Turbidity indicators

Test the solution so obtained for unsaturation by adding cold 1 per cent, potassium permanganate solution a drop at a time. The immediate disappearance of the purple colour and the formation of a brown turbidity indicates the presence of a double bond Baeyer a test). It must be noted that many substances, not unsaturated, decolourise warm acid or neutral potassium permanganate solution. 

To 5 ml. of water add 1-2 drops of the amine if the amine does not dissolve, add a drop or two of concentrated hydrochloric acid. Add 0-5-1 ml. of this amine solution to 2-3 ml. of the reagent an almost immediate precipitate indicates the presence of a primary amine. A slight turbidity indicates the presence of a primary amine as an impurity. (Primary aromatic amines generally require 2-3 minutes for the test. Urea and other amides, as well as amino acids, do not react.)... 

As-polymerized PVDC is not in its most stable state annealing and recrystaUization can raise the temperature at which it dissolves (78). Low crystallinity polymers dissolve at a lower temperature, forming metastable solutions. However, on standing at the dissolving temperature, they gel or become turbid, indicating recrystaUization into a more stable form. 

Activated charcoal, purified - place about 50 g Darco C-5 activated carbon in a wide-neck screw-cap container, add sufficient calcium phosphate extractant to completely wet it, then cap the bottle and shake for 5 min. Filter slowly with suction through a Buchner funnel, then wash three times successively with deionized water. Test the final leachate with a solution of barium chloride (approximately 1.4% m/v in 0.3 M HCI). If turbidity indicates the presence of sulphate, return the charcoal to a beaker, thoroughly mix with deionized water (boil for 15 min if necessary to get a clear test), refilter, wash and test for S as above. When satisfactory, dry overnight at 105°C and store in a tightly capped bottle. 

Distillation is required to remove the primary side-product, di-n-butyl disulfide. Purification by silica gel chromatography gave inferior results because of similar retention times of the two compounds. The initial distillate fractions are turbid, indicating the presence of di-n-butyl disulfide. The absence of turbidity in the higher boiling fractbn indicates distillate that is predominantly the desired n-butyl 4-chlorophenyl sulfide, containing only small amounts of n-butyl disulfide. 

The appearance of turbidity indicates saturation of alkyl halide. In this way both sodium thiosulfate and 2-bromopropane are nearly in a one-phase system, thus shortening significantly the heating period. Furthermore, the competitive hydrogen bromide elimination and the ensuing acid-promoted decomposition of thiosulfate into sulfur and sulfur dioxide are minimized, the checkers added 300 ml. of water over a period of 90 minutes. 

Polyvinyl alcohol content - 16tol9wt% calcd on a dry basis using a turbidimetric procedure consisting of sample aliquot addn to a series of std w-acet solns (differing in the proportions of w to acet) until a clear soln is formed (not turbid) indicating the appropriate wt % of the dry resin... 

The cooling system underwent a simple cleaning procedure, but the passivation and initial inhibitor dose stages were rolled into one. The plan was to maintain 250 ppm of inhibitor in the system for a 3-day period (typical inhibitor dose would be 100 to 120 ppm). However, almost no stabilizer dispersant was added and the cooling water was persistently cloudy. Thus the passivation program was of little value, and the turbidity indicated phosphate precipitation. 

Nickel cupferronate, Ni(C6H5N202)2, or Ni(cup)a, was prepared as follows. 2 g of Ni(0Ac)2-4H20 was dissolved in 150 ml of milli-Q water (0.05 M), and 2.5 g of cupferron dissolved in 100 ml of milli-Q water (0.16 M) by sonication. The two solutions were cooled to 0 °C and the cupferron solution added dropwise to the Ni(OAc)2 solution under vigorous stirring. After a few minutes, the solution became turbid, indicating the formation of complex. It took another 30 min for completion of the reaction. Before filtration, the product was kept at 0 °C for 1 h. The product was filtered and washed with miiii-Q water and dried at room temperature. 

The lime water or baryta water test is best carried out in the apparatus shown in Fig. IV. 1. The solid substance is placed in the test-tube or small distilling flask (10-25 ml capacity), dilute hydrochloric acid added, and the cork immediately replaced. The gas which is evolved (warming may be necessary) is passed into lime water or baryta water contained in the test-tube the production of a turbidity indicates the presence of a carbonate. It must be remembered that,... 

The PVME/PS semi-I, semi-II and sequential IPNs are slightly hazy or turbid, indicating phase separation, whereas the corresponding blends are clear and miscible. 

Historically, the sulfosalicylic acid test was used as a crude measure of proteinuria. This test can be performed by adding five drops of 20% sulfosalicylic acid to 3 mL of urine in one test mbe. The specimen tube is then visually compared with a mbe of untreated urine held against a dark background, with the presence of turbidity indicating proteinuria. 

FIGURE 103-3. Macrotube minimal inhibitory concentration (MIC) determination. The growth control (C), 0.5 mg/dL, and 1 mg/dL tubes are visibly turbid, indicating bacterial growth. The MIC is read as the first clear test tube (2 mg/dL). 

---