System
Suitability
According to the USP, system suitability tests
are an integral part of chromatographic methods.
These tests are used to verify that the
resolution and reproducibility of the system are
adequate for the analysis to be performed.
System suitability tests are based on the
concept that the equipment, electronics,
analytical operations, and samples constitute an
integral system that can be evaluated as a
whole.
System
suitability is the checking of a system to
ensure system performance before or during the
analysis of unknowns. Parameters such as plate
count, tailing factors, resolution and
reproducibility (%RSD retention time and area
for six repetitions) are determined and compared
against the specifications set for the method.
These parameters are measured during the
analysis of a system suitability "sample" that
is a mixture of main components and expected
by-products. Table 3 lists the terms to be
measured and their recommended limits obtained
from the analysis of the system suitability
sample (2).
Table 3 - System Suitability
Parameters and Recommendations |
|
Parameter |
Recommendation |
|
Capacity Factor (k’) |
The
peak should be well-resolved from other
peaks and the void volume, generally
k’>2.0 |
|
Repeatability |
RSD
</= 1% for N >/= 5 is desirable. |
|
Relative retention |
Not
essential as long as the resolution is
stated. |
|
Resolution (Rs) |
Rs
of > 2 between the peak of interest and
the closest eluting potential
interferent (impurity, excipient,
degradation product, internal standard,
etc. |
|
Tailing Factor (T) |
T of
</= 2 |
|
Theoretical Plates (N) |
In
general should be > 2000 |
Documentation of system suitability can be
accomplished by using software specifically
designed for the task to provide a review of the
separation and to summarize the data regarding
reproducibility. The software can also be used
to troubleshoot the method. Results stored in a
relational database can be compared and
summarized on a peak-by-peak or system-by-system
basis to provide the feedback necessary to
determine system performance
|
