The resolution of enantiomers often referred to as chiral compounds.
This stationary phase separates enantiomeric compounds. It can be bonded to a solid support or created in-situ on the surface of the solid support. Alternatively it can be surface cavities that will allow specific interactions with one enantiomeric form.
A plot of detector signal output against time or elution volume during the process of chromatography. A trace of the chromatogram usually has increasing signal intensity plotted from the bottom to the top on the Y-axis and time increasing from left to right , with t=0 defined as the time of sample injection.
An apparatus or instrument used to carry out column chromatography, usually HPLC or GC. Separations are based on the physical and chemical properties of the solute molecules in the sample mixture. The compounds are identified with various types of detectors as they exit the chromatograph. Selection of detectors is dependent on the particular compounds of interest.
Techniques in which sample components (analytes and contaminants) are separated as a result of differential intermolecular interactions with a stationary phase in the presence of a mobile phase that flows through that sorbent.
A functional group of an analyte which absorbs UV or visible light.
Abbreviation for maximum plasma or serum concentration.
Abbreviation for critical micelle concentration. Surfactant (detergent) molecules can self-aggregate if the surfactant concentration exceeds a certain critical micelle concentration, or CMC. The formation of micelles or "micellization" is a direct consequence of the "hydrophobic effect". Under reversed phase conditions, the nonpolar, hydrophobic "tail" of the surfactant will be oriented toward the center of the aggregated molecules, whereas the polar "head" groups point out. Micellar solutions may solubilize hydrophobic compounds which would otherwise be insoluble in aqueous-based chromatography systems.
Bonded phase material used for either reversed phase or normal phase chromatography. Slightly polar, with a unique sensitivity for polar compounds in both reversed and normal phase modes. Also known as CyanoPropyl, Cyano, Nitrile, CPS, PCN.
Often abbreviated "CV", the Coefficient of Variation (also known as Relative Standard Deviation, or RSD), is a relative measure of statistical dispersion. It is used mainly for comparing the dispersion of distributions having different expected values. The Coefficient of Variation is the Standard Deviation (SD) expressed as a percent of the mean. CV = SD x 100 / mean.
When two or more solutes elute at the same time, they are said to co-elute. In effect this means that the solutes have not separated and only one peak will be visible on the chromatogram. Consequently, qualification is not normally possible with standard detection techniques.
A term in Mass Spectrometry for the part of a diffusion pump that is positioned above the stack to reduce oil migration to the mass filter.
Refers to Chromatographic Column. Tubing containing a stationary phase for chromatographic separations. The tubular shape permits flow of the mobile phase (gas or liquid) through the column leading to the retention of analytes. Columns are usually constructed of 316 Grade Stainless Steel, although more inert, biocompatible materials are used such as PEEK and Titanium.
The maximum sample weight which can be separated without changing retention time by more than 10%.
This term describes any form of chromatography that uses a column or tube to hold the stationary phase. Examples are HPLC, open column chromatography and open-tubular capillary chromatography.
The time it takes for solvent molecules or unretained sample bands (for which k' = 0 ) to pass through the column. Uracil is often used to measure tO for reversed phase columns. Also known as Void Volume.
A thermostatically controlled oven containing the column, the temperature of which (Separation Temperature or Column Temperature) can be varied within in a wide range.
This term refers to the efficiency of a column, measured as the number of theoretical plates for a given test compound. It is the ability of a column to separate (resolve) the sample components of interest.
This refers to the use of multiple columns connected by switching valves to give better separations or for cleaning up the sample. Fractions from a primary column can be switched to two or more secondary columns, which can, in turn, be switched to more columns or to a detector.
A hole in the column packing, generally at the inlet of the column, or also a settling of the packing at the column inlet to create a space between the top of the packing and the frit. A void usually makes the column unsuitable for use.
The volume of eluent contained in the column. The retention time of an unretained component times the flow rate is equal to one column volume.
Gradient profile in which the rate of increase of strong solvent continuously increases.
The amount of a particular substance in a given quantity of solution, usually stated as the percentage by weight or volume, as weight per unit volume, as molarity or normality.
A device the response of which is proportional to the concentration of asample component in the eluent.
Preparation of the column to receive the sample. For reversed phase, this process first involves solvation of the bonded functional groups with a solvent such as methanol followed by conditioning with a solvent similar to the sample solution, in which the pH and ionic strength have been adjusted if necessary to optimize extraction. This process removes excess methanol and adjusts the pH and ionic strength of the column. Normal phase columns are conditioned with a solvent similar to the sample solvent. Ion -exchange columns are conditioned with a buffer of appropriate pH and ionic strength.
The flow of gas through a system. In a pumping system, the inverse of pumping resistance. Conductance figures relate to the ease with which a vacuum system si pumped; the higher the conductance, the faster the pumping. Each element of a vacuum system has conductance. Generally speaking, the larger the diameter and straighter the path of the pumping system to the pumps, the greater is the system's conductance.
A detector that measures the ability of the solution in the cell to conduct electric current.
The undesired introduction of impurities of a chemical or microbiological nature, or of foreign matter, into or onto a raw material, intermediate, or API (active pharmaceutical ingredient) during production, sampling, packaging or repackaging, storage or transport.
In HPLC, Contour Map refers to a two - dimensional chart of retention time versus wavelength. Lines of equal absorbance are plotted, usually with different colors. These lines form concentric contours around the chromatographic peaks.
A running plot of a performance parameter used to verify that the parameter is within specifications and to predict when repair or replacement will be necessary.
Electronic devices that convert analog signals to digital form (A/D converter), or digital signals to analog form (D/A converter). Most commonly used in HPLC to convert analog signal output from a detector to digital form.
Gradient profile in which the rate of increase of strong solvent continuously decreases.
A compound that binds in a specific way to another molecule. This involves the electrons of the molecules. It is not the same as a covalent or ionic bond. In ligand exchange chromatography, coordination complexes with metal ions bind solutes to stationary phases to effect the separation of compounds such as amino acids and hydroxy acids. Transition metal ions such as Cu++ and Zn++ are typically used to form the coordination complex.
The covalent linkage of two different polymers.
Using sol-gel processing techniques that incorporate nano structuring technology, a durable, homogeneous porous shell is grown on a solid silica core. This highly optimized process combined with industry leading column packing technology produces highly reproducible columns that generate extremely high plate counts.
Materials that are resistant to corrosion, usually caused by high salt concentrations.
Contact with these substances causes destruction to living tissue as well as equipment.
The ionic species that pairs or associates with the ionic functional group of opposite charge which is covalently attached to the surface of an ion exchange sorbent. In order to be retained, a charged analyte must displace the counter ion associated with the ion exchange group.
A preparative-scale chromatographic technique.
This is a form of column switching which uses a primary column connected to two secondary columns via a selector valve. Fractions from the first column can be selectively transferred to the other two columns for additional separation. The term is also used to describe two or more columns connected in series to provide increased plate numbers.
This is a form of column switching which uses a primary column connected to two secondary columns via a selector valve. Fractions from the first column can be selectively transferred to the other two columns for additional separation. The term is also used to describe two or more columns connected in series to provide increased plate numbers.
Chemically bonding adjacent polymer chains. Cross - linking occurs when difunctional monomers are introduced into the polymerization. The degree of cross - linking is dependent on the amount of monomer added to the reaction.
The point in time delineating a fraction collection.
The Coefficient of Variation (also known as Relative Standard Deviation, or RSD), is a relative measure of statistical dispersion. It is used mainly for comparing the dispersion of distributions having different expected values. The Coefficient of Variation is the Standard Deviation (SD) expressed as a percent of the mean. CV = SD x 100 / mean.
The Coefficient of Variation (also known as Relative Standard Deviation, or RSD), is a relative measure of statistical dispersion. It is used mainly for comparing the dispersion of distributions having different expected values. The Coefficient of Variation is the Standard Deviation (SD) expressed as a percent of the mean. CV = SD x 100 / mean.
Cyclodextrin is an enzymatic breakdown product of starch, which is a homogeneous cyclic alpha (1-4) linked glucopyranose. Alpha Cyclodextrin is comprised of 6 glucose units, beta 7, and gamma 8. Cyclodextrins added to HPLC mobile phases and capillary electrophoresis buffers, promote the separation of enantiomers. Cyclodextrin moieties can also be covalently bound to silica or polymer supports to produce chiral stationary phases.