Iodine chloride, fluorescence

The total lead in gasoline may be determined gravimetrically (ASTM D-52, IP 96), polarographically (ASTM D-1269), by atomic absorption spectrometry (ASTM D-3237, IP 428), by the iodine chloride method (ASTM D-3341, IP 270), by inductively coupled plasma atomic emission spectrometry (ASTM D-5185), and by X-ray fluorescence (ASTM D-5059). When it is desired to estimate tetraethyl lead a method is available (IP 116X whereas for the separate determination of tetramethyl lead and tetraethyl lead recourse can be made to separate methods (ASTM D-1949, IP 188). 

Echinopsine is a weak base. Solutions of its salts, which exhibit no fluorescence, ve precipitates with the usual alkaloid reagents, although not at great dilution. The most senidtive reag ts are iodine and phosphomolybdic acid the former has been employed for investigating the distribution of the alkaloid in the tissues of Eehinopa (1). With ferric chloride, the alkaloid gives an intense blood-red coloration. 

Stannic chloride (Rgt. No. 236) is now only rarely used for detection. If no success is obtained with fluorescence layers, iodine vapour (Rgt. No. 141) or rhodamine B reagent (No. 220) can be used for non-destructive detection. 

Detection The less volatile tar bases can be detected on fluorescent layers (e. g., silica gel GF264)- Other possibilities are using the spray reagents listed for the amines, e. g., iodine solution (Rgt. No. 144), permanganate solution (Rgt. No. 200), antimony(V) chloride (Rgt. No. 18) or the modified Dragendorff reagent for alkaloids (Rgt. No. 98). 

Celade and De Schryver applied the same model to the fluorescence quenching in SDS micelles by neutral molecules [45,46] and in inverted micelles by halogene anions [47]. The intermicellar exchange of the counterions (iodine ions) was studied for cetyltrimethylammonium chloride (CTAC) micelles [48] and the value kg=9A X10 dm mole" s was obtained. 

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