Melissa M. Phillips

Analytical approaches to determination of total choline in foods and dietary supplements

Choline is a quaternary amine that is synthesized in the body or consumed through the diet. Choline is critical for cell membrane structure and function and in synthesis of the neurotransmitter acetylcholine. Although the human body produces this micronutrient, dietary supplementation of choline is necessary for good health. The major challenge in the analysis of choline in foods and dietary supplements is in the extraction and/or hydrolysis approach. In many products, choline is present as choline esters, which can be quantitated individually or treated with acid, base, or enzymes in order to release choline ions for analysis. A critical review of approaches based on extraction and quantitation of each choline ester as well as hydrolysis-based methods for determination of total choline in foods and dietary supplements is presented.

Interlaboratory Trial for Measurement of Vitamin D and 25-Hydroxyvitamin D [25(OH)D] in Foods and a Dietary Supplement Using Liquid Chromatography-Mass Spectrometry

Assessment of total vitamin D intake from foods and dietary supplements (DSs) may be incomplete if 25-hydroxyvitamin D [25(OH)D] intake is not included. However, 25(OH)D data for such intake assessments are lacking, no food or DS reference materials (RMs) are available, and comparison of laboratory performance has been needed. The primary goal of this study was to evaluate whether vitamin D3 and 25(OH)D3 concentrations in food and DS materials could be measured with acceptable reproducibility. Five experienced laboratories from the United States and other countries participated, all using liquid chromatography tandem-mass spectrometry but no common analytical protocol; however, various methods were used for determining vitamin D3 in the DS. Five animal-based materials (including three commercially available RMs) and one DS were analyzed. Reproducibility results for the materials were acceptable. Thus, it is possible to obtain consistent results among experienced laboratories for vitamin D3 and 25(OH)D3 in foods and a DS.

Liquid chromatography with isotope-dilution mass spectrometry for determination of water-soluble vitamins in foods

Vitamins are essential for improving and maintaining human health, and the main source of vitamins is the diet. Measurement of the quantities of water-soluble vitamins in common food materials is important to understand the impact of vitamin intake on human health, and also to provide necessary information for regulators to determine adequate intakes. Liquid chromatography (LC) and mass spectrometry (MS) based methods for water-soluble vitamin analysis are abundant in the literature, but most focus on only fortified foods or dietary supplements or allow determination of only a single vitamin. In this work, a method based on LC/MS and LC/MS/MS has been developed to allow simultaneous quantitation of eight water-soluble vitamins, including multiple forms of vitamins B3 and B6, in a variety of fortified and unfortified food-matrix Standard Reference Materials (SRMs). Optimization of extraction of unbound vitamin forms and confirmation using data from external laboratories ensured accuracy in the assigned values, and addition of stable isotope labeled internal standards for each of the vitamins allowed for increased precision.

Evaluation of the impact of peak description on the quantitative capabilities of comprehensive two-dimensional liquid chromatography

Comprehensive, two-dimensional liquid chromatography (LC × LC) is a powerful technique for the separation of complex mixtures. Most studies using LC × LC are focused on qualitative efforts, such as increasing peak capacity. The present study examined the use of LC × LC-UV/vis for the separation and quantitation of polycyclic aromatic hydrocarbons (PAHs). More specifically, this study evaluated the impact of different peak integration approaches on the quantitative performance of the LC × LC method. For well-resolved three-dimensional peaks, parameters such as baseline definition, peak base shape, and peak width determination did not have a significant impact on accuracy and precision. For less-resolved peaks, a dropped baseline and the summation of all slices in the peak improved the accuracy and precision of the integration methods. The computational approaches to three-dimensional peak integration are provided, including fully descriptive, select slice, and summed heights integration methods, each with its own strengths and weaknesses. Overall, the integration methods presented quantify each of the PAHs within acceptable precision and accuracy ranges and have comparable performance to that of single dimension liquid chromatography.

Developing qualitative LC-MS methods for characterization of Vaccinium berry Standard Reference Materials

Standard Reference Materials (SRMs) offer the scientific community a stable and homogenous source of material that holds countless application possibilities. Traditionally, the National Institute of Standards and Technology (NIST) has provided SRMs with associated quantitative information (certified values) for a select group of targeted analytes as measured in a solution or complex matrix. While the current needs of the SRM community are expanding to include non-quantitative data, NIST is attempting to broaden the scope of how and what information is offered to the SRM community by providing qualitative information about biomaterials, such as chromatographic fingerprints and profiles of untargeted identifications. In this work, metabolomic and proteomic profiling efforts were employed to characterize a suite of six Vaccinium berry SRMs. In the discovery phase, liquid chromatography-tandem mass spectrometry (LC-MS/MS) data was matched to mass spectral libraries; a subsequent validation phase based on multiple-reaction monitoring LC-MS/MS relied on both retention time matching of authentic standards along with fragmentation data for a qualitative overview of the most prominent organic compounds present. Definitive and putative identifications were determined for over 70 metabolites based on reporting guidelines set forth by the Metabolomics Standards Initiative (Metabolomics 3(3):211–221, 2007), and the capability of electrospray ionization mass spectrometry (ESI-MS) to profile untargeted metabolites within a complex matrix using mass spectral matching is demonstrated. Bottom-up proteomic analyses were possible using peptide databases translated from expressed sequence tags (ESTs). Homology searches provided identification of novel Vaccinium proteins based on homology to related genera. Chromatographic fingerprints of these berry materials were acquired for supplemental qualitative information to be provided to users of these SRMs. An unbounded set of qualitative data about a biomaterial is a valuable complement to quantitative information traditionally provided in NIST Certificates of Analysis.

Functional foods and dietary supplements

General interest in improving or maintaining health by increasing intake of “all-natural” and “organic” products combined with busier schedules has created a desire for more streamlined approaches to nutrition. Analysis of data from the 2007–2010 National Health and Nutrition Examination Survey (NHANES) revealed that 49 % of US adults reported using a supplement within 30 days of the study [1]. The main reasons for taking supplements were identified as being to “improve overall health” (45 %) and to “maintain health” (33 %) [1]. The result has been growth in the areas of functional foods and dietary supplements, both in product variety and sales. Functional foods and dietary supplements are two of the major classes of nutraceuticals or food-related products that have purported health or medical benefits, such as improving cardiovascular health and prevention or treatment of disease. Functional foods can include foods that have been either enriched or fortified to restore preprocessed nutrient levels (enriched flour), to improve nutritional quality of an otherwise nutrient-deficient food (calcium in orange juice), or to resolve public health issues (vitamin D in milk, iodized table salt). Some consider a functional food to be any food that provides health benefits beyond basic nutrition, such as the soluble fiber found in oatmeal and the monounsaturated fat found in avocados. Studies are ongoing to identify functional characteristics of traditional foods and to develop new products that exploit beneficial components. A recent survey indicates that two thirds of US grocery shoppers have purchased a food or beverage specifically to address one of a number of common health concerns (e.g., cholesterol, digestive health) [2]. Dietary supplements, including concentrated forms of food-derived nutrients, are the other major class of nutraceuticals. Unlike functional foods, dietary supplements are not intended to be food or meal replacements, but are designed to be taken in addition to daily food consumption for added nutrients or perceived health benefits. Global dietary supplement sales continue to rise, growing 6.1 % in 2011, from

TDRM/TDLM workshop on reference materials and laboratory accreditation at the AOAC annual meeting 2011

79.43 billion to

Liquid chromatography with absorbance detection and with isotope-dilution mass spectrometry for determination of isoflavones in soy standard reference materials

84.26 billion [3]. The most common dietary supplements are multivitamin–mineral products, calcium, ω-3/fish oil, and botanicals [1]. Botanicals are a growing category, however, as the botanical and natural ingredient export trade reached

Best food reference material challenge

33 billion in 2010, with projections of up to

The development and implementation of quality assurance programs to support nutritional measurements

100 billion by 2015 [4]. With a large market share and variety of products comes a need for quality control and regulation. For functional foods, the approach to marketing determines the regulatory category. In the USA, some functional foods are regulated as foods, falling under the Nutritional Labeling and Education Act of 1990 [5]. In other cases, functional foods are regulated as dietary supplements. The current Good Manufacturing Practices (cGMPs), published by the US Food and Drug Administration in 2010, require that dietary supplements produced in the USA are evaluated for identity, purity, and strength as well as for contaminants and adulterants [6]. Qualitymeasurements are also important when establishing efficacy as a clinical trial is much more persuasive when active ingredients and their Published in the topical collection Functional Foods and Dietary Supplements with guest editors Melissa M. Phillips and Catherine A. Rimmer.