科研之友
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摘要
Small specimen volume and high sample throughput are key features needed for routine methods used for population biomonitoring. We modified our routine eight-probe solid phase extraction (SPE) LC-MS/MS method for the measurement of five folate vitamers [5-methyltetrahydrofolate (5-methylTHF), folic acid (FA), plus three minor forms: THF, 5-formylTHF, 5,10-methenylTHF] and one oxidation product of 5-methylTHF (MeFox) to require less serum volume (150 mu L instead of 275 mu L) by using 96-well SPE plates with 50 mg instead of 100 mg phenyl sorbent and to provide faster throughput by using a 96-probe SPE system. Total imprecision (10 days, two replicates/day) for three serum quality control pools was 2.8-3.6 % for 5-methylTHF (19.5-51.1 nmol/L), 6.6-8.7 % for FA (0.72-11.4 nmol/L), and a parts per thousand currency sign11.4 % for the minor folate forms (< 1-5 nmol/L). The mean (+/- SE) recoveries of folates spiked into serum (3 days, four levels, two replicates/level) were: 5-methylTHF, 99.4 +/- 3.6 %; FA, 100 +/- 1.8 %; minor folates, 91.7-108 %. SPE extraction efficiencies were a parts per thousand yen85 %, except for THF (78 %). Limits of detection were a parts per thousand currency sign0.3 nmol/L. The new method correlated well with our routine method [n = 150, r = 0.99 for 5-methylTHF, FA, and total folate (tFOL, sum of folate forms)] and produced slightly higher tFOL (5.6 %) and 5-methylTHF (7.3 %) concentrations, likely due to the faster 96-probe SPE process (1 vs. 5 h), resulting in improved SPE efficiency and recovery compared to the eight-probe SPE method. With this improved LC-MS/MS method, 96 samples can be processed in similar to 2 h, and all relevant folate forms can be accurately measured using a small serum volume.
- 出版日期2013-5
