Trace Elements in Norwegian and Polish Tea Infusions Determined by High-Resolution Inductively Coupled Plasma Mass Spectrometry (HR ICP-MS) and Ion Selective Electrode (ISE) Anne Ingelill Engvik Kronborg Teacher Education with Master of Science Submission date: June 2013 Supervisor: Trond Peder Flaten, IKJ Co-supervisor: Tomasz Ciesielski, IBI Norwegian University of Science and Technology Department of Chemistry Acknowledgements This master thesis has been carried out at the Department of Chemistry at the Norwegian University of Science and Technology (NTNU) as the final part of a Master’s degree in NTNU’s teaching programme – LUR –with specialization in chemistry and biology. First I would like to thank my supervisors, Trond Peder Flaten and Tomasz Cielsielski. They have been helpful and a great support during the work with my master thesis. I also have to thank Syverin Lierhagen, who helped me with the Ultra Clave and did all of the ICP-MS analyses. He has been a great support when I needed help to understand the results he gave me. Øyvind Mikkelsen also deserves my thanks for helping me complete the fluoride analysis. Te og kaffehuset, the local tea and coffee shop in Trondheim, provided me with a great number of samples from their best selling teas, and has provided me information and met me with great interest every time I needed to ask about something. Thank you. As a student at NTNU’s teaching programme LUR, I have been able to combine my interest in chemistry and biology with teaching. This I have done through courses, laboratory work, pedagogical courses and practice teaching, and during my work with this thesis. This has been interesting, challenging and have given me new perspectives about scientific work and myself. I also have to thank all of my fellow students at the Department of Chemistry, who have been ready for tea and mocha whenever the going got tough. I would like to thank the leaders and assistants in the kindergarten that have taken good care of my girls during schooldays and always meeting me with a smile. At least, I would like to thank my family, especially Rakel and Ariel, and friends for their support throughout my entire studies. I would not have done this without your help. Gløshaugen Anne Ingelill Kronborg 1 Abstract Tea from the plant Camellia sinensis is the world’s most popular non-alcoholic beverage, next to water. Tea can be divided into six types, and the most popular teas are black tea, green tea and oolong. In this study infusions of 85 Norwegian and Polish tea samples were analysed to investigate the content of trace elements. 40 samples from Norwegian supermarkets, 30 from the local tea and coffee shop and 15 Polish samples were infused for 5 minutes with ultrapure boiling water (1 gram tea/100 mL). The fluoride content in the tea infusions was determined using an ion selective electrode (ISE), and the rest of the elements were determined by high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS). Tea is a rich source of essential elements as calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn). The infusions also contain non essential elements as nickel (Ni),lead (Pb), fluoride (F) and aluminium (Al). The average concentrations in one cup of tea from the Norwegian market contains among other elements average concentrations of 0.6 mg Ca/L, 2.8 mg P/L, 37.1 mg K/L, 2.0 mg Mg/L, 5.9 µg Fe/L, 14.1 µg Cu/L, 26.4 µg Zn/L, 0.6 mg Mn/L, 9.9 µg Ni/L, 0.16 µg Pb/L, 0.5 µg Cr/L, 1.0 mg F/L and 1.1 mg Al/L. For the essential elements Ca, P, K, Mg, Fe, Cu and Zn the tea infusions will not contribute to attain the recommended dietary allowances (RDAs) in any extent, but for Mn where the AI are 2.3 mg/day (men) and 1.8 mg/day (women) a few cups of tea can exceed the given AI level. The amount of Pb in the infusions is sustainable lower than the provisional tolerable weekly intake (PTWI) of 25 µg/kg body weight. Drinking tea will therefore not contribute in any high extent to the PTWI. There were on the other hand obtained vast variations of F concentrations in different types of tea and tea contributes also in huge extent to AI of F - 3 mg/day (women), 4 mg/day (men) and from 0.5- 1 mg/day (0 -12 year olds). One cup of tea could easily exceed the AI, at least considering children drinking tea. The Al content in tea is high, and for heavy tea drinkers may tea be the largest single source of Al to contribute to the total weekly intake (TWI) of 1 mg/ kg body weight/ week. The study showed higher concentrations of elements in tea infusions made of tea bags than infusions made of loose tea. Suggesting that the elements in the crushed leaves in tea bags are more extractable than in the loose tea leaves. One other explanation is that the tea bags contain older tea leaves with lower quality and therefore older leaves with higher concentrations of e.g. Al. There was also seen a significant difference in the element composition in Norwegian and Polish infusion, with higher concentrations of elements in the Norwegian infusions. 2 Sammendrag Te fra planten Camellia sinensis er den alkoholfrie drikken i verden, som nytes mest, etter vann. Te kan deles inn i tre typer, hvorav de mest populære er svart te, grønn te og oolong te. I denne masteroppgaven ble grunnstoffinnholdet analysert i totalt 85 forskjellige teprøver, preparert av blader fra planten. 40 tesorter ble kjøpt inn fra norske dagligvarehandler, 30 typer kom fra den lokale te og kaffe butikken – Te og kaffehuset – i Trondheim. De siste 15 tetypene kom fra det polske markedet gjennom et samarbeidsprosjekt med Universitetet i Gdansk. 1 gram av de forskjellige prøvene ble trukket i 100 mL kokende ultrarent vann for 5 minutter. Fluorinnholdet i teprøvene ble bestemt ved bruk av ione selektive elektroder (ISE), mens resten av grunnstoffinnholdet i teen ble bestemt ved induktiv koplet plasma massespektrometer (ICP-MS). Te er en rik kilde på essensielle grunnstoffer som kalsium (Ca), fosfor (P), kalium (K), magnesium (Mg), mangan (Mn), jern (Fe), kopper (Cu) og sink (Zn). Teuttrekkene inneholder også ikke essensielle grunnstoffer som bly (Pb), fluor (F) and aluminium (Al). En kopp te fra det norske markedet inneholder blant annet 0.6 mg Ca/L, 2.8 mg P/L, 37.1 mg K/L, 2.0 mg Mg/L, 5.9 µg Fe/L, 14.1 µg Cu/L, 26.4 µg Zn/L, 0.6 mg Mn/L, 9.9 µg Ni/L, 0.16 µg Pb/L, 0.5 µg Cr/L, 1.0 mg F/L og 1.1 mg Al/L. Innholdet av Ca, P, K, Mg, Fe, Cu og Zn i te, vil ikke bidra til å nå de anbefalte inntaksgrensene Soisial og Helsedirektoratet i Norge har satt. Innholdet av Mn i te, vil derimot bidra til å nå de anbefalte inntaksgrensene USA har satt på henholdsvis 2.3 mg Mn/ dag for menn, og 1.8 mg/dag for kvinner. Mengden Pb i teuttrekkene er så lav at tedrikking vil ikke i noen grad påvirke inntaksgrensa på 25 µg/kg kroppsvekt/ uke (PTWI). Innholdet av F i teuttrekkene bidrar i høy grad til å nå anbefalt inntaksgrenser (USA) på 3 mg/dag for kvinner, 4 mg/dag for menn og fra 0.5 – 1 mg/dag for barn i en alder av 0-12 år. Da det ble målt store variasjoner i konsentrasjonen i de forskjellige norske teene, kan en kopp te lett bidra til at inntaksgrenene blir overgått, spesielt hos barn som drikker te. Det samme ble observert med tanke på Al innholdet i te. For de som drikker veldig mye te vil Al i te være en av de viktigste kildene til å bidra til det totale ukentlige inntaket på 1 mg/kg kroppsvekt. De endelige resultatene viste et høyere grunnstoffinnhold i te brygget meg teposer enn te brygget med løs te. Dette kan forklares med at det finmalte materialet i teposene er lettere løselig, enn grunnstoffinnholdet i de løse tebladene, eller med at kvaliteten på teen i teposene er noe lavere enn i den løse teen og at det i denne er brukt eldre blader fra teplanten. De eldre bladene inneholder større mengder av for eksempel Al og vil på denne måten bidra til å øke konsentrasjonen av grunnstoffer i teposene. Det ble også observert forskjeller i grunnstoffinnholdet mellom de norske og de polske teuttrekkene, uten at en kan si noe om hva som forårsaket dette. 3 Table of Contents ACKNOWLEDGEMENTS .................................................................................................................................................... 1 ABSTRACT .......................................................................................................................................................................... 2 SAMMENDRAG ................................................................................................................................................................... 3 TABLE OF CONTENTS .................................................................................................................................................... 4 1 INTRODUCTION .............................................................................................................................................................. 6 2 BACKGROUND AND THEORY ........................................................................................................................................ 7 2.1 Camellia sinensis ....................................................................................................................................................... 7 2.2 Recommended dietary allowance ..................................................................................................................... 8 2.3 Trace elements ..........................................................................................................................................................