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Adriana Canto-Flick, Eduardo Balam-Uc, Jericó Jabìn Bello-Bello, Carlos Lecona-Guzmán, Daniela Solís-Marroquín, Susana Avilés-Viñas, Eunice Gómez-Uc, Guadalupe López-Puc, Nancy Santana-Buzzy, and Lourdes Georgina Iglesias-Andreu

al., 1977 ), and high-performance liquid chromatography ( Weaver and Awde, 1986 ). Of these, high-pressure liquid chromatography (HPLC) is considered the most reliable and rapid method ( Yao et al., 1994 ) available for the identification and

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Sachiko Kawamura, Kyoko Ida, Masako Osawa, and Takashi Ikeda

measured water status. We analyzed sugar contents by high-performance liquid chromatography (HPLC), and water status [water potential, osmotic potential (ψ S ) = osmotic pressure, turgor pressure] with an isopiestic thermocouple psychrometer, and measured

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Margaret D. Collins, Loide Mayer Wasmund, and Paul W. Bosland

An improved high-performance liquid chromatography (HPLC) method for analysis of capsaicinoids in dried Capsicum fruit powder, involving changes in extraction, mobile phase, flow rate, and excitation and emission spectra and resulting in reduced analysis time, increased sensitivity, and safety, is reported. Extraction of Capsicum fruit powder using acetonitrile proved to be the best capsaicinoid extractor in the shortest time interval. Solvents used for HPLC separation and quantification of capsaicinoids include methanol and water at 1 ml·min–1 flow rate. Instrument sensitivity is enhanced by altering the fluorescence detector excitation and emission wavelengths. Two analytical methods have been developed. One method determines total amount of heat units in 7 minutes, while the other provides total amount of heat units as well as separation of all present major and minor capsaicinoids in 20 minutes. These improved techniques provide inexpensive and rapid methods for quantitative and qualitative analysis of capsaicinoids in Capsicum fruit samples along with good sensitivity and no interference or confounding peaks.

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Harold A.A. Gibbs and Leonard W. O'Garro

, Barbados, for his assistance with HPLC determinations and Tanya Edgehill for her part in preparation and extraction of pepper samples.

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Kevin A. Lombard, Emmanuel Geoffriau, and Ellen Peffley

Direct spectrophotometric determination of quercetin content in onions (Allium cepa L.) was investigated as a possible alternative to high-performance liquid chromatography (HPLC) analysis. Quercetin content in five onion varieties was monitored at 362 nm and quantified using simple spectrophotometric and HPLC methods. HPLC revealed that 3,4'-Qdg and 4'-Qmg comprised up to 93% of total flavonol content detected in the studied varieties. These major quercetin conjugates combined (3,4'-Qdg + 4'-Qmg) and total flavonol conjugates quantified by HPLC correlated closely with spectrophotometer values. Correlation coefficients were 0.96 (P < 0.0001) for 3,4'-Qdg + 4'-Qmg and 0.97 (P < 0.0001) for total flavonol conjugates in onion. Simple spectrophotometric procedure proved to be a valid, efficient, and cost-effective method for the quantification of total quercetin in onion. Chemical names used: quercetin-3,4'-O-diglucoside (3,4'-Qdg); quercetin-4'-O-glucoside (4'-Qmg).

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Luping Qu, Ying Chen, Xiping Wang, Richard Scalzo, and Jeanine M. Davis

We investigated patterns of variation in alkamides and cichoric acid accumulation in the roots and aboveground parts of Echinacea purpurea (L.) Moench. These phytochemicals were extracted from fresh plant parts with 60% ethanol and quantified by high performance liquid chromatography (HPLC) analysis. Concentrations of alkamides and cichoric acid were measured on a dry-weight basis (mg·g–1). For total alkamides, concentrations among individual plants varied from 5.02 to 27.67 (mean = 14.4%) in roots, from 0.62 to 3.42 (mean = 1.54) in nearly matured seed heads (NMSH), and 0.22 to 5.25 (mean = 0.77) in young tops (about ½ flower heads, ¼ leaves, and ¼ stems). For cichoric acid, concentrations among individual plants varied from 2.65 to 37.52 (mean = 8.95), from 2.03 to 31.58 (mean = 10.9), and from 4.79 to 38.55 (mean = 18.88) in the roots, the NMSH, and the tops, respectively. Dodeca-2E, 4E, 8Z, 10E-tetraenoic acid isobutylamide and dodeca-2E, 4E, 8Z, 10Z-tetraenoic acid isobutylamide (alkamides 8/9) accounted for only 9.5% of the total alkamides in roots, but comprised 87.9% in the NMSH, and 76.6% in the young tops. Correlations of concentrations of alkamides or cichoric acid between those of roots and those of the NMSH were not statistically significant, and either within the roots, the NMSH, and the young tops. However, a significant negative correlation was observed between the concentration of cichoric acid in the roots and in young tops, and a significant positive correlation was observed between total alkamide concentration in the roots and cichoric acid concentration in the young tops. These results may be useful in the genetic improvement of E. purpurea for medicinal use.

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Liliana S. Muñoz-Ramírez, Laura P. Peña-Yam, Susana A. Avilés-Viñas, Adriana Canto-Flick, Adolfo A. Guzmán-Antonio, and Nancy Santana-Buzzy

, derived from the organoleptic test for the pungency of the chili peppers ( Scoville, 1912 ). This test has been replaced with high-performance liquid chromatography (HPLC) ( Collins et al., 1995 ; Kozukue et al., 2005 ). Currently, the capsaicinoids are

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Vincent A. Fritz, Veronica L. Justen, Ann M. Bode, Todd Schuster, and Min Wang

determined by weight. Further washing of the columns yielded no additional desulphated glucosinolates confirming complete elution. Eluent was stored at –20 °C until high-performance liquid chromatography (HPLC) analysis. High-performance liquid

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Samuel G. Obae, Hillar Klandorf, and Todd P. West

followed the method of Schlag and McIntosh (2006) with slight modifications. The modification included re-extracting pellets at least once to maximize ginsenoside recovery. The high-performance liquid chromatography (HPLC) system used was a Waters model

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Christine M. Bradish, Gad G. Yousef, Guoying Ma, Penelope Perkins-Veazie, and Gina E. Fernandez

(PTFE) membranes (Fisher Scientific, Pittsburgh, PA). Filtered samples were injected into a high-performance liquid chromatography (HPLC) system (1200; Agilent Technologies, Santa Clara, CA) equipped with an ultraviolet-visible diode array detector