Determination of volatile thiols in roasted coffee by derivatization and liquid chromatography–high resolution mass spectrometric analysis

• Published in: Food research international Vol. 64; pp. 610 - 617
• Main Authors: Vichi, Stefania, Jerí, Yenny, Cortés-Francisco, Nuria, Palacios, Oscar, Caixach, Josep
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2014; Elsevier
• Subjects: Acetates; Biological and medical sciences; Coffee; Derivatives; Derivatization; Diagnostic systems; Extraction; Food industries; Fundamental and applied biological sciences. Psychology; High resolution mass spectrometry; HRMS; Liquids; Target recognition; Thiols; High resolution mass spectrometry; HRMS; Thiols; Coffee; Derivatization; Volatile compound; High resolution; Thiol; Analysis; Liquid chromatography; Mass spectrometry; Roasted coffee
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2014.07.044

A fast derivatization/extraction method followed by LC–ESI–HRMS was optimized for the determination of volatile thiols in roasted coffee powder, using ebselen as the derivatization agent. The analytical conditions were optimized on real coffee matrix, which was spiked with representative volatile thiols. The method sensitivity, precision, accuracy and selectivity were evaluated by using representative standard thiols. Estimated LOQs were between 0.02 and 14.8ng/kg for the thiols evaluated. Recoveries and intra-day and inter-day RSD values obtained in coffee matrix were in general around 40% and between 11 and 30%, respectively. The optimized and validated method was applied to real coffee samples. According to the established identification criteria, target thiols were identified and quantified in coffee powder samples. Among them, 4-mercapto-1-butanol and 2-methyl-3-tetrahydrofuranthiol were identified and quantified for the first time in roasted coffee. Moreover, an approach based on the formation of a diagnostic product ion was applied to detect non-target thiols, allowing the detection of nineteen thiol derivatives, fourteen of them were tentatively identified on the basis of their molecular formula. Some of them, such as methanethiol and 3-mercapto-3-methylbutyl acetate were known to be present in coffee volatile fraction, while the rest were not previously described in this product. •A simple method for the assessment of volatile thiols in roasted coffee by HRMS was developed.•A single-step simultaneous derivatization/extraction prior LC–HRMS was optimized.•Method performances were validated and applied to roasted coffee samples.•Limits of quantification of eleven reference thiols were from 0.02 to 14.8ng/kg.•A non-target approach permitted detecting new thiols in roasted coffee.