Always Run a Blank Recently in our infrared spectral studies of biological materials it became apparent that the obtained spectra were similar to a polymer listed in Aldrieh.' In reviewing our method of sample preparation we realized we were using a plastic vial for the Wig-L-Bug operation. 3' ' 4' 9 7 7 10 11 12 13 14 II We therefore placed reagent-grade potassium IW bromide in hoth the plastic vial and a metallic vial I (each vial held a Btainless steel hall hearing). The material in each vial was shaken for 2 min in the Wig-L-BugZ and then pressed in a KBr die a t 8 \ 20,OW pounds for 2 min. Each disk was examined I in a 137 Beekman spectrophotometer. 1 Visual examination of the two spectra (see .. right) immediately showed that the plastic vial (B) E m was contaminating the sample (A). ! The moral of the story is alwarj run a blank ,000 1000 ~ M O ISW 1100 1000 PW 800 7w before starting an experiment
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'Pouchert, Charles J. The AldrichLibrary of Infrared Spectra, 2nd ed.; Aldrich Chemical Co.: Milwaukee, WI, 1975;p 134411. ' Wig-1.-Rug, manufactured by Crrscnr 1)ental Mfg. Co., Chicago, IL. Correspvndencc should be sent LO 1521 Atwood Cay Circle. Sarasota, FL 342:l:l.
'
George Schwartzrnan' Department of Geology
University of South Florida Tampa, FL 33620
Volume 66
Number 7
July 1989
615
