Search results
Results from the WOW.Com Content Network
The United States Pharmacopoeia (USP) has classified HPLC columns by L# types. [20] The most popular column in this classification is an octadecyl carbon chain (C18)-bonded silica (USP classification L1). [21] This is followed by C8-bonded silica (L7), pure silica (L3), cyano-bonded silica (CN) (L10) and phenyl-bonded silica (L11).
The specific weight, also known as the unit weight (symbol γ, the Greek letter gamma), is a volume-specific quantity defined as the weight W divided by the volume V of a material: = / Equivalently, it may also be formulated as the product of density, ρ, and gravity acceleration, g: = Its unit of measurement in the International System of Units (SI) is newton per cubic metre (N/m 3), with ...
The SI system after 1983, but before the 2019 revision: Dependence of base unit definitions on other base units (for example, the metre is defined as the distance travelled by light in a specific fraction of a second), with the constants of nature and artefacts used to define them (such as the mass of the IPK for the kilogram).
C18, an octadecyl-type hydrocarbon with 18 carbon atoms, such as Fatty acids such as Stearic acid, C 18 H 36 O 2; Oleic acid C 18 H 34 O 2; C18 bonded silica stationary phase column, a type of reversed-phase chromatography column; IEC 60320 C18, a power connector; Colorectal cancer (ICD-10 code)
Narrow-bore columns (1–2 mm) are used for applications when more sensitivity is desired either with special UV-vis detectors, fluorescence detection or with other detection methods like liquid chromatography-mass spectrometry. Capillary columns (under 0.3 mm) are used almost exclusively with alternative detection means such as mass spectrometry.
A monolithic HPLC column, or monolithic column, is a column used in high-performance liquid chromatography (HPLC). The internal structure of the monolithic column is created in such a way that many channels form inside the column. The material inside the column which separates the channels can be porous and functionalized.
The column used for GPC is filled with a microporous packing material. The column is filled with the gel. Since the total penetration volume is the maximum volume permeated by the analytes, and there is no retention on the surface of the stationary phase, the total column volume is usually large, relatively to the sample volume.
Giorgi later identified the need for an electrical base unit, for which the unit of electric current was chosen for SI. Another three base units (for temperature, amount of substance, and luminous intensity) were added later. [1] The early metric systems defined a unit of weight as a base unit, while the SI defines an analogous unit of mass.