The Flame Ionization Detector - Chromatography Online
WEBDec 1, 2005 · The Flame Ionization Detector. Flame ionization detection (FID) is the most commonly used gas chromatography (GC) detection method. Flame ionization detectors respond to a wide assortment of hydrocarbons, have a large dynamic range, are... Ionization detection methods include flame ionization detection (FID) and, among others, electron-capture ...
Methods for Changing Peak Resolution in HPLC: Advantages and …
WEBApr 1, 2013 · A potential advantage of changing the mobile phase modifier is that improved peak spacing will sometimes allow higher mobile phase flow rate or a shorter column, reducing separation time. The additional advantage of this method is that modern HPLC instruments often offer access to several solvent reservoirs.
Ultraviolet Detectors: Perspectives, Principles, and Practices
WEBOct 1, 2019 · The principle for UV detection is Beer's law, also called the Beer-Lambert law, where. Absorbance (A) = molar absorptivity (ε) × pathlength (b) × concentration (c) Absorbance is defined as the negative logarithm of transmittance, which is the ratio of intensities of transmitted light and the incident light.
Evaluating the Goodness of Instrument Calibration for …
WEBNov 1, 2020 · Consider a calibration curve that extends from 1 ppb to 100 ppb. A residual of 10% at 1 ppb = 0.1 ppb, while a residual of 10 at 100 ppb =10 ppb. Because the squares of the absolute residuals are minimized, then residual for the 100 ppb level will have 10 2 /0.1 2 = 10,000 times more impact than the residual at the 1 ppb level.
How Reversed-Phase Liquid Chromatography Works
WEBAug 1, 2013 · The technique referred to as reversed-phase liquid chromatography (LC) is the workhorse of all LC techniques. Continued improvements in columns, instrumentation, and application methodologies have led to reversed-phase LC being used in more laboratories and delivering results faster, with higher resolution.
About LCGC International - Chromatography Online
WEBJan 1, 2019 · About LCGC International. Founded in 1983, LCGC International is the leading provider of digital and print content to the separation science market, enhancing the productivity, efficiency, and the overall value of separation techniques globally. With our commitment to editorial excellence, we have pioneered innovation across a broad portfolio ...
GC Temperature Programming—10 Things You Absolutely Need …
WEBJun 1, 2015 · 6. To optimize the separation, alter the isothermal temperature in steps of 10 °C, within a range of ±50 °C. If a suitable separation is not obtained a temperature gradient should be used. 7. For splitless injection, the initial oven temperature should be 20 °C below the boiling point of the sample solvent and an initial hold time of 30 s ...
When Should an Internal Standard be Used? - Chromatography …
WEBJun 1, 2012 · The concept of an internal standard (IS) is quite simple — you just add a known amount of the IS to every sample, both calibrators and unknowns, and instead of basing the calibration on the absolute response of the analyte, the calibration uses the ratio of response between the analyte and the IS. External Standardization.
Looking at the Past to Understand the Future: Soxhlet Extraction
WEBAug 1, 2019 · The Soxhlet apparatus is widely available from glassware and laboratory supply vendors and is inexpensive, only $200–300. The cellulose extraction thimble acts as a filter to separate the extract from the solid residue, and, with the extractor, is available in a variety of sizes to accommodate a range of sample sizes.
Mobile-Phase Degassing: What, Why, and How - Chromatography …
WEBJul 1, 2014 · If mobile-phase outgassing occurs within the LC system, the most common problem areas are the pumps and detector. At the extreme, air in the pump will cause the pump to stop delivering mobile phase to the column. If only an occasional bubble is present, the flow rate will be erratic, causing retention time problems.