Specific turbidity

For toxicity testing with Pseudomonas putida, the inoculum, which has been adjusted to a specific turbidity, is added to the culture flask filled with the cultural medium and the test sample. Each dilution step should encompass three parallel batches. After an incubation period of 16 + 1 hours at a constant temperature of 23°C in the dark, the measurement of turbidity, after homogenization by shaking, was carried out. 

Not only was a larger latex examined in more detail but also a greater study was made of the concentration dependence of the light scattering. The concentration dependence of lateral scattering was first examined by Heller and Tabibian (7). They measured the concentration dependence of the specific turbidity I90/I0c and carried out an extrapolation to zero concentration defined by... 

For small particles the specific turbidity increased with dilution which was explained by decreased intensity loss from the primary and scattered beams due to particle turbidity. For certain particles of a size around the first turbidity maximum where the scattering is strongest, the specific turbidity decreased with dilution as the stray light from multiple scattering decreased. 

Combination of equations (3) and (4) gives a ratio, the specific turbidity, independent of N, as ... 

Therefore, in principle, the parameters of the particle size distribution can be estimated from specific turbidity measurements at different wavelengths. This is not true, however, in the Rayleigh regime (i.e. small particles, (D/Am) less than 0.1). In this case, the extinction coefficient is proportional to (D/Am)4 and... 

Specific turbidity histories for runs B7, BIO and Bll are shown in Figure 2. It is obvious that the results are consistent the reproducibility obtained in runs BIO and B11 is clearly shown, while it is evident that the latex particles formed in run B7 are larger, as expected. 

Specific turbidity histories are also plotted vs. dimensionless time for a continuous emulsion polymerization run the samples were withdrawn from the second reactor of a continuous train where the first reactor is a small seeding reactor. Part A of Figure 3 shows the particle size behaviour during start up all monomer, water, initiator and soap feedrates were kept constant until the process reached a steady state. In part B, the soap concentration in the seed reactor was increased a decrease in the particle size was expected and it is clearly shown from the specific turbidity measurements. 

Hopefully, it has become evident that specific turbidity gives consistent and reproducible qualitative results. Two approaches have been used to translate the specific turbidity measurements from the previously mentioned experiments into latex particle size ... 

Figure 2. Specific turbidity behavior for three batch runs runs B10-B11 are replications.

Figure 4 shows contours of constant sum of squares in the space of the parameters D and o, for a set of specific turbidity measurements, from a batch run. The 95% approximate joint confidence region estimated as ... 

Figure 3. Specific turbidity measurements for the continuous run (02 = residence time in the second reactor of the continuous train).

Table II. Average Diameters from Specific Turbidity Method...

SEC has been shown (7) to give satisfactory results for latexes with broad particle size distributions as well. The method is particularly useful (7) in the determination of distributions of small particles when specific turbidity would provide only a turbidity (or weight) average diameter. 

Turbidity measurements are simple, fast and reproducible. Specific turbidity can successfully follow the particle size evolution during the course of emulsion polymerization and can be translated into weight average diameters. A combination of an on-line spectrophotometer with an on-line densitometer (to obtain concentration) would provide the potential to estimate Dw on-line, as well. An on-line determination of PSD s, for small particles however, would seem quite difficult due to the high correlation of their parameters. One should bear in mind that the above conclusions have been validated only for poly(vinyl acetate) latexes the analysis is currently being extened to other systems, such as polystyrene and poly(methyl-methacrylate). 

Numerous methods for the deterrnination of monomer purity, including procedures for the deterrnination of saponification equivalent and bromine number, specific gravity, refractive index, and color, are available from manufacturers (68—70). Concentrations of minor components are deterrnined by iodimetry or colorimetry for HQ or MEHQ, by the Kad-Eisher method for water, and by turbidity measurements for trace amounts of polymer. 

Typical specifications for several common types or grades of acid are shown in Table 13. Similar limits are generally used for other sulfuric acid concentrations, with the exception of turbidity values for high strength acids (and oleum) and SO2 and nitrate values in oleums. Because kon sulfate is relatively insoluble in concentrated acids, the turbidities of 98—99% H2SO4 and oleum may be higher than shown, even at acceptable total kon concentrations. 

The microbial assay is based on the growth of l ctobacillus casei in the natural (72) or modified form. The lactic acid formed is titrated or, preferably, the turbidity measured photometrically. In a more sensitive assay, l euconostoc mesenteroides is employed as the assay organism (73). It is 50 times more sensitive than T. casei for assaying riboflavin and its analogues (0.1 ng/mL vs 20 ng/mL for T. casei). A very useful method for measuring total riboflavin in body fluids and tissues is based on the riboflavin requirement of the proto2oan cHate Tetrahjmenapyriformis which is sensitive and specific for riboflavin. 

Most surface waters contain varying amounts of suspended solids, including silt, clay, bacteria, and vimses and it is necessary to remove these before to distribution to the domestic or industrial consumer. Suspended soHds not only affect the acceptabiUty of the water but also interfere with disinfection. The principal treatment processes are sedimentation (qv) and filtration (qv). Sedimentation alone is rarely adequate for the clarification of turbid waters and is of htde or no value for the removal of such very fine particles as clay, bacteria, etc. Table 1 shows the effect of particle size on the sedimentation rate of a soHd having a specific gravity of 2.65 in water at 20°C. 

Blanking Schemes. Whereas most clinical assays rely on the specificity of the assay reaction to avoid interferences that would require a blank correction, certain ubiquitous interferences, eg, lipemic turbidity, hemoglobin in hemoly2ed sera, bilinibin [635-65-4] in icteric specimens,... 

These items are highly site specific. Power cost is low because the salinity removed by the selected plant is low. The quality of the feed water, its sahnity, turbidity, and concentration of problematic ionic and fouhng solutes, is a major variable in pretreatment and in conver-... 

Urokinase (from human urine) [9039-53-6] Mr 53,000, [EC 3.4.21.31]. Crystn of this enzyme is induced at pH 5.0 to 5.3 (4") by careful addition of NaCl with gentle stirring until the soln becomes turbid (silky sheen). The NaCl concentration is increased gradually (over several days) until 98% of saturation is achieved whereby the urokinase crystallises as colourless thin brittle plates. It can be similarly recrystd to maximum specific activity [104K CTA units/mg of protein (Sherry et al. J Lab Clin Med 64 145 1964)]. [Lesuk et al. Science 147 880 1965 NMR Bogusky et al. Biochemistry 28 6728 1989.] It is a plasminogen activator [Gold et al. Biochem J 262 1989 ]. 

The USA Military Specification (Ref 8) contains the following chemical criteria and requirements (1) As2Os by sodium thiosulfate—iodine titration 99.0% min, (2) As203 by carbonate-iodine titration 0.05% max, (3) Cl as AgCl turbidity 0.005% max, (4) heavy metals as PbS turbidity 0.010% max, (5) Fe as a Fe(CNS)3. 9KCNS.4H20 red coloration 0,010% max and (6) nitrate as an indigo carmen blue coloration which persists for over 5 mins... 

The caprolactam obtained must meet die specifications of permanganate number, volatile bases, hazen color, UV transmittance, solidification point, and turbidity in order to be used for repolymerization alone or in combination witii virgin CL.5 Reported CL purification methods include recrystallization, solvent extraction, and fractional distillation. One solvent extraction technique involves membrane solvent extraction. Ion exchange resins have been shown to be effective in the purification of aqueous caprolactam solutions. In one such process,... 

As expected for a WWTP effluent, turbidity and E. coli are higher than the specific standards for industrial wastewater reuse included in the new Spanish Regulation of Regenerated Wastewater (RD 1620/2007). Other parameters, such as conductivity or TDS may result in too much high level considering some specific industrial uses of water [11]. Therefore further treatment of the WWTP effluent is needed before reuse. 

Equation (li ) can be used to calculate uncorrected diameter averages. For the number, surface, volume, specific surface, weight and turbidity diameter averages (their definitions have been stated elsewhere (11,12), the following relations can be derived ... 

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