Determination of magnesium stearate in capsule- or tablet-type supplements.
A simple method for the determination of magnesium stearate in capsule- or tablet-type supplements was developed. Free stearic acid in the sample was removed by extraction with tetrahydrofuran. The remaining stearate was converted to stearic acid by reaction with a cation-exchange resin. The resulting stearic acid was determined by gas chromatography with a polar column. Esters of stearic acid were not converted to stearic acid and would not cause a positive error in the amount of stearate. The amount of magnesium stearate was calculated based on the stearic acid concentration thus obtained. Magnesium stearate levels in 5 out of 25 supplements exceeded 2500 microg/g, which indicated the possible admixture of magnesium stearate.
Uematsu
Yoko
Y
Tokyo Metropolitan Institute of Public Health, 3-24-1, Hyakunin-cho, Shinjuku-ku, Tokyo 169-0073, Japan. Yoko_Uematsu@member.metro.tokyo.jp
Ogimoto
Mami
M
Kabashima
Junichirou
J
Ito
Kouichi
K
Yasuda
Kazuo
K
D002138:Calibration; D002214:Capsules; D002852:Chromatography, Ion Exchange; D019587:Dietary Supplements / Q000032:analysis*; D008401:Gas Chromatography-Mass Spectrometry; D007202:Indicators and Reagents; D010168:Palmitates / Q000032:analysis; D012015:Reference Standards; D013229:Stearic Acids / Q000032:analysis*; D013607:Tablets
D002214:Capsules; D007202:Indicators and Reagents; D010168:Palmitates; D013229:Stearic Acids; D013607:Tablets; C031183:stearic acid