Biomedical Engineering Reference
In-Depth Information
XIC of + MRM (6 pairs): 524.0/184.0 amu from Sample 18 (2 004 S07002 STD8 1 1) of S0700202.wiff (Turbo Spray)
Max. 4.0e6 cps.
2.86
Lysophospholipid524-184
4.0e6
2.61
1.95
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
72
144
215
287
358
429
501
572
643
715
Time, min
XIC of + MRM (6 pairs): 496.0/184.0 amu from Sample 18 (2 004 S07002 STD8 1 1) of S0700202.wiff (Turbo Spray)
Max. 4.9e6 cps.
Lysophospholipid496-184
1.81
4.9e6
1.69
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
72
144
215
287
358
429
501
572
643
715
Time, min
XIC of + MRM (6 pairs): 1088.5/407.1 amu from Sample 18(2 004 S07002 STD8 1 1) of S0700202.wiff (Turbo Spray)
Max. 1.0e5 cps.
ISTD 1088-407
2.08
1.00e5
0.00
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
72
144
215
287
358
429
501
572
643
715
Time, min
XIC of + MRM (6 pairs): 1004.5/393.1 amu from Sample 18(2 004 S07002 STD8 1 1) of S0700202.wiff (Turbo Spray)
Max. 5.9e5 cps.
Metabolite 1004-393
1.10
5.0e5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
72
144
215
287
358
429
501
572
643
715
Time, min
XIC of + MRM (6 pairs): 1074.4/393.1 amu from Sample 18(2 004 S07002 STD8 1 1) of S0700202.wiff (Turbo Spray)
Max. 5.9e5 cps.
Active drug 1074-393
1.53
5.0e5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
72
144
215
287
358
429
501
572
643
715
Time, min
Fig. 7
Representative chromatography of a proprietary assay. The lyso-PLs were resolved from
the analytes and the late elution PLs were washed out of the column via backflush and switching
valve
regression is always preferred over quadratic regression. Justification for using a
quadratic regression must be documented. In general, ESI-LC/MS/MS assays have
tendency to demonstrate a quadratic behavior due to ion evaporation and detector
capacity, especially with wide dynamic ranges (>3 orders of magnitude). Therefore,
the first option to avoid quadratic regression model is to reduce linear range.
Additionally, because APCI-LC/MS/MS assays do not have the same limitations
as ESI techniques, they demonstrate less quadratic behavior and are less prone to
be impacted by matrix effects. Therefore, APCI is preferred over ESI. If the antici-
pated concentrations for study samples cannot be adequately covered in a single
assay with a dynamic range of ~3 orders or less, it is often better to develop two
separate assays with complementary low and high concentration ranges. This elim-
inates excessive dilutions to bring the samples into the validated assay.
Not only will a narrow dynamic range increase the likelihood for a true linear
regression, but it also provides another strategic benefit of a reducing carryover.
Carryover is one of the most commonly occurring issues during LC-MS/MS method