Authors:Débora Arruda Frommenwiler, Valeria Maire-Widmer, Roy Upton, Judith Nichols, Günther Heubl, and Eike Reich
The herbal drug licorice root may be derived from the plant species Glycyrrhiza glabra L., Glycyrrhiza uralensis Fisch, and/or Glycyrrhiza inflata Bat. which are morphologically, chemically, pharma-cologically, and toxicologically similar. However, if an ingredient of a dietary supplement is identified as a certain species and labeled as such on the product, appropriate analytical methodologies are required to assure the authenticity. Using high-performance thin-layer chromatography (HPTLC), we were able to distinguish clearly between G. glabra and G. uralensis, the most commonly used species, which allowed us to check the corresponding label claims of twenty-six dietary supplements. Two samples of G. inflata Bat., which were available for the study, were not distinguished from G. glabra by this method. Our investigation revealed that five of the twenty-eight samples made a wrong label claim. The HPTLC results were confirmed by deoxyribonucleic acid (DNA) barcoding. For the quantitative analysis of the marker 18β-glycyrrhizic acid in licorice root, we modified our HPTLC method for base-line separation of the peaks which guaranteed accurate results. Moreover, the new method is also capable to identify and distinguish both species of licorice. The quantitative HPTLC results were in accordance with the data obtained by high-performance liquid chromatography (HPLC) following the United States Pharmacopeia (USP) method on licorice root. In addition, we used two DNA candidate barcodes (internal transcribed spacer [ITS] and psbA‒trnH intergenic spacer) for species identification.
Authors:K. Inn, Zhichao Lin, Zhongyu Wu, C. McMahon, J. Filliben, P. Krey, M. Feiner, Chung-King Liu, R. Holloway, J. Harvey, I. Larsen, T. Beasley, C. Huh, S. Morton, D. McCurdy, P. Germain, J. Handl, M. Yamamoto, B. Warren, T. Bates, A. Holms, B. Harvey, D. Popplewell, M. Woods, S. Jerome, K. Odell, P. Young, and I. Croudace
In 1977, the Low-level Working Group of the International Committee on Radionuclide Metrology met in Boston, MA (USA) to define the characteristics of a new set of environmental radioactivity reference materials. These reference materials were to provide the radiochemist with the same analytical challenges faced when assaying environmental samples. It was decided that radionuclide bearing natural materials should be collected from sites where there had been sufficient time for natural processes to redistribute the various chemically different species of the radionuclides. Over the succeeding years, the National Institute of Standards and Technology (NIST), in cooperation with other highly experienced laboratories, certified and issued a number of these as low-level radioactivity Standard Reference Materials (SRMs) for fission and activation product and actinide concentrations. The experience of certifying these SRMs has given NIST the opportunity to compare radioanalytical methods and learn of their limitations. NIST convened an international workshop in 1994 to define the natural-matrix radionuclide SRM needs for ocean studies. The highest priorities proposed at the workshop were for sediment, shellfish, seaweed, fish flesh and water matrix SRMs certified for mBq per sample concentrations of 90 Sr, 137 Cs and 239 Pu + 240 Pu. The most recent low-level environmental radionuclide SRM issued by NIST, Ocean Sediment (SRM 4357) has certified and uncertified values for the following 22 radionuclides: 40 K, 90 Sr, 129 I, 137 Cs, 155 Eu, 210 Pb, 210 Po, 212 Pb, 214 Bi, 226 Ra, 228 Ra, 228 Th, 230 Th, 232 Th, 234 U, 235 U, 237 Np, 238 U, 238 Pu, 239 Pu + 240 Pu, and 241 Am. The uncertainties for a number of the certified radionuclides are non-symmetrical and relatively large because of the non-normal distribution of reported values. NIST is continuing its efforts to provide the ocean studies community with additional natural matrix radionuclide SRMs. The freeze-dried shellfish flesh matrix has been prepared and recently sent to participating laboratories for analysis and we anticipate receiving radioanalytical results in 2000. The research and development work at NIST produce well characterized SRMs that provide the world's environment-studies community with an important foundation component for radionuclide metrology.
Authors:Yuanyou Yang, Rushan Lin, Ning Liu, Jiali Liao, Min Wei, and Jiannan Jin
With 2,3,5,6-tetrafluorophenyl 3-(nodo-carboranyl) propionate (TCP) as a new potential bi-functional linker, bovine serum albumin (BSA) was conjugated with 211At, and the conjugated model protein (211At-TCP-BSA) was preliminarily evaluated in vitro and in vivo by comparison with 211At-SAB-BSA and 211At-SAPC-BSA, which conjugated with 211At via aryl derivatives ATE (N-succinimidyl-3-(tri-n-butylstannyl) benzoate) or SPC (N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate). The radiolabeled intermediate 211At-TCP was coupled to BSA in yields ranging from 35 to 45% with radiochemical purity of more than 98%. The conjugated 211At-TCP-BSA exhibited considerable stability in vitro in 0.1 mol/L PBS (pH 7.6) at room temperature (RT), similar to 211At-SAPC-BSA and 211At-SAB-BSA. Biodistribution of the 211At conjugated protein was investigated in NIH strain mice by I.V injection. The results showed that 211At-TCP-BSA was constantly stable in vivo as well as in vitro, but more stable than 211At-SAPC-BSA and 211At-SAB-BSA. These results implied that radioastatinated carboranes based on B–At bonds are higher stability than radioastatinated
aryl derivatives based on C–At to in vivo deastatination. In other word, TCP should be a promising bi-functional linker for
211At conjugation of proteins or antibodies.
A theoretical approach has been used to show that, except for certain types of reaction mechanism, the ease with which it
is possible to distinguish the form of the reaction mechanism by the reduced-time plot method depends particularly on the
rate of transfer of heat into the sample. The original reduced-time plots  were calculated from model equatioons which
assume that the sample is, from the outset, at a fixed temperature and remains under isothermal conditions throughout the
reaction. The variations produced in the appearance of reduced-time plots when the sample is programmed to rise to a given
fixed temperature through various temperature schedules have been investigated. It is shown that even relatively rapid temperature
rises can produce distortion of the reduced-time plots for various reaction equations. If the reaction mechanism is known,
however, fairly accurate values of the activation energy for the reaction can be determined, even when the furnace used has
relatively poor heat-transfer characteristics.