Glossary pH Glass Electrode [IUPAC] Hydrogen ion responsive electrode usually consists of a bulb, or other suitable form of special glass attached to a stem of high-resistance glass complete with internal reference electrode and internal filling solution system. Other geometrical forms may be appropriate for special applications. Photometer An instrument used for measuring of photometric quantities by means of a photoreceptor. PID Controller Proportional-Integral-Derivative controller. PLC Programmable Logic Controller. Potentiometric Titration A Potentiometric Titration can increase the precision of ISE measurements and also the number of ionic species that can be determined. ISEs are commonly used as indicators for the titrant or sample species to follow the progress of a precipitation or complexometric titration. A small change in reactant addition corresponds to a large change in electrode potential at its stoichiometric endpoint. An example of a precipitation titration is the determination of chloride using silver nitrate. A silver ISE can be used to follow this titration. A complexometric titration is used for the determination of calcium. A calcium solution is titrated with the complexing reagent EDTA. During the titration, there is a gradual decrease in the free Ca2+ ion concentrations as more EDTA is added. The endpoint corresponds to the point when all the Ca2+ is complexed. The progress of this titration can be monitored using a calcium ISE. ppb parts per billion; as concentration: 1 ppb = 1 μg substance /L solution. ppm parts per million; as concentration: 1 ppm = 1 mg substance /L solution; 1% = 10000 ppm. ppt parts per thousand; as concentration: 1 ppt = 1 g substance /L solution. Pre-amplified Electrode Hanna electrode containing an internal pre-amplifier. The preamplifier converts the high impedance signal from the pH glass to a low impedance signal thus allowing the user to use long runs of sensor cable with ordinary connectors without noisy or voltage drops resulting in erroneous measurements. Precision The precision of an analytical procedure expresses the closeness of agreement (degree of scatter) between a series of measurements obtained from multiple sampling of the same homogeneous sample under the prescribed conditions. Precision may be considered at three levels: repeatability, intermediate precision and reproducibility. Precision should be investigated using homogeneous, authentic samples. However, if it is not possible to obtain a homogeneous sample it may be investigated using artificially prepared samples or a sample solution. The precision of an analytical procedure is usually expressed as the variance, standard deviation or coefficient of variation of a series of measurements. Intermediate precision expresses within-laboratories variations: different days, different analysts, different equipment, etc. Pt100 The most common RTD sensor using platinum is the Pt100, which means a resistance of 100Ω at 0°C with a temperature coefficient of 0.00385Ω per degree Celsius. Similar for Pt1000. PTFE PolyTetraFluoroEthylene. Porous PTFE is a hydrophobic material that is available with different porosities. Because of its chemical advantages, PTFE is widely used in industrial applications. PVC Polyvinyl chloride. PVDF Polyvinylidene Fluoride—a highly non-reactive and pure thermoplastic fluoropolymere. PWT Pure Water Test. QC Quality Control. Range The range of an analytical procedure is the interval between the upper and lower concentrations of analyte in the sample (including these concentrations) for which it has been demonstrated that the analytical procedure has a suitable level of precision, accuracy and linearity. RDT Resistance Temperature Detectors. 16 Glossary 16.13 www.hannainst.com |
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