Horiba LAQUAtwin Conductivity Meter

Conductivity - measurement of the electrical conductivity of water

A large number of parameters play an essential role in the evaluation of water and drinking water quality. One of these parameters is electrical conductivity, which is considered an indicator value for water quality.

It is the measure of the ability of a solution to conduct electric current and depends on the concentration of ions and their mobility.

Conclusions about the water quality can be drawn from the conductivity of the water. Pure water is (almost) non-conductive. Only through substances dissolved in the water, such as carbonates, chlorides or sulfates, can electricity be conducted.

The value of the conductivity measurement can therefore be used to draw conclusions about the quantity of particles dissolved in the water. The more the water contains of them, the more conductive it is.

In other words, the more polluted the water, the better it conducts electric currents.

However, even clean or pure water has a certain, albeit weak, conductivity.

Conductivity analysis, however, does not replace chemical analysis of water, since other dissolved substances, such as pesticides, drug residues, germs, bacteria or hormones, do not conduct and thus cannot be detected by conductivity measurement.

In water treatment as an example, the TDS value is also measured. It is a quantitative measure of the concentration of dissolved, conductive substances present in a solution - in this case water (Total Dissolved Solids).

The TDS value measured here is a sum parameter that provides information about the quantity of these dissolved substances. The basis of the TDS value is again the conductivity measurement. 1 microS/cm corresponds to 0.640 ppm TDS (or mg/l TDS).

Application examples:

The manual conductivity meter LAQUAtwin from Horiba is used, among other things

• in the drinking and waste water sector or water treatment
• in industrial manufacturing processes, e.g. acrylic paints or solvents
• in general quality control
• in food production
• in agricultureWasserqualitätsanalyse

Conductivity measurement is a valuable method for assessing water quality. Electrical conductivity is a non-specific cumulative parameter that provides information about the amount of dissolved substances in water. Dissolved ion species include salts, acids, bases and some organic substances present in the solution. The measured value is proportional to the combined effect of all ions in the sample solution. Therefore, the EC meter (pocket tester for conductivity) is an important tool for monitoring various types of water for quality.

Examples of conductivity of water:

ultra-purified water: about 0.05 μS/cm (non-conductive)

distilled water: up to 20 μS/cm

rainwater: about 30 μS

drinking water: between 300 to 800 μS/cm

seawater: 56 mS/cm

Effects of tap (drinking) water conductivity on health.

If the ions dissolved in the water are only absorbed in low concentrations, this is harmless and even healthy with regard to the dissolved minerals. It so happens that a higher conductivity does not necessarily represent an increased health risk. However, higher concentrations can indicate contamination, which is why more precise water tests, e.g. in the form of a chemical analysis, are required if the limits are exceeded.

In addition, non-conductive dissolved substances, such as germs, bacteria, hormones or pesticides, cannot be detected accordingly via conductivity.

According to the Drinking Water Ordinance (TrinkV Annex 3 to § 7 and § 14), the conductivity limit in Germany is 2790 µS/cm at a constant water temperature of

25 °C or 2500 μS/cm at 20 °C.

During the measurement, the temperature of the sample solution must not fluctuate. For this reason, Horiba pocket testers for measuring conductivity (EC meters) are equipped with a temperature compensator. A deviation from 1 °C already leads to large deviations with regard to the conductivity measured value.

Application examples:

Electrical conductivity of honey

Unlike in the past, the content of minerals and nutrients in honey today is determined by the electrical conductivity. Since minerals and nutrients belong predominantly to the salts, they exhibit - like all salts - a certain electrical conductivity.

Via the different conductivities of the various types of honey, conclusions can be drawn about geographical or botanical origin. This is worth knowing for quality control. To determine the conductivity, an aqueous honey solution must be prepared, which is then placed on the sensor of the EC meter.

Flower honey may have a maximum conductivity of 0.8mS/cm, while the value for forest honeys must be at least 0.8 mS/cm. Since forest honeys generally have a significantly higher mineral content than other varieties, their conductivity is consequently the highest among honeys.

Thus, conductivity analysis with the individual parameter specifics of the individual varieties lends itself to characterizing them and analyzing them for varietal purity - if desired.

The Horiba pocket testers for conductivity allow you to perform the analysis quickly and easily on site.

pH and conductivity measurements in coconut fiber substrate

Coconut fiber is the fibrous material found between the hard inner shell and the outer husk of the coconut. Mature coconuts have strong brown coconut fibers that are typically used for padding, fabric, or in horticulture. Immature coconuts have fine white or light brown coconut fibers that are made to produce household products such as mats, brushes, and ropes. To harvest coconut fiber conventionally, the fibrous husks are soaked in freshwater or seawater to swell and soften the fiber before extraction.

Due to its high lignin content, brown coir fiber has become a popular growing medium in gardening and landscaping because it can store a lot of water and does not shrink when dry. Most commercially available coconut fiber is thoroughly washed to reduce its high sodium and potassium content, as it can be harmful to plants. Then, on the other hand, the substrate is re-enriched with calcium to balance their cation exchange capacity, making the substrate resistant to sudden changes in pH. Good quality coconut fiber is essential to achieve optimal growth for plants. To determine if the coconut substrate is the right quality for its intended use, the conductivity and pH should be checked before use.

Horiba's handheld conductivity meter (EC meter) enables direct analysis within seconds. The dustproof and waterproof pocket meters all feature the automatic calibration function and temperature compensation to ensure accurate and stable measurements.

The EC-22 and EC-33 pocket testers also show the temperature of the measured solution on the display, while the EC-33 pocket tester also measures the solids dissolved in a solution (TDS), which is why it is often used in research, laboratories and universities.

All Horiba Pocket Testers can be stored dry without the highly sensitive sensor drying out.