Determination of Vitamins A and E in Infant Formula and Adult/Pediatric Nutritional Formula by HPLC with UV and Fluorescence Detection: First Action 2012.09

The method presented is for quantification of α-tocopherol (vitamin E), vitamin E acetate, vitamin A acetate, and vitamin A palmitate in infant formula and adult/pediatric nutritionals. The entire lipid fraction, including vitamins A and E, is extracted from product with iso-octane after products are mixed with methanol, which precipitates proteins and disrupts micelles freeing lipids for extraction. Vitamin A palmitate, vitamin A acetate, and vitamin E acetate are separated from α-tocopherol on a 3 cm silica column with a 1% methylene chloride, 0.06% isopropanol in iso-octane mobile phase; eluted onto a 20 cm silica column; and, after a column switch, further separated on the 20 cm column before UV detection at 325 nm (vitamin A palmitate and vitamin A acetate) and 285 nm (vitamin E acetate). α-Tocopherol is further separated from other extraneous compounds on the 3 cm silica column and detected by fluorescence at excitation and emission wavelengths of 295 and 330 nm, respectively. Quantification limits in ready-to-feed products were estimated to be 80 IU/L for vitamin A palmitate, 207 International Units (IU)/L for vitamin A acetate, 2.4 mg/L for vitamin E acetate, and <0.15 mg/L for α-tocopherol. Over-spike recoveries and intermediate precision averaged 100.4 and 2.09% RSD for vitamin A palmitate, 100.4 and 1.52% RSD for vitamin E acetate, and 99.6 and 3.02% RSD for α-tocopherol. Vitamin A acetate spike recovery data averaged 96.6%, and the intermediate precision for the only product fortified with vitamin A acetate was 2.75% RSD.

Methotrexate-Associated Biochemical Alterations in a Patient with Chronic Neurotoxicity

Methotrexate-Associated Biochemical Alterations in a Patient with Chronic Neurotoxicity Intrathecal and/or high-dose intravenous administration of methotrexate (MTX) in the treatment of malignancies such as acute lymphoblastic leukaemia (ALL) has been associated with cases of mild to severe neurotoxicity. The pathogenic mechanism of neurotoxicity is not clear, possibly MTX-associated biochemical alterations of the folate and methyl-transfer metabolic pathways play an important role. We report a case of an adult patient treated for ALL relapse with signs of chronic leukoencephalopathy associated with MTX administration. In order to assess alterations in the folate and methyl-transfer pathway we determined 5-methyltetrahydrofolate (5-methyl-THF), S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in the cerebrospinal fluid (CSF) of the patient. Three CSF samples were obtained by lumbar punction within a four-month period. Concentrations of the metabolites were measured using validated bioanalytical methods based on HPLC with UV and fluorescence detection. The results showed two-fold lower 5-methyl-THF levels (29.3-31.8 nmol/L) in all obtained samples compared to reference values. SAM concentrations were even more than five-fold lower in two samples (5-34.2 nmol/L). SAH concentrations were in the range 7.5-14.3 nmol/L. Our patient had pronounced alterations in the folate and methyltransfer pathway which indicate that MTX-associated biochemical alterations of these pathways may play an important role in the development of leukoencephalopathy.