Evaporative light scattering libraries

Evaporative light scattering is gaining popularity due to its ability to detect analytes on a nonse-lective basis. Basically, this detector works by nebulizing the column effluent, forming an aerosol that is further converted into a droplet cloud for detection by light scattering. This type of detector has been applied to studies of small molecule combinatorial libraries [13,14], carbohydrates [15], and lipids [16,17]. 

Kibbey CE. Quantitation of combinatorial libraries of small organic molecules by normal-phase HPLC with evaporative light-scattering detection. Molecular Diversity 1, 247-258, 1996. 

Fang LL, Wan M, Pennacchio M, Pan JM. Evaluation of evaporative light-scattering detector for combinatorial library quantitation by reversed phase HPLC. Journal of Combinatorial Chemistry 2, 254-257, 2000. 

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. 

Hsu BH, Orton E, Tang S, Carlton RA. Application of evaporative light scattering detection to the characterization of combinatorial and parallel synthesis libraries for pharmaceutical drug discovery. J Chromatogr B 1999 725 103-112. 

Independence of the detector s response from a compound chromophore or ionizability makes it more universal for quantification applications than UV or MS. Recently, the evaporative light-scattering detector has been introduced as a useful tool for quantification and purity assessment of compounds in combinatorial libraries [36, 41]. 

Garr C, The use of evaporative light scattering in quality control of combinatorial libraries, Proceedings of the Materials of Solid and Solution Phase Combinatorial Synthesis Meeting, Princeton, NJ, 1997. 

Cremin, P.A. Zeng, L. High-Throughput Analysis of Natural Product Compound Libraries by Parallel LC-MS Evaporative Light Scattering Detection, Anal. Chem. 74, 5492-5500 (2002). 

Kibbey, C.E. Quantitation of Combinatorial Libraries of Small Organic Molecules by Normal-phase HPLC with Evaporative Light-scattering Detection, Mol. Divers. 1,247-258 (1996). 

Hsu, B.H. Orton, E. Tang, S.Y. Carlton, R.A. Application of Evaporative Light Scattering Detection to the Characterization of Combinatorial and Parallel Synthesis Libraries for Pharmaceutical Drug Discovery, J. Chromatogr. B 725, 103-112 (1999). 

C. Garr, The Use of Evaporative Light Scattering in Quality Control of Combinatorial Libraries, Strategic Research Institute Proceedings of the Conference on Solid and Solution Phase Combinatorial Synthesis, New Orleans (1997). 

Since the UV response as a measure of purity and quantity determination is questionable due to the different extinction coefficients of individual components of a crude preparation, alternative detection systems were advocated, such as the evaporative light scattering detector (ELSD) and the chemiluminescent nitrogen detector (CLND). " In addition, NMR techniques were adopted that allowed structural confirmation, purity characterization, compound solubility, solution stability, and biological testing from a single DMSO stock solution. The quality control process for descriptions of chemical library members was discussed by Yan in 2004. ... 

Because purity determined by liquid chromatography (LC) or LC-mass spectrometry (LC-MS) with ultraviolet (UV) or evaporative light scattering detector (ELSD) detection represents only relative purity, the presence of impurities such as inorganics, materials with poor chromophores and/or good evaporative properties, and materials that tend to be retained by a guard column cannot be detected. Therefore, we measure the absolute purity of six representative compounds in each library at both optimization and production stages. 

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