ELECTROCHEMISTRY LABORATORY
     
AMOUNT OF SUBSTANCE pH ELECTROLYTIC CONDUCTIVITY
     
      AMOUNT OF SUBSTANCE (Inorganic analysis)
       
 

Quantity - Amount of substance

     

Unit - the mole is the amount of substance of a system which constains as many elementary entities as there are atoms in 0.012 kilogram of carbon 12; its symbol is "mol". When the mole is used, the elementary entities must be specified and may be atoms, molecules, ions, electrons, other particles, or specified groups of such particles. The mole is a base unit of the Systeme International d'Unites.

  Tasks
     

The main task is the realisation of base unit mole and its transfer into reference materials.

  International comparisons
     

The accuracy of measurement is substantiated by comparisons organised by BIPM (CCQM-P7, CCQM-P19.1, CCQM-K8, CCQM-P36, CCQM-K42, CCQM-K29, CCQM-K59).
    Available metrological services
      Certified reference materials (CMRs) of chemical composition - pure substances with expanded uncertainty 0.004 % to 0.012 % and calibration solutions with expanded uncertainty 0.2 % to 0.3 %.
 
Methods of measurement:
      - the amount content in primary CRMs is certified by high-accuracy coulometric titration.
 - the mass concentration of monoelemental or anion calibration solutions is certified by refined methods of classical analysis traceable to primary CRMs or directly on the National Standard.
   
    Instruments in use
      National Standard for Amount of Substance High accuracy coulometric equipment, declared as National Standard for Amount of Substance. Measuring range is 0.0001 mol to 0.01 mol. The measurements are traceable to the value of the Faraday constant and Slovak standards of electric resistance, voltage, time and mass.
     
Contact
Dr. Michal Máriássy
phone: + 421 2 60294 522
e-mail: mariassy@smu.gov.sk
   
     
pH
       
  Quantity - pH.
  Unit - dimensionless.
  Tasks
     

The main task is the realisation of the unit of pH. The unit is further transfered by means of Certified Reference Materials.

  International comparisons
      The accuracy of measurement substiated organised by BIPM (CCQM-K9, CCQM-K17, CCQM-P37, CCQM-P52, CCQM-K18) and  organised by COOMET 322/Ru/04.
    Available metrological services
     

Establishing of traceability of pH by the means of CRMs. Production and distribution of primary cerified reference materials - buffers pH range from 1 to 10 with expanded uncertainty 0.005 - 0.02.
 
Methods of measurement:
      - primary buffers are  certified by definition method in Harned's cell,
- secondary CRMs of I. order are traceabled to primary CRMs by measurement in the definition cell with two hydrogen electrodes,
- secondary CRMs of II. order are traceabled to primary CRMs by measurement in the cell with transfer through a glass electrode.
      Traceability is disseminated by means of primary CRMs in the following nominal values: 1.679; 4.000; 7.000; 9.180; 10.000.
   
    Instruments in use
      SMU standard of pH

A National Standard equipment for a determination of defined pH values, consists of hydrogen electrodes, silver - silver chloride electrodes, cell without junction potencial, high purity conditioned hydrogen.
pH range of measurement within 1 to 10.
Expanded uncertainty (k=2) of pH measurement 0.002 to 0.005.
Temperature range of measurement 10°C to 60°C.
 
     
Contact
Dr. Anna Mathiasová Mr. Leoš Vyskočil
phone: + 421 2 60294 226 phone: + 421 2 60294 225
mathiasova@smu.gov.sk vyskocil@smu.gov.sk
   
     
ELECTROLYTIC CONDUCTIVITY
       
  Quantity - electrolytic conductivity.
     

Unit - the unit of electrolytic conductivity is S/m (Siemens per meter). It is defined as the conductivity between two oposite faces of the cube with 1 m edge, filled with the measured solution.

  Tasks
      The main tasks are maintenance, improvement of the realisation and dissemination of the unit of electrolytic conductivity, realisation of the primary standard and certification of the primary Certifed Reference Materials (CRMs) as a means for certification of secondary CRMs. Traceability chain is realised by means of CRMs
  International comparisons
     

2001 - Trilateral measurement comparison - PTB (DE), SMU (SK), UkrCSM (UA); pilot SMU.
2001 - CCQM-P22 (pilot DFM)

2003 - CCQM-P47 (pilot NMi)

2005 - CCQM-K36 (pilot DFM)
    Available metrological services
      Production of electrolytic conductivity CRMs with following nominal values: 0.01, 0.02, 0.05, 0.1, 0.2, 0.5, 1 and 2 S/m. Calibration of conductivity cells. Calibration of solutions supplied by the customer
 
Methods of measurement:
      The measurement system for conductivity is based on the comparison bridge method in a two-electrode Jones cell. The primary RMs (water solutions of KCI) are measured by means of primary standard od electrolytic conductivity in the measuring range of 0.01 - 2 S/m at the temperature of 25.00°C.
       
    Instruments in use
     
Conductivity cell with exchangeable central part		 Measurement of electrolytic conductivity is performed in a cell with exchangeable central tube whose length and cross-section are known. Conductivity is measured by means of an alternating current at a 1000 Hz frequency
Metrological parameters: conductivity range is 0.01 S/m - 2 S/m; relative standard uncertainty, type A is EA = 0.00006; relative standard uncertainty, type B is EB = 0.00023; relative combined standard uncertainty is EC = 0.00024.
                         
     
Contact
Mr. Leoš Vyskočil
phone: + 421 2 60294 225
vyskocil@smu.gov.sk