Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography–Tandem Mass Spectrometry Combined with Rapid-Easy Extraction
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Sample Preparation
2.3. Preparation of Matrix-Matched Calibration Standards
2.4. LC-MS/MS Analysis
2.5. Method Validation
3. Results and Discussion
3.1. Sample Preparation
3.2. Optimum Conditions of LC-MS/MS Analysis
3.3. Method Validation
3.4. Application for Commercial Tea Samples
4. Conclusions
Supplementary Materials
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
- Schaneberg, B.T.; Molyneux, R.J.; Khan, I.A. Evaporative light scattering detection of pyrrolizidine alkaloids. Phytochem. Anal. 2004, 15, 36–39. [Google Scholar] [CrossRef] [PubMed]
- EFSA Panel on Contaminants in the Food Chain (CONTAM). Scientific Opinion on Pyrrolizidine alkaloids in food and feed. EFSA J. 2011, 9, 2406. [Google Scholar] [CrossRef]
- Edgar, J.A.; Molyneux, R.J.; Colegate, S.M. Pyrrolizidine Alkaloids: Potential Role in the Etiology of Cancers, Pulmonary Hypertensions, Congenital Anomalies, and Liver Disease. Chem. Res. Toxicol. 2015, 28, 4–20. [Google Scholar] [CrossRef] [PubMed]
- International Program on Chemical Safety (IPCS). Environmental Health Criteria 80-Pyrrolizidine Alkaloids; World Health Organization (WHO): Geneva, Switzerland, 1988; p. 345. [Google Scholar]
- Mattocks, A.R. Chemistry and Toxicology of Oyrrolizidine Alkaloids; Academic Press: London, UK, 1986; pp. 1–393. [Google Scholar]
- International Agency for Research on Cancer (IARC). Monographs on the Evaluation of Carcinogenic Risks to Humans, Suppl. 7, Overall Evaluations of Carcinogenicity. In An Updating of IARC Monographs; WHOIARC: Lyon, France, 1987; pp. 1–42. [Google Scholar]
- IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, & International Agency for Research on Cancer. Some Traditional Herbal Medicines, Some Mycotoxins, Naphthalene and Styrene; World Health Organization: Geneva, Switzerland, 2002; Volume 82. [Google Scholar]
- Für Risikobewertung, B (BfR). Chemical Analysis and Toxicity of Pyrrolizidine Alkaloids and Assessment of the Health Risk Posed by Their Occurrence in Honey; Federal Institute for Risk Assessment; BfR: Berline, Germany, 2011; Available online: https://www.bfr.bund.de/cm/349/chemical-analysis-and-toxicity-of-pyrrolizidine-alkaloids-and-assessment-of-the-health-risks-posed-by-their-occurence-in-honey.pdf (accessed on 13 June 2019).
- European Food Safety Authority (EFSA); Afonso, A.; Matas, R.G.; Maggiore, A.; Merten, C.; Robinson, T. EFSA’s Activities on Emerging Risks in 2016; EFSA Supporting Publications: Parma, Italy, 2017; Volume 14, p. 1336E. [Google Scholar] [CrossRef] [Green Version]
- Foodnews. Strengthen Safety Management of Pollen Products, Pyrrolizidine Alkaloids. Available online: http://www.foodnews.co.kr/news/articleView.html?idxno=70288 (accessed on 13 June 2019).
- Korea Health Industry Development Institute (KHIDI). National Food & Nutrition Statistics based on 2013. In Korea National Health and Nutrition Examination Survey; KHIDI: Chungju, Korea, 2016. [Google Scholar]
- Korea Customs Service. Export and Import Trade Statistics. Available online: https://unipass.customs.go.kr:38030/ets (accessed on 10 November 2017).
- Ministry of Food and Drug Safety (MFDS). Tea Production record. In Food & Drug Statistical Yearbook 2015; Ministry of Food and Drug Safety (MFDS): Chungju, Korea, 2016. [Google Scholar]
- Mudge, E.M.; Jones, A.M.; Brown, P.N. Quantification of pyrrolizidine alkaloids in North American plants and honey by LC-MS: Single laboratory validation. Food Addit. Contam. Part A 2015, 32, 2068–2074. [Google Scholar] [CrossRef] [PubMed]
- Prada, F.; Stashenko, E.; Martinez, J.R. LC/MS study of the diversity and distribution of pyrrolizidine alkaloids in Crotalaria species growing in Colombia. J. Sep. Sci. 2020, 43, 4322–4337. [Google Scholar] [CrossRef] [PubMed]
- Zhang, Y.; Yang, F.-F.; Chen, H.; Qi, Y.-D.; Si, J.-Y.; Wu, Q.; Liao, Y.-H. Analysis of pyrrolizidine alkaloids in Eupatorium fortunei Turcz. and their in vitro neurotoxicity. Food Chem. Toxicol. 2021, 151, 151–160. [Google Scholar] [CrossRef] [PubMed]
- Chmit, M.S.; Wahrig, B.; Beuerle, T. Quantitative and qualitative analysis of pyrrolizidine alkaloids in liqueurs elixirs and herbal juices. Fitoterapia 2019, 136, 172–178. [Google Scholar] [CrossRef] [PubMed]
- Bodi, D.; Ronczka, S.; Gottschalk, C.; Behr, N.; Skibba, A.; Wagner, M.; Lahrssen-Wiederholt, M.; Preiss-Weigert, A. Determination of pyrrolizidine alkaloids in tea, herbal drugs and honey. Food Addit. Contam. Part A 2014, 31, 1886–1895. [Google Scholar] [CrossRef] [PubMed]
- Hong, J.G.; Yoon, S.H.; Yang, K.R.; Lee, S.K.; Lee, J.Y. Korea Food and Drug Administration research report. In Development of Analytical Method for the Monitoring of Pyrrolizidine Alkaloids in Foods; Ministry of Food and Drug Safety (MFDS): Chungju, Korea, 2013. [Google Scholar]
- Ryu, H.J.; Kim, O.H.; Lee, E.S.; Kim, M.S.; Kim, J.G.; Yun, E.S.; Kim, H.J.; Kim, M.S. Characterization and screening of pyrrolizidine alkaloids by UPLC-MS/MS: Application to honey. Anal. Sci. Techol. 2019, 32, 252–261. [Google Scholar] [CrossRef]
- Für Risikobewertung, B (BfR). Determination of Pyrrolizidine alkaloids (PA) in Plant Material by SPE-LC-MS/MS Method Protocol, BfR-PA-Tea-2.0; Federal Institute for Risk Assessment; BfR: Berline, Germany, 2014. [Google Scholar]
- AOAC International; Guideline Working Group. AOAC INTERNATIONAL guidelines for validation of botanical identification methods. J. AOAC Int. 2012, 95, 268–272. [Google Scholar] [CrossRef] [Green Version]
- Zhuo, L.; Yin, Y.; Fu, W.; Qiu, B.; Lin, Z.; Yang, Y. Determination of paralytic shellfish poisoning toxins by HILIC-MS/MS coupled with dispersive solid phase extraction. Food Chem. 2013, 137, 115–121. [Google Scholar] [CrossRef]
- Griffin, C.T.; Gosetto, F.; Danaher, M.; Sabatini, S.; Furey, A. Investigation of targeted pyrrolizidine alkaloids in traditional Chinese medicines and selected herbal teas sourced in Ireland using LC-ESI-MS/MS. Food Addit. Contam. Part A 2014, 31, 940–961. [Google Scholar] [CrossRef] [PubMed]
- Zhou, Y.; Li, N.; Choi, F.F.K.; Qiao, C.F.; Song, J.Z.; Li, S.L.; Xu, H.X. A new approach for simultaneous screening and quantification of toxic pyrrolizidine alkaloids in some potential pyrrolizidine alkaloid-containing plants by using ultra performance liquid chromatography–tandem quadrupole mass spectrometry. Anal. Chim. Acta 2010, 681, 33–40. [Google Scholar] [CrossRef] [PubMed]
- Joosten., L.; Mulder, P.P.; Vrieling, K.; van Veen, J.A.; Klinkhamer, P.G. The analysis of pyrrolizidine alkaloids in Jacobaea vulgaris; a comparison of extraction and detection methods. Phytochem. Anal. 2010, 21, 197–204. [Google Scholar] [CrossRef]
- Mulder, P.P.; Sánchez, P.L.; These, A.; Preiss-Weigert, A.; Castellari, M. Occurrence of pyrrolizidine alkaloids in food. EFSA Supporting Publ. 2015, 12, 859E. [Google Scholar] [CrossRef]
- Jank, B.; Rath, J. The risk of pyrrolizidine alkaloids in human food and animal feed. Trends Plant Sci. 2017, 22, 191–193. [Google Scholar] [CrossRef] [PubMed]
Analytes | M.W. (g/mol) | Precursor Ion (m/z) | Product Ion (m/z) | Dwell Time (msec) | Q1 (volts) | CEa (volts) | Q3 (volts) |
---|---|---|---|---|---|---|---|
Echimedine | 397.47 | 398.25 | 120.10 b | 4 | −11 | −25 | −24 |
220.10 | 4 | −11 | −17 | −25 | |||
Heliotrine | 313.39 | 314.20 | 138.15 b | 4 | −11 | −20 | −28 |
156.20 | 4 | −11 | −28 | −17 | |||
Lasiocarpine | 411.49 | 412.20 | 120.10 b | 4 | −15 | −28 | −24 |
336.15 | 4 | −14 | −19 | −24 | |||
Lycopsamine | 299.37 | 300.20 | 94.10 b | 4 | −11 | −25 | −18 |
138.10 | 4 | −11 | −20 | −24 | |||
Monocrotaline | 325.40 | 326.15 | 120.10 b | 4 | −12 | −35 | −22 |
94.10 | 4 | −12 | −47 | −17 | |||
Monocrotaline-N-oxide | 341.36 | 342.15 | 137.10 b | 4 | −12 | −29 | −14 |
119.10 | 4 | −12 | −31 | −22 | |||
Retrorsine-N-oxide | 367.40 | 368.20 | 94.20 b | 4 | −13 | −49 | −19 |
118.05 | 4 | −13 | −32 | −21 | |||
Retrorsine | 351.40 | 352.20 | 120.10 b | 4 | −12 | −28 | −13 |
138.15 | 4 | −12 | −30 | −29 | |||
Senecionine-N-oxide | 351.17 | 352.20 | 94.10 b | 4 | −12 | −47 | −19 |
118.05 | 4 | −12 | −30 | −24 | |||
Senecionine | 335.39 | 336.20 | 120.10 a | 4 | −12 | −28 | −21 |
94.05 | 4 | −12 | −35 | −18 | |||
Seneciphylline-N-oxide | 349.40 | 350.20 | 94.10 b | 4 | −12 | −43 | −20 |
120.15 | 4 | −12 | −34 | −24 | |||
Seneciphylline | 333.40 | 334.15 | 120.10 b | 4 | −12 | −28 | −22 |
94.10 | 4 | −12 | −34 | −17 | |||
Senkirkine | 365.42 | 366.20 | 168.15 b | 4 | −10 | −30 | −18 |
122.15 | 4 | −13 | −33 | −22 | |||
Trichodesmone | 353.41 | 354.15 | 189.20 b | 4 | −12 | −29 | −20 |
149.10 | 4 | −12 | −25 | −30 | |||
Europine-N-oxide | 345.39 | 346.30 | 172.05 b | 4 | −17 | −31 | −18 |
111.10 | 4 | −17 | −44 | −12 | |||
Intermedine | 299.37 | 300.30 | 94.15 b | 4 | −15 | −27 | −19 |
138.05 | 4 | −15 | −20 | −14 | |||
Jacobine | 351.40 | 352.30 | 120.15 b | 4 | −17 | −31 | −22 |
155.15 | 4 | −17 | −29 | −16 | |||
Europine | 329.39 | 330.10 | 181.15 b | 4 | −16 | −34 | −19 |
239.10 | 4 | −16 | −25 | −26 | |||
Jacobine-N-oxide | 367.39 | 368.10 | 296.15 b | 4 | −18 | −26 | −20 |
120.15 | 4 | −13 | −38 | −12 | |||
Lasiocarpine-N-oxide | 427.50 | 428.20 | 254.30 b | 4 | −15 | −29 | −28 |
93.85 | 4 | −10 | −48 | −10 | |||
Heliotrine-N-oxide | 329.39 | 330.10 | 172.15 b | 4 | −12 | −27 | −18 |
111.10 | 4 | −12 | −43 | −20 |
Analytes | RT (min) | LOD (μg/kg) | LOQ (μg/kg) | Matrix Effect (%) | Range (μg/kg) | Slope | Intercept | R2 |
---|---|---|---|---|---|---|---|---|
Echimidine | 9.01 | 0.1 | 0.3 | 31.9 | 0.20–6.00 | 4.19 × 105 | −3300.44 | 0.9997 |
Heliotrine | 6.87 | 0.2 | 0.6 | 70.8 | 0.30–12.00 | 4.50 × 105 | 12,495.3 | 0.9999 |
Lasiocarpine | 9.64 | 0.8 | 2.4 | 47.6 | 1.20–48.00 | 5.77× 104 | 3418.49 | 0.9998 |
Lycopasamine | 4.96 | 0.3 | 0.9 | 72.6 | 0.50–18.00 | 1.62 × 106 | 37,066.4 | 0.9998 |
Monocrotaline -N-oxide | 4.32 | 1.0 | 2.9 | 66.7 | 1.50–58.00 | 2.00 × 105 | 9351.2 | 0.9996 |
Monocrotaline | 3.05 | 1.3 | 3.8 | 56.3 | 1.90–76.00 | 3.62 × 105 | 133,155 | 0.9999 |
Retrorsine -N-oxide | 6.46 | 3.0 | 9.0 | 89.7 | 4.50–180.00 | 8.96 × 104 | 241,711 | 0.9987 |
Retrorsine | 6.29 | 2.1 | 6.4 | 83.9 | 3.20–128.00 | 9.82 × 104 | 31,222.1 | 0.9998 |
Senecionine -N-oxide | 8.29 | 0.5 | 1.5 | 76.5 | 0.80–30.00 | 3.69 × 105 | 129,756 | 0.9991 |
Senecionine | 8.01 | 0.6 | 1.8 | 60.1 | 0.90–36.00 | 8.25 × 104 | −6769.52 | 0.9998 |
Seneciphylline -N-oxide | 7.05 | 1.3 | 3.9 | 68.5 | 2.00–78.00 | 9.33 × 104 | 26,725.2 | 0.9999 |
Seneciphylline | 6.67 | 0.9 | 2.8 | 61.2 | 1.40–56.00 | 7.56 × 104 | −2383.93 | 0.9998 |
Senkirkine | 9.11 | 0.3 | 0.8 | 44.4 | 0.40–16.00 | 4.44 × 105 | −30,200.6 | 0.9999 |
Trichodesmine | 8.97 | 0.3 | 0.9 | 50.6 | 0.50–18.00 | 3.10 × 105 | −6440.8 | 0.9998 |
Europine -N-oxide | 5.24 | 0.8 | 2.3 | 94.3 | 1.20–46.00 | 2.67 × 105 | 79,617.5 | 0.9996 |
Intermedine | 4.77 | 0.3 | 1.0 | 73.1 | 0.50–20.00 | 7.14 × 105 | −22,329.7 | 0.9999 |
Jacobine | 4.57 | 1.7 | 5.1 | 67.8 | 2.60–102.00 | 2.89 × 105 | 127,995 | 0.9995 |
Europine | 5.23 | 2.3 | 6.9 | 68.4 | 3.50–138.00 | 6.23 × 104 | 110,903 | 0.9989 |
Jacobine -N-oxide | 4.99 | 0.9 | 2.7 | 68.4 | 1.40–54.00 | 1.34 × 105 | 26,550 | 0.9998 |
Lasiocarpine -N-oxide | 9.89 | 0.3 | 0.8 | 52.6 | 0.40–16.00 | 2.27 × 105 | −790.995 | 0.9999 |
Heliotrine -N-oxide | 7.44 | 0.1 | 0.4 | 79.1 | 0.20–6.40 | 1.70 × 106 | −72,287.8 | 0.9994 |
Analyte | Conc. (μg/kg) | Recovery (RSD%) | Analyte | Conc. (μg/kg) | Recovery (RSD%) | Analyte | Conc. (μg/kg) | Recovery (RSD%) | |||
---|---|---|---|---|---|---|---|---|---|---|---|
Intra-day | Inter-day | Intra-day | Inter-day | Intra-day | Inter-day | ||||||
Echimidine | 0.6 | 90.45 (1.96) | 95.83 (1.05) | Retrorsine | 12.8 | 92.96 (3.88) | 95.25 (4.59) | Europine-N-oxide | 4.6 | 96.65 (2.05) | 96.47 (4.55) |
1.5 | 96.61 (2.45) | 97.01 (3.51) | 32.0 | 93.81 (0.48) | 96.63 (2.99) | 11.4 | 101.44 (0.48) | 98.30 (2.77) | |||
3.1 | 95.12 (2.81) | 96.74 (1.62) | 64.0 | 95.44 (0.08) | 97.01 (2.92) | 22.8 | 101.02 (1.06) | 100.41 (2.87) | |||
Heliotrine | 1.2 | 86.72 (3.09) | 97.38 (0.74) | Senecionine-N-oxide | 2.9 | 94.73 (1.76) | 95.86 (2.39) | Intermedine | 1.9 | 99.24 (0.84) | 97.96 (1.07) |
3.0 | 94.73 (2.13) | 97.65 (1.20) | 7.3 | 92.44 (1.09) | 97.38 (4.14) | 4.9 | 99.02 (1.46) | 96.26 (2.58) | |||
6.0 | 94.96 (1.59) | 97.48 (2.49) | 14.6 | 94.39 (0.99) | 96.81 (1.26) | 9.7 | 97.65 (0.59) | 97.82 (1.16) | |||
Lasiocarpine | 4.8 | 99.09 (0.78) | 96.25 (4.01) | Senecionine | 3.7 | 88.19 (2.88) | 95.72 (2.32) | Jacobine | 10.3 | 97.75 (1.86) | 97.94 (0.95) |
11.8 | 96.47 (2.15) | 96.47 (1.58) | 9.2 | 91.52 (2.27) | 92.71 (2.06) | 25.7 | 100.52 (1.58) | 97.49 (0.37) | |||
23.6 | 99.52 (1.88) | 97.32 (1.12) | 18.5 | 97.06 (0.98) | 97.86 (1.75) | 51.3 | 97.35 (1.19) | 99.89 (2.13) | |||
Lycopasamine | 1.8 | 95.53 (0.88) | 97.23 (0.96) | Seneciphylline-N-oxide | 7.9 | 90.05 (2.26) | 96.94 (4.44) | Europine | 13.8 | 95.20 (1.70) | 95.83 (3.55) |
4.5 | 97.82 (1.46) | 98.16 (1.09) | 19.7 | 91.90 (1.96) | 96.16 (4.32) | 34.5 | 94.92 (2.52) | 96.37 (2.41) | |||
9.0 | 97.02 (0.86) | 98.26 (0.55) | 39.4 | 94.65 (1.16) | 97.47 (3.09) | 68.9 | 92.75 (1.63) | 98.00 (1.49) | |||
Monocrotaline-N-oxide | 5.9 | 91.03 (0.56) | 93.76 (1.12) | Seneciphylline | 5.6 | 94.31 (0.71) | 91.64 (0.96) | Jacobine-N-oxide | 5.4 | 94.03 (2.77) | 97.36 (0.90) |
14.7 | 88.90 (1.09) | 96.42 (2.14) | 14.0 | 90.14 (2.15) | 94.50 (2.85) | 13.5 | 97.43 (0.32) | 97.15 (0.88) | |||
29.4 | 88.94 (1.19) | 94.98 (1.01) | 28.1 | 94.83 (0.41) | 96.06 (0.41) | 27.0 | 97.84 (1.82) | 99.12 (1.49) | |||
Monocrotaline | 7.7 | 92.47 (1.84) | 94.24 (2.36) | Senkirkine | 1.5 | 95.35 (1.52) | 97.91 (3.68) | Lasiocarpine -N-oxide | 1.5 | 101.40 (3.54) | 96.36 (1.94) |
19.2 | 96.34 (0.78) | 95.86 (1.24) | 3.8 | 97.64 (1.24) | 96.59 (0.92) | 3.8 | 99.29 (2.31) | 100.04 (4.18) | |||
38.4 | 99.63 (0.65) | 96.41 (3.26) | 7.6 | 94.12 (0.64) | 97.17 (2.23) | 7.7 | 98.75 (2.10) | 101.32 (3.35) | |||
Retrorsine -N-oxide | 18.0 | 92.61 (0.70) | 96.33 (2.76) | Trichodesmine | 1.8 | 96.95 (3.49) | 95.17 (2.22) | Heliotrine-N-oxide | 0.7 | 92.29 (1.28) | 96.56 (4.82) |
45.0 | 96.28 (0.63) | 94.83 (2.72) | 4.4 | 93.54 (1.14) | 95.22 (1.02) | 1.8 | 96.29 (1.23) | 96.62 (0.15) | |||
90.1 | 95.09 (0.90) | 96.89 (2.10) | 8.8 | 96.55 (1.10) | 97.24 (3.21) | 3.6 | 98.47 (0.96) | 98.89 (2.13) |
Tea Type | n > LOD / n | Mean (mg/kg) | Minimum (mg/kg) | Maximum (mg/kg) |
---|---|---|---|---|
Rooibos | 18/23 | 0.17 | 0.02 | 0.67 |
Peppermint | 11/25 | 0.37 | 0.01 | 1.23 |
Lavender | 8/20 | 0.08 | 0.002 | 0.22 |
Chamomile | 8/21 | 0.07 | 0.02 | 0.12 |
Lemon balm | 6/18 | 0.50 | 0.06 | 1.88 |
Mix tea | 7/25 | 0.37 | 0.01 | 1.49 |
Black tea | 3/31 | 0.12 | 0.07 | 0.16 |
Maté | 1/16 | 0.04 | 0.04 | 0.04 |
Green tea | 0/32 | - | - | - |
Oolong tea | 0/21 | - | - | - |
Chrysanthemum | 0/20 | - | - | - |
Fennel | 0/19 | - | - | - |
Hibiscus | 0/19 | - | - | - |
Total | 62/290 | 0.23 | 0.002 | 1.88 |
PA | Number of Samples (N = 290) | Mean Concentration (mg/kg) | Minimum Concentration (mg/kg) | Maximum Concentration (mg/kg) |
---|---|---|---|---|
Echimidine | 8 | 0.04 | 0.003 | 0.16 |
Heliotrine | 13 | 0.03 | 0.01 | 0.11 |
Lasiocarpine | 13 | 0.11 | 0.02 | 0.40 |
Lycopsamine | 1 | 0.01 | 0.01 | 0.01 |
Retrorsine-N-oxide | 6 | 0.11 | 0.05 | 0.18 |
Senecionine-N-oxide | 29 | 0.09 | 0.01 | 0.36 |
Senecionine | 27 | 0.08 | 0.02 | 0.30 |
Seneciphylline-N-oxide | 7 | 0.20 | 0.01 | 0.53 |
Seneciphylline | 4 | 0.11 | 0.05 | 0.17 |
Senkirkine | 2 | 0.01 | 0.01 | 0.01 |
Trichodesmine | 20 | 0.04 | 0.01 | 0.20 |
Europine-N-oxide | 14 | 0.18 | 0.06 | 0.74 |
Intermedine | 3 | 0.04 | 0.02 | 0.07 |
Lasiocarpine-N-oxide | 12 | 0.07 | 0.01 | 0.35 |
Heliotrine-N-oxide | 14 | 0.06 | 0.004 | 0.29 |
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Kwon, Y.; Koo, Y.; Jeong, Y. Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography–Tandem Mass Spectrometry Combined with Rapid-Easy Extraction. Foods 2021, 10, 2250. https://doi.org/10.3390/foods10102250
Kwon Y, Koo Y, Jeong Y. Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography–Tandem Mass Spectrometry Combined with Rapid-Easy Extraction. Foods. 2021; 10(10):2250. https://doi.org/10.3390/foods10102250
Chicago/Turabian StyleKwon, Yujihn, Yongeui Koo, and Yoonhwa Jeong. 2021. "Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography–Tandem Mass Spectrometry Combined with Rapid-Easy Extraction" Foods 10, no. 10: 2250. https://doi.org/10.3390/foods10102250