SOFT/TIAFT 98 - Chemical Derivatization and the Selection of Deuterated Internal ...

SOFT - TIAFT 1998

Poster Session 4

Friday October 9, 1998

CHEMICAL DERIVATIZATION AND THE SELECTION OF DEUTERATED INTERNAL STANDARDS FOR QUANTITATIVE DETERMINATION: METHAMPHETAMINE EXAMPLE

Dong-Liang Lin¹, Tsung-Li Kuo², Wei-Tun Chang^3,4, and Ray H. Liu⁴

1. Ministry of Justice Bureau of Investigation, Taipei, Taiwan;
2. Department of Legal Medicine, National Taiwan University College of Medicine, Taipei, Taiwan;
3. Central Police University, Taoyuan, Taiwan;
4. Graduate Program in Forensic Science, University of Alabama at Birmingham, Birmingham, AL 35294-2060, USA

Methamphetamine (MA) was selected as the exemplar compound to demonstrate that the most suitable deuterated analog to serve as the internal standard (IS) varies with the adopted derivatization group. Trimethylsilyl (TMS), trichloroacetyl (TCA), and pentafluoropropionyl (PFP) groups and d₅-, d₈-, and d₉-MA were included in this study. Internal standards were purchased from Radian Corp.

Full-scan mass spectra data were used for preliminary selections of candidate ions for selected ion monitoring (SIM) for an analytical protocol. SIM data were then used to calculate the extent, if any, of contribution (by the IS under examination) to the intensity of ions designated for the analyte. Similarly, potential contributions by the analyte to the intensity of ions designated for the IS were also examined. Based on the resulting cross-contribution data shown in the following table, PFP derivatization using d₉-MA appears to provide the more number of ions with least cross-contributions. d₈-MA also provides good results.

Derivatization group Deuterated analog Ions and cross contribution by analog (shown as % inside parentheses)

Analyte Deuterated analog

TMS d₅-MA 130 (2.4), 206 (0.70) 134 (0.57), 211 (0.0)

d₈-MA 130 (0.68), 206 (0.49) 137 (2.3), 214 (0.72)

d₉-MA 130 (0.47), 206 (0.73) 137 (2.4), 215 (0.83)

TCA d₅-MA 204 (0.0) 208 (4.4)

d₈-MA 202 (2.0) 204 (.55) 206 (3.2) 91 (7.1)209 (0.45) 211 (0.0) 213(0.0) 93 (9.0)

d₉-MA 202 (.29) 204 (0) 206 (3.3) 91 (7.0) 209 (0.0) 211 (0.0) 213 (0.0) 93 (5.4)

PFP d₅-MA 118 (3.1), 160 (0.52) 204 (0.23) 163 (0.88) 208 (0.0)

d₈-MA 118 (2.9) 160 (0.93) 204 (0.15) 123 (0.16) 163 (0.38) 211 (0.13)

d₉-MA 118 (2.0) 160 (.62) 204 (.17) 91 (4.5) 123 (0.098) 163 (0.041) 211(0.11) 93 (0.85)

Previous Abstract Friday Index
TIAFT '98 Homepage
TIAFTnet Homepage

Next Abstract