Nitrogen detection

Harrison, C.R., Lucy, C.A. (2002). Determination of zwitterionic and cationic surfactants by high-performance liquid chromatography with chemiluminescent nitrogen detection. J. Chromatogr. A 956(1-2), 237-244. 

Relative purity measurement and the relative purity-based reaction optimization have long been used in combinatorial synthesis. In order to make high-through-put purification a success, the yield-based optimization is essential. Chemiluminescent nitrogen detection (CLND) [4] with HPLC determines the quantitative yield after each reaction step during the library feasibility and rehearsal stages. The yield of each synthetic step provides guidance for the final library synthesis. 

Gradient RP-HPLC separation with 0.1% formic acid and methanol as mobile phase components (0.25 mL/min) combined either with ESI-time-of-flight [23] MS detection or with chemiluminescence nitrogen detection (CLND) was used to identify and, respectively, quantify illicit drugs in seized material without primary reference standards [24], The method exploits the accurate mass measurement provided by TOE MS, enabling the unequivocal identification of molecular formula of the unknown analyte, and the CNLD equimolar response to nitrogen. 

Nitro-n-butane, 302, 307 m-Nitrocinnamic acid, 719 Nitrogen, detection of, 1040, 1045 ... 

In LC/MS analysis of combinatorial libraries, the MS determines the product identity and its purity is determined by other on-line detection techniques such as UV, evaporative light scattering detection (ELSD), and chemiluminescent nitrogen detection (CLND).17-20 UV detection is used here to assess product purity based on the assumption of similar absorption coefficients at 214 nm for the desired product and the side-products. 

Fitch WL, Szardenings AK, Fujinari EM. Chemiluminescent nitrogen detection for HPLC an important new tool in organic analytical chemistry. Tetrahedron Lett 1997 38 1689-1692. 

Bizanek R, Manes JD, Fujinari E, Chemiluminescent nitrogen detection as a new technique for purity assessment of synthetic peptides separated by reversed-phase HPLC, Peptide. Res., 9(l) 40 44, 1996. 

The physical quality of samples is assessed via analytical methods. Liquid chromatography with mass spectrometry (LC-MS) is the most common instrumentation used to determine sample presence and purity (Kerns et al., 2005). Chemiluminescent nitrogen detection (CLND), charged aerosol detection (CAD) and other techniques have also been used to determine concentration (Popa-Burke et al., 2004 Gamache et al., 2003). 

Many other on-line detectors suitable for SEC columns as reviewed [154], including chemiluminescent nitrogen detection, dynamic surface tension detection, high frequency detection and Fourier transform infrared detection, can be applied to FFF the latter being capable of delivering polymer compositions online. 

Due to the very low natural abundance (0.37%) and receptivity (0.066 relative to of the N nucleus, nitrogen-detected experiments often require N-labeled compoimds to obtain good spectra in reasonable amoimts of time, especially if low LODs are needed in the presence of excipients. N SSNMR was used in a study by D Souza et al. to investigate a reaction occurring in a lyophilized peptide/polymer formulation. In this study, N-labeled valine was formulated in a PVP matrix and stored at 70° C for 7 days, with N SSNMR spectra acquired at various intervals. The authors observed at least three nitrogen populations at day 0, two of which disappeared over time, indicating that non-covalent interactions between the peptide and the polymer matrix occurs before the reaction to form an amide bond. 

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