INTRODUCTION: The analysis of plant and herbal samples is a challenging task for analytical chemists due to the complexity of the matrix combined with the low concentration of analytes. In recent years different liquid-phase microextraction (LPME) techniques coupled with a variety of analytical equipment have been developed for the determination of both organic and inorganic analytes. OBJECTIVE: Over the past few years, the number of research papers in this field has shown a markedly growing tendency. Therefore, the purpose of this review paper is to summarise and critically evaluate research articles focused on the application of LPME techniques for the analysis of plant and herbal samples. RESULTS: Due to the complex nature of the samples, the direct application of LPME techniques to the analysis of plants has not often been done. LPME techniques as well as their modalities have been commonly applied in combination with other pretreatment techniques, including a solid-liquid extraction technique supported by mechanical agitation or auxiliary energies for plant analysis. Applications and the most important parameters are summarised in the tables. CONCLUSION: This review summarises the application of the LPME procedure and shows the major benefits of LPME, such as the low volume of solvents used, high enrichment factor, simplicity of operation and wide selection of applicable detection techniques. We can expect further development of microextraction analytical methods that focus on direct sample analysis with the application of green extraction solvents while fully automating procedures for the analysis of plant materials.

Department of Analytical Chemistry Institute of Chemistry P J Šafárik University Košice Slovakia

Department of Botany Institute of Biology and Ecology P J Šafárik University Košice Slovakia

Department of Pharmacy University G d'Annunzio Chieti Pescara Chieti Italy

Faculty of Forestry and Wood Sciences Czech University of Life Sciences Prague Prague Suchdol Czech Republic

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Weinberg ED. Secondary metabolism: raison d'être. Perspect Biol Med. 1971;14:565-577.

Fraenkel GS. The raison d'être of secondary plant substances. Science. 1959;129(3361):1466-1470. https://doi.org/10.1126/science.129.3361.1466

Rabha J, Jha DK. Metabolic diversity of penicillium. In: Gupta VK, Rodriguez Couto S, eds. New and Future Developments in Microbial Biotechnology and Bioengineering: Penicillium System Properties and Applications. Amsterdam: Elsevier; 2018:217-234 https://doi.org/10.1016/b978-0-444-63501-3.00012-0.

Rosenthal GA. Herbivores: their interactions with secondary plant metabolites. 1991. Available at: https://ubdata.univie.ac.at/AC00383432.

Karban R. Induced Responses to Herbivory. Chicago, IL: University of Chicago Press; 1997.

Agosta WC. Bombardier Beetles and Fever Trees: A Close-up Look at Chemical Warfare and Signals in Animals and Plants. New York, NY: Basic Books; 1995:25.

Shi QW, Li LG, Huo CH, Zhang ML, Wang YF. Study on natural medicinal chemistry and new drug development. Chin Tradit Herb Drug. 2010;41:1583-1589.

Fabricant DS, Farnsworth NR. The value of plants used in traditional medicine for drug discovery. Environ Health Perspect. 2001;109:69-75.

Ranković B. Lichen Secondary Metabolites: Bioactive Properties and Pharmaceutical Potential. Cham: Springer; 2019.

Goga M, Elečko J, Marcinčinová M, Ručová D, Bačkorová M, Bačkor M. Lichen metabolites: an overview of some secondary metabolites and their biological potential. In: Merillon J-M, Ramawat KG, eds. Co-evolution of Secondary Metabolites. Cham: Springer International Publishing; 2018, 1-36. https://doi.org/10.1007/978-3-319-76887-8_57-1

Tobiszewski M, Mechlińska A, Namieśnik J. Green analytical chemistry-theory and practice. Chem Soc Rev. 2010;39(8):2869-2878. https://doi.org/10.1039/B926439F

Yan H, Wang H. Recent development and applications of dispersive liquid-liquid microextraction. J Chromatogr a. 2013;1295:1-15. https://doi.org/10.1016/j.chroma.2013.04.053

Albero B, Sánchez-Brunete C, Miguel E, Tadeo JL. Rapid determination of emerging contaminants in water and herbal infusions by in situ derivatization and gas chromatography-tandem mass spectrometry. Anal Methods. 2015;7:3006-3014. https://doi.org/10.1039/c4ay03010a

Aydin F, Yilmaz E, Soylak M. Vortex assisted deep eutectic solvent (DES)-emulsification liquid-liquid microextraction of trace curcumin in food and herbal tea samples. Food Chem. 2018;243:442-447. https://doi.org/10.1016/j.foodchem.2017.09.154

Wang Z, Cao B, Yu A, Zhang H, Qiu F. Ultrasound-assisted ionic liquid-based homogeneous liquid-liquid microextraction high-performance liquid chromatography for determination of tanshinones in Salvia miltiorrhiza Bge. Root. J Pharm Biomed Anal. 2015;104:97-104. https://doi.org/10.1016/j.jpba.2014.11.034

Li L, Huang M, Shao J, Lin B, Shen Q. Rapid determination of alkaloids in Macleaya cordata using ionic liquid extraction followed by multiple reaction monitoring UPLC-MS/MS analysis. J Pharm Biomed Anal. 2017;135:61-66. https://doi.org/10.1016/j.jpba.2016.12.016

Hashemi P, Beyranvand S, Mansur RS, Ghiasvand AR. Development of a simple device for dispersive liquid-liquid microextraction with lighter than water organic solvents: isolation and enrichment of glycyrrhizic acid from licorice. Anal Chim Acta. 2009;655(1-2):60-65. https://doi.org/10.1016/j.aca.2009.09.034

Wang GJ, Tian L, Fan YM, Qi ML. Headspace single-drop microextraction gas chromatography mass spectrometry for the analysis of volatile compounds from herba asari. J Anal Methods Chem. 2013;2013:art. no. 1-6.380705 https://doi.org/10.1155/2013/380705.

Liu X, Li J, Zhao Z, et al. Solid-phase extraction combined with dispersive liquid-liquid microextraction for the determination for polybrominated diphenyl ethers in different environmental matrices. J Chromatogr A. 2009;1216(12):2220-2226. https://doi.org/10.1016/j.chroma.2008.12.092

Wu Y, Xia L, Chen R, Hu B. Headspace single drop microextraction combined with HPLC for the determination of trace polycyclic aromatic hydrocarbons in environmental samples. Talanta. 2008;74(4):470-477. https://doi.org/10.1016/j.talanta.2007.05.057

Yang J, Wei H, Teng X, Zhang H, Shi Y. Dynamic ultrasonic nebulisation extraction coupled with headspace ionic liquid-based single-drop microextraction for the analysis of the essential oil in Forsythia suspensa. Phytochem Anal. 2014;25(2):178-184. https://doi.org/10.1002/pca.2490

Li G, Wu D, Xie W, Sha Y, Lin H, Liu B. Analysis of amino acids in tobacco by derivatization and dispersive liquid-liquid microextraction based on solidification of floating organic droplet method. J Chromatogr A. 2013;1296:243-247. https://doi.org/10.1016/j.chroma.2013.03.076

Lv T, Zhao XE, Zhu S, et al. Development of an efficient HPLC fluorescence detection method for brassinolide by ultrasonic-assisted dispersive liquid-liquid microextraction coupled with derivatization. Chromatographia. 2014;77(23-24):1653-1660. https://doi.org/10.1007/s10337-014-2767-9

Hashemi P, Raeisi F, Ghiasvand AR, Rahimi A. Reversed-phase dispersive liquid-liquid microextraction with central composite design optimization for preconcentration and HPLC determination of oleuropein. Talanta. 2010;80(5):1926-1931. https://doi.org/10.1016/j.talanta.2009.10.051

Lu Q, Chen L, Lu M, Chen G, Zhang L. Extraction and analysis of auxins in plants using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection. J Agric Food Chem. 2010;58(5):2763-2770. https://doi.org/10.1021/jf903274z

Jumepaeng T, Luthria DL, Chanthai S. The effect of surfactant on headspace single drop microextraction for the determination of some volatile aroma compounds in citronella grass and lemongrass leaves by gas chromatography. Anal Methods. 2012;4:421-428. https://doi.org/10.1039/c2ay05646a

Gholivand MB, Piryaei M. A method for fast analysis of volatile components of Citrus aurantium L. Leaves Natural Product Research. 2013;27(14):1315-1318. https://doi.org/10.1080/14786419.2012.730048

Adam M, Dobiáš P, Eisner A, Ventura K. Headspace single-drop microextraction of herbal essential oils. J Sep Sci. 2008;31(2):356-363. https://doi.org/10.1002/jssc.200700377

Cai K, Cai B, Xiang Z, et al. Low-temperature derivatization followed by vortex-assisted liquid-liquid microextraction for the analysis of polyamines in Nicotiana tabacum. J Sep Sci. 2016;39(13):2573-2583. https://doi.org/10.1002/jssc.201600210

Sereshti H, Izadmanesh Y, Samadi S. Optimized ultrasonic assisted extraction-dispersive liquid-liquid microextraction coupled with gas chromatography for determination of essential oil of Oliveria decumbens Vent. J Chromatogr A. 2011;1218(29):4593-4598. https://doi.org/10.1016/j.chroma.2011.05.037

Wen Y, Nie J, Li ZG, Xu XY, Wei D, Lee MR. The development of ultrasound-assisted extraction/dispersive liquid-liquid microextraction coupled with DSI-GC-IT/MS for analysis of essential oil from fresh flowers of Edgeworthia chrysantha Lindl. Anal Methods. 2014;6:3345-3352. https://doi.org/10.1039/c4ay00115j

Jiang C, Sun Y, Zhu X, et al. Solvent-free microwave extraction coupled with headspace single-drop microextraction of essential oils from flower of Eugenia caryophyllata Thunb. J Sep Sci. 2010;33(17-18):2784-2790. https://doi.org/10.1002/jssc.201000148

Kim NS, Jung MJ, Yoo ZW, Lee SN, Lee DS. Headspace hanging drop liquid phase microextraction and GC-MS for the determination of linalool from evening primrose flowers. Bull Korean Chem Soc. 2005;26:1996-2000. https://doi.org/10.5012/bkcs.2005.26.12.1996

Zhang H, Shi Y, Wei S, Wang Y, Zhang H. Ultrasonic nebulization extraction coupled with headspace single-drop microextraction of volatile and semivolatile compounds from the seed of Cuminum cyminum L. Talanta. 2011;85(2):1081-1087. https://doi.org/10.1016/j.talanta.2011.05.020

Xue J, Li H, Liu F, Jiang W, Hou F. Vortex-assisted matrix solid-liquid dispersive microextraction for the analysis of triazole fungicides in cotton seed and honeysuckle by gas chromatography. Food Chem. 2016;196:867-876. https://doi.org/10.1016/j.foodchem.2015.09.093

Yang J, Wei H, Yu C, Shi Y, Zhang H. Extraction of the volatile and semivolatile compounds in seeds of Cuminum cyminum L. using hydrodistillation followed by headspace-ionic liquid-based single-drop microextraction. Chromatographia. 2012;75(23-24):1435-1443. https://doi.org/10.1007/s10337-012-2335-0

Wang Z, Hu J, Du H, He S, Li Q, Zhang H. Microwave-assisted ionic liquid homogeneous liquid-liquid microextraction coupled with high performance liquid chromatography for the determination of anthraquinones in Rheum palmatum L. J Pharm Biomed Anal. 2016;125:178-185. https://doi.org/10.1016/j.jpba.2016.03.046

Yang G, Sun Q, Hu Z, Liu H, Zhou T, Fan G. Optimization of an accelerated solvent extraction dispersive liquid-liquid microextraction method for the separation and determination of essential oil from Ligusticum chuanxiong Hort by gas chromatography with mass spectrometry. J Sep Sci. 2015;38(20):3588-3598. https://doi.org/10.1002/jssc.201500238

Dong W, Yu S, Deng Y, Pan T. Screening of lignan patterns in Schisandra species using ultrasonic assisted temperature switch ionic liquid microextraction followed by UPLC-MS/MS analysis. J Chromatogr B Analyt Technol Biomed Life Sci. 2016;1008:45-49. https://doi.org/10.1016/j.jchromb.2015.11.022

Liang P, Wang J, Liu G, Guan J. Determination of four sulfonylurea herbicides in tea by matrix solid-phase dispersion cleanup followed by dispersive liquid-liquid microextraction. J Sep Sci. 2014;37(17):2380-2387. https://doi.org/10.1002/jssc.201400449

Sereshti H, Heidari R, Samadi S. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry. Food Chem. 2014;143:499-505. https://doi.org/10.1016/j.foodchem.2013.08.024

Deng C, Yao N, Wang B, Zhang X. Development of microwave-assisted extraction followed by headspace single-drop microextraction for fast determination of paeonol in traditional Chinese medicines. J Chromatogr A. 2006;1103(1):15-21. https://doi.org/10.1016/j.chroma.2005.11.023

Ye ZY, Li ZG, Wei D, Lee MR. Microwave-assisted extraction/dispersive liquid-liquid microextraction coupled with DSI-GC-IT/MS for analysis of essential oil from three species of cardamom. Chromatographia. 2014;77(3-4):347-358. https://doi.org/10.1007/s10337-013-2608-2

Wei S, Zhang H, Wang Y, et al. Ultrasonic nebulization extraction-heating gas flow transfer-headspace single drop microextraction of essential oil from pericarp of Zanthoxylum bungeanum maxim. J Chromatogr A. 2011;1218(29):4599-4605. https://doi.org/10.1016/j.chroma.2011.05.047

Ye J, Wang W, Ho C, et al. Differentiation of two types of pu-erh teas by using an electronic nose and ultrasound-assisted extraction-dispersive liquid-liquid microextraction-gas chromatography-mass spectrometry. Anal Methods. 2016;8:593-604. https://doi.org/10.1039/c5ay02652k

Ye J, Wang W, Li J, et al. Influence of the post-fermentation by four aspergillus strains on the aroma of pu-erh tea. Journal of Chinese Pharmaceutical Sciences. 2016;25:284-290. https://doi.org/10.5246/jcps.2016.04.032

Sereshti H, Samadi S, Jalali-Heravi M. Determination of volatile components of green, black, oolong and white tea by optimized ultrasound-assisted extraction-dispersive liquid-liquid microextraction coupled with gas chromatography. J Chromatogr A. 2013;1280:1-8. https://doi.org/10.1016/j.chroma.2013.01.029

Sereshti H, Samadi S. A rapid and simple determination of caffeine in teas, coffees and eight beverages. Food Chem. 2014;158:8-13. https://doi.org/10.1016/j.foodchem.2014.02.095

Sereshti H, Rohanifar A, Bakhtiari S, Samadi S. Bifunctional ultrasound assisted extraction and determination of Elettaria cardamomum Maton essential oil. J Chromatogr A. 2012;1238:46-53. https://doi.org/10.1016/j.chroma.2012.03.061

Ho YM, Tsoi YK, Leung KSY. Highly sensitive and selective organophosphate screening in twelve commodities of fruits, vegetables and herbal medicines by dispersive liquid-liquid microextraction. Anal Chim Acta. 2013;775:58-66. https://doi.org/10.1016/j.aca.2013.02.043

Zhang HF, Shi YP. Temperature-assisted ionic liquid dispersive liquid-liquid microextraction combined with high performance liquid chromatography for the determination of anthraquinones in Radix et Rhizoma Rhei samples. Talanta. 2010;82(3):1010-1016. https://doi.org/10.1016/j.talanta.2010.06.008

Gupta V, Kumar M, Brahmbhatt H, Reddy CRK, Seth A, Jha B. Simultaneous determination of different endogenetic plant growth regulators in common green seaweeds using dispersive liquid-liquid microextraction method. Plant Physiol Biochem. 2011;49(11):1259-1263. https://doi.org/10.1016/j.plaphy.2011.08.004

Sereshti H, Ghiasi A, Naderloo M, Taghizadeh M, Darvish Alipoar Astaneh S. Vortex-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by GC-MS for determination of Achillea Wilhelmsii essential oil. Anal Methods. 2014;6:6695-6701. https://doi.org/10.1039/c4ay00506f

Zhai Y, Sun S, Wang Z, et al. Headspace single drop microextraction coupled with microwave extraction of essential oil from plant materials. J Sep Sci. 2011;34(9):1069-1075. https://doi.org/10.1002/jssc.201000629

Zhang Y, Xu H. Determination of triazoles in tea samples using dispersive solid phase extraction combined with dispersive liquid-liquid microextraction followed by liquid chromatography-tandem mass spectrometry. Food Anal Methods. 2014;7(1):189-196. https://doi.org/10.1007/s12161-013-9617-5

Wei JC, Hu J, Cao JL, et al. Sensitive detection of organophosphorus pesticides in medicinal plants using ultrasound-assisted dispersive liquid-liquid microextraction combined with sweeping micellar electrokinetic chromatography. J Agric Food Chem. 2016;64(4):932-940. https://doi.org/10.1021/acs.jafc.5b05369

Sun J, Zhao XE, Dang J, et al. Rapid and sensitive determination of phytosterols in functional foods and medicinal herbs by using UHPLC-MS/MS with microwave-assisted derivatization combined with dual ultrasound-assisted dispersive liquid-liquid microextraction. J Sep Sci. 2017;40:725-732. https://doi.org/10.1002/jssc.201600711

Li LH, Zhang HF, Hu S, Bai XH, Li S. Dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography for determination of coumarin compounds in Radix Angelicae Dahuricae. Chromatographia. 2012;75(3-4):131-137. https://doi.org/10.1007/s10337-011-2177-1

Yang X, Chen X, Hu S, Bai X-H. In-syringe binary-solvent liquid-phase microextraction for the preconcentration of cinnamic acid derivatives in traditional Chinese medicine samples. Chromatographia. 2017;81(2):257-264. https://doi.org/10.1007/s10337-017-3431-y

Adam M, Dobiáš P, Pavlíková P, Ventura K. Comparison of solid-phase and single-drop microextractions for headspace analysis of herbal essential oils. Cent Eur J Chem. 2009;7(3):303-311. https://doi.org/10.2478/s11532-009-0048-5

Moradi M, Kaykhaii M, Ghiasvand AR, Shadabi S, Salehinia A. Comparison of headspace solid-phase microextraction, headspace single-drop microextraction and hydrodistillation for chemical screening of volatiles in Myrtus communis L. Phytochem Anal. 2012;23(4):379-386. https://doi.org/10.1002/pca.1368

Jiao J, Ma DH, Gai QY, et al. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography-mass spectrometry. Anal Chim Acta. 2013;804:143-150. https://doi.org/10.1016/j.aca.2013.10.035

Jiao J, Gai QY, Wang W, et al. Ionic-liquid-assisted microwave distillation coupled with headspace single-drop microextraction followed by GC-MS for the rapid analysis of essential oil in Dryopteris fragrans. J Sep Sci. 2013;36:3799-3806. https://doi.org/10.1002/jssc.201300906

Wu H, Li G, Liu S, et al. Simultaneous determination of six triterpenic acids in some Chinese medicinal herbs using ultrasound-assisted dispersive liquid-liquid microextraction and high-performance liquid chromatography with fluorescence detection. J Pharm Biomed Anal. 2015;107:98-107. https://doi.org/10.1016/j.jpba.2014.10.031

Moinfar S, Hosseini MRM. Development of dispersive liquid-liquid microextraction method for the analysis of organophosphorus pesticides in tea. J Hazard Mater. 2009;169(1-3):907-911. https://doi.org/10.1016/j.jhazmat.2009.04.030

Ye Q. Rapid analysis of the essential oil components of dried Zanthoxylum bungeanum maxim by Fe2O3-magnetic-microsphere-assisted microwave distillation and simultaneous headspace single-drop microextraction followed by GC-MS. J Sep Sci. 2013;36:2028-2034. https://doi.org/10.1002/jssc.201300205

Arroyo-Manzanares N, García-Campaña AM, Gámiz-Gracia L. Multiclass mycotoxin analysis in Silybum marianum by ultra high performance liquid chromatography-tandem mass spectrometry using a procedure based on QuEChERS and dispersive liquid-liquid microextraction. J Chromatogr a. 2013;1282:11-19. https://doi.org/10.1016/j.chroma.2013.01.072

Qin Y, Chen L, Yang X, Tang Y, Li S, Liu C. Determination of 19 representative pesticides in traditional Chinese medicines by dispersive liquid-liquid microextraction and ultrahigh-performance liquid chromatography-tandem mass spectrometry. Chromatographia. 2016;79(13-14):875-884. https://doi.org/10.1007/s10337-016-3105-1

Deng C, Mao Y, Hu F, Zhang X. Development of gas chromatography-mass spectrometry following microwave distillation and simultaneous headspace single-drop microextraction for fast determination of volatile fraction in Chinese herb. J Chromatogr A. 2007;1152(1-2):193-198. https://doi.org/10.1016/j.chroma.2006.08.074

Hou X, Zheng X, Zhang C, Ma X, Ling Q, Zhao L. Ultrasound-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by gas chromatography for the determination of eight pyrethroid pesticides in tea samples. J Chromatogr B. 2014;969:123-127. https://doi.org/10.1016/j.jchromb.2014.08.010

Chen L, Yin L, Song F, et al. Determination of pesticide residues in ginseng by dispersive liquid-liquid microextraction and ultra high performance liquid chromatography-tandem mass spectrometry. J Chromatogr B. 2013;917-918(77):71-77. https://doi.org/10.1016/j.jchromb.2012.12.034

Li J, Sun M, Chang Q, Hu X, Kang J, Fan C. Determination of pesticide residues in teas via QuEChERS combined with dispersive liquid-liquid microextraction followed by gas chromatography-tandem mass spectrometry. Chromatographia. 2017;80(9):1447-1458. https://doi.org/10.1007/s10337-017-3362-7

Jalali-Heravi M, Sereshti H. Determination of essential oil components of Artemisia haussknechtii Boiss. using simultaneous hydrodistillation-static headspace liquid phase microextraction-gas chromatography mass spectrometry. J Chromatogr A. 2007;1160(1-2):81-89. https://doi.org/10.1016/j.chroma.2007.05.096

Gholivand MB, Abolghasemi MM, Piryaei M, Maassoumi SM, Papzan A. Microwave distillation followed by headspace single drop microextraction coupled to gas chromatography-mass spectrometry (GC-MS) for fast analysis of volatile components of Echinophora platyloba DC. Food Chem. 2013;138(1):251-255. https://doi.org/10.1016/j.foodchem.2012.09.112

Sheikhian L, Shirafkan M. Temperature-assisted ionic liquid-based dispersive liquid-liquid microextraction with following back-extraction for HPLC/UV-vis determination of 3-indole acetic acid in pea plants. J Iranian Chem Soc. 2016;13(5):903-911. https://doi.org/10.1007/s13738-015-0806-6

Aliakbarzadeh G, Sereshti H, Parastar H. Pattern recognition analysis of chromatographic fingerprints of Crocus sativus L. secondary metabolites towards source identification and quality control. Anal Bioanal Chem. 2016;408(12):3295-3307. https://doi.org/10.1007/s00216-016-9400-8

Werner J. Determination of metal ions in tea samples using task-specific ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction coupled to liquid chromatography with ultraviolet detection. J Sep Sci. 2016;39(8):1411-1417. https://doi.org/10.1002/jssc.201501200

Bell EA. Secondary plant products. In: Encyclopedia Plant Physiology. Vol. 8. Berlin: Springer-verlag; 1980.

Jain C, Khatana S, Vijayvergia R. Bioactivity of secondary metabolites of various plants: a review. Int J Pharm Sci Res. 2019;10:494-504. https://doi.org/10.13040/ijpsr.0975-8232.10(2).494-04

Taiz L, Zeiger E. Plant Physiology. International ed. 5th ed. Sunderland, MA: Sinauer Associates; 2010.

Šandrejová J, Campillo N, Viñas P, Andruch V. Classification and terminology in dispersive liquid-liquid microextraction. Microchem J. 2016;127:184-186. https://doi.org/10.1016/j.microc.2016.03.007

Viñas P, Campillo N, Andruch V. Recent achievements in solidified floating organic drop microextraction. TrAC Trends Anal Chem. 2015;68:48-77. https://doi.org/10.1016/j.trac.2015.02.005

Shishov A, Bulatov A, Locatelli M, Carradori S, Andruch V. Application of deep eutectic solvents in analytical chemistry. A review. Microchem J. 2017;135:33-38. https://doi.org/10.1016/j.microc.2017.07.015

Wang L, Wang Z, Zhang H, Li X, Zhang H. Ultrasonic nebulization extraction coupled with headspace single drop microextraction and gas chromatography-mass spectrometry for analysis of the essential oil in Cuminum cyminum L. Anal Chim Acta. 2009;647(1):72-77. https://doi.org/10.1016/j.aca.2009.05.030

Wang L, Wang Z, Li X, Zhang H, Zhou X, Zhang H. Analysis of volatile compounds in the pericarp of Zanthoxylum Bungeanum Maxim by ultrasonic nebulization extraction coupled with headspace single-drop microextraction and GC-MS. Chromatographia. 2010;71(5-6):455-459. https://doi.org/10.1365/s10337-010-1497-x

Mirzaei M, Dinpanah H. Three phases hollow fiber LPME combined with HPLC-UV for extraction, preconcentration and determination of valerenic acid in Valeriana officinalis. J Chromatogr B. 2011;879:1870-1874. https://doi.org/10.1016/j.jchromb.2011.05.005

Bahar S, Babamiri B. Preconcentration and determination of low amounts of cobalt in black tea, paprika and marjoram using dispersive liquid-liquid microextraction and flame atomic absorption spectrometry. J Iranian Chem Soc. 2015;12(1):51-56. https://doi.org/10.1007/s13738-014-0453-3

Arain MB, Yilmaz E, Soylak M. Deep eutectic solvent based ultrasonic assisted liquid phase microextraction for the FAAS determination of cobalt. J Mol Liq. 2016;224:538-543. https://doi.org/10.1016/j.molliq.2016.10.005

Kantürer Acar D, Kara D. A new dispersive liquid-liquid microextraction method for the preconcentration of copper using 4-phenyl-3-thiosemicarbazide and FAAS detection. Water Air Soil Pollut. 2014;225(2):1-9. https://doi.org/10.1007/s11270-013-1864-y

Bahar S, Zakerian R. Determination of copper in human hair and tea samples after dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO). J Brazilian Chem Soc. 2012;23:1166-1173. https://doi.org/10.1590/S0103-50532012000600023

Meng FY, Wei YQ, Lu H, et al. Chelatometric dispersive liquid-liquid microextraction followed by capillary electrophoresis for the analysis of total and water soluble copper in Rhizoma coptidis. Chin Chem Lett. 2013;24:506-508. https://doi.org/10.1016/j.cclet.2013.03.042

Shokri M, Beiraghi A, Seidi S. In situ emulsification microextraction using a dicationic ionic liquid followed by magnetic assisted physisorption for determination of lead prior to micro-sampling flame atomic absorption spectrometry. Anal Chim Acta. 2015;889:123-129. https://doi.org/10.1016/j.aca.2015.07.007

Yilmaz E, Soylak M. Ionic liquid-linked dual magnetic microextraction of lead(II) from environmental samples prior to its micro-sampling flame atomic absorption spectrometric determination. Talanta. 2013;116:882-886. https://doi.org/10.1016/j.talanta.2013.08.002

Hossien-poor-Zaryabi M, Chamsaz M, Heidari T, Zavar MHA, Behbahani M, Salarian M. Application of dispersive liquid-liquid micro-extraction using mean centering of ratio spectra method for trace determination of mercury in food and environmental samples. Food Anal Methods. 2014;7(2):352-359. https://doi.org/10.1007/s12161-013-9633-5

Wen S, Zhu X. Speciation analysis of Mn(II)/Mn(VII) in tea samples using flame atomic absorption spectrometry after room temperature ionic liquid-based dispersive liquid-liquid microextraction. Food Anal Methods. 2014;7(2):291-297. https://doi.org/10.1007/s12161-013-9626-4

Barros JAVA, Aguirre MÁ, Kovachev N, Canals A, Nóbrega JA. Vortex-assisted dispersive liquid-liquid microextraction for the determination of molybdenum in plants by inductively coupled plasma optical emission spectrometry. Anal Methods. 2016;8:810-815. https://doi.org/10.1039/c5ay02561c

Gharehbaghi M, Shemirani F. Ionic liquid-based dispersive liquid-liquid microextraction and enhanced spectrophotometric determination of molybdenum(VI) in water and plant leaves samples by FO-LADS. Food Chem Toxicol. 2011;49(2):423-428. https://doi.org/10.1016/j.fct.2010.11.017

Zhou Q, Lei M, Li J, et al. Selenium speciation in tea by dispersive liquid-liquid microextraction coupled to high-performance liquid chromatography after derivatization with 2,3-diaminonaphthalene. J Sep Sci. 2015;38(9):1577-1583. https://doi.org/10.1002/jssc.201401373

Chen S, Yan J, Li J, Zhang Y, Lu D. Solid phase extraction with titanium dioxide nanofibers combined with dispersive liquid-liquid microextraction for speciation of thallium prior to electrothermal vaporization ICP-MS. Microchim Acta. 2017;184:2797-2803. https://doi.org/10.1007/s00604-017-2309-x

Khayatian G, Hassanpoor S. Ultrasound assisted emulsification microextraction based on dimetyl (E)-2-[(Z)-1-acetyl-2-hydroxy-1-propenyl]-2-butenedioate for determination of total amount of iron in water and tea samples. J Chin Chem Soc. 2012;59:659-666. https://doi.org/10.1002/jccs.201100447

Ezoddin M, Taghizadeh T, Majidi B. Ultrasound-assisted surfactant-enhanced emulsification microextraction for the determination of Cd and Ni in tea and water samples. Environ Technol (United Kingdom). 2014;35:2401-2409. https://doi.org/10.1080/09593330.2014.907361

Arslan O, Karadaş C, Kara D. Simultaneous preconcentration of copper and cadmium by dispersive liquid-liquid microextraction using N,N'-bis(2-hydroxy-5-bromo-benzyl)1,2 diaminopropane and their determination by flame atomic absorption spectrometry. J AOAC Int. 2016;99:1356-1362. https://doi.org/10.5740/jaoacint.16-0134

Aghamohammadi M, Faraji M, Shahdousti P, Kalhor H, Saleh A. Trace determination of lead, chromium and cadmium in herbal medicines using ultrasound-assisted emulsification microextraction combined with graphite furnace atomic absorption spectrometry. Phytochem Anal. 2015;26(3):209-214. https://doi.org/10.1002/pca.2554

Gałuszka A, Migaszewski ZM, Konieczka P, Namieśnik J. Analytical eco-scale for assessing the greenness of analytical procedures. TrAC Trends Anal Chem. 2012;37:61-72. https://doi.org/10.1016/j.trac.2012.03.013

Tobiszewski M. Metrics for green analytical chemistry. Anal Methods. 2016;8:2993-2999. https://doi.org/10.1039/C6AY00478D

Keith LH, Gron LU, Young JL. Green analytical methodologies. Chem Rev. 2007;107(6):2695-2708. https://doi.org/10.1021/cr068359e

Płotka-Wasylka J. A new tool for the evaluation of the analytical procedure: green analytical procedure index. Talanta. 2018;181:204-209. https://doi.org/10.1016/j.talanta.2018.01.013