A conductivity standard is a reference solution of a known conductivity value that is used for sensor calibration or verification. Using the correct conductivity standard solution when preparing to perform a conductivity measurement is important for accuracy. Select from our complete portfolio of conductivity standards covering the entire conductivity range, even when working with low-conductivity samples. To minimize the risk of contamination, choose between small bottles and single-use sachets.
Depending on the type of sensor, conductivity standards are used for calibration or verification. Low conductivity standards require special handling and are mainly used for verification purposes. To determine a cell constant, standards of higher conductivity should be used.
For high accuracy, uncontaminated standards are of utmost importance. Sachets ensure a fresh solution with the appropriate volume to perform a calibration or verification directly in the sachet for maximum ease of use. The 250mL bottles enable easy handling and reduce contamination risk in comparison to bulk containers.
A lot-specific certificate of analysis is available for every calibration solution, documenting the quality control and accuracy and providing traceability to national metrology institutes. To support compliance with regulations, all SDS (Safety Data Sheet) and labels contain information according to GHS (Globally Harmonized System) in various languages. Read more
Thanks to the open magazines of the dispenser box, the number of remaining sachets can be easily determined, even from a distance. A re-order indicator helps to prevent running out of stock.
All our conductivity standards are aqueous, avoiding any possible matrix mismatch errors associated with non-aqueous ones. Due to their aqueous composition, our standards are not hazardous and do not present any shipping, storage, or disposal problems. This makes handling easier and saves on lab disposal costs.
Conductivity accuracy strongly depends on sample temperature. Reduce measurement error by using the correct temperature compensation for each standard, which is available in all our meters and printed right on bottles and sachets.
METTLER TOLEDO provides entire electrochemistry systems - from meters and sensors to calibration solutions and software. Benefit from automatic conductivity standard recognition.
We support and service your measurement equipment through its entire life-cycle, from installation to preventive maintenance and calibration to equipment repair.
A conductivity standard is used for calibration or verification. A low conductivity standard requires special handling and is mainly used for verification purposes. Additionally, the low conductivity standard is directly affected by CO2 when in contact with air. Thus, they have a shorter shelf life and require protection with inert gas or the usage of a flow cell. These types of conductivity standards are only intended for verification and not calibration.
METTLER TOLEDO offers certified standard solutions with a conductivity of 10 μS/cm and lower. These standards are only intended for checking the reading of low conductivity measurements because they are easily affected by any mishandling.
10 μS/cm conductivity standard is highly vulnerable and is directly affected by contamination or influence of CO2 when in contact with air. Due to this high likelihood of a quick value change, it is intended only for measurement verification and not calibration.
The 84 μS/cm standard should be used for the best accuracy of low conductivity calibrations. The consistent linearity of METTLER TOLEDO measuring systems between 84 μS/cm and low conductivity values provides much better accuracy than is typically obtained by using standard solutions with a conductivity below 84 μS/cm.
We always recommend calibrating with a 84 μS/cm conductivity standard and checking with the 10 μS/cm standard, even when measuring in very low conducting media such as pure water.
Conductivity standards of 10 μS/cm and lower can only be used for one calibration or verification right after opening. 84 μS/cm standard should be used within one day after opening.
Measurements of samples with conductivity values lower than 10 μS/cm need special equipment and procedures. First, a two-pole cell featuring a low cell constant (0.01– 0.1 cm-1) is needed. InLab® Trace and InLab 741//742 are specially designed for these requirements.
CO2 from the atmosphere greatly influences the conductivity measurement at this low level. To get reliable conductivity results below 10 μS/cm, the following two approaches are recommended:
The sample is protected by an inert gaseous layer of nitrogen or argon to prevent contamination from the atmosphere. This allows the use of normal dip cells to measure samples in the range of 1 to 10 μS/cm.
A closed system, like a flow cell, eliminates the influence of CO2. This is the best practice to measure samples with a conductivity value lower than 10 μS/cm. However, samples with higher conductivities may also be measured in this manner. For non-pressurized samples, flow cells can be used with a peristaltic or a membrane pump, given that they are completely sealed systems. With other types of pumps, the sample or standard comes into contact with the pump, which can lead to contamination and erroneous readings. For sample and standards, the flow must not introduce any air bubbles.
Contamination from one sample to another or from a calibration standard to a sample can cause incorrect readings. Rinsing the flow cell, tubes, and sensor between each measurement helps to prevent this problem. The following steps are recommended:
To decrease the volume of sample or standard solution that is wasted, the rinsing step 2. can also be performed with deionized water instead.