Getting Started in HPLC

Section 0. The Language of HPLC: R

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

   
RANGE: See ATTENUATION.


 
RECORDER: an LC system module that provides the final chromatogram as a tracing on the recorder chart paper.


 
REFRACTIVE INDEX (RI) DETECTOR: a less popular detector based on change in refractive index of the mobile phase due to the presence of sample; less sensitive than photometric detectors for most compounds, and cannot be used with gradient elution. However it is a more nearly a "universal" detector, in that most compounds will give a response at sufficiently high concentrations. Used mainly for size-exclusion chromatography.


Waters 2410 RI Detector


   
RELATIVE RETENTION: see SEPARATION FACTOR


 
RESERVOIR: in LC the bottle or other container that holds the mobile phase that feeds the pump.


 
RESOLUTION (Rs ): defines how well separated two adjacent bands are. Larger values of resolution mean better separation.


Resolution is the ratio of separation to average baseline width.


   
RESPONSE FACTOR: here it is defined for external-standard analysis as the size of peak X divided by the concentration of X in the calibrator. If the calibration line passes through zero, then the Response Factor is the slope of the calibration line. The concentrations of X in different samples is then obtained by dividing the peak size by the response factor.


The calibration plot is a graphical representation of the relationship between peak size and amount of analyte injected.


   
RETENTION FACTOR (k): see CAPACITY FACTOR.


 
RETENTION TIME (tR): is the time between sample injection (time zero) and the appearance of the band maximum; when all conditions are held constant, the retention time for a given peak (or compound) remains constant.


Retention time can vary with changes in flow or column size.


   
REVERSED-PHASE LC: the most common form of HPLC. Water-containing (polar) mobile phases are used with special column packings that have a hydrophobic (non-polar) surface layer.


 
RUN: a single chromatographic analysis or separation of one sample (one time). In some automated systems, a RUN may refer to a series of chromatograms including both standards and multiple samples in a predefined sequence.


 
   
 

 


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Last revised: April 02, 2001.