tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 23

Introduction to Modern Liquid Chromatography, Third Edition part 23. High-performance liquid chromatography (HPLC) is today the leading technique for chemical analysis and related applications, with an ability to separate, analyze, and/or purify virtually any sample. Snyder and Kirkland's Introduction to Modern Liquid Chromatography has long represented the premier reference to HPLC. This Third Edition, with John Dolan as added coauthor, addresses important improvements in columns and equipment, as well as major advances in our understanding of HPLC separation, our ability to solve problems that were troublesome in the past, and the application of HPLC for new kinds of samples. . | 176 DETECTION a 1 2 3 4 5 6 7 Ä 3 4 A 3 7 Figure Response of chemiluminescent nitrogen detector CLND for different compound types a Response of 50 ng nitrogen-equivalent of 1 N N-dimethyl aniline 2 nitrobenzene 3 miconazole nitrate 4 nicotinamide 5 4-acetamidophenol 6 glycine 7 caffeine b Response of 1 1 ng nitrogen-equivalent of standard to 1 mg injected solvents 2 acetone 3 ethyl acetate 4 hexane 5 isopropanol 6 methanol 7 water. Adapted from 29 . both the concentration of the chiral rotary disprrstnn ORDidctcerots ngrrateon asimilar prindple te polarimeters but use lower wavelengths . the nn5-nm mercury pmission line whichm theory should give stronger signals. Circular dichroism CD detectors are based on measuring the difference in absorption of right and left circularly polarized light whenag analetr oassestirrugh sinnais itis desired thatthe analytehaveachromoohere withabserptionos Die 200to42i nm range. In theaenmcleofHcttte 31 tCrseip onseofCD ORD a ndUV detection is comparer fot i i rt lclr orts 1 loanh cclnntí onoS ibupanfen rnansiomsft. The CD detectoogenesatespeakt withsignal toioiie Sin iboutesfcid kcgdr tiiac the ORD rtiectrrinutoniyhait tlis toi ignUVigeettor. Ns nclhatlneiwo chirai detectors nsnCuce both negative and positive peaks. Another study 32 compared the response of nLgORD nd PDdetection for6phatmlreotiralhomcohnds. For naproxen CDwasaboud 6-tolg sore icos Hr nnd n4-fotn moradam REFRACTIVE INDEX DETECTORS 177 250 - Asn Figure 4 20 Response of chemiluminescent nitrogen detector CLND for amino acids. a 10 xL injection of a mM standard solution of 13underivatized amino acids b 10 xL injection of wine filtered through a 1000 Da filter. Adapted from data of 30 . ORD. The relative response for the various test compounds varied but CD was superior in all cases. REFRACTIVE INDEX DETECTORS The differential refractometer or refractive index RI detector responds