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Determination of theanine in commercial tea by liquid chromatography with fluorescence and diode array ultraviolet detection.
J Agric Food Chem. 2006 Sep 20; 54(19):7014-9.JA

Abstract

Two liquid chromatographic methods that involve precolumn derivatization with o-phthaladehyde (OPA) and phenylisothiocyanate (PITC) with fluorescence and diode array UV detection for the determination of theanine have been developed. The chromatographic separations were achieved by reverse-phase high-performance liquid chromatography using octadecyl columns and gradient elution. The methods were applied to evaluate the theanine content of commercial tea leaves. The coefficient of variation of the peak area repeatability for within day (n = 8) and between day (n = 8 over 10 days) was lower than 3% for both of the methods. The estimated limit of detection (LOD) and limit of quantitation (LOQ) for the OPA method was 0.12 and 0.35 microg theanine, respectively. The PITC method was 500-fold more sensitive with LOD and LOQ values of 0.25 and 0.75 ng, respectively. The theanine content of the commercial tea samples varied from 2-5 mg/g leaf. The overall % recoveries for these methods ranged from 93-99.3. The sensitivity and simplicity of the method render them suitable for use in quality control laboratories.

Authors+Show Affiliations

Food Safety and Analytical Quality Control Laboratory, Central Food Technological Research Institute, Mysore 570 020, India.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article

Language

eng

PubMed ID

16968057

Citation

Thippeswamy, R, et al. "Determination of Theanine in Commercial Tea By Liquid Chromatography With Fluorescence and Diode Array Ultraviolet Detection." Journal of Agricultural and Food Chemistry, vol. 54, no. 19, 2006, pp. 7014-9.
Thippeswamy R, Gouda KG, Rao DH, et al. Determination of theanine in commercial tea by liquid chromatography with fluorescence and diode array ultraviolet detection. J Agric Food Chem. 2006;54(19):7014-9.
Thippeswamy, R., Gouda, K. G., Rao, D. H., Martin, A., & Gowda, L. R. (2006). Determination of theanine in commercial tea by liquid chromatography with fluorescence and diode array ultraviolet detection. Journal of Agricultural and Food Chemistry, 54(19), 7014-9.
Thippeswamy R, et al. Determination of Theanine in Commercial Tea By Liquid Chromatography With Fluorescence and Diode Array Ultraviolet Detection. J Agric Food Chem. 2006 Sep 20;54(19):7014-9. PubMed PMID: 16968057.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Determination of theanine in commercial tea by liquid chromatography with fluorescence and diode array ultraviolet detection. AU - Thippeswamy,R, AU - Gouda,K G Mallikarjun, AU - Rao,Devavratha H, AU - Martin,Asha, AU - Gowda,Lalitha R, PY - 2006/9/14/pubmed PY - 2006/11/3/medline PY - 2006/9/14/entrez SP - 7014 EP - 9 JF - Journal of agricultural and food chemistry JO - J Agric Food Chem VL - 54 IS - 19 N2 - Two liquid chromatographic methods that involve precolumn derivatization with o-phthaladehyde (OPA) and phenylisothiocyanate (PITC) with fluorescence and diode array UV detection for the determination of theanine have been developed. The chromatographic separations were achieved by reverse-phase high-performance liquid chromatography using octadecyl columns and gradient elution. The methods were applied to evaluate the theanine content of commercial tea leaves. The coefficient of variation of the peak area repeatability for within day (n = 8) and between day (n = 8 over 10 days) was lower than 3% for both of the methods. The estimated limit of detection (LOD) and limit of quantitation (LOQ) for the OPA method was 0.12 and 0.35 microg theanine, respectively. The PITC method was 500-fold more sensitive with LOD and LOQ values of 0.25 and 0.75 ng, respectively. The theanine content of the commercial tea samples varied from 2-5 mg/g leaf. The overall % recoveries for these methods ranged from 93-99.3. The sensitivity and simplicity of the method render them suitable for use in quality control laboratories. SN - 0021-8561 UR - https://www.unboundmedicine.com/medline/citation/16968057/Determination_of_theanine_in_commercial_tea_by_liquid_chromatography_with_fluorescence_and_diode_array_ultraviolet_detection_ L2 - https://doi.org/10.1021/jf061715+ DB - PRIME DP - Unbound Medicine ER -