Model mkm6003

Dry hawthorn plants were ground using three different grinders. ‘Coarse’ and ‘fine’ hawthorn materials were obtained by grinding 2 g of raw material using Delonghi (Model KG79, Trevise, Italy) grinder at the positions ‘coarse’ and ‘fine’, respectively. ‘Ultrafine 10 s or 30s’ hawthorn materials were obtained by grinding 2 g of raw material using the Bosch grinder (Model MKM6003, Munich, Germany) at different manual shaking times (10 s and 30 s) as indicated in the text. The ‘1 mm’ and ‘2 mm’ hawthorn materials were obtained by grinding the required amount of raw material on a laboratory Ika grinder (Ika-Werke GmbH, Model MF10 basic, Staufen, Germany). The density of each hawthorn material was simply determined by measuring the volume occupied by 2 g hawthorn material in a 10 mL (or 25 mL) graduated test tube (n = 3 determinations). Distribution in size of each hawthorn material was determined by a dry laser Malvern granulometer (Malvern Panalytical, Royston, United Kingdom).

Khat leaves, air-dried for 5 days at ambient temperature, were powdered using a Bosch blender (Model MKM6003). The powdered sample was sieved in a nylon sieve of 100 µm. A 250 g portion of the powdered leaves was extracted using the typical acid/base extraction method for alkaloids, as reported by [13 ], but the volumes of solvents were adjusted. The plant material was extracted with 0.1 M HCl (3 L) by stirring with a magnetic stirrer for 90 min. The mixture was filtered using vacuum filtration. This extraction process was repeated twice, where after the combined filtrates were basified with 10% aqueous NaOH (pH 9–10). A mixture of the khat alkaloids was then extracted into diethyl ether (3 × 4 L). Oxalic acid (1% in diethyl ether) was added drop wise to the organic fraction, which was left for 24 h at 4 °C. After filtering, a 1.25 g mass was recovered as a mixture of oxalate salts (0.51% dry plant mass). The oxalate salt was directly injected to preparative HPLC.