Journal of research of the National Bureau of Standards最新文献

{"title":"Trace Element Speciation in Food: A Combined Enzymolysis—SEC-ICP-MS Approach","authors":"H. Crews, R. Massey, D. J. Mcweeny, J. Dean","doi":"10.6028/jres.093.072","DOIUrl":"https://doi.org/10.6028/jres.093.072","url":null,"abstract":"Trace elements in food can be either desirable, tolerable or undesirable. They occur in the diet as natural constituents of agricultural produce, as deliberate additives and as contaminants from environmental and processing sources. Historically, their significance to man has been assessed on the basis of total concentration of the element in the food item-or the total amount in the diet as a whole (with the exception of the measurement of mercury and to a lesser extent arsenic where specific forms are sometimes measured). In recent years the inadequacy of simply measuring the total concentration has been increasingly appreciated and efforts to provide information which is targeted more accurately to the needs of the nutritionist and the toxicologist are now being made. Over the last few years, the MAFF Food Science Laboratory has had a small programme investigating ways of obtaining more meaningful information about the chemical forms of trace elements in food. As a first stage of a general approach to the problem, attention has been restricted to species which are soluble at around neutral pH after treatment with normal monogastric mammalian digestive enzymes. A procedure has been developed in which food is treated sequentially with pepsin at around pH 2 and with pancreatic enzymes at around pH 7 at 37 'C. A limitation of this procedure is that it is a \"static\" system, whereas absorption is dynamic; if there is equilibrium between soluble and insoluble species, the system will underestimate the amount which is potentially available biologically. In some very simple experiments, food composites representing the cereal, meat, fish and green vegetable components of the UK diet were examined with and without the addition of small amounts of copper, zinc, cadmium and lead as inorganic salts. The properties of the endogenous element which was soluble after enzyme treatment has been compared with that of the added element. For all the foods studied, endogenous and added copper behaved similarly, but there were marked differences for some of the other elements. For instance, zinc from fish is largely insoluble, and added zinc also becomes insoluble; other foods release much zinc in soluble form. On the other hand, iron from meat is largely soluble but added iron becomes insoluble [1]. This investigation has been developed further in studies of the effect of one food upon the release of trace elements from another. The amount of acidsoluble cadmium available from crab meat is reduced by 75% by digesting it along with wholemeal bread; white bread has very little effect. Similar experiments show that addition of 10% soya to ground beef gives a much lower release of zinc from the beef-presumably a soya phytate effect. Processing of beef can affect the solubility of iron; inorganic iron as taken in dietary supplements is much more soluble if digested along with cereals and vegetables than with meat and fish [2]. The broad conclusions of these experiments we","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"349 - 350"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applications of the reaction interface mass-spectrometer technique to the analysis of selected elements and nuclides from submicrogram quantities of biological macromolecules and xenobiotics","authors":"D. Chace, F. Abramson","doi":"10.6028/JRES.093.101","DOIUrl":"https://doi.org/10.6028/JRES.093.101","url":null,"abstract":"Markey and Abramson [1] developed a microwave-powered chemical reaction interface, a device which converts a complex organic molecule in the presence of a reactant gas into small stable molecules which are detected by mass spectrometry. For a given reactant gas the molecules formed are a representation of the elemental composition of the original anlayte. The combination of the reaction interface and a mass spectrometer produces an isotopeor element-selective detector for samples either introduced directly into the reaction interface or flowing from a capillary gas chromatograph column. Microgram and submicrogram samples of a variety of proteins were analyzed for their sulfur content relative to their carbon content by introducing the samples directly into the reaction interface. With CO, as the reactant gas, S02 at m/z 64 is produced. This quantifies the amount of sulfur which was introduced into the reaction interface. In the presence of N2, HCN at m/z 27 is produced and is used to quantify the carbon content of the sample. The observed ratio of S/C for various proteins correlated well with the elemental formulas [2]. In the presence of S02, 4NO at m Iz 30 and 5NO at m/z 31 are produced. Following administration of 50 mg of triple-labeled 5,5-diphenylhydantoin (1, 3(\"N); 2('C)] to a male beagle dog, a urine sample was selectively analyzed for its 15N content by capillary gas chromatography-reaction interface/ mass spectrometry. The corrected ratio of m/z 31 to m/z 30 produced a highly selective chromatogram showing only peaks of '5N enrichment. Mass spectra of these peaks were obtained which Alkylation of DNA In Vivo: Development of Analytical Methodology for Trace Quantitative Analysis","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"419"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Applications of Lasers in Bioanalytical Chemistry","authors":"E. Yeung","doi":"10.6028/jres.093.136","DOIUrl":"https://doi.org/10.6028/jres.093.136","url":null,"abstract":"Lasers have grown from being an exotic device in the research laboratory to become an important part of practical bioanalytical instrumentation. Laser-excited fluorescence offers extremely high sensitivity for the detection of trace components in ultramicro environments. This has led to a new generation of cellular and subcellular probes for the biochemical and the clinical laboratory. Examples of upcoming technologies that are relevant to medicine and biotechnology are presented, including (1) high-speed DNA mapping and sequencing, where the analysis time is decreased by 1000× and where the accuracy is improved substantially; (2) the detection of various intracellullar enzymes in blood cells, providing information about aging and carcinogenesis; (3) the characterization of individual enzyme molecules, showing how protein folding and refolding can lead to different activities among a population of otherwise identical molecules; (4) the measurement of zeptomole quantities of antigens, paving the way for early diagnosis of diseases; and (5) the monitoring of trace impurities in biopharmaceuticals, potentially leading to new standards for quality control in their production. New types of lasers optimized for these applications will therefore have significant market potential.","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"502 - 504"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accuracy in Quantitative Electron Probe Microanalysis","authors":"K. Heinrich","doi":"10.6028/jres.093.139","DOIUrl":"https://doi.org/10.6028/jres.093.139","url":null,"abstract":"Electron probe microanalysis (EPMA) is based on the interpretation of x-ray spectra emitted by specimens which were exposed to a focused, accelerated electron beam. One of the attractions of this technique is the simplicity of the x-ray emission line spectra which is particularly striking if we do not pay attention to the fine details of x-ray spectrometry such as line position and shape changes with chemical composition or the extended structure of absorption edges. In close analogy, the inventor of EPMA, R. Castaing, found in early investigations that quite simple approximations to quantitation with this technique could yield results of remarkable analytical accuracy, considering the state of art of instrumentation at that time, and the small volumes from which the compositional analysis was elicited [1]. While Castaing favored a simple approach based on physical principles, Ziebold and Ogilvie [2] chose an empirical technique based on the use of composite standard materials; again, a pleasing simplicity was observed, and the empirical method is still widely used, particularly in the analysis of minerals. As experience and areas of applications widened, it became obvious that to increase the accuracy of the procedure, some of this apparent simplicity had to be abandoned. Fortunately, the availability of small computers permitted the on-line execution of more involved data reduction schemes; larger computers could be used in Monte Carlo simulations of the events in the target [3], and the quality of estimates of pertinent parameters, such as the x-ray absorption coefficients, was also improved [4]. The x-ray line spectra observed in EPMA are caused by electrons which penetrate the specimen surface with energies which typically range between 5 and 30 keV. In the typical flat, thick specimen, most of the electron paths are contained within a homogeneous specimen matrix. The penetrating electrons lose energy due to inelastic interactions which usually are treated as a continuous process and described by Bethe's law of electron deceleration or by expressions related to this law [4]. The direction of the penetrating electron is altered mainly due to inelastic collisions; the scattering of electrons causes a significant number of electrons to be re-emitted from the specimen (backscattering), and the fraction of electrons which are backscattered depends strongly on the mean atomic number of the target. The backscattered electrons conserve most of the energy they had when entering the specimen; therefore, a significant fraction of the energy which would otherwise cause x-ray emission is lost through backscattering, and the loss varies strongly with specimen composition. A small fraction of electron-target interactions, described by ionization cross-sections produces xrays, and the x-ray emission directed toward the specimen surface suffers attenuation which is determined by the distribution in depth of the loci of excitation and by the x-ray absorption ","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"509 - 510"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Compositional Mapping on a Micrometer Scale","authors":"D. Newbury","doi":"10.6028/jres.093.141","DOIUrl":"https://doi.org/10.6028/jres.093.141","url":null,"abstract":"[38] Stevie, F. A., Kahora, P. M., Singh, S., and Kroko, L., Atomic and Molecular Relative Secondary Ion Yields of 46 Elements in Si for 0?and Cs' Bombardment, Proceedings of SIMS VI Conference, Versailles, 1987, J. Wiley, Chichester, in press. [39] Wilson, R. G. and Novak, S. W., Systematics of SIMS Relative Sensitivity Factors versus Electron Affinity and Ionization Potential for Si, Ge, GaAs, GaP, InP and HgCdTe Determined from Implant Calibration Standards for about 50 Elements, Proceedings of the SIMS VI Conference, Versailles, 1987, J. Wiley, Chichester, in press.","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"518 - 520"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Determination of Trace Elements in Uranium Oxide (U3O8) by Inductively Coupled Plasma Emission Spectrometry and Graphite Furnace Atomic Absorption Spectrometry","authors":"P. Santoliquido","doi":"10.6028/jres.093.116","DOIUrl":"https://doi.org/10.6028/jres.093.116","url":null,"abstract":"[1] Shan Xiao-quan, Ni Zhe-ming, and Zhang Li, At. Spectrosc. 5, 1 (1984). [2] Shan Xiao-quan, Ni Zhe-ming, and Zhang Li, Talanta 31, 150 (1984). [3] Shan Xiao-quan, and Hu Kaijin, Talanta 32, 23 (1985). [4] Shan Xiao-quan, and Wang Dian-Xun, Anal. Chim. Acta 173, 315 (1985). [5] Liu Ping, Keiichiro Fuwa, and Kazuko Matsumoto, Anal. Chim. Acta 171, 279 (1985). [6] Schlemmer, G., and Welz, B., Poster 077, presented at Colloquium Spectroscopicum Internationale XXIV, Garmisch-Partenkirchen, FRG, September (1985). [7] Niskavaara, H., Virtasalo, J., and Lajunen, L., Spectrochim. Acta, Part B 40, 1219 (1985). [8] Voth-Beach, L., and Shrader, D., Spectroscopy 1(10), 49 (1986). [9] Voth-Beach, L., and Shrader, D., Jour. of Anal..At. Spect. 2, 45 (1987). [10] Grobenski, Z., Erler, W., and Voellkopf, U., At. Spectrosc. 6, 91 (1985). The Determination of Trace Elements in Uranium Oxide (U30d by Inductively Coupled Plasma Emission Spectrometry and Graphite Furnace Atomic Absorption Spectrometry","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"37 1","pages":"452 - 454"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71363011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accuracy in Analysis: The Role of Standard Reference Materials","authors":"S. Rasberry","doi":"10.6028/jres.093.020","DOIUrl":"https://doi.org/10.6028/jres.093.020","url":null,"abstract":"Probably it is the last of these questions that brings the greatest difficulty and the most soul searching to the analyst. If this were not the case, why are there so many cars in chemistry building parking lots on weekends and holidays? Why are analysts often reluctant to report results without \"just one more retest\"? This paper will attempt to pick apart some of these questions. While it may answer none of them conclusively, it is aimed at demonstrating the role of Standard Reference Materials (SRMs) in the analyst's pursuit of accuracy. In the case of trace analysis near the detection limit of state-of-the-art methods, certifiers of reference materials face a very special problem: certified error limits often seem unacceptably high when considered on a relative basis. This paper will include a brief discussion of this problem.","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"213 - 216"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71361738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Importance of Quality Assurance in Trace Analysis","authors":"J. K. Taylor","doi":"10.6028/jres.093.026","DOIUrl":"https://doi.org/10.6028/jres.093.026","url":null,"abstract":"Materials and Natural Waters by Evaluating and Controlling the Extent and Sources of Industrial Lead Contamination Introduced During Sample Collecting, Handling, and Analysis, in Accuracy in Trace Analysis: Sampling, Sample Handling, Analysis, LaFleur, P. D., Ed., U.S. Government Printing Office: Washington, DC (1976) 321-351. (6] Kelly, W, R., and Fassett, J. D., Anal. Chem. 55, 1040 (1983). [7] Kelly, W. R., Fassett, J. D., and Hotes, S. A., Health Phys. 52, 331 (1987).","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"232 - 234"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71361796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Computer Assisted Pesticide and PCB Identification System (CAPPIS)","authors":"J. Dierkes","doi":"10.6028/jres.093.052","DOIUrl":"https://doi.org/10.6028/jres.093.052","url":null,"abstract":"[I] Wang, J., Envir. Sci. Technol. 16, 104A (1982); Stripping Analysis, VCH Publishers, Inc., Deerfield Beach, FL (1985) Chap. 1. [2] Zirino, A., Voltammetry of Natural Sea Water, in Marine Electrochemistry, M. Whitfield and D. Jagner, eds., John Wiley and Sons, New York (1981) Chap. 10. [3] Czae, M.-Z., and Lee, J.-H., Bull. Envir. Sci. (Hanyang Univ., Seoul, Korea) 6, 153 (1985). (4] Kim, E., Czae, M.-Z., et al., Studies on the Effect of Cooling Water to the Cultivated Marine Organism around Poryung and Samchunpo Power Plants, Part I and 11, KRC-84C-J01, Korea Electric Corp., Seoul, March 1985. [5] Ben-Yaakov, S., and Lazar, B., Talanta 27, 1061 (1980). (6] Lee, J.-H., Autoranging Amplifier for the Simultaneous Determination of Some Trace Metals in Seawater by DPASV. Thesis (MS), Hanyang University, Seoul, Korea. [7] Czae, M.-Z., Lee, J.-H., and Hong, T., Validation of Anodic Stripping Voltammetry for Determination of Some Metals in Sea Samples, Proc. First Korea-Japan Joint Symp. on Anal. Chem. (Korean Chem. Soc.), Seoul, Korea (April 1985) 27-36.","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"298 - 299"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Accurate Measurement of Vitamins in Foods and Tissues","authors":"J. Thompson","doi":"10.6028/jres.093.077","DOIUrl":"https://doi.org/10.6028/jres.093.077","url":null,"abstract":"Besides the inorganic constituents, phytate was also determined in the dry material, and was found to contain an initial level of 1.4±0.2 mg/g [3]. The storage stability of this constituent is being investigated. This preliminary investigation has demonstrated the feasibility of exploring a total mixed diet matrix for certification as a multicomponent Standard Reference Material (SRM). A bigger batch of a second mixed total diet is under investigation as part of a systematic study to evaluate the stability of several components over a period of at least 3-5 years. The experience gained from this investigation has helped in understanding some of the practical difficulties faced in the preparation of a natural biological reference matrix for multiple components, especially organic constituents. The authors are thankful to John Jones and Kathleen Cook (FDA) and Robert Watters (NBS) for elemental analysis, Michele Schantz (NBS) for organic analysis, and Eugene Morris (USDA) for phytate analysis.","PeriodicalId":17082,"journal":{"name":"Journal of research of the National Bureau of Standards","volume":"93 1","pages":"362 - 364"},"PeriodicalIF":0.0,"publicationDate":"1988-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71362237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}