同分异构现象在合成大麻素中普遍存在,因其结构与性质上的差异并不显著,当同时存在时分离鉴定较为困难,为公安实践中合成大麻素的检验鉴定带来了一定的挑战。本研究利用超高效液相色谱-高分辨质谱技术(UHPLC-HRMS)建立了5F-EMB-PICA与5F-MDMB-PICA、ADB-BINACA与AB-PINACA这2对酰胺类合成大麻素同分异构体的检验方法。选用Hypersil GOLD C₁₈色谱柱(100 mm×2.1 mm, 1.9 μm)进行UHPLC分离,以含0.1%甲酸的甲醇溶液和含10 mmol/L甲酸铵的0.1%甲酸水溶液为流动相进行梯度洗脱。高分辨质谱采用一级质谱全扫描/数据依赖二级质谱扫描(Full MS/dd-MS²)进行检验。结果表明,采用上述仪器条件,能够实现4种合成大麻素同分异构体的分离分析,5F-EMB-PICA和5F-MDMB-PICA的分离度为2.06, ADB-BINACA和AB-PINACA的分离度为1.22,均达到了有效分离的目的。研究进一步开展了方法学指标考察,5F-EMB-PICA、5F-MDMB-PICA、ADB-BINACA和AB-PINACA这4种酰胺类合成大麻素同分异构体的线性关系均较好,相关系数(R²)均大于0.99。毛发中4种合成大麻素的基质效应范围为88.67%~111.76%,回收率为96.23%~105.11%,日内、日间精密度(RSD)均小于10%。使用本研究建立的检验方法鉴别案件检材,在毛发检材中检出了AB-PINACA,含量为0.73 μg/g;在烟丝检材中检出了5F-MDMB-PICA,含量为11.3 mg/g。研究结果表明所建方法可应用于公安机关对实际案件检材的检验,可为合成大麻素同分异构体的检验鉴定提供方法参考与思路借鉴。

Isomerization commonly occurs in synthetic cannabinoids (SCs). Owing to the few differences in their structure and properties, it is difficult to simultaneously separate and identify them. Thus, the identification of synthetic cannabinoids is challenging, posing a threat to public security. This study aims to separate and identify four SCs, which are 2-[1-(5-fluoropentyl)-1H-indole-3-formylamino]-3,3-dimethylbutyrate methyl ester (5F-MDMB-PICA), 2-[1-(5-fluoropentyl)-1H-indole-3-formylamino]-3-methylbutyrate ethyl ester (5F-EMB-PICA), N-(1-amino-2,2-dimethyl-1-oxobutyl-2-yl)-1-butyl-1H-indazole-3-formamide (ADB-BINACA), N-(1-carbamoyl-2-methylpropyl)-1-pentyl indazole-3-formamide (AB-PINACA).Supercritical fluid chromatography-mass spectroscopy (SFC-MS) can realize the effective separation of some cannabinoid isomers. However, most laboratories are not equipped with SFC-MS systems. Ultra-high performance liquid chromatography-high resolution mass spectroscopy (UHPLC-HRMS) effectively combines the excellent efficient separation characteristics of liquid chromatography and the powerful qualitative ability of mass spectrometry. It is a commonly used technical method for the detection of amide synthetic cannabinoids and their metabolites in vivo and in vitro because of its advantages of high accuracy and efficiency. Liquid chromatography allows the separation of tested components by exploiting the difference in the partition coefficients between the mobile and stationary phases. When the two phases are in relative motion, the tested components are divided between the two phases, facilitating the separation and analysis of each component. Although the difference in the polarities of the tested amide synthetic cannabinoid isomeric substances is extremely small, liquid chromatography can induce a strong separation effect. The advantages of UHPLC-HRMS include high resolution imparted by mass spectrometry and high sensitivity, allowing its application in the qualitative analysis of various substances. Through UHPLC-HRMS, trace analytes at the nanogram scale as well as pure drugs and their metabolites in biosamples can be detected.

This study proposed a method for the determination of two pairs of amide synthetic cannabinoid isomers-5F-EMB-PICA and 5F-MDMB-PICA, ADB-BINACA and AB-PINACA-through UHPLC-HRMS. A Hypersil GOLD C₁₈ column (100 mm×2.1 mm, 1.9 μm) was selected for separation via liquid chromatography, and gradient elution was performed with methanol containing 0.1% formic acid and a 0.1% formic acid aqueous solution containing 10 mmol/L ammonium formate. Full scan/data-dependent secondary mass spectrometry (Full MS/dd-MS²) was conducted in the positive ion mode for detection. The results indicated that the four synthetic cannabinoid isomers could be accurately detected under the abovementioned conditions. The resolution between 5F-EMB-PICA and 5F-MDMB-PICA was 2.06, while that between ADB-BINACA and AB-PINACA was 1.22, indicating the effective separation and detection of both pairs. Furthermore, method validation was conducted to ensure the accuracy of the proposed method. The relationship of the four amide synthetic cannabinoid isomers exhibited excellent linearity. The correlation coefficients (R²) were >0.99. Moreover, the matrix effects of the four SCs in hair samples were between 88.67% and 111.76% and the recoveries were 96.23%-105.11%. The intra-day and inter-day precisions (RSDs) were <10%. The proposed method was used to identify the case materials. AB-PINACA was detected in a hair sample at a content of 0.73 μg/g. 5F-MDMB-PICA was detected in a tobacco sample at a content of 11.3 mg/g. The results indicate that the proposed method can be used for the examination of practical samples conducted by public security organizations. This study provides a reference method for the identification of synthetic cannabinoid isomers.