Confirmation of phenylbutazone residues in bovine kidney by liquid chromatography/mass spectrometry

A confirmatory method is described for phenylbutazone (PB) residues in bovine kidney tissue. Ground kidney tissue is diluted with water, and the mixture is made basic with 25% ammonium hydroxide in water; the lipids are extracted with ethyl and petroleum ethers. The ether layer is discarded, and the tissue is acidified with 6N HCl. PB residues are extracted with tetrahydrofuranhexane (1 + 4). The extract is passed through a silica solid-phase extraction column, and the eluate is evaporated to dryness. The residue is dissolved in acidified acetonitrile-water-acetic acid (50 + 49.4 + 0.6). A single quadrupole mass spectrometer coupled to a liquid chromatograph with an electrospray interface is used to confirm the identity of the PB residues in the kidney extract. Negative-ion detection with selected-ion monitoring of 4 ions is used. Sets of control and fortified-control kidney tissues (at 50, 100, and 200 ppb PB) and several kidney tissue field samples were analyzed for method validation. The method was tested further during the course of a survey to determine the incidence of PB residues in bovine kidney samples obtained from slaughterhouses across the country. In addition, the method was tested for use with an ion-trap mass spectrometer coupled to a liquid chromatograph, which allowed confirmation of PB at lower levels (5-10 ppb) in kidney tissue.     

On assignment of fundamental vibrational modes of hypophosphite anion and its deuterated analogue

Results of ab initio and density functional theory calculations on the structure and vibrational frequencies of hypophosphite anion indicate earlier experimental assignments of the fundamental vibrational modes are correct while the recent reassignments of several modes proposed by Bickley et al. are inconsistent with the calculated results.     

Service oxygen analyses with 14 mev neutrons at iowa state university

A 14 MeV neutron activation analysis system is described that is being used primarily to determine trace levels of oxygen in metals. No sample container is required for relatively inert solid metal samples thus increasing the sensitivity of the method by a factor of five. Under these conditions the sensitivity and precision foroxygen is about 6±3.3 μg in a single determination, resulting from collecting 1.2¹⁶N counts per μg of oxygen. A method is described for calibrating the system for the analyses of large metal samples. The preparation and use of sample containers for the analyses of particulate and/or reactive samples is also presented. Work was performed at the Ames Laboratory of the U.S. Atomic Energy Commission. Contribution No. 2567.     

Chemical reactions of double bonds in activated carbon: microwave and bromination methods

The reaction of localised C[double bond, length as m-dash]C bonds on the surface of activated carbons has been shown to be an effective method of chemical modification especially using microwave-assisted reactions.     

Esca applied to polymers. XXIII. RF glow discharge modification of polymers in pure oxygen and helium–oxygen mixtures

The oxidation of polyethylene, polypropylene, and polystyrene by exposure to plasmas excited in pure oxygen and helium–oxygen mixtures at low power levels has been studied. A detailed curve resolution procedure is outlined, and the rate of oxidation is shown to be a strong function of the polymer structure for pure oxygen plasmas, as is the composition of the oxidized layer; this is not the case, however, for oxidation effected by helium–oxygen mixtures. It seems likely, from a consideration of the available data, that the oxidation is confined to the outermost monolayer and is initiated by a crosslinking mechanism that involves oxygen-containing functionalities.     

Direct observation of insertion events at rac-(C2H4(1-indenyl)2)Zr(MeB(C6F5)3)-polymeryl intermediates: distinction between continuous and intermittent propagation modes

The propagating species for 1-hexene, propene, and ethene polymerization as catalyzed by [rac-(C2H4(1-indenyl)2)Zr(CH3)][CH3B(C6F5)3] has been intercepted at T < -40 degrees C and characterized by NMR methods. Observation of the propagating species permits direct monitoring of initiation, propagation, and termination processes by NMR. Detailed examination of alkene incorporation into Zr-polymeryl species using 13C-labeled 1-alkenes supports a continuous insertion mechanism whereby the anion re-coordinates after each alkene insertion.     

Macrocycles in the construction of acyclic stereochemistry

The conformations of macrocyclic intermediates provide a useful medium through which distant chiral centers may control chemical reactions. In this paper, we show that macrocycles made by cyclization of simple acyclic starting materials with an auxiliary spacer may be used to prepare stereochemically complex acyclic products.     

GC-MS identification of amine-solvent condensation products formed during analysis of drugs of abuse.

The use of methanol or ethanol as the injection solvent for the gas chromatographic-mass spectral (GC-MS) analysis of low molecular weight amine drugs of abuse results in the formation of additional components in the sample. Primary amines, such as amphetamine, 3,4-methylenedioxyamphetamine, and phenethylamine, yield imines upon injection as methanol or ethanol solutions. In methanol, the imine formed has a mass that is 12 mass units higher than the parent compound. In ethanol, the products formed have 26 additional mass units. Secondary amines appear to undergo methylation under similar conditions with methanol as the injection solvent. These products are absent from the analysis of equivalent amine samples dissolved in chloroform.     

ESCA study of the surface photo-oxidation of some non-aromatic polymers

Changes in the surface composition and structure of a number of non-aromatic polymers subjected to ultraviolet irradiation in oxygen (～ 1 atm., 20°C) have been studied. No changes in surface composition were detected after photo-oxidation of poly(vinylidene fluoride) (12 h of irradiation), low density polyethylene (7·5 h) or high density polyethylene (22·3 h). This reflects the absence in these polymers of an efficient ultraviolet absorber to initiate the photo-oxidation. The surfaces of poly(methyl methacrylate) and nylon 66 show an increase in oxygen content following irradiation. In these polymers this added oxygen is present principally as carboxyl groups and, in the case of poly(methyl methacrylate), as carbonyl groups. In nylon, there is no evidence for changes in the amide group and no oxidation of the nitrogen is detected.