Sulfide photometrical determination

The pKd of 2-amino-4-methyl-6//-l,3-thiazine-6-one has been spectro-photometrically determined and is high (13.30) similar to that of disodium sulfide (80CCC732). 

Radford-Knoery J, Cutter GA. 1993. Determination of carbonyl sulfide and hydrogen sulfide species in natural waters using specialized collection procedures and gas chromatography with flame photometric detection. Anal Chem 65 976-982. 

Andreae [324,325] has described a gas chromatographic method for the determination of nanogram quantities of dimethyl sulfoxide in natural waters, seawater, and phytoplankton culture waters. The method uses chemical reduction with sodium borohydride to dimethyl sulfide, which is then determined gas-chromatographically using a flame photometric detector. 

X-ray intensities were measured photometrically. To reduce the effect of absorption as much as possible, the sulfide was diluted with magnesium oxide. The value of the coefficient julR was experimentally determined. Moreover, to eliminate the effect of preferred orientation, which arises when the sample assumes the form of a cylindrical rod, we adopted a spherical sample shape of 0.3-mm. diameter. 

Hydrocarbon impurities in propylene can be determined by gas chromatographic methods (ASTM D-2712, ASTM D-2163), and another test is available for determination of traces of methanol in propylene (ASTM Test Method D4864). A gas chromatographic method (ASTM D-5303) is available for the determination of trace amounts of carbonyl sulfide in propylene with a flame photometric detector. Also, sulfur in petroleum gas can be determined by oxidative microcoulometry (ASTM D-3246). 

Furthermore, based on specific color reactions, indicator papers for the continuous measurement of ammonia, bromine, chlorine, hydrocyanic acid, hydrofluoric acid, ozone, phosgene, sulfur dioxide, and hydrogen sulfide are commercially available using photometric evaluation. Because of the often extremely intense coloration, detection hmits as low as the lower ppb range can be achieved by this method. Table 6.34 gives an overview of the range of determination and the detec-... 

Other example is the determination of fuel parameters including the diene value and mercaptan sulfur. First, the robot weighs the sample, refluxes it in the presence of maleic anhydride, and extracts the analytes into an aqueous phase, which is poured into the titration vessel, where the robot inserts the photometric or potentiometric probe. For the determination of mercaptan sulfur, the robot also weighs the sample and removes sulfide by precipitation with a CdS04 solution and liquid-liquid extraction. Once the fuel is sulfide free, which is checked by using a photometric probe, it is poured into the titration vessel by the robot arm, which also plunges an Ag electrode prior to addition of the titrant (an AgNOs solution). In both cases, the automated titrator acts as a module of the robotic station and is operated by the robotic arm. 

Earlier investigations using an external closed loop inlet device (ECID) in conjunction with a packed colunm and a sulfur specific flame photometric detector, indicated that the concentration of HjS varied inversely with temperature 14, 24). This resulted in a temperature-dependent variability in the concentrations of the dimethyl sulfides (14). In order to determine whether the dimethyl sulfides were being created during desorption, meat samples were cooked to three end-point temperatures and then desorbed at these same three temperatures. Additionally, the meat was stored for periods of 0, 2, and 4 days before being sealed and analyzed. 

Because both apparatus and reagents may contribute silica, avoid using glassware as much as possible and use reagents low in silica. Also, make a blank determination to correct for silica so introduced. In this method, tarmin, large amoimts of iron, color, turbidity, sulfide, and phosphate interfere. Treatment with oxalic acid eliminates interference from phosphate and decreases interference from tannin. If necessary, use photometric compensation to cancel interference from color or turbidity. 

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