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 ...
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.
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.
Troubleshooting Basics, Part IV: Peak Shape Problems
WEBJul 1, 2012 · A buffer concentration of 5–10 mM usually is adequate to buffer the mobile phase, column, and injection solvent in reversed-phase separations. If buffer concentration problems are suspected, double the concentration and see if this fixes the peak shape. After the mobile phase is eliminated as the problem source, look to the column.
Going Low: Understanding Limit of Detection in Gas …
WEBLCGC North America May 2021. Volume 39. Issue 5. Pages: 232–235. Limit of detection (LOD) is among the most important and misunderstood analytical variables of merit for both instruments and analytical methods. In this installment, we review the history and fundamentals for determining and reporting LOD for analytical instruments and methods.
The Vital Role of Blanks in Sample Preparation - Chromatography …
WEBAug 1, 2018 · Matrix blank: These blanks contain all sample components except the analytes of interest and are subject to all sample processing steps. They are used to measure the presence of significant interference from the matrix. Method blank: Method blanks are used to determine background contamination …
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.
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.
Precision of Internal Standard and External Standard Methods in …
WEBApr 1, 2015 · Internal standard methods are used to improve the precision and accuracy of results where volume errors are difficult to predict and control. A systematic approach has been used to compare internal and external standard methods in high performance liquid chromatography (HPLC).
Validation of Stability-Indicating HPLC Methods for …
WEBNov 1, 2020 · This installment is the third in a series of three articles on stability testing of small-molecule pharmaceuticals. This article provides a comprehensive and updated overview of the validation of stability-indicating methods for drug substances and drug products, and addresses regulatory requirements, validation parameters, methodologies, acceptance criteria, trends, and software tools.