title: Determination of vitamin K1 in medical foods by liquid chromatography with postcolumn reduction and fluorometric detection.
abstract: A liquid chromatographic (LC) method is described for the determination of vitamin K1 in medical foods. The sample is enzymatically digested with lipase and alpha-amylase and extracted with 1% sodium bicarbonate solution-isopropanol (1 + 1). After C18 solid-phase extraction, vitamin K1 is separated by nonaqueous reversed-phase LC, converted to the hydroquinone by postcolumn zinc reduction, and quantitated by fluorescence detection. The limit of detection is 8 pg (3 sigma), and the limit of quantitation is 27 pg (10 sigma) on column. Linear response ranged from 0.1 to 1.0 ng vitamin K1 (r= 0.9999). The mean recovery (n = 38) for all spiking levels was 101.6 +/- 2.85%. Analysis of Standard Reference Material 1846, Infant Formula, gave a mean value of 0.95 +/- 0.088 mg vitamin K/kg (K or K1?) (n = 31) with a coefficient of variation of 9.26.
authors.affiliation: US Food and Drug Administration, Southeast Regional Laboratory, Atlanta, GA 30309, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Ware
authors.forename: G W
authors.initials: GW
authors.lastname: Chase
authors.forename: R R
authors.initials: RR
authors.lastname: Eitenmiller
authors.forename: A R
authors.initials: AR
authors.lastname: Long
authors.forename: G M
authors.initials: GM
authors.lastname: Ware
authors.forename: G W
authors.initials: GW
authors.lastname: Chase
authors.forename: R R
authors.initials: RR
authors.lastname: Eitenmiller
authors.forename: A R
authors.initials: AR
authors.lastname: Long
mesh_terms: D019840:2-Propanol; D002021:Buffers; D002853:Chromatography, Liquid / Q000379:methods*; D005470:Fluorometry; D005526:Food, Formulated / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones; D008049:Lipase / Q000378:metabolism; D011786:Quality Control; D012680:Sensitivity and Specificity; D017693:Sodium Bicarbonate; D010837:Vitamin K 1 / Q000032:analysis*; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D002021:Buffers; D006873:Hydroquinones; D010837:Vitamin K 1; D017693:Sodium Bicarbonate; D008049:Lipase; D000516:alpha-Amylases; D019840:2-Propanol; C031927:hydroquinone