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A rapid, sensitive, precise and accurate liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for levo 3,4-dihydroxyphenylalanine (L-DOPA) determination in Vicia faba during different growth stages. The method applied a simple sample preparation step followed by a chromatographic separation on a Kinetex XB Core-Shell C18 (100 mm x 4.6 mm, 2.6 µm) column, using a mixture of ultrapure pure water (A) with 0.5 % (v/v) formic acid and methanol (B) as mobile phase. Analysis of L-DOPA was carried out by MS/MS applying a Multiple Reaction Monitoring (MRM) method using the transition m/z 198 → m/z 152. This LC-MS/MS method allowed a well-resolved detection of L-DOPA in ca. 2 min within 6 min run. Method was validated showing a linear range from 0.05 to 10 mg L-1 (R 2 = 0.99); repeatability showed RSD value of 1.40%. Recoveries ranged from 94.14 to 116.62% with RSD values ≤ 5.66% and detection and quantification limits were 0.01 and 0.05 mg L-1 , respectively. Applying this validated method, L-DOPA was determined in Vicia faba samples to determined its tissue distribution. As expected, a broad range of L-DOPA content finding the lowest content in seeds (4.72±2.12 mg g-1) and the highest in sprouts (133.60±5.65 mg g-1).

Capsaicinoids are organic compounds present in several foods like chili peppers. This group of molecules are responsible of fruit pungency, as well as, of several healthy properties. The present work reports an optimized and validated liquid chromatography method coupled to fluorescence and mass spectrometry detectors for a selective determination of capsaicin in Chili peppers (Capsicum annum and C. pendulum). To the best our knowledge this is the first report about capsaicin determination in chili peppers commercialized in Chile. Chromatographic conditions were optimized giving the following optimal conditions: 76% organic phase (MeOH: ACN: acetic acid (50:50:0.1 v/v/v) at 9 min of gradient program and column temperature of 35°C. With these conditions capsaicin, dihydrocapsaicin and nordihydrocapsaicin were separated in 15 min. Data calibration curve (0.01-2.00 mg L -1 ) fitted a linear regression model with a determination coefficient (R 2 ) of 0.9986. Repeatability (relative standard deviation, RSD) and intermediate precision (RSD) showed values of 1.51% (n=6) and 1.04% (n=3), respectively. Recovery (n=3) at three levels ranged from 94.80 to 109.40%, (RDS <2.39%). The method was applied to analyze 10 chili peppers varieties commercialized in Chile. A broad -1 .

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