The Estimation of Sulfhydryl Groups in Wool by Means of 1-(4-Chloromercuriphenylazo)- Naphthol-2

Abstract

IT has recently been reported [4] that sulfhydryl groups in wool fibers may be detected and estimated by means of a formamide solution of Bennett's color reagent, 1-(4-chloromercuriphenylazo ) -naphthol-2 [ 1,15,16] . Further experiments have now shown that the acidity and water content of the formamide are important in determining the rate and extent of penetration of this reagent into the fiber, and that the values reported earlier are therefore too low. This communication gives directions for increasing the reliability of the method for use on intact fibers and describes the standardization of the reagent on known sulfhydryl compounds. A subsequent communication will describe how the method can be shortened by using supercontracted and pulverized wool. A brief outline of the methods, without experimental details, has already been given [5]. Materials WoolThe wool samples used, which unless otherwise stated, were from the root ends of one good quality South African merino fleece (from sheep B51.3), were purified by Soxhlet-extraction for 24 hr. with hexane, then for 12 hr. with ethyl alcohol, followed by soaking for 24 hr. in frequently changed distilled water.

Experiments on Wool from Copper-Deficient Sheep

“…Thus, although there is an indication that the decrease in disulficle-group concentration is responsible for the difference in the initial part of the extension-time curves, these results suggest that other factors may be important as well. ' Tests on the Accessibility of Sulfhydryl Groiips and on Fiber Diameter S'welling : During studies on 'sulfhy<lryl groups in wool, reported already [8). it was found that the sulfhydrylgroup reagent 1-(4-ch!oromercuripheny!azo) -naphthol-2 in solution in formamide penetrates copperdeficient wool more rapidly than normal wuul.…”

The Polarographic Estimation of Sulfydryl and Disulfide Groups in Wool

“…The Determinatiopi of Sr~lfhl~dr~~l Sulfur in Intact I~'ool It is well known that mercuric chluride reacts with the -SH in intact wool (see, for example, Burley [ 5], p. 335) ; however, when an approximately twofold excess of this reagent in buffers of pH 8 or 9 was added to a sample of wool, the reaction, followed over a period of days in the apparatus shown in Figure 1, was not limited to -SH only, for mercuric I ions continued to be removed slowly from the solution after the 30 ~moles/g. stage.…”

Continuous Contacting of Porous Materials in Treatment Tanks

“…The fluid behaviour in this situation has been previously described in detail [ 1,2] , and it is sufficient here to state that, at the exit from a given roller pair, fluid is entrained within the interstices of the moving porous material and carried to the succeeding nip. The distance between consecutive roller pairs will be called a stage or section, as shown in…”