Sodium acetate

Absolute ethanol, methanol (HPLC grade), glacial acetic acid, and sodium acetate were purchased from RCI Labscan Limited (Bangkok, Thailand). Polysorbate 80 (P-80), polyethylene glycol-40 hydrogenated castor oil (PEG-40H), and polyethylene glycol-400 (PEG-400) were purchased from Sigma-Aldrich (Darmstadt, Germany). Trimethylamine and phosphoric acid were purchased from Loba Chemie Pvt, Ltd. (Mumbai, India). Analytical standard nicotine (NCT), with a purity of 98.9%, was purchased from Sigma-Aldrich (St. Louis, MO, USA). Hydroxypropyl methylcellulose E15; HPMC E15 (AnyCoat^®-C AN15, substitution type 2910, viscosity 15 mPa·s) was purchased from Lotte Fine Chemical Co., Ltd. (Seoul, Korea).

The light air-cured leaves of N. tabaccum were received from Maejo Tobacco Experiment Station, Chiang Mai, Thailand, under the TOAT organization. The plant voucher specimen (No. 0023267) was deposited at the Herbarium of the Faculty of Pharmacy, Chiang Mai University (CMU), and authenticated by the CMU staff botanist. Chloroform, ethanol, glacial acetic acid, methanol, and sodium acetate were purchased from RCI Labscan Limited (Bangkok, Thailand). Sodium carbonate and sodium hydroxide were purchased from Merck (Darmstadt, Germany). ethanol (99% v/v) was purchased from Liquor Distillery Organization (Bangkok, Thailand). Trimethylamine was purchased from Loba Chemie Pvt, Ltd. (Mumbai, India). Nicotine standard was purchased from Sigma-Aldrich (St. Louis, MO, USA). Hydroxypropyl methylcellulose E15 (HPMC E15, AnyCoat^®-C AN15) was purchased from Lotte Fine Chemical Co., Ltd. (Seoul, Korea).

HPLC grade acetonitrile, ethanol and methanol were obtained from Burdick & Jackon (Ulsan, Korea). Analytical grade acetic acid glacial, ethanol, methanol, sodium acetate, hydrochloric acid (HCl) and sodium hydroxide (NaOH) came from RCI Labscan (Bangkok, Thailand). Sterile water was from A.N.B. Laboratories (Bangkok, Thailand). Analytical reagent grade citric acid (C₆H₈O₇), potassium chloride (KCl), sodium bicarbonate (NaHCO₃) and tri-sodium citrate (Na₃C₆H₅O₇) were purchased from Ajax Finechem (Seven Hills, New South Wales, Australia). Sodium azide (NaN₃) and Trizma^® base were obtained from Sigma-Aldrich (St. Louis, MO, USA).
The standard compounds 1 and 2 were provided by Assoc. Prof. Boonchoo Sritularak (Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand), while the standard compound 3 was obtained from Assist. Prof. Dr. Uthai Wichai (Faculty of Sciences, Naresuan University, Thailand). The purities of these compounds were more than 95%, as determined by NMR.