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The purpose of the current study was to develop a LC-MSnmethod for the analysis of pyrrolizidine alkaloids PAs in comfrey. Published data presents an extensive list of PAs and their N-oxides present in comfrey. However, standards are not commercially available for any of the PAs typically present in comfrey. Those PAs that are not stereoisomers were readily resolved on a C18column using a water–acetonitrile gradient as the mobile phase. The use of a selective technique, LC-MSMS, allowed us to identify groups of PAs and their N-oxides, as well as identify the number of PAs present in each group, including those that were not completely resolved chromatographically.

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mm Na2b4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.

A He/Ar mixed-gas plasma has been investigated as an optical emission source for the determination of iodine at 2063 Angstroms. The effects of adding varying amounts of He to an argon plasma were studied. Optimal conditions were found with a total plasma composition of 34% helium. The auxiliary gas was 100% argon, whereas the carrier gas and the coolant gas were composed of 88% and 35% He, respectively. The mixed-gas plasma reduced the detection limit for iodine to 0.4 ppm, a sevenfold improvement over the detection limit obtained with a 100% Ar plasma. At the optimum conditions for iodine, detection limits for most other elements studied improved or stayed the same.

The metal profiles characterizing stack emissions, fly ashes and coals of three coal-fired power plants in the United States using one high-sulfur Eastern and two low-sulfur Western coals were obtained by quantitating 21 elements via inductively coupled plasma atomic emission spectroscopy. The stack emissions were collected with a modified sampling train approved by the U.S. EPA. Aluminum, calcium, iron, sodium, potassium and magnesium predominated in all the samples and the emission was greatest from the high sulfur coal. Silicon could not be accurately quantitated because of the digestion procedure used. Volatile elements were lead, zinc, beryllium and molybdenum. Chemical speciation in stack emissions was shown to be important by atypical collection for Pb, Bi, Be, Na, Cu and Zn in the three impingers of the sampling train.

The initial nutritional status of experimental animals can influence their response to subsequent dietary regimens. In the present study, we determined the variations in minerals in diet NIH-31, a breeding colony stock diet, and in tissues of weanling rats nursed by dams fed this diet. Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine nine elements (Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) in diet and in liver, kidney, spleen, duodenum and femur from 22- to 26-day-old rats. Wet digestions were performed in mixtures of nitric, perchloric, and sulfuric acids (diets and soft tissues) or nitric and perchloric acids (femur). Solution concentrations ranged from <25 ng/ml for the trace elements to >100 µg/ml for the major elements. Large variations in mineral content were found between batches of commercially prepared NIH-31 diet; relative amounts of Cu, Fe, Mn and Zn varied markedly. Significant differences in concentrations of major and trace minerals in liver, kidney, spleen and duodenal tissue were found among groups of weanling rats obtained from the same supplier at different times. Mn was readily quantitated in all tissues except spleen, where it was below detection limits. The precision obtained with the ICP-AES methodology has significant advantages for establishing variations in tissue mineral levels.

Standardized purified diets limited to required nutrients are needed for nutritional and toxicological studies. In the present study, we formulated a biotin- and cellulose-free diet of reproducible mineral composition (diet A), based on diet AIN-76, and fed it to weanling Long-Evans rats for 3 wk. Inductively coupled argon plasma atomic emission spectrometry was used to determine Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn in liver, duodenum, kidney, spleen and femur. Results were compared with those obtained with rats fed biotin- and/or cellulose-supplemented variations of diet A, diet AIN-76 and diet NIH-31 (an open-formula stock diet). Weanling rats grew slowly and steadily on purified diet A. Growth rates increased when diet A was supplemented with biotin and cellulose. In general, differences among tissue mineral levels in rats fed diet NIH-31 and those fed diet AIN-76 were more pronounced than those among groups fed our purified diets. Values for hemoglobin and hematocrit were significantly lower in rats fed all purified diets than in those fed diet NIH-31. Diets A + biotin, A + cellulose and A + cellulose + biotin appear satisfactory as reference diets for measuring mineral interactions at near-requirement levels as well as effects of fiber on mineral utilization or for studies on vitamins whose endogenous synthesis may be influenced by dietary fiber.

Commercial moist snuff products are used by placing a portion of tobacco inside the mouth between the inner cheek or lip and gum. Nicotine is absorbed into the blood stream via transfer across various oral membranes including the buccal mucosa (cheek lining). The resulting salivary pH when a given moist snuff product is placed in the mouth is an important factor for nicotine absorption because it will affect the proportion of free base nicotine that is readily available for absorption. The resulting salivary pH for a given moist snuff product will be determined in part by the relative acid-base buffering capacities of the saliva and moist snuff, as well as the pHs of the saliva and moist snuff prior to coming in contact with one another. In the current study, the acid-base buffering capacities (µeq/g) of a series of commercial moist snuff products were determined and compared to the acid-base buffering capacity for unstimulated, whole human saliva. The buffering capacities of the moist snuff products were determined to be 10–20 times higher than the buffering capacity of human saliva. The resulting salivary pH ranges after contact between an artifical saliva and the various moist snuff products were also determined; the results were used to predict the proportion of free base nicotine that can be expected to occur in the mouth during the first few minutes of product use. These studies provide a basis for examining and understanding the effects that moist snuff product pHs and buffering capacities may be expected to have on nicotine absorption.