Acetone, methanol, methyl-tert-butil-eter (MTBE) and tetrahydrofuran stabilised with 250–350 mg/L butylated hydroxytoluene were of analytical grade and suitable for HPLC (Sigma–Aldrich, St. Louis, USA). The high purity water was taken from a Milli-Q plus water system from Millipore (Bardford, MA, USA). Pyrogallol (Sigma–Aldrich, St. Louis, USA) was used as antioxidant. Standards of lutein and α-carotene were purchased from Santa Cruz Biotechnology Inc. (Santa Cruz, USA) and standards of β-cryptoxanthin, β-carotene and lycopene from Sigma–Aldrich (St. Louis, USA).