806 DOBROWSKA ET AL.: JOURNAL OF AOAC INTERNATIONAL VOL. 99, NO. 3, 2016 A Novel Liquid–Liquid Extraction for the Determination of Nicotine in Tap Water, Wastewater, and Saliva at Trace Levels by GC-MS JOANNA SONIA DOBROWSKA, 1 SEZIN ERARPAT, and DOTSE SELALI CHORMEY Yıldız Technical University, Faculty of Art and Science, Chemistry Department, 34210, İstanbul, Turkey Krystyna PyrzyńsKa University of Warsaw, Department of Chemistry, Pasteura 1, 02-093 Warsaw, Poland SEZGIN BAKIRDERE 2 Yıldız Technical University, Faculty of Art and Science, Chemistry Department, 34210, İstanbul, Turkey Determination of nicotine at trace levels in different matrixes is crucial because of nicotine’s strongly addictive property. In this study, a simple and fast analytical method was developed using liquid– liquid extraction with GC-MS. Chloroform was used as an extraction solvent. Different parameters for extraction, such as pH of the solution, types and volumes of extraction and supporter solvents for dispersion, extraction period, and salt type and its amount, were optimized. To improve the precision, naphthalene was used as an internal standard. The calibration plot of nicotine was linear from 0.010 to 2.0 mg/L with a correlation coefficient 0.9996. The LOD and LOQ for nicotine after extraction were 2.6 and 8.8 ng/mL, respectively. Under the optimum conditions, tap water, wastewater, and saliva samples were analyzed for their nicotine content. The spiking experiments yielded satisfactory recoveries of 97.6 ± 3.5, 96.8 ± 1.1, and 85.1 ± 1.3% for tap water, wastewater, and saliva samples, respectively. N icotine is known as one of the most important pharmacologically active alkaloids in tobacco samples. It has been reported that the lethal dose of nicotine, 3-(1-methyl-2-pyrrolidinyl) pyridine, is 30–60 mg/kg. Tobacco leaves consist of about 2–8% nicotine (1, 2), as well as some carcinogens nitrosamines that have been observed during the processing and curing steps (3, 4). Cardiovascular hazards, peripheral vascular diseases, emphysema, and 12 types of cancers are caused by the consumption of tobacco products. In addition, some risks during pregnancy such as deceleration of fetal development, perinatal morbidity, and mortality have been reported in literature (5). It is also known that nicotine was previously used as an insecticide against sucking insects on products such as fruits, vines, vegetables, and ornamentals. Annual consumption of nicotine can be estimated at about 5 × 10 4 tons and, together with its derivatives in urine, nicotine may be discharged from domestic water into natural waters (6, 7). Hence, determination of nicotine in environmental samples at trace levels has become popular in recent years. There are many analytical methods including gravimetry, spectrophotometry, GC, and HPLC for the quantitative determination of nicotine. Because of the complexity of matrixes and sensitivity problems, chromatographic methods with different detectors have been most commonly used, as reported in the literature (8–15). To eliminate the matrix effect and also to improve the sensitivity, some extraction/preconcentration methods have been proposed. Liquid–liquid extraction (LLE), cloud point extraction, pressurized liquid extraction, liquid phase microextraction, SPE, liquid–liquid microextraction, solid-phase microextraction, and single drop microextraction (SDME) have been applied for nicotine in a variety of biological and environmental samples (16–26). Although LLE and SPE have been applied for the determination of nicotine and cotinine in different matrixes, these methods have some drawbacks, such as the demands of a large amount of organic solvent, time consumption, and the high cost of SPE columns/devices. Because of the long mixing period and the low interaction between the extractant and the analyte, not many application areas have been found for SDME as an alternative extraction/ preconcentration method for this analyte (27). Different and new approaches in LLE have been applied to overcome the main drawbacks and to obtain a short extraction period, a high extraction efficiency, and a low amount of organic solvent (28, 29). The main purpose of this study was to develop a sensitive and accurate analytical method for the determination of nicotine at trace levels. In the extraction/preconcentration of nicotine from tap water, wastewater, and saliva samples, LLE was used, and GC-MS was applied in the determination step. Experimental Chemicals and Reagents (-)-Nicotine (99%), chloroform (99.0–99.4%), sodium chloride (99.5–100.5%), methanol (99.5%), and naphthalene were purchased from Merck. Deionized water obtained from Milli-Q Reference System was used for all standard and sample preparations. Other common chemicals used were of the highest purity commercially available. Received February 10, 2016. Accepted by AK March 17, 2016. 1 Additional address: University of Warsaw, Department of Chemistry, Pasteura 1, 02-093 Warsaw, Poland. 2 Corresponding author’s e-mail: bsezgin23@yahoo.com DOI: 10.5740/jaoacint.16-0041 RESIDUES AND TRACE ELEMENTS