Simultaneous Identification and δ¹³C Classification of Drugs Using GC with Concurrent Single Quadrupole and Isotope Ratio Mass Spectrometers*

Abstract

In this study, δ¹³C values of six cocaine samples were identified and classified using a single quadrupole mass spectrometer and an isotope ratio mass spectrometry (IRMS) as simultaneous gas chromatography detectors. Our instrument modification is simple to use and is useful (i) when the sample is of limited size or can only be injected once, (ii) to help identify peaks in a complicated IRMS chromatogram, and (iii) to help differentiate very simple systems when impurity profiling is not possible. The EI-MS confirmed the identity of cocaine in each sample. The IRMS data distinguished 12 of the 15 possible pair-wise comparisons at the 95% CL. Three samples could not be differentiated by their δ¹³C ratios for cocaine. ANOVA demonstrated that the measurement variance was consistently larger than the sample variance. As the δ¹³C values clearly show, this technique enables the exclusion of a potential common source even when two samples have otherwise identical chemical and physical properties.

Increasing the linear dynamic range in LC–MS: is it valid to use a less abundant isotopologue?

“…This research has focussed mainly on comparing illicit drug seizures with regard to their source. A survey of the literature revealed a large number of measured isotope ratios for individual drug and drug precursor samples . The isotope ratio variation for carbon ( n = 883), nitrogen ( n = 709), and hydrogen ( n = 567) are shown in Figure .…”

Fast profiling of cocaine seizures by FTIR spectroscopy and GC-MS analysis of minor alkaloids and residual solvents

“…Within this group some differences are found: • samples nos. 2,5,9,16,22 show a greater content of acetone, ethanol, and methylene chloride; taking into account that acetone was often found at significative amounts in samples originating from Bolivia [7], samples of this subgroup might be associated to Bolivia as origin country; • samples nos 1,8,12,14,15, and 17 show a higher content of norcocaine (an impurity due to the use of oxidants during the clandestine production; it is not naturally found in coca leaves), 2-propanol, and isopropyl acetate;…”

“…Some examples are the use of a single quadrupole mass spectrometer and an isotope ratio mass spectrometry (IRMS) as simultaneous GC detectors [8], the application of desorption electrospray ionization-mass spectrometry (DESI-MS), [9] and the possibility of feeding a common conventional GC-MS database with data coming from ultra-high-pressure liquid chromatography (UHPLC) [10]. Even if GC-MS currently remains the technique of choice to achieve drug profiling, mainly because it is generally present in most of analytical laboratories, UHPLC-MS/MS allows to avoid the derivatization step, could offer better chromatographic performance, and moves forward to the trend of "fast profiling.…”

Source inference of exogenous gamma-hydroxybutyric acid (GHB) administered to humans by means of carbon isotopic ratio analysis: novel perspectives regarding forensic investigation and intelligence issues

“…Beyond this problem, investigations on intoxication cases and forensic drug intelligence could benefit from such information for the assessment of the linkage between GHB found in a biological sample and drug seizures. Actually, the potential of stable isotope analysis for drug profiling is valuable, as enlightened for cocaine, heroin, amphetaminebased molecules, marijuana and GBL [28][29][30][31][32][33][34][35][36][37]. However, this methodology has only been applied to the raw matrix at present, and linking the aforementioned molecules found in biological fluids and in seizure samples remains a promising topic yet to be explored.…”