Amino acids evaporative light scattering

Progress has been made in developing electrochemical methods for detection of amino acids without derivatization.74 75 Evaporative light scattering (ELSD) is also a promising detection method.76 Flow-injection analysis... 

Peterson, J. A., Lorenz, L. J., Risley, D. S., and Sandmann, B. J., Amino acid analysis of peptides using HPLC with evaporative light scattering detection, /. Liq. Chromatogr. Related Technol., 22, 1009, 1999. 

A simple and efficient alternative to the traditional UV detection of amino acids and related compounds is nowadays represented by the evaporative light scattering (ELS) detector, which allows the direct chromatographic separation, with no need for preliminary derivatization. In the field of glycopeptides-based CSPs, it was applied for the first time in the chromatographic resolution of carnitine and 0-acylcarnitine enantiomers on a TE CSP [61]. The considered compounds are nonvolatile solids and gave optimal ELS response under a variety of experimental conditions (buffered and unbuffered mobile phases, flow-rates from 0.5 to 1.5 mL/min, different kind and... 

HJ Chaves das Neves, ZB Morais. HPLC assay of underivatized free amino acids with column switching and evaporative light-scattering detection. J High Resol Chromatogr 20 115-118, 1997. 

Petritis, K. et al. Validation of ion-interaction chromatography analysis of underivatized amino acids in commercial preparation using evaporative light scattering detection. 

If no derivatization takes place, detection is preferably accomplished by UV at a low wavelength (200-210 nm) in order to enhance detection sensitivity. However, detection selectivity is sacrificed at such low wavelengths. Electrochemical detection, when applied to the analysis of free amino acids, offers higher selectivity but suffers from a small linearity range. Furthermore, most amino acids (with the exception of tryptophan, tyrosine, and cysteine) are not intrinsically electrochemically active within the current useful potential range [5]. Lately, the development of the evaporative light-scattering detector (ELSD) offers an attractive alternative for the determination of nonderivatized amino acids (see Fig. 1). 

Source From Amino acid analysis of peptides using HPLC with evaporative light scattering detection, in J. Liq. Chromatogr. Relat. Technol. ... 

Figure 8.64 Isocratic separation of 12 native amino acids utilizing evaporative light scattering detection. Separator column Purospher RP-18 column dimensions 125 mm x 4 mm id. eluent 05 mmol/L pentadecafluorooctanoic acid flow rate 1 mL/min detection ELSD (drift tube 60 °C, nebulizer gas 23 bar, gain 9) ...

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