An efficient and environmentally friendly sample preparation method based on the application of hydrophobic 1-Hexylpyridinium hexafluorophosphate [Hpy][PF6] ionic liquid (IL) as a microextraction solvent was proposed to preconcentrate terazosin. The performance of the microextraction method was improved by introducing a common ion of pyridinium IL into the sample solution. Due to the presence of the common ion, the solubility of IL significantly decreased. As a result, the phase separation successfully occurred even at high ionic strength, and the volume of the settled IL-phase was not influenced by variations in the ionic strength (up to 30%？w/v). After preconcentration step, the enriched phase was introduced to the spectrofluorimeter for the determination of terazosin. The obtained results revealed that this system did not suffer from the limitations of that in conventional ionic-liquid microextraction. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.027？μg？L？1 and a relative standard deviation (R.S.D.) of 2.4%. The present method was successfully applied to terazosin determination in actual pharmaceutical formulations and biological samples. Considering the large variety of ionic liquids, the proposed microextraction method earns many merits, and will present a wide application in the future. 1. Introduction Terazosin is a selective potent adreno-receptor antagonist. It is an effective drug for hypertension and benign prostatic hyperplasia [1, 2]. The needs of monitoring trace levels of terazosin in treated patients with initiate or chronic treatment routine in chronic regimen, especially in renal impairment cases, are necessary. To prevent excess employed dosage, it is critical to develop the sensitive and accurate techniques for its quantitative analysis. Several analytical methods have been developed for the measurement of terazosin in bulk, pharmaceuticals, or biological fluids [3–8]. Sample preparation is a critical step to isolate the analytes of interest from the sample matrix as well as to increase the concentration of analytes prior to their determination, especially when their levels are lower than the detection limit of analytical techniques. Liquid-liquid extraction (LLE) and solid-phase extraction (SPE) have been widely used as basic, simple, and adaptable methods for sample preconcentration. However, some drawbacks such as the use of large amount of hazardous organic solvents, and the employment of multistep procedures associated with the high risk of analyte losses make LLE and SPE
References
[1]
R. Mudiyala and A. Ahmed, “Effect of terazosin on clinical benign prostatic hyperplasia in older adults,” Journal of the American Geriatrics Society, vol. 51, no. 3, pp. 424–426, 2003.
[2]
H. Lepor, K. Jones, and W. Williford, “The mechanism of adverse events associated with terazosin: An analysis of the Veterans Affairs cooperative study,” Journal of Urology, vol. 163, no. 4, pp. 1134–1137, 2000.
[3]
H. H. Abdine, F. A. El-Yazbi, S. M. Blaih, and R. A. Shaalan, “Spectrophotometric and spectrofluorimetric methods for the determination of terazosin in dosage forms,” Spectroscopy Letters, vol. 31, no. 5, pp. 969–980, 1998.
[4]
C. Q. Jiang, M. X. Gao, and J. X. He, “Study of the interaction between terazosin and serum albumin -Synchronous fluorescence determination of terazosin,” Analytica Chimica Acta, vol. 452, no. 2, pp. 185–189, 2002.
[5]
R. A. Silva and A. N. Masi, “Sensitive determination of terazosin by x-ray fluorescence spectrometry based on the formation of ion-pair associates with zinc thiocyanate,” X-Ray Spectrometry, vol. 36, no. 4, pp. 279–283, 2007.
[6]
P. Y. Cheah, K. H. Yuen, and M. L. Liong, “Improved high-performance liquid chromatographic analysis of terazosin in human plasma,” Journal of Chromatography B, vol. 745, no. 2, pp. 439–443, 2000.
[7]
A. P. Zavitsanos and T. Alebic-Kolbah, “Enantioselective determination of terazosin in human plasma by normal phase high-performance liquid chromatography-electrospray mass spectrometry,” Journal of Chromatography A, vol. 794, no. 1-2, pp. 45–56, 1998.
[8]
M. M. Ghoneim, M. A. El Ries, E. Hammam, and A. M. Beltagi, “A validated stripping voltammetric procedure for quantification of the anti-hypertensive and benign prostatic hyperplasia drug terazosin in tablets and human serum,” Talanta, vol. 64, no. 3, pp. 703–710, 2004.
[9]
M. Zeeb, M. R. Ganjali, and P. Norouzi, “Dispersive liquid-liquid microextraction followed by spectrofluorimetry as a simple and accurate technique for determination of thiamine (vitamin B1),” Microchimica Acta, vol. 168, no. 3, pp. 317–324, 2010.
[10]
P. Hemmatkhah, A. Bidari, S. Jafarvand, M. R. M. Hosseini, and Y. Assadi, “Speciation of chromium in water samples using dispersive liquid-liquid microextraction and flame atomic absorption spectrometry,” Microchimica Acta, vol. 166, no. 1-2, pp. 69–75, 2009.
[11]
S. Jafarvand, A. Bidari, P. Hemmatkhah, M. R. M. Hosseini, and Y. Assadi, “Dispersive liquid-liquid microextraction of silver prior to determination by microsample introduction-flame atomic absorption spectrometry,” Analytical Letters, vol. 42, no. 14, pp. 2214–2231, 2009.
[12]
F. Rezaei, A. Bidari, A. P. Birjandi, M. R. Milani Hosseini, and Y. Assadi, “Development of a dispersive liquid-liquid microextraction method for the determination of polychlorinated biphenyls in water,” Journal of Hazardous Materials, vol. 158, no. 2-3, pp. 621–627, 2008.
[13]
A. Jain, A. K. K. V. Pillai, N. Sharma, and K. K. Verma, “Headspace single-drop microextraction and cuvetteless microspectrophotometry for the selective determination of free and total cyanide involving reaction with ninhydrin,” Talanta, vol. 82, no. 2, pp. 758–765, 2010.
[14]
A. Garbi, V. Sakkas, Y. C. Fiamegos, C. D. Stalikas, and T. Albanis, “Sensitive determination of pesticides residues in wine samples with the aid of single-drop microextraction and response surface methodology,” Talanta, vol. 82, no. 4, pp. 1286–1291, 2010.
[15]
Y. He and H. K. Lee, “Liquid-phase microextraction in a single drop of organic solvent by using a conventional microsyringe,” Analytical Chemistry, vol. 69, no. 22, pp. 4634–4640, 1997.
[16]
A. Sanchez-Ortega, N. Unceta, A. Gómez-Caballero et al., “Sensitive determination of triazines in underground waters using stir bar sorptive extraction directly coupled to automated thermal desorption and gas chromatography-mass spectrometry,” Analytica Chimica Acta, vol. 641, no. 1-2, pp. 110–116, 2009.
[17]
S. Pandey, “Analytical applications of room-temperature ionic liquids: a review of recent efforts,” Analytica Chimica Acta, vol. 556, no. 1, pp. 38–45, 2006.
[18]
N. Hirayama, M. Deguchi, H. Kawasumi, and T. Honjo, “Use of 1-alkyl-3-methylimidazolium hexafluorophosphate room temperature ionic liquids as chelate extraction solvent with 4,4,4-trifluoro-1-(2-thienyl)- 1,3-butanedione,” Talanta, vol. 65, no. 1, pp. 255–260, 2005.
[19]
P. Berton, E. M. Martinis, L. D. Martinez, and R. G. Wuilloud, “Room temperature ionic liquid-based microextraction for vanadium species separation and determination in water samples by electrothermal atomic absorption spectrometry,” Analytica Chimica Acta, vol. 640, no. 1-2, pp. 40–46, 2009.
[20]
M. Gharehbaghi, F. Shemirani, and M. D. Farahani, “Cold-induced aggregation microextraction based on ionic liquids and fiber optic-linear array detection spectrophotometry of cobalt in water samples,” Journal of Hazardous Materials, vol. 165, no. 1–3, pp. 1049–1055, 2009.
[21]
L. Vidal, A. Chisvert, A. Canals, and A. Salvador, “Ionic liquid-based single-drop microextraction followed by liquid chromatography-ultraviolet spectrophotometry detection to determine typical UV filters in surface water samples,” Talanta, vol. 81, no. 1-2, pp. 549–555, 2010.
[22]
E. Aguilera-Herrador, R. Lucena, S. Cárdenas, and M. Valcárcel, “Determination of trihalomethanes in waters by ionic liquid-based single drop microextraction/gas chromatographic/mass spectrometry,” Journal of Chromatography A, vol. 1209, no. 1-2, pp. 76–82, 2008.
[23]
M. Gharehbaghi, F. Shemirani, and M. Baghdadi, “Dispersive liquid-liquid microextraction based on ionic liquid and spectrophotometric determination of mercury in water samples,” International Journal of Environmental Analytical Chemistry, vol. 89, no. 1, pp. 21–33, 2009.
[24]
H. Abdolmohammad-Zadeh and G. H. Sadeghi, “Combination of ionic liquid-based dispersive liquid-liquid micro-extraction with stopped-flow spectrofluorometry for the pre-concentration and determination of aluminum in natural waters, fruit juice and food samples,” Talanta, vol. 81, no. 3, pp. 778–785, 2010.
[25]
M. Zeeb, M. R. Ganjali, P. Norouzi, and M. R. Kalaee, “Separation and preconcentration system based on microextraction with ionic liquid for determination of copper in water and food samples by stopped-flow injection spectrofluorimetry,” Food and Chemical Toxicology, vol. 49, no. 5, pp. 1086–1091, 2011.
[26]
Q. Zhou, H. Bai, G. Xie, and J. Xiao, “Temperature-controlled ionic liquid dispersive liquid phase micro-extraction,” Journal of Chromatography A, vol. 1177, no. 1, pp. 43–49, 2008.
