Development of stable isotope dilution assays for the quantitation of the food odorants hydrogen sulphide, methanethiol, ethanethiol, and propane-1-thiol and application to durian (Durio zibethinus L.) pulp

Characterization of the Key Odorants in a High-Grade Chinese Green Tea Beverage (Camellia sinensis; Jingshan cha) by Means of the Sensomics Approach and Elucidation of Odorant Changes in Tea Leaves Caused by the Tea Manufacturing Process

“…The quantitation of methanethiol was performed after the derivatization with 3-buten-2-one as recently described . The tea infusion was diluted with phosphate buffer (75 mL), sealed with a Teflon cover glass stopper and cooled in an ice bath.…”

“…The following reference compounds used for volatile identification were purchased from several suppliers. The number in bold refers to the respective tea aroma compound in Tables 2and 3: hexanal (2), (Z)-4-heptenal ( 5), 1-octen-3-one ( 6), (Z)-3-hexen-1-ol (9), 2-isopropyl-3-methoxypyrazine (10), 2-furanmethanethiol (11), 3-(methylthio)propanal ( 12), 2,3-diethyl-5-methylpyrazine (13), (E,E)-2,4-heptadienal ( 14), 2-secbutyl-3-methoxypyrazine (15), 2-isobutyl-3-methoxypyrazine ( 16), (E)-2-nonenal (17), linalool and (R)-linalool (18), (E,Z)-2,6nonadienal (19), phenylacetaldehyde (21), 3-methylbutanoic acid (22), (E,E)-2,4-nonadienal (23), pentanoic acid (25), (E,E)-2,4decadienal (27), geraniol (28), 2-methoxyphenol (29), 2-phenylethanol (31), γ-octalactone (32), β-ionone (33), 4-hydroxy-2,5dimethyl-3(2H)-furanone (36), 3-methylphenol (39), 4-allyl-2methoxyphenol (40), 4-ethylphenol (41), 3-ethylphenol (42), 3hydroxy-4,5-dimethyl-2(5H)-furanone (43), decanoic acid (44), indole (46), coumarin (47), phenylacetic acid (48), vanillin (49), acetaldehyde (50), dimethyl sulfide (53), 2-methylpropanal (54), 2,3butanedione (55), 3-methylbutanal (56), 2-methylbutanal (57), dimethyl disulfide (58), 1-penten-3-one, 2,3-pentanedione, and 2ethyl-3,5-dimethylpyrazine were from Sigma-Aldrich. 4-Mercapto-4methylpentan-2-one (8), butanoic acid (20), and 2-methylbutanoic acid (22) were from Alfa Aesar (Kandel, Germany).…”

“…The quantitation of methanethiol was performed after the derivatization with 3-buten-2-one as recently described. 19 The tea infusion was diluted with phosphate buffer (75 mL), sealed with a Teflon cover glass stopper and cooled in an ice bath. After adding the internal standard [ 2 H 3 ]-sodium thiomethoxide (dissolved in phosphate buffer), the mixture was stirred for 5 min.…”

Quantitation of 4-Methyl-4-sulfanylpentan-2-one (4MSP) in Hops by a Stable Isotope Dilution Assay in Combination with GC×GC-TOFMS: Method Development and Application To Study the Influence of Variety, Provenance, Harvest Year, and Processing on 4MSP Concentrations

“…The calibration line equation was previously determined by linear regression applied to the data obtained from analysis of 4MSP/( 13 C 4 )-4MSP mixtures covering ratios ranging from ∼1:10 to ∼10:1. 27 The resulting calibration line equation was y = 1.049x − 0.034, with y = concentration of ( 13 C 4 )-4MSP/concentration of 4MSP and x = peak volume of ( 13 C 4 )-4MSP/ peak volume of 4MSP. Standard deviations (STDEV) of the concentration data were calculated in MS Excel (Microsoft, Redmond, WA).…”

“…Derivatization reagents that have been used for quantitation of thiols in different matrices include vinylpyridine, 22 dithiodipyridine, 23 ethyl propiolate, 18,24 epselene, 25 pentafluorobenzyl bromide, 26 and 3-buten-1-one. 27 An alternative to derivatization is the application of a stable isotope dilution assay (SIDA). This approach includes the use of a stable isotopologue of the target compound as internal standard which compensates for any losses during workup procedures.…”