Certificate of Ana lysis Apura Certified Reference Material Producer: Accreditation: Description of CRM: Lot No.: Composition: Merck KGaA, Frankfurter Str. 250, 64293 Darmstadt, Germany. Merck KGaA, Darmstadt, Germany is accredited as calibration laboratory according to DIN EN ISOIIEC 17025. Water Standard Oven certified reference material for coulometric Karl Fischer Titration in combination with the Karl Fischer Oven technique FN1299854 potassium sulfate I sodium wolframate dihydrate =- Certified value and uncertainty: 0.99% ± 0.02 % (9.9 mg/g ± 0.2 mg/g) water content with expanded uncertainty UcRM Traceability: Method of Analysis: Storage: The certified value of this reference material is directly traceable to SJ-Unit (kg). The water content is determined by coulometric Karl Fischer oven method at 170 C and an extraction time of 600s on 10 samples according to ISO 760. The measurement value is add itionally checked by thermogravimetry as independent procedure. +15 C to +25 C tightly closed in the original container Application and correct use: Th is certified reference material is intended for use as a standard for checking the accuracy of coulometric and volumetric water determinations using a Karl Fischer oven and thermobalances according to ISO 9001 chapter 7.1.5 "Monito ring and measunn g resources". For the daily verification we recommend to accept a deviation of ± 0.03% (± 0.3 mg/g) from the certified value. Date of release: Minimum shelf life: 2016/03/01 2019/02/28 Dipl.-lng. Ayfer Yildirim (Laboratory manager) Merck KGaA Frankfurter StraBe 250, 64293 Darmstadt, Germany: +49 6151 72-0 EMD Millipore Corp. 290 Concord Road, Billerica, MA 01821, USA: +1-781-533-6000
Expanded uncertainty UcRM: The expanded uncertainty UcRM is calculated as UcRM=k-ucRM, where k=2 is the coverage factor for a 95% coverage probability and UcRM is the combined standard uncertainty in accordance to ISO Guide 34. U c RM = 2 2 2 U Characterisation + U Homogeneity + U Stability The combined standard uncertainty UcRM is obtained from the standard uncertainties of the characterisation, the homogeneity and the stability. Ucharacterisation UHomogeneity Ustabillty is the uncertainty in accordance with DIN EN ISO/IEC 17025 which includes the contributions of the primary reference material and the measuring system. Ucharacterlsation in the certified value is calculated in accordance to EA-4/02 and GUM. Ucharacterisatlon is 0.01% (0.1 mg/g) (calculated as Ucharacterisation = k. Ucharactensation with k=2) is the between-bottle variation in accordance with ISO Guide 34. The assessment of homogeneity is performed by analysis of a representative number of systematically chosen sample units-:- is the uncertainty obtained from short-term and longterm stability in accordance with ISO Guide 34. The stability studies are the basis for the quantification of the minimum shelf life of this water standard for the unopened ampoule. Instructions for correct use The oven standard can be used in a temperature range of 150 C and 400 C. A minimum heating time (extraction time) of 300 sec is recommended. The weigh-in quantity for the KF oven technique is usually in the range of 80 mg to 300 mg. Setting parameters for the oven like minimum temperature and heating time as well as optimum sample size of the standard substance could vary depending on the used instrument.