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In the article titled “Screening of psychoactive components in fresh khat using direct analysis in real time-time of flight-mass spectrometry”, published on pages 45 - 50, Issue 3, Volume 1 in The Saudi Journal of Forensic Medicine and Sciences,[1] the paragraph titled “Experimental ”on page 47 is repeated in the article and needs to be deleted.

The paragraph to be removed:

Experimental

Fresh samples of C. edulis were obtained from Jazan (Saudi Arabia) and stored at 4°C, before their investigation by DART-ToF-MS. The different parts of the selected plant were cut into small pieces with separation of leaves and stems as shown in [Figure 1]. Each small piece was then directly submitted to the DART ion source without any treatment as shown in [Figure 2]. The distance between the DART ion source exit and the mass spectrometer inlet was about 25 mm. The mass spectra were recorded using

the experimental conditions given below. The instrument used was an AccuTOF LC-Plus from JEOL (Tokyo, Japan) including a DART ion source running under atmospheric pressure (IonSense, Saugus, MA, USA) and a ToF mass spectrometer. The volatile components of each fresh part were evaporated in a stream of helium heated at 350°C, then ionized by the excited metastable helium atoms, before

entering the ion source inlet of the TOF mass spectrometer. The analyses were performed in positive mode, in which the molecules are mainly protonated without fragmentation. The potentials of orifices 1 and 2 were set at 20 and 5 V, respectively. The ring lens potential was set to 13 V and the temperature of orifice 1 was 80°C. The radiofrequency ion guide potential was 300 V. High purity helium was used as

ionization gas at 4.0 L/min flow heated to 350°C for sample evaporation. The potential on the discharge needle electrode of the DART source was set to 3.0 kV, while the perforated and grid electrodes were at 100 and 250 V potentials, respectively. The mass spectra acquisition range was 50–1000 Da and the mass resolution was 3760 full width at half maximum. Before recording each spectrum, mass

calibration was performed using a 200 μg/mL solution of polyethylene glycol (PEG) 600 (Sigma-Aldrich, Darmstadt, Germany) in methanol. The elemental composition of selected peaks was determined using the MassCentre JEOL software (version 1.3.8e, algorithm, JEOL USA, Inc., Peabody, USA).

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