Biomedical Engineering – From Theory to Applications

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Biomedical Engineering – From Theory to Applications
Linearity of the calibration lines is indicated by the values of the corresponding correlation
coefficient (r) and coefficient of determination (r 2). Column coupled techniques show
acceptable linearity, in many cases better as it is in single column systems. Moreover, a
linear dynamic range of the analytes can be considerably extended because of an elimination
of major matrix constituents, higher sample load capacity, and sample preconcentration.
Precision (the repeatability) is usually expressed via relative standard deviation (RSD) of (i)
peak areas measured within the concentration range of calibration line and/or (ii) migration
times of analytes. Hydrodynamically closed separation systems contributed to high
precisions of both the migration and quantitation data in comparison with the flow
electrophoretic and non electrophoretic systems. It is because of a fluctuation of the flow
velocity in the separation system contributing to a dispersion of the data.
Accuracy (expressed via relative error, RE) is evaluated through the recovery test of the
analytes from relevant matrices (dosage form, urine, blood, etc.) at different concentration
levels. Recovery is evaluated by spiking of blank complex matrix (dosage form, urine, blood,
etc.) and water samples with an analyte at different concentration levels and comparing
resulting peak areas of the analyte obtained in the different matrices (spiked complex matrix
vs. spiked water). An on-line sample pretreatment can considerably enhance the recovery and
accuracy of the method due to well controlled sample preparation procedure, minimization of
the analyte losses, and effective elimination of the interfering matrix constituents.
The main performance parameters of particular column coupled methods are introduced in
the Table 1 for a quick overview, what these electrophoretic techniques offer when using
them in biomedical analysis.
Method
(Detection)
LOD
(LOQ)
Capillary arrangement
9.3 ng/mL
ITP-CZE (DAD) (LOQ
28.3 ng/mL)
6.5 ng/mL
ITP-CZE (DAD) (LOQ
9.7 ng/mL)
ITP-CZE (DAD)
ITP-CZE (DAD)
ITP-CZE (UV)
ITP-CZE (UV)
9.3 and 10.4
ng/mL
(LOQ 28.2 and
31.5 ng/mL)
5.2 and 6.8
ng/mL
(LOQ 7.7 and
10.1 ng/mL)
4.8, 1.1, 3.2
ng/mL
(LOQ 16.0, 3.7,
10.7 ng/mL)
250 ng/mL
(LOQ
830 ng/mL)
Linearity
(r)
Precision a
(RSD, %)
Recovery (%),
(matrix)
0.99989 - 104.7 (urine) Robustness