Spectral Interferences - Instrumental Analytical Chemistry - Lecture Slides, Slides of Analytical Chemistry

Download Spectral Interferences - Instrumental Analytical Chemistry - Lecture Slides and more Slides Analytical Chemistry in PDF only on Docsity! Spectral Interferences • Can be caused by overlapping lines but is very rare due to the emission lines of the hollow- cathode sources being so narrow • Can also result from the presence of combustion products that exhibit broadband absorption or particle products that scatter radiation • Both reduce the power of the transmitted beam and lead to positive analytical errors Docsity.com Continued • A more troublesome problem occurs when the source of absorption or scattering originates in the sample matrix • Interferences because of scattering by products of atomization is most often encountered when concentrated solutions containing elements such as Ti, Zr, and W are aspirated in the flame Docsity.com Two-Line Correction Method • Uses a line from the source as a reference it should be as close as possible to the analyte line • This makes any decrease in power of the reference line from that observed during the calibration arises from absorption or scattering and is then used to correct the absorbance of the analyte line Docsity.com The Continuum-Source Correction Method • Deuterium lamp provides a source of continuum radiation throughout the ultraviolet region • The radiation from the continuum source and the hollow cathode lamp are passed alternately through the electrothermal atomizer, the absorbance from the deuterium radiation is then subtracted from the analyte beam Docsity.com Chemical Interferences • More common than spectral interferences • Can be minimized by suitable operating conditions Docsity.com