CENTRO DE METROLOGIA QUIMICA

DEVELOPMENT OF CERTIFIED REFERENCE MATERIALS (CRMs) IN Intec

SELECTION CRITERIA FOR THE CRMs DEVELOPED SO FAR BY Intec FROM INTERVIEWS WITH THE STAFF OF CHILEAN FIELD LABORATORIES AND REGULATORY AGENCIES, THE MOST RELEVANT CRMs WERE IDENTIFIED AT THIS INITIAL STAGE, THE MOST FREQUENTLY ASKED CRMs WERE AQUEOUS INORGANIC SOLUTIONS CONTAINING ANIONS AND CATIONS ONE IMPORTANT CONSIDERATION WAS THAT THE CONCENTRATION OF THESE MATERIALS BE IN THE RANGE THAT IS USUALLY FOUND IN WATER ANALYSES FIELD LABORATORIES

BASIC STEPS FOR THE PREPARATION AND CERTIFICATION OF A REFERENCE MATERIAL  ACQUISITION OR DEVELOPMENT OF THE STARTING MATERIAL  PREPARATION AND BOTTLING OF MATERIAL  ANALYTICAL ASSESSMENT  HOMOGENEITY TESTS  STATISTICAL EVALUATIONOF RESULTS  VALUE AND UNCERTAINTY ASSIGNMENT  PREPARATION OF CRM CERTIFICATE  STABILITY TESTS

PREPARATION OF A REFERENCE MATERIAL CRM or pure salts Type I analytical water

MATERIAL HOMOGENEITY  THE WAY THAT THE HOMOGENEITY TESTS ARE DESIGNED DEPEND ON THE ANTICIPATED NATURE OF THE HETEROGENEITY  RANDOM, STRATIFIED SAMPLING  AFTER SAMPLES ARE SELECTED THE NULL HYPOTHESIS (NO DIFERENCE AMONG THEM), MUST BE TESTED (ANOVA)  THE ANALYTICAL METHOD TO BE USED FOR THIS ASSESSMENT MUST BE THE MOST PRECISE AVAILABLE

CERTIFICATION PROCEDURES OF CRMs PREPARED AT Intec ANALYTICAL METHOD A ANALYTICAL METHOD B PREPARATION CERTIFIED VALUE ± U

ANALYTICAL PROCEDURE FOR CRM CERTIFICATION  VALUE ASSIGNMENT USING BRACKETING TECHNIQUE  INDEPENDENT SAMPLES ARE TAKEN FROM ANY SELECTED BOTTLE  READINGS ARE PERFORMED IN A RANDOM SEQUENCE FOR EACH GROUP OF SAMPLES.  CALIBRATION STANDARDS: CRM (1)  CONTROL: CRM (2)  MEASUREMENT OF BLANK SAMPLES FOR THE WHOLE SEQUENCE  THE ANALYTICAL PROCEDURE IS REPETEAD ON A SECOND DAY

CONCENTRATION VALUE ASSIGNMENT AND ITS UNCERTAINTY PREPARATION AND ONE INDEPENDENT ANALYTICAL METHOD  CRM CONCENTRATION VALUE  COMBINATION OF PREPARATION VALUE WITH THE MEAN VALUE OBTAINED FROM ANALYTICAL METHOD  EXPANDED UNCERTAINTY  IT IS OBTAINED THROUGH THE COMBINATION OF THE STANDARD UNCERTAINTIES OF PREPARATION AND ANALYTICAL METHOD; u c IS MULTIPLIED BY A COVERAGE FACTOR, ADDING THE BIAS ALLOWANCE U= ( 2  u c )+ 

CONCENTRATION VALUE ASSIGNMENT AND ITS UNCERTAINTY TWO INDEPENDENT ANALYTICAL METHODS  WEIGHTED MEAN COMPUTATION (PAULE Y MANDEL)  UNCERTAINTY ESTIMATION OF THE MEAN VALUE FOR EACH METHOD  BETWEEN-METHOD VARIANCE ESTIMATION AND CALCULATION OF THE STATISTICAL WEIGHTS OF BOTH METHODS  CALCULATION OF THE WEIGHTED MEAN AND ITS COMBINED VARIANCE  ESTIMATION OF THE EFFECTIVE DEGREES OF FREEDOM FOR THE COMBINED VARIANCE  CALCULATION OF THE STATISTICAL INTERVAL FOR THE CERTIFIED VALUE U= ( 2  u (VC) ) + 

STABILITY TESTS

ANIONIC REFERENCE MATERIALS RM ELEMENT CONCENTRATION U mg/L mg/L INTEC-I-002 LOT N°002: Cl F INTEC-I-002 LOT N°003: Cl F INTEC-I-005 LOT N°001: Cl F NO SO 4 = CRMs PREPARED AND CERTIFIED BY Intec

CATIONIC REFERENCE MATERIALS RM ELEMENT CONCENTRATION U mg/L mg/L INTEC-I-004 LOT N°001 : Mn Cu Zn Fe As (  g/L) (  g/L) INTEC-I-004 LOT N°002: Mn Cu Zn Fe As (  g/L) (  g/L) CRMs PREPARED AND CERTIFIED BY Intec

CRMs APPLICATIONS CONTROL MATERIALS IN MEASUREMENT PROCESSES CALIBRATION STANDARDS INTERCOMPARISON STUDIES ORGANIZED AND CARRIED OUT BY Intec

CRMs UNDER DEVELOPMENT AT Intec  CYANIDE IN AQUEOUS SOLUTION  ADDITIONAL CATIONS IN AQUEOUS MATRIX: Cd, Pb, Cr, Se, etc.  PESTICIDES IN HEXANE SOLUTION  Pb, Cu, Cd, Fe and Zn, IN WINE