Square Cuvet Holder for the Spectronic 20 We have constructed a useful holder for square cuvets which fits the ubiquitous Spectronic 20 spectrophotometer' and enables us to take advantage of very inexpensive standard shape polystyrene cuvets2 so as to gain greater precision than is usually available with test tube cuvets. The design (see figure), which fits into the B&L 1-in. test tube adapter No. 33-39-30, was milled from a 1-in. diameter.Nylon or polypropylene rod. It is simple and inexpensive t o make. A square hole was drilled the entire 12-cm length of the rod using a %-in. broach. A Xs-in. end mill was used to put a 3-cm long slit through the rod perpendicular to two sides of the center hole and 15-mm from one end of the rod. An additional slot 8-cm long, located 5-mm from the bottom end, was milled with a s&in. end mill through one wall only and perpendicular to the light path slit. This slot was convenient for removing the cuvets from the holder with a microspatula. A K-in. square Nylon plug 5-mm thick was used t o close the bottom end of the cuvet holder. A mark was made on the top of the holder in line with the center of the light pathway slit and opposite t o the positioning mark on the B&L I.in adapter Thii arrangement iq particularly useful fur protein drrrrminnrionr in whwh the highly alkaline rraacntr might rreh ~ w quartz d cuvets. In additim, it is nuffirwntly inexpenawr for mrtrurliunal lalwralory use. 'Bsuseh and Lomb, Rochester, NY 14602. 2For example, three standard styles are available a t less than lo$ each from Walter Sarstedt. he.. Princeton. NJ 08540: the micro-cuvet and the 4.0 rnl cuvet have outside dimensionstoo large for t h e square hoie drilled with the %-in. broach described here J o h n N.Aronsan S t a t e University of New York a t Albany Albany. NY 12222
000 / Journal of ChemicalEducation
Square cwet adapter made from I-inch Nylon or polypropylene.
