13 z β carotene

The analyzed samples were −80°C stored K3-EDTA fasting plasma that had been drawn at baseline. Handling of all samples and standards was always done under cool conditions and avoiding exposure to light. Carotenoid standards: astaxanthin, canthaxanthin, E-β-apo-8′-carotenal, α-carotene, β-carotene, fucoxanthin, and lycopene were obtained from Sigma-Aldrich (St. Louis, MO, USA). Lutein was purchased from Cayman Chemical (Ann Arbor, MI, USA), zeaxanthin and β-cryptoxanthin were provided by Extrasynthese (Genay, Lyon, France). 13-Z-β-carotene and 9-Z-β-carotene were purchased from Carbosynth (Newbury, Berkshire, UK).
Methanol of LC-MS grade, n-hexane, ethanol, and methyl tert-butyl ether (MTBE) of HPLC grade, blank human plasma, and butylated hydroxytoluene (BHT) were obtained from Sigma-Aldrich. Ammonium acetate (AMAC) and acetic acid of HPLC grade were purchased from Panreac Quimica SLU (Barcelona, Spain). Ultrapure water (Milli-Q) was generated by a Millipore system (Bedford, MA, USA).

K3-EDTA fasting plasma samples from the baseline blood extractions were analyzed. These samples were drawn in the first visit of the study, just after being randomly assigned to an intervention group and stored at −80 °C until use. All samples and standards were always handled avoiding exposure to light and under cool conditions. Carotenoid standards: astaxanthin, canthaxanthin, E-β-apo-8′-carotenal, α-carotene, β-carotene, fucoxanthin, and lycopene were purchased from Sigma-Aldrich (St. Louis, MO, USA). Lutein was provided by Cayman Chemical (Ann Arbor, MI, USA), zeaxanthin and β-cryptoxanthin were purchased from Extrasynthese (Genay, Lyon, France). 13-Z-β-carotene and 9-Z-β-carotene were purchased from Carbosynth (Newbury, Berkshire, UK). Standards were stored in powder form at −20 °C and protected from light.
Methanol of LC-MS grade, n-hexane, ethanol and methyl tert-butyl ether (MTBE) of HPLC grade, blank human plasma and butylated hydroxytoluene (BHT) were obtained from Sigma-Aldrich. Ammonium acetate (AMAC) and acetic acid of HPLC grade were purchased from Panreac Quimica SLU (Barcelona, Spain). Ultrapure water (Milli-Q) was generated by a Millipore system (Bedford, MA, USA).