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.