Identity Efficiency for High-Performance Ambient Pressure Ion Mobility Spectrometry

Abstract

A new approach to reduce the false-positive responses commonly encountered in the field when drugs and explosives are detected is reported for an electrospray ionization high-performance ion mobility spectrometry (ESI-HPIMS). In this article, we report on the combination of reduced mobility and the width-at-half-height of a peak to give a new parameter called conditional reduced mobility (CRM). It was found that the CRM was capable of differentiating between real drugs peaks from that of a false-positive peak and may help to reduce false-positive rates. This effect was demonstrated using 11 drugs (amphetamine, cannabidiol, cocaine, codeine, heroine, methamphetamine, morphine, phentermine, L-phenylepherine, proglitazone, and rosiglitazone) and seven interferences chosen from off-the-shelf products. This report determined and compared CRM, resolving power (R(m)), and diffusion-limited conditional theoretical reduced mobility (DLCTRM) for ESI-HPIMS. The most important parameters for determining CRM are reduced mobility and width-at-half-height of a peak. There is a specific optimum voltage, gate pulse width, resolving power, and now CRM for each ion. DLCTRM indicate the optimum reduced mobility that is not normally possible under field conditions. CRM predicts the condition at which a target compound can be differentiated from a false-positive response. This was possible because different ions exhibits different drifting patterns and hence a different peak broadening phenomenon inside an ion mobility tube. Reduced mobility for target compounds reported were reproducible to within 2% for ESI-HPIMS. The estimated resolving power for the ESI-HPIMS used in this study was 61 ± 0.22. Conditional reduced mobility introduced in this paper show differences between target compounds and false-positive peaks as high as 74%, as was the case for cannabidiol and interference #1 at 70 μs gate pulse width.

Thermal desorption-ion mobility spectrometry: A rapid sensor for the detection of cannabinoids and discrimination of Cannabis sativa L. chemotypes

“…The K0 values of some of these peak signals agreed well with those previously reported in literature, i.e. the protonated monomer of CBD (1.08 ± 0.02 cm 2 V -1 s -1 ) [18] and Δ 9 -THC (1.05 ± 0.0004 and 1.06 cm 2 V -1 s -1 ) [15,18,19]. In these previous studies, only the K0 value of the most intense peak was pointed out in a drift time measurement using TD-IMS [15], while other used electrospray ionization, a soft volatilization/ionization source [18].…”

“…the protonated monomer of CBD (1.08 ± 0.02 cm 2 V -1 s -1 ) [18] and Δ 9 -THC (1.05 ± 0.0004 and 1.06 cm 2 V -1 s -1 ) [15,18,19]. In these previous studies, only the K0 value of the most intense peak was pointed out in a drift time measurement using TD-IMS [15], while other used electrospray ionization, a soft volatilization/ionization source [18]. Moreover, nicotinamide (with a high proton affinity, 918.3 kJ/mol) was employed as an internal calibrant using TD-IMS in the positive ionization mode [15,19].…”

“…However, some drawbacks were reported, such as poor selectivity and the existence of false-positive responses [15][16][17]. Moreover, most of these methods were tested using standards and no real samples [17][18][19][20].…”

Ion mobility spectrometry as a fast screening tool for synthetic cannabinoids to uncover drug trafficking in jail via herbal mixtures, paper, food, and cosmetics

“…Some publications are concerned with the reduction of false positive responses commonly encountered in the field when drugs and explosives are detected. 113,114 The topic of this article is the fast and effective detection of syn-…”

“…With the high sensitivity of IMS, it is possible that disturbing matrix components are detected and generate an alarm due to a false positive result. Some publications are concerned with the reduction of false positive responses commonly encountered in the field when drugs and explosives are detected …”