Sciex API 3000 Versus Finnigan TSQ 7000: A Head to Head Comparison of Linearity #2463
A. Witkowski1 , C. Serpe1 , G. Baker1 , D. Gray1, J. Burrows2, K. Watson2 , J. Chiu2
1BAS Analytics: West Lafayette, IN United States
2BAS Analytics Ltd.: Kenilworth, United Kingdom
ABSTRACT
Purpose
To perform a head to head linearity comparison of the Finnigan TSQ 7000 and the Sciex API 3000 LC/MS/MS systems.
Methods
An LC/MS/MS assay based on solid phase extraction was developed for a proprietary new chemical entity and its metabolite in human plasma. Initially, the assay was validated on the Finnigan TSQ 7000. The assay linearity on the Finnigan was assessed by analyzing 6 replicates of each calibration standard over the validated range, as well as above and below these concentrations. To compare the linearity of the Sciex, the API 3000 was tuned for both analytes and 6 replicates of each calibration standard were run. Both data sets were evaluated by constructing sensitivity plots (response/concentration versus log concentration) and comparing the observed behavior to theoretical models. In addition, the mean percent biases using various regression fits were calculated. The background signal as a function of concentration injected was also examined.
Results
Both LC/MS/MS platforms performed well, and conditions were found that gave less than ~10% average bias on both instruments. Based on the sensitivity plots and their theoretical fits, the Sciex API 3000 is more linear over the validated concentration range. Furthermore, the Sciex showed smaller mean percent bias values than the Finnigan. The Sciex also had lower background signals after high concentrations of drug were injected.
EXPERIMENTAL
Matrix: |
100 μL EDTA human plasma |
SPE: |
Empore Mixed Phase Cation - MPC, 7mm/3mL |
HPLC Column: |
Nova-Pak CN HP Radial Compression cartridge
(5 x 100 mm, 4μm, Waters) |
Mobile Phase: |
50%/50% methanol/80 mM formic acid, pH 3 |
Drug: |
312.8 (m/z) ® 224.3 (m/z) |
Metabolite: |
284.7 (m/z) ® 197.5 (m/z) |
Internal Standards: |
d isotopes of drug and metabolite 3 |
Validated Range: |
Drug = 1 to 250 ng/mL
Metabolite = 10 to 10,000 ng/mL |
Regression Shown: |
1/X Linear |
| Finnigan TSQ 7000 |
|
Parameter: |
Value |
Sheath gas: |
70 psi |
Auxiliary gas: |
40 units |
Capillary: |
300°C |
CID gas: |
Argon |
CID gas pressure: |
~ 2.1 mT |
Collision offset (drug): |
-13.4 V |
Collision offset (ISTD): |
-13.4 V |
Scan time: |
300 msec |
Electron Multiplier: |
1250 V |
Spray Voltage: |
4.5 kV |
|
| Sciex API 3000 |
|
NEB |
12 |
CUR |
11 |
IS |
1800 |
TEM |
400 |
CAD |
4 |
DP |
29 |
FP |
210 |
EP |
-7 |
CE |
16 |
CXP |
13 |
|
Sensitivity Plots
(y/x versus x)
linear y = ax + b
quadratic y = ax2 + bx + c
if no signal observed in absence of analyte,
then intercept = 0 and
linear y/x = a
quadratic y/x = ax + b
Drug Sensitivity
 
Drug % Bias
 
Metabolite Sensitivity
 
Metabolite % Bias
 
Background Signal
 
CONCLUSIONS
- Sciex API 3000 more linear over the validated concentration range than the Finnigan TSQ 7000.
- Sciex API 3000 showed slightly lower percent bias for the calibration standards.
- Sciex API 3000 had lower background signal for drug after injections.
|
