Russell D. Day

Development and certification of green tea-containing standard reference materials.

AbstractA suite of three green tea-containing Standard Reference Materials (SRMs) has been issued by the National Institute of Standards and Technology (NIST): SRM 3254 Camellia sinensis (Green Tea) Leaves, SRM 3255 Camellia sinensis (Green Tea) Extract, and SRM 3256 Green Tea-Containing Solid Oral Dosage Form. The materials are characterized for catechins, xanthine alkaloids, theanine, and toxic elements. As many as five methods were used in assigning certified and reference values to the constituents, with measurements carried out at NIST and at collaborating laboratories. The materials are intended for use in the development and validation of new analytical methods, and for use as control materials as a component in the support of claims of metrological traceability. FigureGreen Tea - Camellia sinensis

Improved Calibration Strategy for Measurement of Trace Elements in Biological and Clinical Whole Blood Reference Materials via Collision-Cell Inductively Coupled Plasma Mass Spectrometry

A multi-element quantification strategy based on the method of standard additions incorporating internal standards and collision cell inductively coupled plasma mass spectrometry (ICP-MS) is presented. Approaches to experimental design are discussed in the context of streamlining analytical measurement protocols employing ratio-based standard additions quantification schemes for the certification of multiple elements in Certified Reference Materials, including reduction of the number of required analytical samples and measurement of analytes and internal standards at alternate quadrupole mass resolution settings. This strategy was implemented for the measurement of As, Se, Fe, Mn, Rb, Cu, and Zn levels in a candidate fish tissue NIST Standard Reference Material and measurement of Cd and Pb in two clinical, whole blood Certified Reference Materials. A simple approach to calculating analytical uncertainties for concentration data, as determined using standard additions calibrations, is presented which utilizes regression and prediction uncertainties and quotient propagation of error formulae.

Determination of mercury in the eggs of common murres (Uria aalge) for the seabird tissue archival and monitoring projectDisclaimer: Any mention of commercial products within this manuscript is for information only; it does not imply recommendation or endorsement by NIST.

An analytical method using isotope dilution cold vapor inductively coupled plasma mass spectrometry (ID-CV-ICPMS) was developed for the determination of total mercury in the eggs of seabirds. Components including error magnification, verification of method accuracy and assignment of analytical uncertainty are presented in the context of collecting mercury data for single sample aliquots. Forty-one egg samples collected from common murre (Uria aalge) colonies on Little Diomede and Saint George Islands in the Bering Sea and East Amatuli and Saint Lazaria Islands in the Gulf of Alaska yielded mercury mass fraction values ranging from approximately 0.010 µg g−1 to 0.360 µg g−1. Relative expanded uncertainties for the individual determinations ranged from 1.2% to 4.4%. A one-way analysis of variance including pairwise comparisons across the colonies showed that mercury levels in eggs collected from the Gulf of Alaska colonies were significantly higher than their counterparts in the Bering Sea. Mercury data from each colony were normally distributed, suggesting a ubiquitous regional deposition of mercury and corresponding incorporation into local foodwebs.