## 2 Analytical Methods for Phytocannabinoid Profiling
### Instrumental Analysis
#### 2.2.1 GC-Based Methods
Wide employed thin-filmed capillary columns with non-polar stationary phases are used, such as 5%-diphenyl-dimethylpolysiloxane columns, including HP-5 (for FID) or HP-5 MS (for MS) [50; 52; 57; 58; 62; 70; 85; 89; 91; 100; 103; 104; 126; 133; 141; 142; 154; 156], DB-5 MS [99; 108; 128; 151; 163; 164], Kai-5 MS [73], Mega-5 MS [146], BP-5 [45], RTX-5 [94; 161], MDN-5S [91], SE-52 [128], ZB-5 [95], Zebron ZB-5 HT Inferno [102] and SLB-5 MS [152]. 100% dimethylpolysiloxane columns, such as HP-1 [10; 109; 112; 165], SPB-1 [85], OV-1 [74] and DB-1 [17; 17; 23; 75; 77; 84; 144; 148] are preferred for more successful separation of CBC and CBD, apart from all other phytocannabinoids, or are used only for separation of CBC and CBD [10; 109; 112]. Such columns are appropriate for analysis of CBDV, THCV, CBD, CBC, \(\Delta^{8}\)-THC, \(\Delta^{9}\)-THC, CBN but not for CBG [163]. Simultaneous injection on two column with different polarities, i.e., a medium-polar (HP-50+) and non-polar column (DB-1 MS) is another option for better separation of CBC and CBD [18]. Columns with intermediate polarity, such as Rai-35 Sil MS [90] and DB-35 MS [163] (35% (-phenyl)methylpolysiloxane) and Zebron ZB-624 (6%- cyanopropyl-phenyl, 94-dimethylpolysiloxane) [106] are also used for cannabinoid separation. Rai-35 Sil MS may offer slightly wider retention window than a 5% silphenylene phase (DG-5 MS) and 5% diphenyl phase (HP-5 MS) [90]. However, columns with 35% (phenyl)methylpolysiloxane stationary phase might produce multiple peaks for CBC, one of which coeluted with THCV. Low to mid-polarity columns, such as DB-170 (14%-cyanopropyl-phenyl)-methylpolysiloxane) are not appropriate, as they produce low responses, distorted peak shape and tailing [163]. Despite this, the nonpolar 100% dimethylpolysiloxane column DB-1 HT was used for successful separation of \(\Delta^{9}\)-THC, CBD, CBC, CBN and other minor cannabinoids, along with terpenes, sesquiterpenes, sterols, diglycerides and triglycerides [166]. * GC Detectors  
A large proportion of the profiling studies employ FID [10; 17; 49; 52; 55; 56; 58; 70; 73; 74; 75; 76; 79; 82; 85; 93; 94; 95; 96; 98; 101; 103; 106; 108; 109; 110; 111; 112; 113; 114; 115; 116; 117; 118; 119; 138; 141; 157; 158; 159] or dual FID [9; 75; 121; 144]. FID offers more accurate quantitative response with respect to MS, but at the price of lower sensitivity and specificity. The need of analogue analytical standards only makes FID low-cost and simpler analyzer when compared to MS, which needs the use of the corresponding deuterated analytical standards [1]. Moreover, GC-FID methods are more robust than GC-MS methods both in full scan and SIM mode [107]. However, due to its inability to discriminate CBD and CBC, FID is often replaced by MS detectors for more thorough cannabinoid profiling. GC-MS is the most researched analytical platform for cannabinoid profiling to date [1; 42; 153; 167]. Electron impact ionization (EI) is the most commonly used ionization technique in cannabinoid profiling, while others, i.e., chemical ionization (CI) in positive/negative mode and atmospheric pressure ionization (API) are preferred in forensic analysis of phytocannabinoids in biological samples. Mass selective detector (MSD) [45; 47; 49; 55; 59; 74; 81; 86; 89; 90; 94; 96; 121; 122; 123; 124; 128; 139; 146; 148; 154; 160; 166], single quadrupole (Q) [57; 66; 76; 163] and triple quadrupole (QQQ) are the most frequently used configurations. Improved sensitivity, specificity and reproducibility, with reduced noise level and interferences are achieved by monitoring specific ions (selected ion monitoring, SIM mode, MSDs and Qs) or fragmentation reactions (multiple reaction monitoring mode, MRM mode, QQQ), then using the analyzers in scan mode. Ion trap (IT) is seldomly used [23; 70; 151], despite its advantageous ability to acquire structural information by higher fragmentation (MS\({}^{3}\), MS\({}^{4}\)\(\ldots\) MS\({}^{n}\)).