**1. Introduction**

During the past decade, there has been a significant increase in the circulation of new psychoactive substances (NPS) within the EU. This evolution in the drugs market, and the speed at which new substances are being created, is a cause of great concern for regulatory bodies. In 2016, NPS were reported to the EU Early Warning System at a rate of one per week, and it is estimated that a similar trend continued during the following years [1]. At the EU level, two agencies have a particular interest in this field—the European Monitoring Center for Drugs and Drug Addiction (EMCDDA) and EUROPOL [1–3].

Customs authorities are responsible for controlling the flow of goods into the EU, acting as the first control and contact point for NPS. However, the majority of customs laboratories are not equipped for the analysis of these substances, as they normally lack the advanced analytical and chemo-informatics tools that enable the complete identification and characterization of any new and/or relatively unknown NPS. These tools and expertise are available at the European Commission's Joint Research Centre (JRC), and, therefore, a collaborative project with the Customs Laboratories European Network (CLEN) has been established. Whenever an EU customs laboratory cannot completely identify an unknown seized substance/mixture, it is sent to the JRC for additional analysis. Since 2014, dozens of substances have been identified in the frame of this collaboration, including some which were previously unreported [3].

One of the most well-known and characterized psychoactive substances is d-lysergic acid diethylamide (LSD), which is most commonly circulated through small pieces of paper called "blotter paper" and is widespread all over the world because of its strong hallucinogenic effect [4]. In recent years, structurally modified LSD-type NPS have been found on the market, as is reported in several scientific papers [5–9]. One of them, 1-propionyl-d-lysergic acid diethylamide (1P-LSD), was identified and characterized after extraction from a seized sample by applying 1H and 13C-NMR along with GC–MS and UHPLC-qTOF-MS analysis [5]. Another closely related LSD derivative, 1-butanoyl-d-lysergic acid diethylamide (1B-LSD), appears to have already reached the street market, although no seizure of this drug has yet been reported (Figure 1). The only articles published present the analysis of commercial standards, using some analytical techniques (GC–MS, NMR, LC-MS) [9], or the screening procedures for the detection of nine LSD derivatives in rat urine, including 1B-LSD, using LC–HR-MS/MS [10].

**Figure 1.** Chemical structures, molecular formulas and molecular masses (Da) of 1-butyl-lysergic acid diethylamide (1B-LSD) and 1-propionyl-lysergic acid diethylamide (1P-LSD).

The current study reports the integrated approach used for the extraction and identification of 1B-LSD, from a blotter paper sample (labeled "1B-LSD Blotters (25 MCG)") found in a package seized by the Swedish customs on 05/11/2018 at Arlanda airport. The chemical identification was performed using GC–MS, HR–MS, NMR and chemo-informatics tools.

#### **2. Results**

#### *2.1. GC-MS Analysis*

From the chromatogram of the GC–MS analysis (Figure S1), it could be concluded that the matrix was quite complex. The main peak was among the last to be eluted, with a retention time of 23.5 min, and was identified as potentially 1B-LSD (see Figure 2), in agreement with the fragmentation patterns of 1P-LSD and the 1B-LSD, as reported by Brandt et al. [5,9]. The complete identification has been verified and confirmed by the results obtained from NMR and HR-MS.

**Figure 2.** MS spectrum resulting from the GC–MS peak, identified as 1B-LSD.

The resulting identification of the most relevant fragments, as received from the chemo-informatics tool for the GC–MS analysis, are presented in Table 1. Nevertheless, it shall be highlighted that all GC–MS fragmentation patterns were consistent with those reported by Brandt et al. [9].


**Table 1.** GC–MS-identified fragments for 1B-LSD (ACD/Spectrus Processor 2017.2.1).

<sup>1</sup> *m*/*z* Exp.: experimental *m*/*z*; <sup>2</sup> RI Exp. (%): Relative Intensity (%) of experimental *m*/*z*.
