Cambridge Isotope Laboratories

Numerous deuterated neuroactive steroids are now available from commercial sources (Cambridge Isotope Laboratories Inc, Andover, MA C/D/N/Isotopes Inc., Pointe-Claire, Quebec, Canada Steraloids Inc., Newport, RI). The most useful of these deuterated steroids are those containing two or more nonexchangeable deuteriums, such as the [3a, 7,7- H3]-analogs of DHEA sulfate (O Figure 7-4c) and PREG... 

Additional or different internal standards can be used. Labeled and unlabeled acylcarnitine standards are available from Dr. Herman J. ten Brink, VU University Medical Center, Amsterdam, The Netherlands (http //www.vumc.nl/metabool/in-dex.html) or from Cambridge Isotope Laboratories, Andover, Massachusetts, USA (http //www.isotope.com). 

L-Valine-U-13C5 (Cambridge Isotope Laboratories, CLM-2249) 48 mg is added to a 10-ml volumetric flask, which is then filled to 10 ml with water. 

The following companies supply most of the labeled internal standards used in these studies and potential investigators should review their online catalogues CIL (Cambridge Isotope Laboratories, www.isotope.com) CDN Isotopes (www.cdniso-topes.com) Medical Isotopes (www.medicalisotopes.com), and Isotec (www.sig-maaldrich.com). These manufacturers will undertake custom syntheses. 

All reagents are commercially available. For the gas chromatography approach, isopropylamine may be used as an internal standard [28]. It is dried over granular calcium chloride. TMA is purchased as the hydrochloride salt and TMA N-oxide as the dehydrate (Sigma, UK). TMA and TMA N-oxide are stored in desiccators over silica gel and are heated at 105 C for 2 h prior to use [28]. For head-space mass spectrometry, [2H9]-TMA is purchased from Cambridge Isotope Laboratories (UK) [27]. 

Isotope labeled standards a few aroma volatiles are commercially available from CDN Isotopes and Cambridge Isotope Laboratories (CIL) custom synthesis is available from Aspen Research Laboratories and Aldrich the standards may also be synthesized in-house Purified aroma compounds to be quantified Ester of high GC purity (e.g., methyloctanoate)... 

N-labeled amino acids (Cambridge Isotope Laboratories, Andover, MA)... 

Materials. Sodium dodecylsulfate (SDS) and fully deuterated sodium dodecylsulfate (SDS-d ) were obtained from Sigma and Cambridge Isotope Laboratories respectively, and used as received. The cationic surfactants, dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB), and didodecyldimethylammonium bromide (DDAB) were purchased from Eastman Kodak, and purified by repeated recrystallization from an ethanol/acetone solvent pair. Even so, a small amount of surface active impurity was observed in surface tension plots for DTAC. The tetradecyldimethylamine oxide (C14AO) was a commercial sample (Ammonyx MO) obtained from Stepan (Control No. 533-30027). This sample is primarily C14AO, but also contains other chain length components. Sodium chloride (NaCl) was obtained from EM Science and used as received. Water was purified by a three stage Bamstead water purification system. 

Production, Import/Export, Use, Release, and Disposal. CDDs are not manufactured commercially in the United States except on a laboratory scale for use in chemical and toxicological research (Cambridge Isotope Laboratories 1995). They are produced as undesired by-products during the manufacture of chlorophenols (e.g., PCP and 2,4,5-trichlorophenol) and during combustion processes (IARC 1977 NTP 1989 Podoll et al. 1986). CDDs are ubiquitous in the environment and have been found at low levels (ppt or lower) in air, water, soil, sediment, and foods. Current disposal methods are efficient and are subject to EPA and state regulations. 

Cambridge Isotope Laboratories. 1995. Environmental Contaminant Standards. Andover, Massachusetts. 

The ammonia (NH3 and ND3, with minimum purity of 99.98%) used in these experiments was obtained from Union Carbide and Cambridge Isotope Laboratories. These gases were used without further purification. 

Referenzmaterialien hergestellt durch Cambridge Isotope Laboratories, Woburn, USA... 

Heavy water (2.5 mL at least 95 percent D2O) benzoyl chloride (70 g) ice or Dry Ice and isopropanol liquid nitrogen or a 5-L flask of DCl gas (available from Cambridge Isotope Laboratories, 20 Commerce Way, Woburn, MA 01801, and other suppliers of iso-topically substituted compounds). 

Materials. l NH Cl, l N-Leucine, N-Glycine, N-Valine and l N-Lysine were purchased from Cambridge Isotope Laboratories (Andover, MA). l3c-C6-Glucose and H-dodecylphosphocholine were obtained from Isotec. Inc. (Miamisburg, Ohio). Unlabeled amino acids were obtained from Sigma Chemical Co. (St. Louis, MO)... 

H3, 98%] sodium acetate, [ N, 99%] ammonium chloride, and D2O were obtained from Cambridge Isotope Laboratories. NMR experiments were carried out on a 3-channel Varian Unity 600 spectrometer using a triple-... 

Multiplicities in parentheses. Signals of residual solvent protons. Chemical shift highly dependent on pH and temperature. (Courtesy of Cambridge Isotope Laboratories, Andover, MA) ... 

Labeled amino acides. [DsJ-L-Tryptophan and [DsJ-tryptamin were prepared by the deuterium-exchange method as previously described. [ CsJ-L-Isoleucine and [ N2]-L-arginine were obtained from Cambridge Isotope Laboratories and Spectra Stable Isotopes, respectively. 

L-Arg (guanido- N2, N, >98%) hydrochloride, L-Trp (indole-Ds, D, 98%), and L-Ile (Uniform- Ce, C, 98%) were purchased from Cambridge Isotope Laboratories, Inc. The enrichment of these compounds (>95%) was reconfirmed by MALDI-TOFMS analysis. All other chemicals were of highest grade commercially available. Complete release of luciferin (1) from Vargula by electric stimulation The individuals were put into 10 mL of artificial seawater in a Petri dish, which was equipped with two carbon electrodes (spare lead). In order to release the luciferin completely, AC 30 V was charged to the electrodes for one second repeatedly (20-30 times), until no bioluminescence was observed after the pulse stimulation. Preparation of the formula bait... 

A- Merk, Sharp, Dohme Isotopes, Montreal, Canada B - Cambridge Isotope Laboratories Inc., 50, Frontage Road, Andover, Mass. 01810 5413, USA C - Professor L.N. Mander, Australian National University, Canberra, ACT. Australia D - Apex Organics Ltd., 14, Durham Way, Heathpark Industrial Estate, Honiton EX14 8SQ, Devon, UK. " For abbreviations of cytokinins see Letham and Palni [48]. 

All NMR spectra were recorded quantitatively with a Bruker ARX-500 spectrometer (Bruker, Rheinstetten, Germany) at a frequency of 125 MHz and a 5-mm dual probe. The sample solutions were prepared in deuterochloroform (CDCI3, 99.8% D, Cambridge Isotope Laboratories, Inc., Andover, MA). Standard operating conditions were used with 30° pulse angle, 3 seconds between pulses, and H decoupling. 

Enriched ° Pd (97% ° Pd) standard material for ID was obtained from Cambridge Isotope Laboratories (Woburn, Ma, USA) and dissolved in aqua regia (HChHNOa, 3 1). 

Materials. NMR solvents tetrahydrofuran-ds (THF-dg), D2O, and chloroform-d (CDCI3) were obtained from Cambridge Isotope Laboratories. Lithium trifluoromethanesulfonate (LiOTf) was purchased from Aldrich Chemical Co. and used as r eived. The two isotopically labels polyphosphazenes... 

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