:
11 U = confidence interval at 95 % confidence level t = factor t de Student s = desviación estándar of best estimate of true value n = número de ensayos Uncertainty of the best estimate of the true value: Uncertainty of reference value: The higher value of the - reference method´s confidence interval (Europe) or of - the material´s uncertainty will be attributed to the reference value.
Stastistical evaluations will be based on true values achieved by those laboratories using the reference method after the Grubbs outlier test. Laboratories will receive values for: Stastistical evaluations will be based on true values achieved by those laboratories using the reference method after the Grubbs outlier test. Laboratories will receive values for: z-score CRD- value z-score CRD- value
Calculation of difference of Laboratory mean – Mean of all values = di Calculation of buffer size = di / standard deviation by comparing buffer size with Grubbs-values (dependent on number of participants n) an outlier exists, if the buffer size is bigger than the Grubbs-value. The results are acceptable, if the buffer size is smaller than the Grubbs-value. The Grubbs-test will be repeated until no outliers are detected anymore. Grubbs outlier test
14 X lab = laboratory value X reflab = best estimate for the true value (EU oe SA) u r = SD of reflabs (EU or SA) u m = standard uncertainty of the material The z-score gives the difference of the laboratory result to the mean of all reflabs in units of standard deviations taking the standard deviation of the material and the standard deviation of testing values of the applied reference method in this ILC into account. z-score
The z´-score is a performance criterion for the laboratory (acc. to ISO Statistical methods for use in proficiency testing by interlaboratory comparison). It is calculated by dividing the difference between laboratory mean and the best estimate of the true value (reference value from the actual PT-scheme) by the square root of the sum of the squared standard deviation of the material and the squared standard deviation of testing values of the applied reference method. Performance is questionable for (absolute) z-scores between 2 and 3 and unsatisfactory for absolute values exceeding 3. z-score
16 Incertidumbre de medición y distribución normal
Example for z´-score calculation in determination of fat: X lab = laboratory value = 0,86 % X ref = mean of laboratory having applied the reference method (EU or SA) = 0,78 % u r = standard deviation of reference labs (EU or SA) = 0,11 % u m = standard uncertainty of the material = 0,015 % 2
18 m = mean value of all labs x i = result of the individual lab s = standard deviation of all labs after outlier test S met = S R of reference method z-score The z-score gives the difference of the laboratory result to the mean of all laboratories in units of standard deviations.
Tabla 1, valores utilizados para el cálculo de Z y Z´ Las unidades de la tabla corresponden a las unidades utilizadas en los informes. Muestra Valor Ref EUSTD EUValor Ref SASTD SAu materialRS(R) Grasa Proteína Lactosa x WL0.021 x WL Ceniza Nitrato Lactico (IDF 69- B) <100 = 15 >100= 0.2 x Wlac x Wlac Materia Seca (IDF 26 A- 1993)
CRD-value CRD-value < 1 = laboratory is satisfying CRD-value > 1 = laboratory is not satisfying CRD-value < 1 = laboratory is satisfying CRD-value > 1 = laboratory is not satisfying
21 New Referencia Eurolab Technical Report No. 1/2007 (March 2007) Measurement uncertainty revisited – Alternative approaches to uncertainty evaluation Eurolab Technical Report No. 1/2007 (March 2007) Measurement uncertainty revisited – Alternative approaches to uncertainty evaluation
23 General information about skimmed milk powder General information about skimmed milk powder Moisture: max. 4 % Ash: 5 – 10 % Fat: max. 1 % Protein: 30 – 50 % Lactose: 40 – 50 %
24 General information about non-defatted milk powder General information about non-defatted milk powder Moisture: max. 4 % Ash: 5 – 10 % Fat: % Protein: 25 – 35 % Lactose: 30 – 40 %
ParameterMethod rRs R CRD Fat Low Fat MP High Fat MP IDF 9C:1987 0,2 % 0,1 % 0,3 % 0,2 % 0,106 % 0,071 % 0,187 % 0,132 % Dry matter 102 °C IDF 26A:19930,2 %0,4 %0,141 %0,265 % Protein (Factor 7,5) § 64 LFGB L /1 0,3 %0,8 %0,283 %0,545 % Ash§ 64 LFGB L entspr. DIN ,06 %0,14 %0,049 %0,094 % Reference methods Dr. Leist,
ParameterMethod rRs R CRD Lactose (enzymatic) § 64 LFGB L True value x 0,05 True value x 0,06 R 2,83 Lactic acid (enzymatic) IDF 69B10 mg/100 g15 mg/100 g5,3 mg/ 100 g 9,354 mg/ 100 g Nitrat (Cd- reduction) DIN EN ISO mg/kg8 mg/kg2,827 mg/kg 5,454 mg/ kg Reference methods Dr. Leist,
28 Training idea: Communication technology, whats the problem? Because of elegant cable technology the structure of the network can be easily explained to anybody.
29 Training idea: Communication technology, whats the problem? The precise documentation of each communication line ensures the safe, fast and confidential access to everybody connected to the system. The massive construction of coverage avoids any manipulation of the sensible technology.
30 The clear and systematic approach seems to be oversized but in any case of emergency this is a real must. Because of precise overview there is always one hand to smoke a cigarette. Training idea: Communication technology, whats the problem?
31 Muchas gracias por su atención !!! por su atención !!!
32 Proyecto: Metrologia Química Which methods are the reference methods....?
33 Determination of Water Content, IDF 26A:1993 Determination of Water Content, IDF 26A: Heat uncovered dish and its lid in the oven at °C for 1 h 2. Cool down in desiccator and weigh to the nearest of 0.1 mg 3. Weigh 1 – 3 g whey powder into the dish to the nearest of 0.1 mg 4. Place it in the oven for 2 h at °C 5. Cool down the dish and weigh to the nearest of 0.1 mg 7. Repeat heating until constant weight (< 0.5 mg to previous weight) Repeatability: Absolute difference between the results of two single determinations shall not exceed 0.2 g of water per 100 g of product. Reproducibility: The absolute difference between the results of two single determinations, found out by different operators shall not exceed 0.4 g per 100 g product
34 Determination of Ash Content, IDF 27:1964 Determination of Ash Content, IDF 27: Heat the platinum or silica dish in the furnace at 500°C for 30 min 2. Cool down in desiccator and weigh to the nearest of 0.1 mg 3. Weigh 2 – 2.5 g whey powder into the dish to the nearest of 0.1 mg 4. Cover wish ashless filter and start ashing using bunsen burner 5. Ashing of content in the dish at 500°C (max. 550°C) 6. Cool down the dish and weigh to the nearest of 0.1 mg 7. Repeat heating in the furnace for 15 min until constant weight Repeatability: Absolute difference between the results of two single determinations shall not exceed 0.15 % of ash.
35 Determination of Fat Content, (Röse Gottlieb), IDF 9C:1987 Determination of Fat Content, (Röse Gottlieb), IDF 9C: After homogeneition about 1.5 g of dried whey (nearest to 1 mg) transferred to fat-extraction flask (Mojonnier type) 2. Prepare a blank test, instead of dried whey take 10 ml water 3. Prepare fat-collecting vessels: drying of vessels, add a few boiling aids, heating at °C for 1 h, cooling down and weigh to the nearest of 0.1 mg. 4. Add 10 ml water at °C to wash the test portion into the small bulb of the flasks until the product is completely dispersed. 5. Add 2 ml 25% ammonia, mixing 6.Heat the flask at °Cin the water bath, occasionally shaking. 7. Cooling down to room temperature
36 8. Add 10 ml EtOH, at least 94% (v/v), mix gently 9. Add two drops of Congo red solution (1 g, dilution to 100 ml) 10. Add 25 ml diethyl ether, shaking vigorously avoiding emulsions 11. Transfer organic layer into fat-collecting vessel by decantation 12. Add 25 ml light petroleum (boiling point 30-60°C) 13. Shaking gently and then centrifuge the flask (500– 600 rpm) 14. Allow the closed flask to stand for at least 30 min (separation of the organic supernatant layer has to be clear and separated from the aqueous layer (if necessary cool the flask 15. Rinsing of organic layer to fat-collecting vessel, adding gently some water to raise the aqueous layer and transfer again organic layer into fat-collecting vessel by decantation
Rinse the outside of the extraction flask with some mixed solvent, collecting the rinsings in the fat-collecting vessel 17. If desired, solvent parts may be removed from the vessel by evaporation etc. 18. Add 5 ml ethanol to the rests in extraction flask 19. Carry out a second extraction by repeating steps 10 to Carry out a third extraction (without addition of ethanol) by repeating steps 10 to Remove solvents from fat-collecting vessel as completely possible (evaporation, destillation) 22. Heat fat-collecting vessel for 1 hour at °C, allow to cool 23. Weigh to the nearest of 0.1 mg. 24. Repeat the heating for checking removal of solvents
38 Determination of Protein Content, IDF 20B:1993, IDF 20:2001, ISO Determination of Protein Content, IDF 20B:1993, IDF 20:2001, ISO Determination of nitrogen using Kjeldahl method Calculation of protein, please use Protein = Nitrogen x 6.38 It must be clarified with Dr. Leist which factor shall be used.
39 Determination of Lactic Acid and Lactates, IDF 69B:1987, IDF 79-1 and IDF 79-2:2002 ISO and ISO :2002 Determination of Lactic Acid and Lactates, IDF 69B:1987, IDF 79-1 and IDF 79-2:2002 ISO and ISO :2002 Both determination are based on enzymatic reactions: ISO IDF 79-1: Utilizes the glucose moiety of the lactose ISO IDF 79-2: Utilizes the galactose moiety of the lactose Please look at GLP requirements in the Annex A
40 Determination of Nitrate and Nitrate, ISO IDF 189 with Parts 1 to 3 Determination of Nitrate and Nitrate, ISO IDF 189 with Parts 1 to 3 Determinations are based on spectrophotometric determinations of nitrite: ISO IDF 189-1:2005 Method using cadmium reduction and spectrometry ISO IDF 189-2:2005 Method using segmented flow analysis (Routine method) ISO IDF 189-3:2005 Method using cadmium reduction and flow injection analysis with in-line dialysis (Routine method) Please take care about repeatability and reprodicibility requirements in standards.