Physikalisch-Technische Bundesanstalt

Tasks

• Reliable measurement of electrochemical measurands, traced back to the SI
  
  • pH-value
  • Ion activity
  • Elektrolytical conductivity
  • Coulometry
• Research and development with respect to metrological aspects of electro-chemical measurement procedures
  
  • Bases of conductivity measurements in the field of pure and ultra-pure water
  • Salinity measurement traced back to the SI
  • Primary basis for measuring the pH of seawater
  • Calibration procedure for ion activity, in particular for clinically relevant analytes
  • Reference procedure for pH-measurements in clinical chemistry
  • Reliable electrochemical quality parameters for biofuels
  • State of Health (SoH) of batteries

Services / Measurement and Calibration Capabilities

pH-value of reference buffer solutions

A primary measurement procedure, which has been agreed at the internal level (IUPAC 2002, DIN 19266), allows the pH-value of reference buffer solutions in the temperature range from 5 °C to 80 °C to be measured with an expanded measurement uncertainty (k=2) in pH between 0.002 and 0.004 (at 25 °C), depending on the buffer.

Ion activity

The miniature ISE flow cell developed at PTB allows the ion activity of the following ions to be determined:

 ¹ can, where appropriate, be adapted; ²coverage factor  k=2

Conductivity of Reference Solutions

The primary conductivity measuring facility for reference solutions developed at PTB allows the conductivity of electrolyte solutions to be measured in the range between 0.1 mS/m and 20 S/m with a relative  expanded (k=2) uncertainty of up to 0.04 %.

Cell Constant of Conductivity Measuring Cells for Applications in the Range of Ultra-pure Water

The measuring facility developed at PTB allows the cell constants of flow cells to be calibrated. It is designed for measuring cells which are used in the field of pure and ultra-pure water and covers the conductivity range from 5.5 µS/m to approx. 15 mS/m with an expanded (k=2) relative measurement uncertainty of approx. 1 %. 

Special Requests

The working group intends to design its measuring facilities as flexible as possible and is at any time open to special calibration requests. We have, for example, already measured the conductivity and the pH-value of paints or fuels.

	Test and Calibration Offer
	Download (PDF file) 250 KBytes
	Calibration and Measurement Capabilities (CMC) Certified measurement capabilities within the scope of the Mutual Recognition Arrangement: http://kcdb.bipm.fr/appendixC/search.asp?reset=1&met=QM

Projects

T2J10/ TRACEBIOACTIVITY (2008-2011)

In medical diagnosis, quantitative information about the chemical active form of the analyte (species) is required.

T2J10 –WP3: Metrological Aspects of Chemical Activity Measurements of Essential Ionic Species

Development of a procedure and establishment of a measuring set-up to measure the activity of ions in the flow. For this purpose, new ISE miniature flow measuring cells are developed and reference materials for calibration of the measurement process in the clinically relevant measurement range (sodium135-150 mmol/L, potassium 3.5-4.5 mmol/L, calcium 1.1-1.3 mmol/L and magnesium 0.7-1.6 mmol/L) and of chloride are characterized. For calculation of the ion activity, the semi-experimental model of K.S. Pitzer is used.

TP2-J10 – WP4: Ionic Contamination of Ultra-pure Water

Development of a procedure and establishment of a measuring set-up to measure the conductivity of ultra-pure water – which is doped with ions in the μmol/L range – in the flow, with traceability to the SI. Part of the task is the development of a general model for determination of the solution resistance for this conductivity range.

ENG09  Biofuels (2010-2013)

ENG09 –WP3: Quality Parameter for Bioethanol

The conductivity and the pH-value are quality parameters which are easy to measure to check the ionic contamination of bioethanol. Within the scope of the project, a primary measurement procedure will be developed to allow the conductivity of bioethanol to be measured with traceability to the SI. The pH-value of bioethanol-water mixtures is measured with a primary pH measurement procedure (Harned cell). The suitability of glass electrode measuring chains for the measurement in bioethanol is investigated.

ENV05 Metrology of Ocean Salinity and Acidity- OCEAN ( 2011-2014)

The project EMRP ENV05 "Metrology of Ocean Salinity and Activity" is coordinated by Petra Spitzer  (Petra.Spitzer@ptb.de), PTB, 3.13.

ENV05 – WP1: Traceability of Practical Salinity based on Density Standards

Development and establishment of a measuring set-up to measure the practical salinity – a measure of the salinity of seawater – traced back to the density at temperatures and pressures which are relevant to oceanography.
The WP is coordinated by Steffen Seitz  (Steffen.Seitz@ptb.de), PTB, 3.13.

Conductivity Measuring Cells for Oceanography

In connection with the ENV05 project, a measuring set-up for the calibration of conductivity measuring cells, which are used in oceanography for pressures of up to 70 MPa (700 bar), is currently being established.

ENV05 – WP3: Primary and Reference Methods for Acidity and Composition of Seawater

In the project ENV05, a primary method for determination of the pH-value of seawater is to be developed and a guideline for field measurements of the pH-value to be drawn up.

Batteries

The working group plans to establish a reference measuring set-up to measure – by means of electrochemical impedance spectroscopy (EIS) – the state of health of Li ion batteries which are used in the field of electric traction.