Glossary High Input Impedance Meter It is the measurement device that processes the voltage from the electrochemical cell and converts it into a meaningful measurement unit (pH). The measurement is done with virtually zero current ow to prevent polarization of the electrodes. Modern pH meters also may provide sensor diagnostics, automatic buer recognition, calibration reminders and user prompts. HOLD Function Function that lets the user know when to take readings and freezes the readings on display for easy and accurate recording. HPLC High Performance Liquid Chromatography. HR High Range. HT Glass Designed for extended use at elevated temperature. The glass impedance has a temperature coe«cient of about 14.3% per degree Celsius. HT sensitive glass has an impedance of 400 M at approximately 25°C (77°F). At extremely high temperatures, the impedance drops signicantly. This glass makes it possible to obtain accurate, high temperature pH measurements for extended periods of time 90°C (194°F) and for a few weeks at 100°C (212°F). At room temperature, the response time may increase so additional time for equilibration in buers should be allowed. This glass is clear. HVAC Heating, Ventilating, and Air Conditioning - refers to technology of indoor or automotive environmental comfort. Hygrometer The hygrometer is an instrument used to measure relative humidity (RH), that is, the quantity of water vapor present in the air. Hygrometers are often available in versions that also measure temperature—these are normally called thermohygrometers. IARC International Agency for Research on Cancer iButton® Tags Install the optional TAGs near your sampling points for quick and easy iButton® readings. Each TAG contains a computer chip with a unique identication code encased in stainless steel. Users can order and install a virtually unlimited amount of TAGs to meet any need of traceability requirements. ICUMSA International Commission for Uniform Methods of Sugar Analysis. Incremental Method Incremental Methods are useful techniques used to determine ion concentration quickly in samples whose constituents are variable or concentrated. Incremental Methods have some inherent advantages over direct potentiometry. The techniques can reduce errors from variables such as temperature, viscosity, pH or ionic strength. The electrodes remain immersed throughout the process thus reducing sample carry over and possible liquid junction changes in the reference and analysis steps are reduced. Known addition, known subtraction, analyte addition, and analyte subtraction methods are four of these incremental techniques. All techniques involve adding a standard to the sample, or sample to the standard and the meter calculates the sample’s ion concentration directly. IP Ingress Protection. See page 16.3 IR Infrared. Electromagnetic radiation with a wavelength longer than VIS (according to CIE the IR band is 700 nm to 1 mm). ISA Ionic Strength Adjusters (ISA) are formulated to provide a constant ionic strength in sample and standards alike, thus permitting concentration rather than activity measurements to be made. In some cases ISA’s adjust pH and eliminate matrix eects. ISE Ion Selective Electrode, also known as a specic ion electrode. ISE’s are sensors that convert the activity of a specic ion dissolved in a solution into an electrical potential, which can be measured by a pH meter or a voltmeter. ISO Standards See page 16.5 ISOPOTENTIAL pH Is the pH at which the cell voltage does not change when the temperature changes. ISSS International Society of Soil Science. ITS International Temperature Scale. Junction The junction (the part in contact between the two liquids) is typically made with inert materials that will not increase a junction potential or be chemically attacked by the measured solutions. 16 Glossary 16.10 | www.hannainst.com
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