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The naturally occurring α-tocopherol stereoisomer α-tocopherol is known to be more bioactive than synthetic α-tocopherol (-α-tocopherol). However, the influence of this difference on the α-tocopherol stereoisomer profile of human milk is not understood. We investigated whether supplemental α-tocopherol or-α-tocopherol differentially affected the distribution of α-tocopherol stereoisomers in milk and plasma from lactating women. Eighty-nine lactating women aged 19-40 y and with a body mass index (in kg/m) ≤30 were randomly assigned at 4-6 wk postpartum to receive a daily supplement containing 45.5 mg -α-tocopherol acetate (ARAC), 22.8 mg-α-tocopherol acetate + 20.1 mg -α-tocopherol (MIX), or 40.2 mgα-tocopherol (RRR). Milk and plasma were analyzed for α-tocopherol structural isomers and α-tocopherol stereoisomers at baseline and after 6 wk supplementation with the use of chiral HPLC. There were no significant treatment group or time-dependent changes in milk or plasma α, γ, or δ-tocopherol. α-tocopherol was the most abundant stereoisomer in both milk and plasma in each group. Supplementation changed both milk and plasma percentageα-tocopherol (RRR > MIX > ARAC) ( < 0.05) and percentage non-α-tocopherol (ARAC > MIX > RRR) ( < 0.05). In the RRR group, percentage α-tocopherol increased in milk (mean ± SEM: 78% ± 2.3% compared with 82% ± 1.7%) ( 0.05) and plasma (mean ± SEM: 77% ± 1.8% compared with 87% ± 1%) ( 0.05). In contrast, the percentage α-tocopherol decreased in the MIX and ARAC groups (MIX, 0.05; ARAC, 0.0001), and percentage non-α-tocopherol stereoisomers increased (MIX, 0.05; ARAC, 0.0001) commensurate with an accumulation of α-tocopherol stereoisomers ( < 0.05) in both milk and plasma. Milk and plasma α-tocopherol was positively correlated at baseline ( = 0.67; 0.0001) and 6 wk ( = 0.80; 0.0001). The α-tocopherol supplementation strategy differentially affected the α-tocopherol milk and plasma stereoisomer profile in lactating women. α-tocopherol increased milk and plasma percentageα-tocopherol, whereas -α-tocopherol acetate reduced these percentages. Becauseα-tocopherol is the most bioactive stereoisomer, investigating the impact of supplement-driven changes in the milk α-tocopherol stereoisomer profile on the α-tocopherol status of breastfed infants is warranted.

A selective, sensitive, and fast High Performance Liquid Chromatography with mass spectrometric (MS) detection method was developed and validated in human plasma. Nevirapine and Enalapril (internal standard, IS) were extracted from human plasma via solid phase extraction (SPE) technique. After the elution through SPE cartridge, samples were directly analyzed using LC-ESI-MS/MS system. An isocratic mode is used to separate interference peaks using a hypurity advanced C-18, 50 X 4.6 mm ID, 5µ, column. The mobile phase composition was 0.1% formic acid in Milli-Q water (v/v) to acetonitrile at a ratio of 15:85, v/v.The m/z of nevirapine and IS were 267.00 /226.20 and 377.10 /234.10, respectively. Linearity ranges were 10.00 to 5000.50 ng/mL. Calibration functions, lower limit of quantitation (LLOQ), stability, intra-and inter-day reproducibility, accuracy, and recovery are estimated. This method was free from matrix effects and any abnormal ionization. This method was successfully applied to a pharmacokinetic study of nevirapine.

No abstract

A selective, sensitive, and fast high performance liquid chromatography (HPLC) method with mass spectrometric (MS) detection mode has been developed and validated completely in human plasma. Atorvastatin (ATO), p-hydroxy atorvastatin (p-HATO), o-hydroxy atorvastatin (o-HATO) and internal standard (IS) are extracted from human plasma via solid phase extraction (SPE) technique. After elution, the solution is evaporated, then reconstituted with 250 µL of Mobile Phase and analyzed using HPLC/MS/MS system. An isocratic mode is used to separate interference peaks using a Symmetry C-18, 75 × 4.6 mm ID, 3.5 µ, column. The m/z of ATO, o-HATO and p-HATO are 559.2/440.2, 575.3/440.4 and 575.0/440.4 respectively. Linearity ranges are 0.05 to 252.92 ng/mL for ATO, p-HATO and o-HATO respectively. Calibration functions, lower limit of quantitation (LLOQ), stability, intra- and inter-day reproducibility, accuracy, and recovery are estimated. This method is free from matrix effects and any abnormal ionization. This method was successfully applied to a single dose 80 mg tablet bioequivalence (BE) study of Atorvastatin. Copyright © 2011 John Wiley & Sons, Ltd.

No abstract

Matrix effect (ME) is a major concern during any LC-ESI-MS/MS analysis. It affects reproducibility, sensitivity and reliability of these analytical techniques. There are, however, no standardized approaches available to overcome the ME related issues. The approach varies from molecule to molecule. Here we examined that sample extraction technique is an approach to overcome the ME during LC-MS/MS bioanalysis. Three types of conventional extraction techniques i.e. protein precipitation, liquid-liquid extraction and solid phase extraction (SPE) were used during extraction of nevirapin from human plasma. It was observed that nevirapin sample when prepared by SPE, eliminates or reduces dramatically the MEs ipso facto. Protein precipitated samples showed highest degree of ME with average matrix factor of 0.30; liquid-liquid extraction had an average matrix factor of 0.80; and the matrix factor obtained by solid phase extraction was 0.99. Different phospholipids were identified by performing the precursor ion scanning at m/z 104 and 184, which interfered with the analyte during chromatographic elution. From the experiment it was observed that long retained phospholipids had significant role on ME. So it is a good practice to observe the phospholipids during precursor scanning for a period which is at least three times of the actual analytical run time. Among all the applied extraction techniques, solid phase extraction produces the cleanest sample, and methanol precipitation produces the dirtiest sample due to high solubility of the phospholipids into it.

In resource-limited settings, mass food fortification is a common strategy to ensure the population consumes appropriate quantities of essential micronutrients. Food and government organizations in these settings, however, lack tools to monitor the quality and compliance of fortified products and their efficacy to enhance nutrient status. The World Health Organization has developed general guidelines known as ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end-users) to aid the development of useful diagnostic tools for these settings. These guidelines assume performance aspects such as sufficient accuracy, reliability, and validity. The purpose of this systematic narrative review is to examine the micronutrient sensor literature on its adherence towards the ASSURED criteria along with accuracy, reliability, and validation when developing micronutrient sensors for resource-limited settings. Keyword searches were conducted in three databases: Web of Science, PubMed, and Scopus and were based on 6-point inclusion criteria. A 16-question quality assessment tool was developed to determine the adherence towards quality and performance criteria. Of the 2,365 retrieved studies, 42 sensors were included based on inclusion/exclusion criteria. Results showed that improvements to the current sensor design are necessary, especially their affordability, user-friendliness, robustness, equipment-free, and deliverability within the ASSURED criteria, and accuracy and validity of the additional criteria to be useful in resource-limited settings. Although it requires further validation, the 16-question quality assessment tool can be used as a guide in the development of sensors for resource-limited settings.