Chemistry Reference
In-Depth Information
Installation Qualification (IQ):
IQ ensures that all the activities associated with
properly installing the instrument (new, preowned, or existing) at the users'
site are documented.
Intermediate:
A material produced during steps of the processing of an API that
undergoes further molecular change or purification before it becomes an API.
Intermediate Precision (formerly referred to as ruggedness):
Precision results
from within-laboratory variations due to random events such as different
days, analysts, equipment, etc. Experimental design should be employed so
that the effects (if any) of the individual variables can be monitored.
Internal Standard:
There are any number of ways to perform absolute quantitation
in demonstrating accuracy and precision in the validation steps. One is to
use an internal standard, which is placed into the sample before any extrac-
tion or isolation steps are performed. This standard, in known chemical
purity, mimics the analyte of interest in efficiency of extraction from the
sample matrix, chromatographic/UV/MS performance properties, and it
elutes close to the analyte of interest but distinct from it in UV/MS profiles.
A useful internal standard will have about the same recovery efficiency as
the analyte itself from the sample matrix. The absolute, ideal internal stan-
dard would be an isotopically (nonradioactive) labeled analyte, in known
chemical and isotopic purity, commercially available at reasonable cost,
which will then have all the same chromatographic/UV/MS properties as
the analyte itself. But, because it is resolvable in the MS from the analyte
itself, it can serve as the perfect internal standard to quantitate recovery and
levels of the analyte itself.
Isocratic:
Use of a constant-composition mobile phase in chromatography.
Linear Regression:
A method that determines the best-fit line through a collection
of data points that represent the paired values of both an independent and
dependent variable.
Linear Velocity (ยต):
The velocity of the mobile phase moving through the col-
umn, in cm/s. Related to flow rate by the cross-sectional area of the
column.
Linearity:
The ability of the method to elicit test results that are directly, or by a
well-defined mathematical transformation, proportional to analyte concen-
tration within a given range.
Lot:
A collection of units of a single type or composition manufactured under iden-
tical conditions that are expected to have the same quality and uniformity
within specifications.
Mean:
The average of a series of measurements.
Mean or Standard Distribution:
The average of the deviations of individual mea-
surements from the average of the group.
Median:
For observations arranged in order of magnitude, the median is the value
for which an equal number of observations are above it and below.
Method Transfer:
Comparison of key validation parameters between two testing sites.
Method Validation:
The process by which it is established, through laboratory stud-
ies, that the performance characteristics of the method meet the require-
ments for its intended purpose.
