Weight percent determination

The identity of indapamide can also be determined by an elemental weight percent determination of carbon, hydrogen and nitrogen. The elemental analysis of an indapamide sample is performed and the results are compared to the following theoretical values (12). 

The amount of oxalic acid in a sample of rhubarb was determined by reacting with Fe as outlined in reaction 2.2. In a typical analysis, the oxalic acid in 10.62 g of rhubarb was extracted with a suitable solvent. The complete oxidation of the oxalic acid to CO2 required 36.44 mb of 0.0130 M Fe. What is the weight percent of oxalic acid in the sample of rhubarb ... 

Using X-ray diffraction, Karstang and Kvalhein reported a new method for determining the weight percent of kalonite in complex clay minerals To test the method, nine samples containing known amounts of kalonite were prepared and analyzed. The results (as %w/w kalonite) are shown. 

Directions are provided for preparing and using a simple coring device using PVC pipe. This experiment also details a procedure for determining the weight percent of organic material in sediments as a function of depth. 

Alkalinity (Soluble Soda) Determination. The surface alkalinity or soluble or leachable soda is determined by making a fixed weight percent slurry in water and determining the alkalinity of the solution by pH measurement or acid titration. Sodium ion-sensitive electrodes have been investigated. 

The thermal glass-transition temperatures of poly(vinyl acetal)s can be determined by dynamic mechanical analysis, differential scanning calorimetry, and nmr techniques (31). The thermal glass-transition temperature of poly(vinyl acetal) resins prepared from aliphatic aldehydes can be estimated from empirical relationships such as equation 1 where OH and OAc are the weight percent of vinyl alcohol and vinyl acetate units and C is the number of carbons in the chain derived from the aldehyde. The symbols with subscripts are the corresponding values for a standard (s) resin with known parameters (32). The formula accurately predicts that resin T increases as vinyl alcohol content increases, and decreases as vinyl acetate content and aldehyde carbon chain length increases. 

Bentonite has expected sihca content of 0.5 weight percent (F is 0.005). Silica density (A ) is 2.4 gm per cii cm, and bentonite (Ag) is 2.6. The calculation requires knowledge of mineral properties described by the factor (fghd ). Value of the factor can be estabhshed from fundamental data (Gy) or be derived from previous experience. In this example, data from testing a shipment of bentonite of 10 mesh top-size screen analysis determined value of the mineral factor to be 0.28. This value is scaled by the cube of diameter to ys-in screen size of the example shipment. The mineral factor is scaled from 0.28 to 52 by multiplying 0.28 with the ratio of cubed 9.4 mm (ys-in screen top-size of the shipment to be tested) and cubed 1.65 mm (equivalent to 10 mesh). 

Several components of the organic phase contribute greatly to the character of the final product. The pore size of the gel is chiefly determined by the amount and type of the nonsolvent used. Dodecane, dodecanol, isoamyl alcohol, and odorless paint thinner have all been used successfully as nonsolvents for the polymerization of a GPC/SEC gel. Surfactants are also very important because they balance the surface tension and interfacial tension of the monomer droplets. They allow the initiator molecules to diffuse in and out of the droplets. For this reason a small amount of surfactant is crucial. Normally the amount of surfactant in the formula should be from 0.1 to 1.0 weight percent of the monomers, as large amounts tend to emulsify and produce particles less than 1 yam in size. 

Active matter (anionic surfactant) in AOS consists of alkene- and hydroxy-alkanemonosulfonates, as well as small amounts of disulfonates. Active matter (AM) content is usually expressed as milliequivalents per 100 grams, or as weight percent. Three methods are available for the determination of AM in AOS calculation by difference, the two-phase titration such as methylene blue-active substances (MBAS) and by potentiometric titration with cationic. The calculation method has a number of inherent error factors. The two-phase titration methods may not be completely quantitative and can yield values differing by several percent from those obtained from the total sulfur content. These methods employ trichloromethane, the effects from which the analyst must be protected. The best method for routine use is probably the potentiometric titration method but this requires the availability of more expensive equipment. 

V0x/Zr02 catalysts were designated as ZVx(y)pHz, where x gives the analytical vanadium content (weight percent), y specifies the preparation method (a, adsorption, i, impregnation or acac, acetylacetonate) and z the AV solution pH. The V-content was determined by atomic absorption (Varian Spectra AA-30) after the sample had been dissolved in a concentrated (40%) HF solution. 

The response factor of the product was determined by preparing a concentration series and analyzing as above using Method 5. The weight percent yield of the cis-1,2/1,4 product as shown in scheme 5 calculated as a function of time and is shown in Table 3 and Figure 16. The product is formed in almost 40% yield within 3 minutes of the start of the reaction. 

Under some conditions, it is difficult to incorporate an internal standard into a method. If the chromatogram is very complex, an internal standard may interfere with quantitation of a peak of interest. The development of highly precise sample transfer techniques, including modem autoinjectors, reduces the dependence of the experimentalist on the use of an internal standard to correct for effects of dilution and transfer losses. In many cases, external standardization can be used effectively. The weight percent purity is determined by comparing the area of each peak in a chromatogram with those generated by separately injected pure standards of known concentration. 

To determine the weight percent of compounds 2 and 3 of the LANA reaction presented in scheme 3, Method 6 was developed as an external standard technique. Figure 17 shows a typical chromatogram. 

To determine the weight percent of each compound in the reaction sample, a standard and sample of known weight concentration were prepared and analyzed. The weight percent of each component purity was determined as described in the External Standard Method. 

Table I summarizes conditions for the synthesis of two series of PDMAAm-1 -PIBs. The samples are identified by a code consisting of a letter and two numbers the letter (A) denotes the hydrophilic monomer DMAAm, whereas the two numbers indicate the Mn of the starting MA-PIB-MA (divided by 1,000) and the weight percent of PIB in the network (determined by elemental analysis). For example, A-4-26 denotes an amphiphilic network prepared with DMAAm as the hydrophilic moiety, containing a Mn=4,000 MA-PIB-MA, whose composition is 26% PIB.

Using zinc oxide as the internal standard, the relative amounts of two polymorphic forms of fenretinide were quantified [55], Mixtures containing 25, 50, and 75% w/w form I were prepared by mixing authentic standards of form I and form II fenretinide. After the addition of the internal standard, the maximum intensities (peak heights) of the 4.6 A line (peak at 19.1° 20) of fenretinide form I (/19. i) and the 2.8 Aline (peak at 31.8° 20) of zinc oxide (/318) were determined. A plot of the intensity ratio (/19.//31.8) as a function of the weight percent form I was linear. The method was reported to be precise and accurate to within 6%. 

The elemental compositions in weight percent of the four samples coded Brine Surge 1, Brine Surge 2, MBL-1A and MBL-1B collected from brine surge tank and MBL-1 sampling points were determined by EDX analysis. The clays are composed dominantly of 02 ( 70-80 wt. %) and Si ( 10-15 wt. %), and minor amounts of Na, Mg, and Al (below 5 wt.%). Trace to nil K, Ca, Fe, Mn, Zn, and Cl are also present. In MBL-1 B, however, significant amounts of Fe ( 6.5 wt. %) is present in the sample. These elemental compositions are consistent with the general formula of smectite as will be discussed later. 

XAS provides a powerful probe of both physical and electronic structure of an element within a sample, and has the ability to determine the molecular level speciation of As, Mo and Se over the concentration range of 50 pg/g to several weight percent (typical of mine tailings solids) (Brown et al. 1998) at the micron to mm scale. 

To form the process model, regression analysis was carried out. The alkylate yield x4 was a function of the olefin feed xx and the external isobutane-to-olefin ratio jc8. The relationship determined by nonlinear regression holding the reactor temperatures between 80-90°F and the reactor acid strength by weight percent at 85-93 was... 

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