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11.
Standard reference materials for foods and dietary supplements 总被引:1,自引:0,他引:1
Sharpless KE Thomas JB Christopher SJ Greenberg RR Sander LC Schantz MM Welch MJ Wise SA 《Analytical and bioanalytical chemistry》2007,389(1):171-178
Well-characterized certified reference materials are needed by laboratories in the food testing, dietary supplement, and nutrition
communities to facilitate compliance with labeling laws and improve the accuracy of information provided on product labels,
so that consumers can make good choices. As a result of the enactment of the Nutrition Labeling and Education Act of 1990
and the Infant Formula Act of 1980, the National Institute of Standards and Technology (NIST) worked to develop a series of
food-matrix standard reference materials (SRMs) characterized for nutrient concentrations. These include SRM 1544 Fatty Acids
and Cholesterol in a Frozen Diet Composite, SRM 1546 Meat Homogenate, SRM 1548a Typical Diet, SRM 1566b Oyster Tissue, SRM
1846 Infant Formula, SRM 1946 Lake Superior Fish Tissue, SRM 1947 Lake Michigan Fish Tissue, SRM 2383 Baby Food Composite,
SRM 2384 Baking Chocolate, SRM 2385 Slurried Spinach, and SRM 2387 Peanut Butter. With the enactment of the Dietary Supplement
Health and Education Act of 1994, NIST has been working to develop suites of dietary supplement SRMs characterized for active
and marker compounds and for toxic elements and pesticides, where appropriate. An updated SRM 1588b Organics in Cod Liver
Oil, a suite of ephedra-containing materials (SRMs 3240–3245), a carrot extract in oil (SRM 3276), and a suite of ginkgo-containing
materials (SRMs 3246–3248) are available. Several other materials are currently in preparation. Dietary supplements are sometimes
provided in forms that are food-like; for these, values may also be assigned for nutrients, for example SRM 3244 Ephedra-Containing
Protein Powder. Both the food-matrix and dietary supplement reference materials are intended primarily for validation of analytical
methods. They may also be used as “primary control materials” in assignment of values to in-house (secondary) control materials
to confirm accuracy and to establish measurement traceability to NIST. 相似文献
12.
Stapleton HM Keller JM Schantz MM Kucklick JR Leigh SD Wise SA 《Analytical and bioanalytical chemistry》2007,387(7):2365-2379
Standard reference materials (SRMs) are valuable tools in developing and validating analytical methods to improve quality
assurance standards. The National Institute of Standards and Technology (NIST) has a long history of providing environmental
SRMs with certified concentrations of organic and inorganic contaminants. Here we report on new certified and reference concentrations
for 27 polybrominated diphenyl ether (PBDE) congeners in seven different SRMs: cod-liver oil, whale blubber, fish tissue (two
materials), mussel tissue and sediment (two materials). PBDEs were measured in these SRMs, with the lowest concentrations
measured in mussel tissue (SRM 1974b) and the highest in sediment collected from the New York/New Jersey Waterway (SRM 1944).
Comparing the relative PBDE congener concentrations within the samples, we found the biota SRMs contained primarily tetrabrominated
and pentabrominated diphenyl ethers, whereas the sediment SRMs contained primarily decabromodiphenyl ether (BDE 209). The
cod-liver oil (SRM 1588b) and whale blubber (SRM 1945) materials were also found to contain measurable concentrations of two
methoxylated PBDEs (MeO-BDEs). Certified and reference concentrations are reported for 12 PBDE congeners measured in the biota
SRMs and reference values are available for two MeO-BDEs. Results from a sediment interlaboratory comparison PBDE exercise
are available for the two sediment SRMs (1941b and 1944). 相似文献
13.
Davis WC Christopher SJ Pugh RS Donard OF Krupp EA Point D Horvat M Gibicar D Kljakovic-Gaspic Z Porter BJ Schantz MM 《Analytical and bioanalytical chemistry》2007,387(7):2335-2341
This paper describes the development of two independent analytical methods for the extraction and quantification of methylmercury
from marine biota. The procedures involve microwave extraction, followed by derivatization and either headspace solid-phase
microextraction (SPME) with a polydimethylsiloxane (PDMS)-coated silica fiber or back-extraction into iso-octane. The identification
and quantification of the extracted compounds is carried out by capillary gas chromatography/mass spectrometric (GC/MS) and
inductively coupled plasma mass spectrometric (GC/ICP-MS) detection. Both methods were validated for the determination of
methylmercury (MeHg) concentrations in a variety of biological standard reference materials (SRMs) including fresh-frozen
tissue homogenates of SRM 1946 Lake Superior fish tissue and SRM 1974a organics in mussel tissue (Mytilus edulis) and then applied to the certification effort of SRM 1947 Lake Michigan fish tissue and SRM 1974b organics in mussel tissue
(Mytilus edulis). While past certifications of methylmercury in tissue SRMs have been based on two independent methods from the National
Institute of Standards and Technology (NIST) and participating laboratories, the methods described within provide improved
protocols and will allow future certification efforts to be based on at least two independent analytical methods within NIST. 相似文献
14.
Sharpless KE Lindstrom RM Nelson BC Phinney KW Rimmer CA Sander LC Schantz MM Spatz RO Thomas JB Turk GC Wise SA Wood LJ Yen JH 《Journal of AOAC International》2010,93(4):1262-1274
Standard Reference Material (SRM) 1849 Infant/Adult Nutritional Formula has been issued by the National Institute of Standards and Technology (NIST) as a replacement for SRM 1846 Infant Formula, issued in 1996. Extraction characteristics of SRM 1846 have changed over time, as have NIST's analytical capabilities. While certified mass fraction values were provided for five constituents in SRM 1846 (four vitamins plus iodine), certified mass fraction values for 43 constituents are provided in SRM 1849 (fatty acids, elements, and vitamins) and reference mass fraction values are provided for an additional 43 constituents including amino acids and nucleotides, making it the most extensively characterized food-matrix SRM available from NIST. 相似文献
15.
John R. Kucklick Michele M. Schantz Rebecca S. Pugh Barbara J. Porter Dianne L. Poster Paul R. Becker Teri K. Rowles Stefan Leigh Stephen A. Wise 《Analytical and bioanalytical chemistry》2010,397(2):423-432
The National Institute of Standards and Technology (NIST) has a diverse collection of control materials derived from marine
mammal blubber, fat, and serum. Standard Reference Material (SRM) 1945 Organics in Whale Blubber was recertified for polychlorinated
biphenyl (PCB) congeners, organochlorine pesticides, and polybrominated diphenyl ether (PBDE) congeners. SRM 1945 has also
been assigned mass fraction values for compounds not frequently determined in marine samples including toxaphene congeners,
coplanar PCBs, and methoxylated PBDE congeners which are natural products. NIST also has assigned mass fraction values, as
a result of interlaboratory comparison exercises, for PCB congeners, organochlorine pesticides, PBDE congeners, and fatty
acids in six homogenate materials produced from marine mammal blubber or serum. The materials are available from NIST upon
request; however, the supply is very limited for some of the materials. The materials include those obtained from pilot whale
blubber (Homogenates III and IV), Blainville’s beaked whale blubber (Homogenate VII), polar bear fat (Homogenate VI), and
California sea lion serum (Marine Mammal Control Material-1 Serum) and blubber (Homogenate V). 相似文献
16.
Background
Several studies have shown that Stroop interference is stronger in children than in adults. However, in a standard Stroop paradigm, stimulus interference and response interference are confounded. The purpose of the present study was to determine whether interference at the stimulus level and the response level are subject to distinct maturational patterns across childhood. Three groups of children (6–7 year-olds, 8–9 year-olds, and 10–12 year-olds) and a group of adults performed a manual Color-Object Stroop designed to disentangle stimulus interference and response interference. This was accomplished by comparing three trial types. In congruent (C) trials there was no interference. In stimulus incongruent (SI) trials there was only stimulus interference. In response incongruent (RI) trials there was stimulus interference and response interference. Stimulus interference and response interference were measured by a comparison of SI with C, and RI with SI trials, respectively. Event-related potentials (ERPs) were measured to study the temporal dynamics of these processes of interference.Results
There was no behavioral evidence for stimulus interference in any of the groups, but in 6–7 year-old children ERPs in the SI condition in comparison with the C condition showed an occipital P1-reduction (80–140 ms) and a widely distributed amplitude enhancement of a negative component followed by an amplitude reduction of a positive component (400–560 ms). For response interference, all groups showed a comparable reaction time (RT) delay, but children made more errors than adults. ERPs in the RI condition in comparison with the SI condition showed an amplitude reduction of a positive component over lateral parietal (-occipital) sites in 10–12 year-olds and adults (300–540 ms), and a widely distributed amplitude enhancement of a positive component in all age groups (680–960 ms). The size of the enhancement correlated positively with the RT response interference effect.Conclusion
Although processes of stimulus interference control as measured with the color-object Stroop task seem to reach mature levels relatively early in childhood (6–7 years), development of response interference control appears to continue into late adolescence as 10–12 year-olds were still more susceptible to errors of response interference than adults. 相似文献17.
Analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples: a critical review of gas chromatographic (GC) methods 总被引:1,自引:0,他引:1
Polycyclic aromatic hydrocarbons (PAHs) are frequently measured in the atmosphere for air quality assessment, in biological
tissues for health-effects monitoring, in sediments and mollusks for environmental monitoring, and in foodstuffs for safety
reasons. In contemporary analysis of these complex matrices, gas chromatography (GC), rather than liquid chromatography (LC),
is often the preferred approach for separation, identification, and quantification of PAHs, largely because GC generally affords
greater selectivity, resolution, and sensitivity than LC. This article reviews modern-day GC and state-of-the-art GC techniques
used for the determination of PAHs in environmental samples. Standard test methods are discussed. GC separations of PAHs on
a variety of capillary columns are examined, and the properties and uses of selected mass spectrometric (MS) techniques are
presented. PAH literature on GC with MS techniques, including chemical ionization, ion-trap MS, time-of-flight MS (TOF-MS),
and isotope-ratio mass spectrometry (IRMS), is reviewed. Enhancements to GC, for example large-volume injection, thermal desorption,
fast GC, and coupling of GC to LC, are also discussed with regard to the determination of PAHs in an effort to demonstrate
the vigor and robustness GC continues to achieve in the analytical sciences. 相似文献
18.
W. W. Brubaker Jr. M. M. Schantz S. A. Wise 《Analytical and bioanalytical chemistry》2000,367(5):401-406
The concentrations of three non-ortho (“coplanar”) polychlorinated biphenyls, 3,3′,4,4′-tetrachlorobiphenyl (IUPAC PCB 77), 3,3′,4,4′,5-pentachlorobiphenyl (IUPAC PCB 126), and 3,3′,4,4′,5,5′-hexachlorobiphenyl (IUPAC PCB 169), were determined in five NIST Standard Reference Materials (SRMs) of environmental and biological interest. The measured levels were approximately between (0.2 to 1.3) ng/g in SRM 1588?a (Organics in Cod Liver Oil), (0.3 to 9) ng/g in SRM 1944 (New York/New Jersey Waterway Sediment), (0.2 to 0.4) ng/g in SRM 1945 (Organics in Whale Blubber), ¶(1 to 18) ng/g in SRM 2974 (Organics in Freeze-dried Mussel Tissue [Mytilus edulis]), and (0.1 to 0.4) ng/g ¶in candidate SRM 1946 (Lake Superior Fish Tissue). PCB 169 was present at < 0.1 ng/g in SRMs 1944 and 2974. 相似文献
19.
Barbara R. Hillery James E. Girard Michele M. Schantz Stephen A. Wise 《Journal of separation science》1995,18(2):89-96
A novel p,p-cyanobiphenyl stationary phase (p-cyanobiphenyl, p-allyloxy methylpolysiloxane) has been evaluated for the GC investigation of polychlorinated biphenyls (PCBs). Several PCB congeners which coelute on the phases typically used for PCB analysis (e.g. 5% phenyl methylpolysiloxane) are separated on the p,p-cyanobiphenyl phase, including the hexachlorobiphenyl congeners PCB 163, PCB 164, and PCB 138. In this work, a p,p-cyanobiphenyl stationary phase was used to measure selected PCB congeners in two Standard Reference Materials (SRMs) available from the National Institute of Standards and Technology (NIST), and two Certified Reference Materials (CRMs) available from the Community Bureau of Reference (BCR). The materials analyzed were SRM 1588, Organics in Cod Liver Oil; SRM 1945, Organics in Whale Blubber; CRM 349, Chlorobiphenyls in Cod Liver Oil; and CRM 350, Chlorobiphenyls in Mackerel Oil. Concentrations are reported for several PCB congeners which coelute on the 5% phenyl methylpolysiloxane, including PCB 163 and PCB 164. 相似文献
20.
Manuela Ulberth-Buchgraber Monica Potalivo Andrea Held Annarita Baldan Adriaan M. H. van der Veen Hugo Ent Valnei S. Cunha Romeu J. Daroda Brian Lang Michele Schantz Ruth Hearn Richard J. C. Brown Paul J. Brewer 《Accreditation and quality assurance》2013,18(1):29-39
The results of an interlaboratory comparison, using various measurement methods to carry out biodiesel testing, are presented and the findings are discussed. The interlaboratory comparison was organised within the framework of an EU-funded project called BIOREMA. A general overview of the project and results of an interlaboratory comparison on bioethanol are published as Part 1 and 2 of this series of papers. In the study presented here, reference values, provided by national metrology institutes and expert laboratories, were used for evaluating the results. Consensus values, derived from the results of all participants, were used to assess any bias between the results from the national metrology institutes and testing laboratories. The emphasis in this interlaboratory comparison was not the performance rating of the individual laboratories, but recognising and interpreting differences caused by the measurement methods applied. For most biodiesel parameters, a good agreement of measurement results was found among different methods, and between the consensus and reference values. The study material was a rapeseed oil fatty acid methyl ester, for which it was demonstrated that it is feasible to prepare and characterise reference materials for biodiesel with well-established reference values for many parameters. 相似文献