Advantages and Disadvantages of KBr Pellets

One of the beauties of KBr pellets is that practically any powdered solid can be analyzed. If a solid is not a powder, but if it can be broken into pieces and ground into a powder, its spectrum can be obtained as well. If only small amounts of sample are available, micro KBr pellet presses can be used to make pellets as small as several millimeters in diameter. KBr pellets can also be used for quantitative work. 

FIGURE 4.5 A Wig-L-Bug , which can be used to mechanically grind KBr and samples to make KBr pellets. (Photo courtesy of PIKE Technologies.) 

However, this requires measuring out precise amounts of KBr and sample to make the pellet. Also, since the pathlength of the peUet is irreproducible, band area ratios must be used to eliminate pathlength as a variable. 

The mull technique is a second way of taking the spectra of solids in transmission. It works on powders or anything that can be ground into a powder, and competes directly with the KBr pellet method. Mulls are made by first grinding the sample to reduce particle size. This is to avoid light scattering and sloped 

Works on many types of solids Opacity problem 

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