## 3 Analytical Platforms for Terpenoids  
### Chromatographic Techniques  
A number of methods used for analyzing terpenoids have already been developed; the most common approach is chromatographic analysis, specifically GC-MS or LC-MS. Compounds of monoterreponids and sesquiterpenoids were determined by various methods such as GC-MS, GC-MS/MS, GC-FID (GC-Flame Ionization Detection), and GC-GC [51]. Each method has its own advantages and disadvantages. The main advantage of using GC-MS is that it is sensitive and robust, and also capable of routinely and reproducibly measuring hundreds of analytes across thousands of samples. Among the different methods, the best one for analyzing terpenes is solvent extraction followed by GC-FID analysis. The FID is a powerful instrument for quality control because of its low cost, accuracy, and simple interface. But the main disadvantage is that it provides little information other than the retention time. For better identification and characterization, various types of columns, dimensions, and oven programs were used (Table 1) [52; 53; 54; 55; 56; 57; 58; 59]. Despite this, the optimum GC detector for terpene analysis is still unknown. The column ZB-5 PLUSTM is used selectivity for high temperature limitations, allowing for a high resolution of essential terpenoids. Phenomenex TM groups that used this column in GC-FID identified 33 cannabis-derived primary and secondary terpen [56]. Another reliable method for determining terpenoids is HS-GC-FID. Headspace sampling is a technique that involves heating a solid or liquid sample inside a sealed vial (which converts the volatile substance to the gas phase). This approach increases column lifetime and minimizes inlet maintenance by preventing non-volatile material from entering the GC system. Apart from the aforementioned approaches, the use of GC-MS, another frequently used technique, has the additional advantage of spectral peak identification to ensure that selection is accurate. However, it may not be the optimal detector for terpene analysis due to the structural and functional similarity of terpene class molecules. Moreover, GC-MS provides a different level of sensitivity. GC-MS with high-temperature headspace sampling was used to quantify selected terpenoids using a TG-624 SilMS column [53]. The separated constituents were tentatively identified by comparing their mass spectra with those in the available MS library such as: Wiley, Flavors and Fragrances of Natural and Synthetic Compounds (FFNSC) and NIST08 (National Institute of Standards and Technology, Gaithersburg, MD, USA) and by comparing their retention indices (RIs) with literature values. Each constituent was quantified based on the comparison of its peak area with that of the internal standard, and the contents are expressed as ng/g FW. Despite the advantages of various GC methods, the main disadvantage is that degraded chemicals cannot be quantified effectively. In this case, researchers prefer LC-MS/MS for the characterization of degraded chemicals such as GPP and FPP. It is challenging to isolate these compounds using HPLC due to the ionic nature of the phosphate groups. MS, on the other hand, has an adequate sensitivity and specificity. These metabolites have been determined using HPLC-tandem MS (MS/MS) and ultra HPLC-MS/MS [60; 61]. Furthermore, obtaining the proper analytical result of terpene analysis is a difficult task that necessitates the evaluation of a number of critical factors, such as equipment selection, instrument parameters, and the optimization of extraction methods. The general process of GC-MS analysis includes the injections of extracted compounds directly into the GC, and the separation of different components using capillary columns or similar columns of 30 m in length or greater. Helium (99.99%), the carrier gas, will continuously pass through at a flow rate of 1 mL/min.