( min 65-90% B in 0.5 min 90-5%B in 1 ...)Determination of Acepromazine and its Major Metabolite in Equine Serum by LC-MS/MS using the Finnigan LCQ Deca XP Plus Ion Trap Mass Spectrometer

Mass Spectrometer
Mass spectrometer: Finnigan LCQ Deca XP Plus
Ionization mode: Positive ESI
Temperature: 300 C
Spray voltage: 4.5 kV
Sheath gas: 45 units
Sweep gas: 6 units
Isolation width: 1.5

Standards
Calibration standards were prepared as follows:

Samples
Acepromazine was administered to the horse, and serum samples were drawn 30, 45 min and 1, 2, 4, 6 and 24 hrs after dosing.

Internal Standard
Chlorpromazine at a concentration of 100 ng/mL (9:1 ACN:1 M acetic acid) was used as the internal standard.

Sample Preparation
0.5 mL of the calibration standard/horse serum sample was mixed with 0.6 mL of chlorpromazine internal standard. The standard/sample was then refrigerated for 30 min, centrifuged and the supernatant used for analysis. The resulting internal standard concentration in the calibration standard and the sample was 120 ng/mL of serum.

Results and Discussions
Full Scan LC-MS/MS Analysis

Figure 1 shows extracted ion chromatograms from fullscan MS/MS analysis of acepromazine (ACE), its major metabolite 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) and the internal standard chlorpromazine. These chromatograms represent injection of horse serum containing 2 ng/mL of ACE and HEPS (40 pg on-column). The MS/MS spectra of the three analytes is also shown in Figure 1. The extracted ion chromatograms are generated by summing the intensities of the three most abundant ions in the MS/MS spectra as shown in Table 1.

Quantitation and Linear Dynamic Rang
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