Determination of glucosinolates in canola seeds using anion exchange membrane extraction combined with the high pressure liquid chromatography detection
Szmigielska, A.M., J.J. Schoenau and V. Levers . 2000. J. Agric. Food Chem. 48: 4487-4491
Abstract
A rapid, simple and reliable method
for the determination of individual glucosinolates in
canola seeds was developed using a semiquantitative
extraction of glucosinolates with anion exchange
membranes and HPLC detection. In this one-step extraction
procedure, a membrane (7 cm2) is placed in the
seed suspension prepared by grinding and boiling 0.8 g of
seeds in 20 mL of water. After 10 min of shaking on the
mechanical shaker, the membrane is removed from the
suspension, washed, and transferred to a vial containing
5 mL of 1 N tetramethylammonium chloride. The
glucosinolates are eluted from the membrane by shaking
the membrane for 10 min with the eluting solvent. The
glucosinolate content in membrane eluates is determined
by HPLC using sinigrin standards. A coefficient of
variation ranging from 1.9 to 7.6% for aliphatic
glucosinolates indicated very good reproducibility of the
method. Because of the instability of
4-hydroxyglucobrassicin, the coefficient of variation for
the determination of this indolyl glucosinolate was
13.9%. To verify the results of the membrane
extraction/HPLC detection, this new method was compared
with the existing colorimetric and GC procedures. Very
good correlation (R2
= 0.98) was obtained between the total glucosinolates
determined by the membrane extraction/HPLC method and the
palladate colorimetric procedure for 17 canola varieties.
Concentrations of individual glucosinolates in five
canola varieties were compared with the GC data. Very
good agreement between these two methods was obtained for
aliphatic glucosinolates. However, the membrane
extraction/HPLC method yielded slightly higher values for
4-hydroxyglucobrassicin that the GC method, possibly
indicating that the decomposition of this glucosinolate
was reduced during the sample extraction with the
membranes. The simplicity and low cost of the membrane
extraction/HPLC method make it an attractive alternative
to the existing procedures for glucosinolate analysis in
canola seeds.
Key Words
Canola, glucosinolates, anion exchange membranes, extraction, HPLC
