Donald A. Cooper

Geo-location of heroin and cocaine by stable isotope ratios

Analyses of the carbon and nitrogen stable isotope ratios in heroin and cocaine samples obtained from different geographic regions indicated stable isotope ratio combinations that were strongly correlated with geographic location. Further analyses of the isotope ratios of morphine derived from the deacetylation of heroin exhibited more pronounced isotopic differences among regions, increasing its potential as a tool for geo-location and for sample-to-sample comparison.

Capillary gas chromatographic-electron capture detection of coca-leaf-related impurities in illicit cocaine: 2,4-diphenylcyclobutane-1,3-dicarboxylic acids, 1,4-diphenylcyclobutane-2,3-dicarboxylic acids and their alkaloidal precursors, the truxillines.

A method has been developed that allows for the detection of the eleven stereoisomers of diphenylcyclobutanedicarboxylic acid in illicit cocaine samples, including alpha-, gamma-, and epsilon-truxillic acids and beta- and delta-truxinic acids. These, and other carboxylic acids, were also detected as ester moieties of alkaloidal impurities in illicit cocaine as well as in alkaloids of the South American coca leaf, e.g., alpha- and beta-truxilline. After lithium aluminum hydride reduction of the acidic and basic extracts of a prepared sample, the reduced species were derivatized with heptafluorobutyric anhydride in the presence of pyridine. The heptafluorobutyryl derivatives of the reduced diphenylcyclobutanedicarboxylic compounds were easily detected on-column at low picogram levels using a moderately polar fused-silica capillary column in the splitless mode and interfaced with a 63Ni electron-capture detector.

Identification of Fentanyl Derivatives

An interpretative approach to the identification of fentanyl homologs and analogs is presented. The techniques employed are liquid/liquid extractions; capillary gas chromatography; and infrared, mass, and nuclear magnetic resonance spectral characterization. Spectral data are presented for eight fentanyl derivatives of clandestine origin.

Determination and in-depth chromatographic analyses of alkaloids in South American and greenhouse-cultivated coca leaves

Methodology is described for the detection and/or determination of cocaine and minor alkaloids in South American coca as well as in greenhouse- and tropical-cultivated field coca of known taxonomy. Coca leaf from Bolivia, Peru, Ecuador and Colombia were subjected to the determination of cocaine, cis- and trans-cinnamoylcocaine, tropacocaine, hygrine, cuscohygrine and the isomeric truxillines. The greenhouse samples were cocaine-bearing leaves of the genus Erythroxylum and included E. coca var. coca, E. novogranatense var. novogranatense and E. novogranatense var. truxillense, and the alkaloids determined were cocaine, ecgonine methyl ester, cuscohygrine, tropacocaine and the cinnamoylcocaines. The tropical-cultivated coca were E. novogranatense var. novogranatense and E. coca var. coca. Cocaine and minor alkaloids were isolated from basified powdered leaf samples using a toluene extractant, followed by acid-Celite column chromatography. The isolated alkaloids were determined by capillary gas chromatography with flame ionization or electron-capture detection. Methodology is also presented for the isolation and mass spectral analysis of numerous trace-level coca alkaloids of unknown structure.

Analysis of manufacturing by-products and impurities in illicit cocaine via high-performance liquid chromatography and photodiode array detection

An high-performance liquid chromatography (HPLC) method is reported for the detection of manufacturing by-products and impurities in illicitly produced cocaine. For the first time peak enriched chromatograms were obtained using HPLC, and were accomplished using reversed-phase chromatography and photodiode array detection. The use of sodium dodecylsulfate as an ion-pairing reagent permitted the simultaneous separation of acids, mono-protic amines and di-protic amines, and, in combination with gradient elution, greatly increased the number of compounds separated. A mixed binary-ternary gradient was used to further optimize the separation. Dual UV detection at 215 and 277 nm was used. The chromatogram at 215 nm consisted first of carboxylic acids such as benzoic acid, cinnamic acid (cis and trans) and several isomers of truxillic and truxinic acid; next the mono-protic amines benzoylecgonine and cinnamoylcocaine (cis and trans); and last a group of compounds which are believed to be isomers of the di-protic amine truxilline. In addition, simultaneous detection at 277 nm permitted the selective detection of various compounds, some of which are additional components. The rapid acquisition of UV spectra greatly facilitated compound identification.

Isolation, identification and separation of isomeric truxillines in illicit cocaine

Abstract Seven out of the eleven possible intact isomeric truxillines present in illicit cocaine have been isolated and identified. These truxilline alkaloids included α-, β-, γ-, δ-, e-, ω- and neo -isomers. The individual truxillines were characterized via high-performance liquid chromatography—diode array detection, capillary gas chromatography—electron ionization mass spectrometry and capillary supercritical fluid chromatography—flame ionization detection. α- and β-truxilline were also identified using nuclear magnetic resonance spectrometry. Good resolution of the intact truxillines was obtained using high-performance liquid chromatography.

High-performance liquid chromatographic analysis of benzodiazepines using diode array, electrochemical and thermospray mass spectrometric detection

Abstract Twenty benzodiazepines were examined via a combination of high-performance liquid chromatography (HPLC)-diode array-dual electrochemical detection and HPLC-thermospray mass spectrometric detection. Although UV detection at 230 nm resulted in extensive overlap of the benzodiazepines, each compound gave unique UV spectra. Twenty percent of the benzodiazepines tested gave response ratios via oxidation detection, and the values obtained were unique. All compounds except chlorazepate gave MH + ions as the base peak via thermospray-mass spectrometric detection with filament off; additional ions were detected for many compounds. Using single ion chromatograms all benzodiazepines can be chromatographically resolved.

Comparative determination of total isomeric truxillines in illicit, refined, South American cocaine hydrochloride using capillary gas chromatography-electron capture detection

Abstract The isomeric truxillines and their hydrolysis products are present as manufacturing impurities in most illicit, refined cocaine samples. Methodology is described for the comparative gas chromatographic determination of total isomeric truxilline manufacturing impurities/by-products, i.e., intact truxillines and their hydrolysis products, in illicit, refined cocaine samples seized in South America. These isomers, namely, alpha-, beta-, delta-, epsilon-, gamma-, omega-, zeta-, peri-+neo- and epi-truxilline, were all quantified relative to mu-truxillic acid, a structurally-related internal standard. In this method, the cocaine samples were first subjected to treatment with boron trifluoride-methanol, followed by lithium aluminum hydride reduction and then acylation with heptafluorobutyric anhydride. The resultant di-heptafluorobutyryl derivatives of the truxillyl and truxinyl diols exhibited excellent chromatography and low-picogram on-column detection when using a moderately polar fused-silica capillary column interfaced with an electron-capture detector. This methodology demonstrated good reproducibility, as determined by the repetitive analysis of a selected illicit cocaine exhibit. The analysis of 117 unadulterated, illicit, refined cocaine samples revealed that total truxilline levels ranged from 0.2–12.3% (w/w relative to cocaine), with the two most abundant truxillines being the alpha- and beta- isomers. Truxilline data for the total individual truxilline isomers in cocaine hydrochloride exhibits from five South American countries are presented.

The Application of Capillary Gas Chromatography-Electron Capture Detection in the Comparative Analyses of Illicit Cocaine Samples

The gas chromatographic detection of manufacturing impurities in illicit cocaine can be enhanced by chemical derivatization and the use of an electron-capture detector. After derivatization of illicit cocaine hydrochloride samples with heptafluorobutyric anhydride, the isolated heptafluorobutyryl derivatives of the cocaine impurities were subjected to capillary gas chromatography-electron capture detection analysis. The on-column detection of cocaine impurities at low picogram levels was possible for compounds such as N-norcocaine and other N-demethylated impurities, amidic by-products, including N-benzoylnorecgonine methyl ester and tertiary amines possessing hydroxy functions. The latter compounds include the so-called hydroxycocaine impurities, believed to be new coca leaf alkaloids. This methodology is especially suited for sample comparison analyses.

The Cocaine Diastereoisomers

In the past, it has been argued in court, from a theoretical basis, that the techniques available to the forensic chemist would differentiate the “cocaines.” This work has moved that argument from the realm of the theoretical into that of experimental fact. The techniques of infrared spectroscopy (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) will unequivocally identify the racemic cocaine diastereoisomer. In addition, this work shows that the enantiomeric form of cocaine can be assigned by crystal tests, IR, and melting point techniques. The pure enantiomers of allococaine and pseudoallococaine were not isolated. This does not create a problem because the techniques of NMR and MS, as performed in this study, will not differentiate enantiomers. Therefore, the logical sequence of first identifying the diastereoisomer (via IR, MNR, or MS) and then determining the chirality by crystal tests, IR, melting points, or optical rotation measurements is valid.