Application of UPLC-MS/MS Method for Analyzing B-vitamins in Human Milk

Objective To determine ten B-vitamins in human milk by ultra-high performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）. Methods The pretreated human milk samples were adequately separated and quantified within 11 min by UPLC-MS/MS with an Acquity UPLC HSS T3 column （2.1×100 mm, 1.8 μm）. The mobile phase was a gradient of 2.5 mmol/L ammonium formate aqueous solution and acetonitrile at a flow rate of 0.35 mL/min. Stable isotope internal standards were used in the analysis, to correct for the method variability, including matrix and ionization effects. The homogenized human milk samples were deproteinzed using methanol, unknown contaminants were extracted with diethyl ether and hydrophobic phase was discarded. The analytes were monitored via ESl＋ionization and detected in multiple reaction monitoring （MRM） with three acquisition functions. Results Calibration curves ranged from 0.5-160 ng/mL （thiamin, riboflavin, biotin, nicotinic acid, pyridoxine, pyridoxamine, pyridoxal）, and 2.5-800 ng/mL （pantothenic acid, FAD and nicotinamide） （R^2=0.990-0.999）. The relative recovery ranged from 80.1% to 120.2%; accuracy was determined to be 98.3% to 108.0%. Intra-day and inter-day variation were 3.4%-19.9% and 5.9%-18.1%, respectively. The limit of quantification （LOQ） for all vitamins was between 0.25 and 3 lag/L. Conclusion This method was successfully applied for simultaneous analysis of ten B-vitamins in human milk.

Role of vitamin B12 deficiency in ischemic stroke risk and outcome

Currently,ischemic stroke is the most prevalent form of stroke compared to hemorrhagic and there is a high incidence in older adults.Nutrition is a modifiable risk factor for stroke.B-vitamins are part of a metabolic network that integrates nutritional signals with biosynthesis,redox homeostasis,and epigenetics.These vitamins play an essential role in the regulation of cell proliferation,stress resistance,and embryo development.A deficiency in vitamin B12 is common in older adults and has been reported to be implicated in ischemic stroke.The aim of this review was to investigate whether vitamin B12 deficiencies impact the risk and outcome of ischemic stroke.Clinical data from our literature review strongly suggest that a deficiency in vitamin B12 is a risk factor for ischemic stroke and possible outcome.Our survey of the literature has identified that there is a gap in the understanding of the mechanisms through which a vitamin B12 deficiency leads to an increased risk of stroke and outcome.A vitamin B12 deficiency can increase homocysteine levels,which are a well-established risk factor for ischemic stroke.Another potential mechanism through which vitamin B12 deficient may impact neurological function and increase risk of stroke,is changes in myelination,however this link requires further investigation.Further studies are required in model systems to understand how a vitamin B12 deficiency changes the brain.