Chromatography Glossary



A solution that intentionally has no analyte present in it. In HPLC, it usually refers to an injection of the sample solvent. It is designed to monitor the introduction of artifacts into the measurment process.

Blank Run

Blank Run is the elution of a column with no sample injected; used often to look for system noise or drift.

Bonded Phase

A chromatographic support or sorbent in which an organic functional group is covalently bonded to the silica surface in order to produce support materials with a wide range of chemical and physical properties. Typical bonded phases are octadecyl (C18), octyl (C8), cyanopropyl (CN).


Lack of analyte retention that occurs when the total mass of the solutes (analyte plus interferences) that are present in the sample loading step exceeds the capacity of the sorbent, or in situations in which the loading conditions are not properly optimized.

Breakthrough Volume

Is the volume at which the solute of interest pumped continuously through a column, will begin to elute. The breakthrough volume is useful in determining the total sample capacity of the column for a particular solute.


Abbreviation of Bovine Serum Albumin, a common bovine protein often used as a ligand in biochromatography and chiral chromatography.


The second term of the van Deemter equation. It is also known as the longitudinal or axial diffusion term. This is important in bandspreading at very low flow rates below the minimum plate height, where the diffusion of individual solutes can occur in a longitudinal direction on the column. Also known as as the Molecular diffusion term.


Aqueous solutions that efficiently resist and prevent major changes in pH following the addition of acid or base; this is due to the presence of either a weak acid and its conjugate base or a weak base and its conjugate acid that have pKa values near the target pH.

Bulk Active Ingredient

Any substance or mixture of substances used in the manufacturer of a therapeutic that furnishes the pharmacological activity of the drug product.


Bonded reversed phase material also known as Trimethylsilyl, TMS, Methyl silane or SAS. Offers unique selectivity for polar and multifunctional compounds and is least retentive of all alkyl bonded phases for non-polar solutes.


Bonded reversed phase material. More retentive than C1, but less than C4, C8, C18 etc. Also referred to as RP-2 or ethyl silane.


Bonded reversed phase material.Used in Hydrophobic Interaction Chromatography (HIC) of proteins and peptides. Also referred to as propyl or propyl silane phase.


Also known as butyl or butyl silane phase, a reversed phase bonded material. Useful in ion Pairing chromatography. Offers less retention than C8, C18 phases for non polar solutes. Is an ideal phase for analyzing large proteins and peptides when bonded to a 300Å silica particle.


Also known as pentyl or pentyl silane phase, a reversed phase bonded material. Offers less retention than C8, C18 phases for non polar solutes.


Also known as hexyl or hexyl silane phase; a reversed phase bonded material. Useful in ion pairing chromatography. Offers less retention than C8, C18 phases for non polar solutes.


Also known as MOS, RP-8, LC-8 or Octyl. Bonded reversed phase material. Similar selectivity to C18 but less retentive. Wide applicability - pharmaceuticals, nucleosides, steroids, etc.


Also known as ODS, ODS-2, RP-18, LC-18 or Octyl Decyl and is the most retentive of all bonded phases for non polar solutes, but with similar selectivity to C8.


The systematic determination of the relationship between the response of the measurement system and the concentration of the analyte of interest.

Instrument calibration performed before any samples are analyzed is called "initial calibration." Subsequent checks on the instrument calibration throughout the analysis are called "continuing calibration."

Sample Calibration is performed after instrument calibration. During sample calibration, the detector response is related to standards of known concentration.

Calibration Compound (External Standard)

In Mass Spectrometry, a component of the sample introduced in the LC for the purpose of generating a quantitation data base.

Calibration Compound (Internal Standard)

In Mass Spectrometry, a chemical introduced into the MS system for the purposes of tuning, adjustment, alignment, and mass calibration. PFTBA is a commonly used calibration compound.

Calibration Curve

A plot of peak area or peak height versus concentration or mass injected. Used to calculate component concentrations where the detector response is non-linear.

Calibration Standard

In chromatography, a sample of known concentration, used to obtain obtain a response from an instrument. This response can then be correlated to samples of unknown concentration in order to accurately quantify them. A set of standards may be used if the response factor is not linear with concentration range.


The motor driven, eccentric rotary component that drives the piston of a reciprocating piston pump.


The total mass of solutes (target analytes plus interferences) that a given sorbent mass can retain under a specific set of loading conditions. More generally, the maximum amount of sample/matrix that can be loaded without decreasing the recovery of the target analyte(s). An overload can occur either on the column (i.e., isotherm) or in the detector (i.e., signal).

Capacity Factor (k')

In terms of measured parameters, the capacity factor is: k' = (tr - to)/to: Where is the (tr) is the retention time of the measured peak and (to) is the retention time of a non retained component.

Capillary Column

A general term for columns having a small diameter. A capillary column may contain a packing or have the stationary phase supported on its inside wall. With regards to mass spec, capillary columns are small-diameter columns generally without packing material. The flow rates of many capillary columns are acceptable for direct introduction into mass spectrometer.

Capillary Direct Interface

In mass spec, an inlet that accepts a capillary column. The column effluent is routed directly into the ion source.

Capillary Tubing

This is the tubing that connects various parts of the chromatograph. Most analytical HPLC tubing is <0.010in in internal diameter. The smallest diameter which could be of any use is approximately 0.004in. The outer diameter of capillary tubing is typically 1/16".

Capture and Hold Principle

A term used in Mass Spectrometry for a type of vacuum pump that removes molecules and other specis by collecting them on an absorbent.

Carbon Load

The carbon load is a number which indicates the level of carbon (carbon-based functional groups) covalently bound to the support surface. The value is given as a percentage in terms of the ratio of carbon weight due to the bonded phase of the support.


Is the term used in affinity chromatography. It refers to the support used to carry the active ligand, usually by a covalent bond.

Carrier Gas

The gas passing through a GC column.

Cartridge Column

This is a type of column with no endfittings. It is a replaceable tube packed with stationary phase.


The electrode at which reduction occurs in electrochemical cells.

Cation Exchanger

A negatively charged sorbent that retains cations.


Also known as flow cell. The small chamber in the detector in which sample eluent passes through. Response to component concentrations are measured as the eluent passes through. Micro LC requires smaller cell sizes (>5uL) in order to reduce extra-column effects.


Is a carbohydrate polymer consisting of 1,4B linked glucopyranose units found typically in the walls and skeletons of plant cells. Cellulose-based chiral stationary phases are widely used in biochromatography and chiral chromatography.

Cellulose Acetate

Used to make filter membranes and are compatible with aqueous solutions only. Cellulose Acetate membranes exhibit ultra-low protein binding and are broadly used in the filtration of biological samples.

Chain Length

Refers to the length of the carbon chain in the hydrocarbon part of a bonded reversed phase packing. It is expressed as the number of carbon atoms eg C4, C8 etc.


This occurs when voids created in the column packing material cause mobile phase and accompanying solutes to move more rapidly than the average flow velocity. This results in band broadening. These voids are created by poor packing of the column or by erosion of the packing.


Any salt which enhances denaturation of proteins.


Precisely deciphering and describing a molecular entity’s physical and chemical properties.

Charge Density

The number of positive or negative charges on a molecule or support.

Check Valve

A valve which allows flow in only one direction.

Chemical Ionization

A "soft" ionization process in Mass Spectrometry, where a selected reagent gas is first ionized. The ionized gas then interacts with the GC eluent forming adduct ions of the compounds in the GC eluent. CI spectra are frequently used to ascertain the molecular weight of the compounds in the sample.

Chemiluminescence Detector

A detector typically used for HPLC which measures luminescent light energy produced by a chemical reaction. This measured signal can then be used as the basis for quantitation.


This is sorption caused by a chemical reaction with the packing material in the column. Most interactions of this type are irreversible. They usually occur on packing containing reactive functional groups such as silanol or bonded amino phases.


A molecular configuration which is not superimposable with its mirror image. Chiral molecules are also called enantiomers or optical isomers.