Preparatio n Procedures

3. Preparatio n Procedures

1 ) Choose and l oad film

A 3 5 - m m camera is used for the photodocu mentation of the TLC plate. General ly, both a black-and -white print and a color slide are made of the TLC plate . If two camera bodies are avai lable , one can be loaded with the black-and-wh ite fi l m , and the other with the slide fi l m . The camera bod ies

can be interchanged during the documentation of the plate .

High-speed films are needed for the documentation of the visible fluores­ cence resulti ng from the i l l u m i n ation of the plate with ultraviolet light. Films used for ultraviolet fluorescence photography include the Kodak TMAX 400

black-and -white print film and the Fujichrome 400 color slide film. These

Striegel . H i l l

accord ing to the procedures specified in the camera manual. Set the camera ASA to 800 , and set the f-stop to f 8.0.

2) Choose and mount filters on camera Gel fi lters are used with ultraviolet fluorescence photography to elimi nate reflected u ltraviolet rad i ation and, in the case of color slide fi l m , to correct the color balance of the fi l m so that the resulting slide will accu rately reprod uce the color of the fluoresce nt spots see n . Gel filters are rather fragile

and easily dete riorate; they should be hand led carefu lly. The Kodak Wratten gel fi lter 2 E is used for black-and-wh ite pri nts . For color slides, the Kodak Wratte n gel color correction fi lters designated 1 0R ,

1 0M , a n d 2 0 Y are used i n addition t o t h e 2 E filter. T h e order i n which the filters are loaded i nto the holder is i m portant. The 2 E filter, which blocks u ltraviolet rad iation, should be placed closest to the TLC plate being photo­ graphed. The color correction filters are placed between the 2E filter and the lens.

3 ) Set u p copy stand and mount camera

The copy stand is set up in a room that can be made completely dark . Although a photographic darkroom is ideal , a closet or other wi ndowless room can be used. A standard 50-mm lens (or a 60- m m macro lens, depending on the size of the plate) i s attached to the camera body, which is mou nted in turn on the arm of the copy stand .

4 ) Position T L C plate and set u p the UV l ight box

(See Attachment A of this protocol for i nstructions on the manufacture of an

i nexpensive UV box.) Place the TLC plate on the base of the copy stand , and center the plate w h i le looking through the viewfi nder o f the camera. Place the UV light box over the TLC plate and position it so that the

open ing is aligned with the lens of the camera. Move the arm of the copy stand so that the vertical position of the lens is at or near the opening of the box .

5) Set up UV lamps Two labo ratory UV lamps are used to illuminate the TLC plate . One lamp is placed on each side of the box. Each lamp is positioned so that the lamp area is flush with the window o r open i n g of the box.