GC instrument (GC2010, Shimadzu Co., Japan) used in the study
was equipped with an auto injector of Aoc-20i, a capillary column
of DB-WAX (30 m 0.320 mm, 0.25 id., J & M Scientific Co., USA)
and a flame ionization detector. The following temperature procedure
was followed: isothermal at 50 C was first maintained for
5 min, then the temperature was increased to 160 C at 5 C/min,
and to 200 C at 10 C/min, and finally the temperature was held at
200 C for 5 min. 1000 mg/L stock standard solution of each standard
higher alcohol was made. The standard solution of n-propyl
alcohol was prepared with water as solvent, and the iso-butyl
alcohol and iso-amyl alcohol standard solutions were prepared
with methanol as solvent. Then the mixed working standard solutions
of 5 mg/L, 10 mg/L, 100 mg/L were made with methanol as
solvent. The mixed standards solutions (1 mL) were filtrated into
glass vials through 0.22 mm nylon membrane. OFM samples were
diluted by 20 folds with water. Then 1 mL diluted samples was
filtered into the glass vial through 0.22 mm nylon membrane, and
1 mL was injected into GC with a split ratio of 25 being used.