pH, ions, DO, conductivity applications
Measuring concentrations with sensors is one of the simplests analytical methods available. Our experts have compiled numerous application documents on pH, ions, dissolved oxygen, and conductivity measurements of various samples.
Use the filters to search the applications by analyte/parameter, sample matrix, norm, or industry.
- AN-T-235Determination of pH in carbon black
The pH value in carbon black, an essential additive in modern lithium-ion batteries, is accurately and reliably analyzed in this Application Note by using the 913 pH Meter equipped with a Unitrode easyClean according to ASTM D1512 as well as ISO 787-9 and GB/T 1717-1986.
- TA-066Webinars: pH Measurement Made Easy
Even though pH measurement is one of the most often used analytical methods in chemistry and is considered rather simple to perform, several factors have to be taken into account to obtain accurate and precise measuring results. The accompanying article for the two webinars on pH measurement summarizes the most important points. In the first part of the webinar the focus lies on the basics of pH measurement. It gives further insights on which parameters have a direct influence on pH measurement and how to control them as well as electrode selection, maintenance and storage. The second part of the webinar targets troubleshooting of common errors, and tips and tricks for a correct pH measurement in matrices other than simple aqueous solutions.
- AB-221Standard methods in water analysis
This Bulletin gives a survey of standard methods from the field of water analysis. You will also find the analytical instruments required for the respective determinations and references to the corresponding Metrohm Application Bulletins and Application Notes. The following parameters are dealt with: electrical conductivity, pH value, fluoride, ammonium and Kjeldahl nitrogen, anions and cations by means of ion chromatography, heavy metals by means of voltammetry, chemical oxygen demand (COD), water hardness, free chlorine as well as a few other water constituents.
- AN-T-183Ethanol as blending component for petrol – Determination of pHe according to EN 15490
The pHe value is an indicator for the acid strength and shows the presence of strong acids or bases in ethanol. In Europe, ethanol is used as a blending component in gasoline and needs to have a pHe value between 6.5 and 9.0. This Application Note describes a fast and accurate determination of the pHe value using the EtOH-Trode.
- AN-T-211Fully automated wine analysis – Determination of free and total sulfurous acid, reductants, total acidity and pH value according to OIV
The analysis of the reductants, free and total sulfurous acid, pH and total acidity of wine can be performed fully automated on an OMNIS system based on the directive OIV-MA-AS323-04B, OIV-MA-AS313-01 and OIV-MA-AS313-15. Added components like SO2 have preserving properties and affect the microbiological environment (anti-microbacterial and enzyme-deactivating), they trap fermentation byproducts such as acetaldehyde and suppress a coloring into brown. The bound and free sulfurous acid are in an equilibrium with each other and can be determined via iodometric titration. Iodometric titration is also the method of choice to quantify other reductants, such as dyes, tanning agents, degradation products of carbohydrates and ascorbic acid. Finally, the acidity of wine is an important quality parameter, which affects the color and taste of wines. The total acidity and the pH of wine can be determined on the same system. Hence, Metrohm offers an all-in-one solution for the analysis of these mentioned key parameters.
- AB-428Automatic conductometry in water samples with low electrical conductivity in accordance with USP<645>
This Bulletin describes the automatic measurement of conductivity in water samples with low electrical conductivity in accordance with USP<645>. Conductivity measurement is demonstrated on the example of ultrapure water, which is used, among other things, to produce injection solutions in the pharmaceutical sector.
- AN-I-006Chloride content of water samples
Determination of chloride in water by direct potentiometry using the Cl-ISE.
- AN-I-002Low levels of ammonia in distilled water
Determination of ammonia (ammonium) in distilled water by direct potentiometry using the NH3-ISE.
- AN-I-018Ammonium in liquid fertilizer – Reliable determination by standard addition with NH4 - ISE
As nitrogen is essential nutrient for plants, it is an essential constituent of many fertilizers. It is present there in different forms, mainly as ammonium or nitrate. Knowing the nitrogen concentration and the form in which is present helps to select the right fertilizer for the plants. For producers of fertilizers, it is therefore necessary to indicate the concentration of ammonium nitrogen in their product. This Application Note shows how to determine ammonium in liquid fertilizers by means of a standard addition.
- AN-I-022Potassium in surface water – Fast and inexpensive determination by direct measurement
Potassium is naturally occurring in surface water caused by weathering of stones and soil. As potassium in drinking water is regulated and should not exceed a certain threshold value, it is necessary to assess the potassium concentration. This can easily be done by direct measurement using a potassium selective electrode. First, a calibration is performed, afterwards, the samples are measured within tens of seconds. This is a fast, inexpensive and reliable method to determine the potassium content in various water samples.
