Acetonitrile deuterated

The cartridge was preconditioned with 0.5 mL toluene and each of the above benzodiazepine solutions passed through it. Analytes retained on the MIP were eluted with 0.5 mL of 15% acetic acid in acetonitrile. Internal standard (corresponding deuterated benzodiazepine) was added and subjected to LC/MS/MS. The results obtained for recovery, limit of detection (LOD), and quantitation (LOQ) are shown in Table 1.22. The binding capacity of diazepam to the templated MIP was found to be 110 ng/mg polymer. The same results were obtained for postmortem hair samples. 

The formation of N,iV -dialkyl-4,4 -bipyridine cation-radical proceeds through the reduction of the corresponding dication (alkylviologen) by tributylphosphine. Yasui et al. (2001) measured the reaction kinetics in the acetonitrile-methanol mixture. The rate of cation-radical formation decreases in all of the cases when the alkyl groups are deuterated. 

When the addition is carried out in acetonitrile-dj, mono and di-deuterated [l-i F]l,l,l,2-tetrafluoroethanes are obtained, suggesting that the solvent acts as a source of protons. This reaction was the first demonstration of an efficient addition of [ F]fluoride to a fluoro-olefin it achieves the equivalent of the addition of hydrogen [ F] fluoride. 

The increased solvent requirements for LC-NMR over tube NMR make the technique expensive if fully deuterated solvents are used. D2O is usually substituted for H2O in the eluent, mainly because of its low cost ( 150 per 1), but also because it provides a lock solvent for the NMR. Fully deuterated organic modifiers such as 3-acetonitrile may not be absolutely required, but in practice they are often also used in many pharmaceutical laboratories as they give reduced solvent signals. This reduces the need for solvent suppression, which lessens the risk that diagnostic resonances are also suppressed in error. 

Within the IR spectroscopy arena, the most frequently used techniques are transmission-absorption, diffuse reflectance, ATR, specular reflectance, and photoacoustic spectroscopy. A typical in situ IR system is shown in Fig. 7. Choosing appropriate probe molecules is important because it will influence the obtained characteristics of the probed solid and the observed structure-activity relationship. Thus, the probe molecules cover a range from the very common to the very rare, in order to elucidate the effect of different surfaces to very specific compounds e.g. heavy water and deuter-ated acetonitrile, CDsCN). The design of the IR cell is extremely important and chosen to suit the purposes of each particular study. For catalytic reactions, the exposure of catalytic metals must be eliminated in cell construction, otherwise the observed effect of the catalyst may not be accurate. 

A different approach was followed by Blanchflower et al. (23) in a liquid chromatographic-mass spectrometric method for the determination of chloramphenicol residues in milk and animal tissues, using deuterated chloramphenicol as internal standard. For milk analysis, the sample is diluted with 1 volume of water and purified by loading the diluted milk onto a Cis Sep-Pak extraction column. Following column washing with water, chloramphenicol is eluted with methanol. The eluate is evaporated to dryness, and the residue is dissolved in water/acetonitrile (7 3). 

DMSO, DMF, THF, aqueous acetonitrile, and n-butanol, since the overall kinetic form was first-order in dibenzylmercury37. Later work38 indicated that the situation was more complex than first thought dibenzylmercury and DC1 in solvents DMSO, DMF, acetonitrile, and dioxan afforded not only the compound C6H5CH2D, but other deuterated species such as (XI) and (XII). 

However, there is one major drawback implemented by the use of solvent mixtures. The commonly used solvent system of acetonitrile/water displays a strange behaviour. Typically, the line shape of the water and the acetonitrile is different. As normally the water is used in its deuterated form, the spectrometer is also locked on to the D2O component. Trying to shim such a sample by using the lock level, and therefore the line shape of the D2O, provides a good line shape for the water. However, for the acetonitrile component, severe distortions can be observed, and the sample signals show a similar behaviour like the signals of the acetonitrile. 

An example of a spectrum with automated solvent suppression is given in Figure 2.6. Normally, one has to deal with a mixture of two solvents, where often one of the solvents is water and is replaced by D2O. This leads to one or two intense solvent lines which have to be suppressed. In this figure, a worst-case scenario is presented. The mixture consists of two non-deuterated solvents (acetonitrile and methanol) which show, in total, three intense solvent lines. The solvent suppression parameters were adjusted automatically, and an additional digital filtering to remove the residual solvent signals was also carried out. 

The photochemically produced PtCPEt fragment, stabilized as the cis- and trans-PtH (PEt- )2 complexes, has proved (54,55,56) to be an efficient and long lived homogeneous catalyst for H2/D2 exchange (Equation 17), deuteration of acetone or acetontrile (Equations 18 and 19), decomposition of formic acid (Equation 20), and hydrolysis of acetonitrile (Equation 21). Because of the catalytic promise... 

Irradiation of trimethylsilylmethylamino derivatives in wet acetonitrile leads to the desilylated product. Deuterated products are obtained by substituting H20 for D20.322 323... 

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