Concentration ranges

Using the Gibbs-Diihem equation ((A2.1.27) with dT = 0, dp = 0), one can show that the solvent must obey Raoult s law over the same concentration range where Hemy s law is valid for the solute (or solutes) ... 

Concentration methods frequently have both lower and upper limits for the amount of analyte that can be determined. The lower limit is dictated by the smallest concentration of analyte producing a useful signal and typically is in the parts per million or parts per billion concentration range. Upper concentration limits exist when the sensitivity of the analysis decreases at higher concentrations. 

Accuracy When spectral and chemical interferences are minimized, accuracies of 0.5-5% are routinely possible. With nonlinear calibration curves, higher accuracy is obtained by using a pair of standards whose absorbances closely bracket the sample s absorbance and assuming that the change in absorbance is linear over the limited concentration range. Determinate errors for electrothermal atomization are frequently greater than that obtained with flame atomization due to more serious matrix interferences. 

Directions for preparing a potentiometric biosensor for penicillin are provided in this experiment. The enzyme penicillinase is immobilized in a polyacrylamide polymer formed on the surface of a glass pH electrode. The electrode shows a linear response to penicillin G over a concentration range of 10 M to 10 M. 

Analyte Sample Volume Sample (liL) Concentration Range Sampling Frequency (h-1)... 

These normal stresses are more pronounced for polymers with a very broad molecular weight distribution. Viscosities and viscoelastic behavior decrease with increasing temperature. In some cases a marked viscosity decrease with time is observed in solutions stored at constant temperature and 2ero shear. The decrease may be due to changes in polymer conformation. The rheological behavior of pure polyacrylamides over wide concentration ranges has been reviewed (5). 

Hexafluorozirconic acid [12021 -95-3]], H2ZrP, is formed by dissolving freshly prepared oxide, fluoride, or carbonate of zirconium in aqueous HP. This acid is produced commercially in a concentration range of 10 to 47%. The acid can be stored at ambient temperatures in polyethylene or Teflon containers... 

Formaldehyde is sold in aqueous solutions with concentrations ranging from 25 to 56 wt % HCHO. Product specifications for typical grades (18,117—119)... 

The effect of pressure on the solubility of chlorine ia hydrochloric acid has been reported for pressures varying from about 100 to 6500 kPa (1—6.5 atm) (20). At pressures above 200 kPa, there is a linear dependence of pressure on the solubility in the acid concentration range of 0.1—5.0 N. 

Analytical Methods. Most analytical methods use the oxidizing power of iodine for its deterrnination. The results are generaHy expressed as an equivalent concentration of elemental iodine. The choice of a method for the analysis of iodine depends on the concentration range to be deterrnined. 

The recovery of vanadium from these slags is of commercial interest because of the depletion of easily accessible ores and the comparatively low concentrations (ranging from less than 100 ppm to 500 ppm) of vanadium in natural deposits (147,148). In the LILCO appHcations the total ash contained up to 36% 20 (147). Vanadium is of value in the manufacture of high strength steels and specialized titanium alloys used in the aerospace industry (148,149). Magnesium vanadates allow the recovery of vanadium as a significant by-product of fuel use by electric utiUties (see Recycling, nonferrous LffiTALS). 

HMnO 2H20 [24653-70-1] decomposes at 18°C. Aqueous solutions of permanganic acid below a concentration of 3 wt % are stable over time, whereas in the concentration range of 5—15% HMnO, the decomposition rate increases with increasing initial solution concentration at room temperature (103). 

When the spent sulfuric acid must be reconcentrated, it has been found that reconcentration to 100% sulfuric acid is not necessary (13). An energy savings can be realized if the sulfuric acid is concentrated under a vacuum to only 75—92%. If the process is carried out at 130—195°C, these medium concentration ranges are sufficient to destroy trace organics, thus preventing any loss in the efficiency or capacity of the nitration process. This process is adaptable to existing manufacturing installations. 

Sulfite concentrations for scavenging oxygen ate typically in the 100— 300 mg/L range. Zinc compounds for sulfide scavenging ate used at concentrations of 1.4—14 kg/m (0.5—5 lb/bbl) synthetic magnetite concentrations range to 140 kg/m (50 lb/bbl) and higher if the need arises. 

Ha/ogenation. Heats of reaction are highly exothermic for halogens, particularly fluorine (qv), and chain reactions can result in explosions over broad concentration ranges. Halogens also present severely challenging corrosion problems (see Corrosion and corrosion control). 

These data together with those from wastewater treatment plants at Darmstadt, Germany Gothenburg and Stockholm, Sweden and Noord-Brabant, the Netherlands, show that the concentrations of DEHP, and in some cases total phthalates, entering wastewater treatment plants vary from 1 to 167 )-lg/L. After treatment the concentrations range from <1 to 36.8 )-lg/L. 

These photoinitiators or photocatalysts are usually added to the reactive coating formulations in concentration ranges from less than 1 to 20 wt % based on the total formulation. 

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