4- Toluidine sample preparation

To verify the quenching interaction between the Re-complex and the di-methyl-/7-toluidine, a Stem-Volmer plot of the results of a concentration dependent study of Re-complex fluorescence intensity as a function of amine concentration in fluid MMA was prepared (Figure 3). The samples contained 1.6 X IQ- mol Re-complex, and up to a maximum of 2.6 X 10 mol of amine, in —2.5 g of MMA. Re-complex CT band peak heights at 612 nm were measured from uncorrected fluorescence spectra taken in single scans following excitation at 350 nm. The Stern-Volmer plot is linear over the range of amine concentrations studied. A linear Stem-Volmer plot. 

The NTP has a study in progress on "Aryl Amine Adducts in Blood as Indicators of Exposure" (NTP 1991a). In this study, blood samples from 100 workers will be analyzed for hemoglobin o-toluidine adducts. MBOCA will be used to develop an HPLC method for separation and isolation of mitochondrial or total aryl amine-DNA adducts. In addition, the in vitro activation of potential carcinogens will be studied, and a mathematical model for MBOCA distribution, metabolism, and adduct formation will be prepared. The overall objective of the project is to develop a more sensitive adduct isolation procedure to be used for biological monitoring. The contact person for this is K. Cheever(NTP 1991a). 

The catalysts used in the present study were prepared from anunonium tetrathiotungstate (ATT), containing 10 wt% tungsten. The content of fluorine in the fluorinated catalyst was 1 wt%. Details of the catalyst preparation can be found elsewhere [2]. The HDN reactions were carried out in a continuous-flow microreactor. 0.4 to 1.2 g of the catalyst sample diluted with 8 g SiC was sulfided in situ with a mixture of H2S (10 mol%) and H2 (90 mol%) at 400°C and 1.5 MPa for 4 h. After sulfidation the temperature was cooled to 370°C, the pressure was increased to 3.0 MPa, and the liquid feed was introduced to the reactor by means of a high-pressure pump, with n-octane as the solvent and n-hqjtane as internal standard. Dimethyldisulfide was added to the feed to generate H2S (6 kPa) in the reaction stream. The partial pressure of o-toluidine varied fipom 1 to 9 kPa. 

Nuttall and Bush (102) described a TLC chromatographic method for the analysis of multivitamin preparations. After extraction of fat-soluble vitamins, water-soluble vitamins and water-soluble materials were separated in three TLC systems. Biotin was resolved with acetone-acetic acid-benzene-methanol (1 1 14 4) as solvent and visualized by spraying o-toluidine-potassium iodide. Standards can be included if quantitative results are required. However, the reproducibility of the technique has not been tested. Groningsson and Jansson (105) worked out a TLC method for the determination of biotin in the presence of other water-soluble vitamins. After dissolution of the lyophilized preparation and addition of the internal standard (2-imidazolidone), the sample was applied on a silicagel plate and eluted with chloroform-methanol-formic acid (70 40 2). Biotin was visualized by spraying with p-DACA and determined in situ by reflectance measurements. The sensitivity of the method could be increased by spraying with paraffin after the coloring procedure. LFnder these conditions the detection limit was 10 ng. 

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