@phdthesis{1109568,
  abstract     = {{This work presents the development of a qualitative and quantitative method to determine individual folates, i.e. THF, 5-MTHF, 5,10-CH+THF, 5-CHOTHF, 10-CHOFA en FA, in rice. 
Folates are essential nutrients for human beings. To decrease folate deficiencies and consequences thereof such as spina bifida in developing areas like Northern China, biofortification of rice by means of genetic modification is one of the approaches. To control this biotechnological interventions, a HPLC-MS/MS method and a UPLC-MS/MS method were optimised and validated for the analysis of 6 monoglutamate folates in rice. HPLC chromatography was performed on a Polaris C18-A column, UPLC on a Acquity HSS T3 column, both with 0.1% HCOOH in water and acetonitrile as mobile phases. UPLC offered higher sensitivities and is therefore the method of choice for the analysis of low concentrated folates in rice (e.g. concentration 5,10-CH+THF in Wild Type (WT) rice 0.4 µg/100g). 
Folate analysis remains a challenge because of the instability of the individual folates. The stability and eventual interconversion of folates during the typical sample preparation steps (heat treatment during 10 min at 100°C and incubation during 2 hours at 37°C) at different pH values have been investigated. 
Folate concentrations were determined in WT and genetic modified rice. WT rice had folate concentrations of 20-40 µg/100g, while the maximum level of folates in biofortified rice lines, reached 1700 µg/100g, which is the highest folate content reported for plant species thus far. 5-MethylTHF was the dominant natural folate form (± 90% of total folate content for biofortified rice). After cooking for 30 minutes about 45% of the folates were lost. In wild type rice 50% of the folates is polyglutamylated, in contrast to transgenic  rice where only 2-14% of folates occur in their polyglutamate form. Polyglutamylation decreases the folate bioavailability, so biofortified rice will probably have a higher bioavailability.}},
  author       = {{De Brouwer, Veerle}},
  language     = {{eng}},
  pages        = {{XVIII, 216}},
  publisher    = {{Ghent University. Faculty of Pharmaceutical Sciences}},
  school       = {{Ghent University}},
  title        = {{Quantitative determination of folates in rice with liquid chromatography coupled to tandem mass spectrometry}},
  year         = {{2011}},
}