Generic placeholder image

Current Pharmaceutical Analysis

Editor-in-Chief

ISSN (Print): 1573-4129
ISSN (Online): 1875-676X

Review Article

A Review of Analytical Methods for the Determination of Tibolone: Pharmacokinetics and Pharmaceutical Formulations Analysis and Application in Doping Control

Author(s): Marilene Lopes Ângelo, Fernanda de Lima Moreira*, Ana Laura Araújo Santos, Hérida Regina Nunes Salgado and Magali Benjamim de Araújo

Volume 17, Issue 1, 2021

Published on: 25 October, 2019

Page: [31 - 39] Pages: 9

DOI: 10.2174/1573412916666191025143214

Price: $65

Abstract

Background: Tibolone is a synthetic steroid commercialized by Organon under the brand name Livial (Org OD14), which is used in hormone therapy for menopause management and treatment of postmenopausal osteoporosis. Tibolone is defined as a selective tissue estrogenic activity regulator (STEAR) demonstrating tissue-specific effects on several organs such as brain, breast, urogenital tract, endometrium, bone and cardiovascular system.

Aims: This work aims to (1) present an overview of important published literature on existing methods for the analysis of tibolone and/or its metabolites in pharmaceutical formulations and biological fluids and (2) to conduct a critical comparison of the analytical methods used in doping control, pharmacokinetics and pharmaceutical formulations analysis of tibolone and its metabolites.

Results and Conclusion: The major analytical method described for the analysis of tibolone in pharmaceutical formulations is High Pressure Liquid Chromatography (HPLC) coupled with ultraviolet (UV) detection, while Liquid Chromatography (LC) or Gas Chromatography (GC) used in combination with Mass Spectrometry (MS) or tandem mass spectrometry (MS/MS) is employed for the analysis of tibolone and/or its metabolites in biological fluids.

Keywords: Tibolone, HPLC, LC-MS/MS, UPLC-MS/MS, GC-MS, analytical methods.

Graphical Abstract

[1]
Dennerstein, L.; Dudley, E.C.; Hopper, J.L.; Guthrie, J.R.; Burger, H.G. A prospective population-based study of menopausal symptoms. Obstet. Gynecol., 2000, 96(3), 351-358.
[PMID: 10960625]
[2]
Sherman, S. Defining the menopausal transition. Am. J. Med., 2005, 118(Suppl. 12B), 3-7.
[http://dx.doi.org/10.1016/j.amjmed.2005.11.002] [PMID: 16414321]
[3]
Cohen, L.S.; Soares, C.N.; Vitonis, A.F.; Otto, M.W.; Harlow, B.L. Risk for new onset of depression during the menopausal transition: the Harvard study of moods and cycles. Arch. Gen. Psychiatry, 2006, 63(4), 385-390.
[http://dx.doi.org/10.1001/archpsyc.63.4.385] [PMID: 16585467]
[4]
ACOG Practice Bulletin No 141: management of menopausal symptoms. Obstet. Gynecol., 2014, 123(1), 202-216.
[http://dx.doi.org/10.1097/01.AOG.0000441353.20693.78] [PMID: 24463691]
[5]
NIH State-of-the-Science Conference Statement on manifestations and management of chronic insomnia in adults. NIH Consens. State Sci. Statements, 2005, 22(2), 1-30.
[PMID: 17308547]
[6]
Modelska, K.; Cummings, S. Tibolone for postmenopausal women: Systematic review of randomized trials. J. Clin. Endocrinol. Metab., 2002, 87(1), 16-23.
[http://dx.doi.org/10.1210/jcem.87.1.8141] [PMID: 11788614]
[7]
Dubey, R.K.; Gillespie, D.G.; Grögli, M.; Kloosterboer, H.J.; Imthurn, B. Tibolone and its metabolites induce antimitogenesis in human coronary artery smooth muscle cells: Role of estrogen, progesterone, and androgen receptors. J. Clin. Endocrinol. Metab., 2004, 89(2), 852-859.
[http://dx.doi.org/10.1210/jc.2003-031272] [PMID: 14764805]
[8]
Verheul, H.A.; Timmer, C.J.; Kloosterboer, H.J. Pharmacokinetic parameters of sulfated tibolone metabolites in postmenopausal women after single and multiple doses of tibolone. Clin. Pharmacol. Ther., 2007, 81(4), 573-579.
[http://dx.doi.org/10.1038/sj.clpt.6100094] [PMID: 17301737]
[9]
Timmer, C.J.; Huisman, J.A. Effect of a standardized meal on the bioavailability of a single oral dose of tibolone 2.5 mg in healthy postmenopausal women. Pharmacotherapy, 2002, 22(3), 310-315.
[http://dx.doi.org/10.1592/phco.22.5.310.33186] [PMID: 11899948]
[10]
Timmer, C.J.; Verheul, H.A.M.; Doorstam, D.P. Pharmacokinetics of tibolone in early and late postmenopausal women. Br. J. Clin. Pharmacol., 2002, 54(2), 101-106.
[http://dx.doi.org/10.1046/j.1365-2125.2002.01619.x] [PMID: 12207627]
[11]
Son, J.; Moon, J.Y.; Kim, S.A.; Cho, Y.D.; Kim, J.D.; Kim, D.H.; Choi, M.H. Improved detectability in pharmacokinetic study of tibolone by gas chromatography-high resolution mass spectrometry with selected ion monitoring. Talanta, 2006, 70(1), 37-42.
[http://dx.doi.org/10.1016/j.talanta.2006.02.003] [PMID: 18970725]
[12]
British Pharmacopoeia. London: British Pharmacopoeia Convention., (8th. ) 2017, 3, 1222-1224.
[13]
MHRA. Medicines and Healthcare products Regulatory Agency: 2017. United Kingdom. Tibolone 2.5 mg tablets., http://www.mhra.gov.uk/home/groups/par/documents/websiteresources/con809941.pdf2019.
[14]
[15]
Kloosterboer, H.J. Tissue-selectivity: The mechanism of action of tibolone. Maturitas, 2004, 48(Suppl. 1), S30-S40.
[http://dx.doi.org/10.1016/j.maturitas.2004.02.012] [PMID: 15337246]
[16]
Vos, R.M.E.; Krebbers, S.F.M.; Verhoeven, C.H.J.; Delbressine, L.P.C. The in vivo human metabolism of tibolone. Drug Metab. Dispos., 2002, 30(2), 106-112.
[http://dx.doi.org/10.1124/dmd.30.2.106] [PMID: 11792677]
[17]
Falany, J.L.; Macrina, N.; Falany, C.N. Sulfation of tibolone and tibolone metabolites by expressed human cytosolic sulfotransferases. J. Steroid Biochem. Mol. Biol., 2004, 88(4-5), 383-391.
[http://dx.doi.org/10.1016/j.jsbmb.2004.01.005] [PMID: 15145448]
[18]
Miller, E.; Zalzala, M.H.; Abunnaja, M.S.; Kurogi, K.; Sakakibara, Y.; Suiko, M.; Liu, M.C. Effects of Human Sulfotransferase 2A1 Genetic Polymorphisms 3 on the Sulfation of Tibolone. Eur. J. Drug Metab. Pharmacokinet., 2018, 43(4), 415-421.
[http://dx.doi.org/10.1007/s13318-017-0458-2] [PMID: 29392568]
[19]
Rymer, J.; Robinson, J.; Fogelman, I. Ten years of treatment with tibolone 2.5 mg daily: Effects on bone loss in postmenopausal women. Climacteric, 2002, 5(4), 390-398.
[http://dx.doi.org/10.1080/cmt.5.4.390.398] [PMID: 12626219]
[20]
Landgren, M.B.; Helmond, F.A.; Engelen, S. Tibolone relieves climacteric symptoms in highly symptomatic women with at least seven hot flushes and sweats per day. Maturitas, 2005, 50(3), 222-230.
[http://dx.doi.org/10.1016/j.maturitas.2004.06.001] [PMID: 15734603]
[21]
Kloosterboer, H.J. Tibolone: A steroid with a tissue-specific mode of action. J. Steroid Biochem. Mol. Biol., 2001, 76(1-5), 231-238.
[http://dx.doi.org/10.1016/S0960-0760(01)00044-9] [PMID: 11384882]
[22]
Reed, M.J.; Kloosterboer, H.J. Tibolone: A selective tissue estrogenic activity regulator (STEAR). Maturitas, 2004, 48(Suppl. 1), S4-S6.
[http://dx.doi.org/10.1016/j.maturitas.2004.02.013] [PMID: 15337241]
[23]
Lindsay, R.; Hart, D.M.; Kraszewski, A. Prospective double-blind trial of synthetic steroid (Org OD 14) for preventing postmenopausal osteoporosis. BMJ, 1980, 280(6225), 1207-1209.
[http://dx.doi.org/10.1136/bmj.280.6225.1207] [PMID: 6992927]
[24]
Ederveen, A.G.H.; Kloosterboer, H.J. Tibolone exerts an estrogenic effect on bone leading to prevention of bone loss and reduction in bone resorption in ovariectomized rats. Osteoporos. Int., 1998, 8, 95.
[25]
Rymer, J.; Chapman, M.G.; Fogelman, I. Effect of tibolone on postmenopausal bone loss. Osteoporos. Int., 1994, 4(6), 314-319.
[http://dx.doi.org/10.1007/BF01622189] [PMID: 7696824]
[26]
Berning, B.; Bennink, H.J.; Fauser, B.C. Tibolone and its effects on bone: A review. Climacteric, 2001, 4(2), 120-136.
[http://dx.doi.org/10.1080/cmt.4.2.120.136] [PMID: 11428176]
[27]
Bjarnason, N.H.; Bjarnason, K.; Haarbo, J.; Bennink, H.J.; Christiansen, C. Tibolone: Influence on markers of cardiovascular disease. J. Clin. Endocrinol. Metab., 1997, 82(6), 1752-1756.
[http://dx.doi.org/10.1210/jcem.82.6.3995] [PMID: 9177376]
[28]
Kalder, M.; Kyvernitakis, I.; Hars, O.; Kauka, A.; Hadji, P. Comparison of combined low-dose hormone therapy vs. tibolone in the prevention of bone loss. Climacteric, 2016, 19(5), 471-477.
[http://dx.doi.org/10.1080/13697137.2016.1198313] [PMID: 27345158]
[29]
Kotani, K.; Sahebkar, A.; Serban, C.; Andrica, F.; Toth, P.P.; Jones, S.R.; Kostner, K.; Blaha, M.J.; Martin, S.; Rysz, J.; Glasser, S.; Ray, K.K.; Watts, G.F.; Mikhailidis, D.P.; Banach, M. Tibolone decreases Lipoprotein(a) levels in postmenopausal women: A systematic review and meta-analysis of 12 studies with 1009 patients. Atherosclerosis, 2015, 242(1), 87-96.
[http://dx.doi.org/10.1016/j.atherosclerosis.2015.06.056] [PMID: 26186655]
[30]
Kloosterboer, H.J. Historical milestones in the development of tibolone (Livial®). Climacteric, 2011, 14(6), 609-621.
[http://dx.doi.org/10.3109/13697137.2011.580639] [PMID: 21942642]
[31]
von Eckardstein, A.; Crook, D.; Elbers, J.; Ragoobir, J.; Ezeh, B.; Helmond, F.; Miller, N.; Dieplinger, H.; Bennink, H.C.; Assmann, G. Tibolone lowers high density lipoprotein cholesterol by increasing hepatic lipase activity but does not impair cholesterol efflux. Clin. Endocrinol. (Oxf.), 2003, 58(1), 49-58.
[http://dx.doi.org/10.1046/j.1365-2265.2003.01666.x] [PMID: 12519412]
[32]
Anedda, F.M.; Velati, A.; Lello, S.; Orrù, M.; Paoletti, A.M.; Melis, G.B.; Binaghi, F. Observational study on the efficacy of tibolone in counteracting early carotid atherosclerotic lesions in postmenopausal women. Horm. Res., 2004, 61(1), 47-52.
[PMID: 14646402]
[33]
Demirol, A.; Guven, S.; Guvendag Guven, E.S.; Kirazli, S.; Gurgan, T.; Ayhan, A. Comparison of the effects of tibolone and estrogen therapy on hemostasis in surgical menopause: a randomized, double-blind, placebo-controlled study. Fertil. Steril., 2007, 87(4), 842-848.
[http://dx.doi.org/10.1016/j.fertnstert.2006.08.090] [PMID: 17222829]
[34]
Godsland, I.F. Effects of postmenopausal hormone replacement therapy on lipid, lipoprotein, and apolipoprotein (a) concentrations: analysis of studies published from 1974-2000. Fertil. Steril., 2001, 75(5), 898-915.
[http://dx.doi.org/10.1016/S0015-0282(01)01699-5] [PMID: 11334901]
[35]
Gaeta, G.; Lanero, S.; Barra, S.; Silvestri, N.; Cuomo, V.; Materazzi, C.; Vitagliano, G. Sex hormones and lipoprotein(a) concentration. Expert Opin. Investig. Drugs, 2011, 20(2), 221-238.
[http://dx.doi.org/10.1517/13543784.2011.548804] [PMID: 21204723]
[36]
Anagnostis, P.; Karras, S.; Lambrinoudaki, I.; Stevenson, J.C.; Goulis, D.G. Lipoprotein(a) in postmenopausal women: assessment of cardiovascular risk and therapeutic options. Int. J. Clin. Pract., 2016, 70(12), 967-977.
[http://dx.doi.org/10.1111/ijcp.12903] [PMID: 28032426]
[37]
Beral, V.; Banks, E.; Reeves, G. Evidence from randomised trials on the long-term effects of hormone replacement therapy. Lancet, 2002, 360(9337), 942-944.
[http://dx.doi.org/10.1016/S0140-6736(02)11032-4] [PMID: 12354487]
[38]
Román, M.; Graff-Iversen, S.; Weiderpass, E.; Vangen, S.; Sakshaug, S.; Hofvind, S.; Ursin, G. Postmenopausal Hormone Therapy and Breast Cancer Prognostic Characteristics: A Linkage between Nationwide Registries. Cancer Epidemiol. Biomarkers Prev., 2016, 25(11), 1464-1473.
[http://dx.doi.org/10.1158/1055-9965.EPI-16-0240] [PMID: 27461048]
[39]
Jadhav, V.; Gholve, S.; Kadam, V. Validation of high performance liquid chromatographic method for the determination of Tibolone in bulk and pharmaceutical dosage form. J. Pharm. Res., 2009, 2, 694-697.
[40]
Rosa, H.B.; Tolotti, R.C.; Miron, D.S.; de Souza, K.C.B. Desenvolvimento e validação de método para o doseamento de tibolona em cápsulas por cromatografia líquida de alta eficiência. Quim. Nova, 2012, 35, 1030-1035.
[http://dx.doi.org/10.1590/S0100-40422012000500030]
[41]
Shah, D.K.; Prajapati, H.G.; Sakhreliya, B. Development and Validation of Stability Indicating RP-HPLC Method for Estimation of Tibolone in Tablet Dosage Form. J. Pharm. Sci. Bio-sci. Res., 2014, 4, 281-285.
[42]
Zhao, Y.; Gao, Q.; Li, Y.; Han, Y.; Liu, L.; Sun, H. Method for detection of tibolone in human plasma by reversed phase high performance liquid chromatography. Journal of Hebei University 2012.
[43]
Bonfilio, R.; Souza, M.C.O.; Leal, J.S.; Viana, O.M.M.S.; Doriguetto, A.C.; Araújo, M.B. Solubility and dissolution studies of tibolone polymorphs. Braz. J. Pharm. Sci., 2017, 53, 1-12.
[44]
Ângelo, M.L. Análise farmacêutica de tibolona em cápsulas magistrais por cromatografia líquida de alta eficiência. Master's degree dissertation, Federal University of Alfenas: Alfenas, Minas Gerais, Brazil, , 2013.
[45]
Ban, F.; Shin, H.S.; Kim, S.T.; Kim, C.K. Determination of 3α-hydroxytibolone by LC/MS/MS with electrospray ionization method and its application to bioequivalence study in human plasma. J. Pharm. Investig., 2012, 42, 353-360.
[http://dx.doi.org/10.1007/s40005-012-0047-y]
[46]
Shinde, V.P.; Pudage, A.; Jangid, A.; Mistri, H.; Patel, P.K. Application of UPLC-MS/MS for separation and quantification of 3α-Hydroxy Tibolone and comparative bioavailability of two Tibolone formulations in healthy volunteers. J. Pharm. Anal., 2013, 3(4), 270-277.
[http://dx.doi.org/10.1016/j.jpha.2013.02.006] [PMID: 29403827]
[47]
de Santana e Silva Cardoso, F.F.; César, I.C.; Mundim, I.M.; de Souza Teixeira, L.; da Silva, E.P.; Bonfim, R.R.; Gomes, S.A.; Ferreira, D.P.; Lopes, A.R.B.; Pascoal, H.D.; de Souza, W.C.; Pianetti, G.A. Determination of 3-α-hydroxytibolone in human plasma by LC-MS/MS: application for a pharmacokinetic study after administration of a tibolone formulation. Biomed. Chromatogr., 2013, 27(11), 1457-1462.
[http://dx.doi.org/10.1002/bmc.2943] [PMID: 23813413]
[48]
Portela, L.A.; Laurito, T.L.; Severino, B.; Perissutti, E.; Mendes, G.D.; Ronilson, A.M.; De Nucci, G. Quantification of 3α-hydroxytibolone in human plasma by high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS): Application in a bioequivalence study in healthy postmenopausal volunteers. Anal. Chem. Res., 2016, 8, 16-25.
[http://dx.doi.org/10.1016/j.ancr.2016.04.002]
[49]
Zuo, M.; Gao, M.J.; Liu, Z.; Cai, L.; Duan, G.L. p-Toluenesulfonyl isocyanate as a novel derivatization reagent to enhance the electrospray ionization and its application in the determination of two stereo isomers of 3-hydroxyl-7-methyl-norethynodrel in plasma. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci., 2005, 814(2), 331-337.
[http://dx.doi.org/10.1016/j.jchromb.2004.10.054] [PMID: 15639456]
[50]
Penning, T.M.; Lee, S.H.; Jin, Y.; Gutierrez, A.; Blair, I.A. Liquid chromatography-mass spectrometry (LC-MS) of steroid hormone metabolites and its applications. J. Steroid Biochem. Mol. Biol., 2010, 121(3-5), 546-555.
[http://dx.doi.org/10.1016/j.jsbmb.2010.01.005] [PMID: 20083198]
[51]
Verhoeven, C.H.J.; Vos, R.M.E.; Delbressine, L.P.C. The in vivo metabolism of tibolone in animal species. Eur. J. Drug Metab. Pharmacokinet., 2002, 27(1), 1-10.
[http://dx.doi.org/10.1007/BF03190399] [PMID: 11996321]
[52]
Kang, K.W.; Kim, Y.G. Bioequivalence studies of tibolone in premenopausal women and effects on expression of the tibolone-metabolizing enzyme AKR1C (aldo-keto reductase) family caused by estradiol. J. Clin. Pharmacol., 2008, 48(12), 1430-1437.
[http://dx.doi.org/10.1177/0091270008323262] [PMID: 18832293]
[53]
de Gooyer, M.E.; Deckers, G.H.; Schoonen, W.G.; Verheul, H.A.; Kloosterboer, H.J. Receptor profiling and endocrine interactions of tibolone. Steroids, 2003, 68(1), 21-30.
[http://dx.doi.org/10.1016/S0039-128X(02)00112-5] [PMID: 12475720]
[54]
McLeod, M.D.; Waller, C.C.; Esquivel, A.; Balcells, G.; Ventura, R.; Segura, J.; Pozo, O.J. A constant ion loss method for the untargeted detection of bissulfate metabolites. Anal. Chem., 2017, 89(3), 1602-1609.
[http://dx.doi.org/10.1021/acs.analchem.6b03671] [PMID: 27982580]
[55]
Gosetti, F.; Mazzucco, E.; Gennaro, M.C.; Marengo, E. Ultra high performance liquid chromatography tandem mass spectrometry determination and profiling of prohibited steroids in human biological matrices. A review. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci., 2013, 927, 22-36.
[http://dx.doi.org/10.1016/j.jchromb.2012.12.003] [PMID: 23317577]
[56]
Kim, S.H.; Cha, E.J.; Lee, K.M.; Kim, H.J.; Kwon, O.S.; Lee, J. Simultaneous ionization and analysis of 84 anabolic androgenic steroids in human urine using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry. Drug Test. Anal., 2014, 6(11-12), 1174-1185.
[http://dx.doi.org/10.1002/dta.1747] [PMID: 25382000]
[57]
Van Thuyne, W.; Van Eenoo, P.; Delbeke, F.T. Implementation of gas chromatography combined with simultaneously selected ion monitoring and full scan mass spectrometry in doping analysis. J. Chromatogr. A, 2008, 1210(2), 193-202.
[http://dx.doi.org/10.1016/j.chroma.2008.09.049] [PMID: 18849031]
[58]
Jeong, E.S.; Kim, S.H.; Cha, E.J.; Lee, K.M.; Kim, H.J.; Lee, S.W.; Kwon, O.S.; Lee, J. Simultaneous analysis of 210 prohibited substances in human urine by ultrafast liquid chromatography/tandem mass spectrometry in doping control. Rapid Commun. Mass Spectrom., 2015, 29(4), 367-384.
[http://dx.doi.org/10.1002/rcm.7113] [PMID: 26406349]
[59]
Abushareeda, W.; Lyris, E.; Kraiem, S.; Wahaibi, A.A.; Alyazidi, S.; Dbes, N.; Lommen, A.; Nielen, M.; Horvatovich, P.L.; Alsayrafi, M.; Georgakopoulos, C. Gas chromatographic quadrupole time-of-flight full scan high resolution mass spectrometric screening of human urine in antidoping analysis. J. Chromatogr. B Analyt. Technol. Biomed. Life Sci., 2017, 1063, 74-83.
[http://dx.doi.org/10.1016/j.jchromb.2017.08.019] [PMID: 28850889]
[60]
Van Eenoo, P.; Van Gansbeke, W.; De Brabanter, N.; Deventer, K.; Delbeke, F.T. A fast, comprehensive screening method for doping agents in urine by gas chromatography-triple quadrupole mass spectrometry. J. Chromatogr. A, 2011, 1218(21), 3306-3316.
[http://dx.doi.org/10.1016/j.chroma.2010.09.082] [PMID: 20970803]
[61]
Desfontaine, V.; Nováková, L.; Ponzetto, F.; Nicoli, R.; Saugy, M.; Veuthey, J.L.; Guillarme, D. Liquid chromatography and supercritical fluid chromatography as alternative techniques to gas chromatography for the rapid screening of anabolic agents in urine. J. Chromatogr. A, 2016, 1451, 145-155.
[http://dx.doi.org/10.1016/j.chroma.2016.05.004] [PMID: 27185056]
[62]
De Brabanter, N.; Van Gansbeke, W.; Geldof, L.; Van Eenoo, P. An improved gas chromatography screening method for doping substances using triple quadrupole mass spectrometry, with an emphasis on quality assurance. Biomed. Chromatogr., 2012, 26(11), 1416-1435.
[http://dx.doi.org/10.1002/bmc.2714] [PMID: 22362568]
[63]
Kim, S.H.; Cha, E.J.; Lee, K.M.; Kim, H.J.; Kwon, O.S.; Lee, J. Simultaneous ionization and analysis of 84 anabolic androgenic steroids in human urine using liquid chromatography-silver ion coordination ionspray/triple-quadrupole mass spectrometry. Drug Test. Anal., 2014, 6(11-12), 1174-1185.
[http://dx.doi.org/10.1002/dta.1747] [PMID: 25382000]
[64]
World Anti-doping Agency., www.wada-ama.org 2019.
[65]
Bayer, E.; Gfrörer, P.; Rentel, C. Rentel. C. Coordination-Ionspray-MS (CIS-MS), a universal detection and characterization method for direct coupling with separation techniques. Angew. Chem. Int. Ed. Engl., 1999, 38(7), 992-995.
[http://dx.doi.org/10.1002/(SICI)1521-3773(19990401)38:7<992:AID-ANIE992>3.0.CO;2-K] [PMID: 29711860]
[66]
Hayen, H.; Álvarez-Grima, M.M.; Debnath, S.C.; Noordermeer, J.W.M.; Karst, U. Liquid chromatography/coordination ion spray-mass spectrometry for the analysis of rubber vulcanization products. Anal. Chem., 2004, 76(4), 1063-1068.
[http://dx.doi.org/10.1021/ac035017p] [PMID: 14961739]
[67]
Gaub, M.; von Brocke, A.; Roos, G.; Kovar, K.A. High-performance liquid chromatography-coordination ion spray-mass spectrometry (HPLC-CIS/MS): a new tool for the analysis of non-polar compound classes in plant extracts using the example of Piper methysticum Forst. Phytochem. Anal., 2004, 15(5), 300-305.
[http://dx.doi.org/10.1002/pca.782] [PMID: 15508834]
[68]
Alvarez, E.J.; Brodbelt, J.S. Evaluation of metal complexation as an alternative to protonation for electrospray ionization of pharmaceutical compounds. J. Am. Soc. Mass Spectrom., 1998, 9, 463-472.
[http://dx.doi.org/10.1016/S1044-0305(98)00007-5]

© 2024 Bentham Science Publishers | Privacy Policy