Merck

Evaluation of ice-tea quality by DART-TOF/MS.

Journal of mass spectrometry : JMS (2015-10-28)
Aleš Rajchl, Jana Prchalová, Vojtěch Kružík, Rudolf Ševčík, Helena Čížková
ABSTRACT

DART (Direct Analysis in Real Time) coupled with Time-of-Flight Mass Spectrometry (TOF/MS) has been used for analyses of ice-teas. The article focuses on quality and authenticity of ice-teas as one of the most important tea-based products on the market. Twenty-one samples of ice-teas (black and green) were analysed. Selected compounds of ice-teas were determined: theobromine, caffeine, total phenolic compounds, total soluble solids, total amino acid concentration, preservatives and saccharides were determined. Fingerprints of DART-TOF/MS spectra were used for comprehensive assessment of the ice-tea samples. The DART-TOF/MS method was used for monitoring the following compounds: citric acid, caffeine, saccharides, artificial sweeteners (saccharin, acesulphame K), and preservatives (sorbic and benzoic acid), phosphoric acid and phenolic compounds. The measured data were subjected to a principal components analysis. The HPLC and DART-TOF/MS methods were compared in terms of determination of selected compounds (caffeine, benzoic acid, sorbic acid and saccharides) in the ice-teas. The DART-TOF/MS technique seems to be a suitable method for fast screening, testing quality and authenticity of tea-based products.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Saccharin, ≥98%
Sigma-Aldrich
Sodium carbonate, anhydrous, powder, 99.999% trace metals basis
Sigma-Aldrich
D-(−)-Fructose, BioXtra
Sigma-Aldrich
D-(−)-Fructose, ≥99%
Sigma-Aldrich
D-(−)-Fructose, BioReagent, suitable for cell culture, suitable for insect cell culture
Sigma-Aldrich
Methanol, anhydrous, 99.8%
Sigma-Aldrich
D-(−)-Fructose, BioUltra, ≥99.0% (HPLC)
Sigma-Aldrich
Sodium carbonate, BioUltra, anhydrous, ≥99.5% (calc. on dry substance, T)
Sigma-Aldrich
Theobromine, ≥98.0%
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D-(−)-Fructose, meets USP testing specifications
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Sodium carbonate, BioXtra, ≥99.0%
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Liquified Phenol, ≥89.0%
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trans,trans-2,4-Hexadienoic acid potassium salt, ReagentPlus®, 99%
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Methanol, HPLC Plus, ≥99.9%, poly-coated bottles
Sigma-Aldrich
Saccharin, ≥99%
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Sodium carbonate, anhydrous, free-flowing, Redi-Dri, ReagentPlus®, ≥99.5%
Sigma-Aldrich
Sodium carbonate, anhydrous, powder or granules, free-flowing, Redi-Dri, ACS reagent, ≥99.5%
Sigma-Aldrich
Sodium carbonate, anhydrous, free-flowing, Redi-Dri, ACS reagent (primary standard), 99.95-100.05% dry basis
Sigma-Aldrich
Sodium carbonate, anhydrous, free-flowing, Redi-Dri, ACS reagent, ≥99.5%
Sigma-Aldrich
Sodium carbonate, ACS reagent, anhydrous, ≥99.5%, powder or granules
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Sodium carbonate, powder, ≥99.5%, ACS reagent
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Methanol, Laboratory Reagent, ≥99.6%
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Methanol, Absolute - Acetone free
Sigma-Aldrich
Sodium carbonate, puriss., meets analytical specification of Ph. Eur., BP, NF, FCC, E500, anhydrous, 99.5-100.5% (calc. to the dried substance)
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
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Methanol, BioReagent, ≥99.93%
Sigma-Aldrich
Sodium carbonate, ACS reagent (primary standard), anhydrous, 99.95-100.05% dry basis
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Methanol, puriss., meets analytical specification of Ph Eur, ≥99.7% (GC)
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Methanol, ACS spectrophotometric grade, ≥99.9%