Color-indicating tubes

Direct reading samplers include simple devices such as colorimetric indicating tubes in which a color change indicates the presence of the contaminant in air passed through the tube, or instruments which are more or less specific for a particular substance. In the latter category are carbon monoxide indicators, combustible gas indicators (explosimeters) and mercury vapor meters, as well as a number of other instruments. 

Test Ttibe 3 6 M NH3 1 carefully smelled all tubes to begin with and this tube was definitely ammonia. Since I was able to rule out this tube initially, I then mixed a small amount of known ammonia with all other tubes. As I mixed the ammonia with the other tubes, I noticed considerable heat being produced in tubes 1, 4 and 7, which I suspected was due to an acid present. With tube 1, smoke appeared, which led me to believe that tube 1 was the HC1 which produced a white cloud (smoke) of NH4C1. Tubes 1 and 3 were now ruled out. I then noticed precipitates formed in tubes 8 (blue), tube 6 (blue), tube 5 (white), tube 10 (brownish-grey) and tube 7 (white). When excess ammonia was added to tube 10, the precipitate dissolved. When excess ammonia was added to test tube 8, the precipitate dissolved and the solution turned dark blue indicative of Cu2+. When I added excess ammonia to test tube 6, the precipitate dissolved and the solution turned a medium blue color, indicative of the presence of Ni(NH3)62+. 

CH3)20 was monitored via a manometer and never allowed to exceed 400 mm of pressure. Following condensation of 20 mL of (CH3)20, the lecture bottle valve was closed and the tube, still immersed in the — 78°C bath, the contents were periodically swirled, and the tube quickly reinserted into the slush bath. After 30 min the solution appeared dark blue in color, indicating that the solvent was dry. The solvent may be stored as a liquid infinitely at — 78°C behind a safety shield. 

VII. Treatment with Benzylamine Reagent. Add ca O.lg of sample to ca 5ml of benzylamine reagent(a 5% soln of C6Hg.CH2.NH2 in 95% alcohol) in a test tube. Note the color developed and see if any change takes place- after placing the tube in boiling w. A viol color indicates the presence of TNT and orn color TNAns or HNDPhA(See also Chart B)... 

XIII. Treatment with Alkali-Acetone Reagent. Dissolve in a test tube ca O.lg of the sample in ca 5ml of acetone, add ca 2ml of 10% NaOH soln and shake the mixt. After allowing to stand for lmin, note the color. A blue color indicates DNT and its presence may be confirmed by M-D(Meyer-Drutel) Test, which would give purple-red. A viol color indicates DNB which would give red-brn by M-D test. A light red indicates PETN, which would give with benzylamine no color(See item VII). A deep red indicates Tetryl, which would give with... 

H2S exposure may be monitored by diffusion type colorimetric dosimeters (such as Vapor Gard) color changes from white to brown-black dosage exposure measured from the length of stain in the indicator tube. 

Iron(III) chloride test. Place into separate clean, dry test tubes (100 X 13 mm), labeled as before, 5 drops of sample to be tested. Add 2 drops of iron(III) chloride solution to each. Note any color changes in each solution. (Remember, a purple color indicates the presence of a phenol.) Record your observations on the Report Sheet (6). 

Solution A Pipet 2.0 mL of Standard Lead Solution (20 pig of Pb) into a 50-mL color-comparison tube, and add water to make 25 mL. Adjust the pH to between 3.0 and 4.0 (using short-range pH indicator paper) by adding 1 N acetic acid or 6 N ammonia, dilute to 40 mL with water, and mix. 

Wash resin beads in a 75-nnm test tube as for the Kaiser test. For N-terminal proline or hydroxyproline residues, add chloranil (2 drops) and acetone (2 drops). For all other N-terminal residues, add chloranil (2 drops) and acetaldehyde (2 drops). Mix and allow to stand at rt for 5 min. A blue color indicates N-terminal free amino groups. 

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