Analysis sulfide content

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

On the other hand, when the content of sulfur in the gas was sufficiently high (1000-2(X)0 ppmv) for bulk nickel sulfide (NijSj) formation (ascertained by X-ray diffraction analysis), the distribution of sulfur in the catalyst bed was fairly even in different parts of the bed (Table 1) and also within catalyst particles. According to SEM/EDS analysis the content of sulfur on the surface ranged from 4.0 to 7.5 wt% and in the middle of particles from 5.3 to 9.3 wt%. However, nickel forms a liquid sulfide product at temperatures above 635 C [18, 19]. According to the SEM analysis of the firesh and spent catalyst particles, no liquid formation on the catalysts was detected. 

Like cements, the elemental composition is determined by XRF or AAS techniques. The XRF bead is made using lithium tetraborate at 1050°C. Sulfide content cannot be determined by XRF. Sulfite, SO3 , and sulfate, S04 , are safely analyzed by XRF. Na2C03 -I- K2CO3 fusion is carried out for Ca, Mg, Fe, and A1 analysis by AAS. Lanthanum chloride is used as a sulfate interference suppressant. Gravimetric sulfate determinations are also carried out by precipitation as barium sulfate. The Leco Carbon-Sulfur Analyzer can also be used for quality control purposes. The fluoride is determined by XRF or a pyrohydrolysis method. The measurement of particle size distribution is carried out in a manner similar to that for cements and clays. 

The total jnessure at the second tray is estimated by assuming a pressure drop of about 0.50 psi per theoretical tray (based on 0.25 psi per actual tray and 50% tray efficiency) and the above procedure repeated. The tray-by-tray analysis is continued down fee column until fee liquid leaving a tray meets fee product water specification wife regard to ammonia and hydrogen sulfide content. If necessary, the entire process is repeated with different initial... 

The water (moisture) content can rapidly and accurately be determined in polymers such as PBT, PA6, PA4.6 and PC via coulometric titration, with detection limits of some 20 ppm. Water produced during heating of PET was determined by Karl Fischer titration [536]. The method can be used for determining very small quantities of water (10p,g-15mg). Certified water standards are available. Karl Fischer titrations are not universal. The method is not applicable in the presence of H2S, mercaptans, sulfides or appreciable amounts of hydroperoxides, and to any compound or mixture which partially reacts under the conditions of the test, to produce water [31]. Compounds that consume or release iodine under the analysis conditions interfere with the determination. 

In sample 1, it is clear that the predominant form of sulfur in the residuum is thiophenic, while the sulfide forms seem to predominate in residua 2 and 3. In asphaltene samples 1 and 3, the thiophenic sulfur content increases relative to the respective residua, indicating that the molecules containing sulfide sulfur may be more soluble in heptane than those containing thiophenes. For sample 2, there appears to be no such discrimination within the 10% accuracy limits currently established for the XANES analysis. 

V)Analysis of Mixtures Containing Lead Azide, Barium Nitrate, Basic Lead Styph-nate and Antimony Sulfide. As an example of such mixts may be cited the NOL No 130 Primer Mixture used in T—32E1 and M47 Detonators LA(dextrinated) 20.0, Ba(NOs)2 20.0, LSt (basic) 40.0, tetracene 5.0, St Sb,S, 15.0/5, Its max moisture content is 0.3%, The method of analysis of such mixts was developed at PicArsn by J.Campisi, ChemLabRept 52—HI—2114(1952) and was incorporated in the Purchase Descriptions PA—PD—202(Rev 1)(1952) and PA-PD-124 (1953)... 

Although these electrodes are customarily referred to as sulfides, they are of a broadly varied composition strictly speaking they can even be regarded as amorphous materials [442], In fact, X-ray analysis has shown that NiSx is poorly crystalline and that some crystallinity is achieved only as the sulfur content is higher than a critical value (ca. 30%) [439]. The crystalline compound has then be identified as Ni3S2 [446]. Usually, the sulfur content is much lower than the stoichiometric one [442, 444, 446, 447], i.e., only a minor part, if any, of the metal can be really present as a sulfide. The composition can also differ between the bulk and the surface where there may be a sulfur-rich layer which passivates to some extent the electrode [139,448]. 

High concentrations of sulfide may interfere with the CVAA mercury measurement. Free chlorine that is generated in the oxidation step of seawater samples or in other samples with high chloride contents absorbs radiation at 253 nm. Sulfide and chloride can be chemically removed from the sample matrix prior to analysis. 

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