Development and comparison of low- and high-field quantitative nuclear magnetic resonance (qNMR) and gas chromatography–mass spectrometry (GC–MS) approaches to the analysis of bulk cocaine samples seized by law enforcement

Quantitative analysis of seized or surrendered drug samples provides valuable insight for health-related services (e.g. treatment, harm reduction) and judicial services (e.g. intelligence gathering). Cocaine is frequently encountered in these samples. This study utilises low- (60 MHz) and high- (500 MHz) field 1 H NMR spectroscopy to quantify cocaine hydrochloride or freebase present within a sample. Method validations were performed on cocaine hydrochloride (in D 2 O) and cocaine freebase (in CDCl 3 ) showing good linearity (R 2 = 0.9967–0.9995), precision (1.53–3.54% RSD) and accuracy (98.4–99.5%). LoD (0.289–0.724 mg/mL) and LoQ (0.875–2.193 mg/mL) were obtained with sample recoveries within acceptable ranges (87.3–111.0%). Quantification was performed using an internal standard (TMS or TSP, median values = 89.39% w /w ( n = 93) and 90.10% w/w ( n = 96) for low- and high-field NMR respectively) or against an externally collected reference standard (median values = 89.90% w /w (n = 93) and 88.43% w/w (n = 96) for low- and high-field NMR respectively). Sample quantification was similar to GC–MS (median value = 84.80% w/w ( n = 92)). Comparable data showcases that acquisition of low-field NMR data can provide relevant and timely (~6 min) quantification of samples containing cocaine. • Cocaine hydrochloride ( n = 87) or freebase samples ( n = 10) were quantified by low- (60 MHz) and high- (500 MHz) field NMR, and GC–MS. • NMR quantification at high- and low-field using an internal standard (TMS or TSP) or an externally collected reference standard produced median values of cocaine content of 89.39–90.10% w /w and 89.90–88.43% w/w respectively. • The median value for cocaine content determined by GC–MS was 84.80% w/w.