R. D. Suenram, Justin Lindsay Neill, Jason J. Pajski, Gordon G. Brown, Brooks H. Pate Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box , Charlottesville, VA Michael Tubergen Department of Chemistry, Kent State University, Kent, Ohio BROADBAND ROTATIONAL SPECTRA OF THE HYDROXY BUTYRIC ACID SYSTEM

Gamma Hydroxybutyric Acid History of abuse since the 1980’s Originally thought to have anabolic effects to increase muscle mass In 2000 it became a Federally controlled substance and was designated a Schedule I depressant Active field of study by Forensic chemists

Gamma Hydroxybutyric Acid GC analysis is difficult because of high polarity and thermal instability. Thus conversion to derivatives is necessary –Gamma butyrolactone –Silyl derivatives

Hydroxybutyric Acids B-Hydroxybutyric acid G-butyrolactone G-Hydroxybutyric acid A-Hydroxybutyric acid

11 GHz CP-FTMW Spectrometer Pulse Monitor 12 GHz Oscilloscope (40 Gs/s) Free Induction Decay 0.5– 11.5 GHz Arbitrary Waveform Generator Chirped Pulse Frequency Sweep 4 GS/s x GHz TWT Amplifier FID acquisition and Fourier transform 9.9 GHz PDRO 2 GHz Bandwidth Nozzle Sample Feed GHz PDRO

AHB Conformer I

AHB Conformer II Spectrum

AHB Structures Gauche-1 Trans-1

Summary of AHB Results

BHB Spectrum

Gauche and Trans BHB

Summary of BHB Results

GHB and GBL Gamma Hydroxybutyric AcidGamma Butyrolactone

GBL Spectrum

GHB Survey

Ab Initio Conformers GHB E = 0 cm-1 E = 3 cm-1 E = 95 cm-1 E = 160 cm-1

GHB Conformers

Summary Hydroxybutyric acids have internal H-bond Hydroxyl H to carbonyl oxygen is preferred Theory and experiment agree - generally For the GHB system, the lactone is preferred for analysis because of stability and intense spectrum

Acknowledgements Funding: NSF Chemistry and MRI Program University of Virginia