Sampling solid products

Ion chromatography has been successfully applied to the quantitative analysis of ions in many diverse types of industrial and environmental samples. The technique has also been valuable for microelemental analysis, e.g. for the determination of sulphur, chlorine, bromine, phosphorus and iodine as heteroatoms in solid samples. Combustion in a Schoniger oxygen flask (Section 3.31 )is a widely used method of degrading such samples, the products of combustion being absorbed in solution as anionic or cationic forms, and the solution then directly injected into the ion chromatograph. 

As most sensors are limited to single point probing, their application is confined to samples where the investigated point(s) are representative for the sample. Though this is the case for the majority of fluid samples, solid objects may not fulfil this requirement. This is true for high-tech products containing a wide range of different materials as well as e.g. in the food industry, where an item that is analysed as edible at one spot may very well be rotten at a different one. 

IR is one of three forms of vibrational spectroscopy that is in conunon use for process analytical measurements the other two being near-lR (NIR) and Raman. Each one of these techniques has its pros and cons and the ultimate selection is based on a number of factors ranging from sample type, information required, cost and ease of implementation. The sample matrix is often a key deciding factor. NIR has been the method of choice for many years within the pharmaceutical industry, and sample handling has been the issue, especially where solid products are involved. IR is not particularly easy to implement for the continuous monitoring of solid substrates. However, often there is no one correct answer, but often when the full application is taken into account the selection becomes more obvious. In some cases very obvious, such as the selection of IR for trace gas analysis - neither NIR nor Raman is appropriate for such applications. 

Melting points are important for determining the purity of solid products. A small amount of sample is packed into the closed end of a capillary tube with a wire or small glass rod. It is then attached to a thermometer, keeping the sample next to the bulb as shown (see Figure 19). Next submerge into oil filled tube, keeping setup in the middle of tube (do not touch the sides or bottom). Watch for temperature at which solid sample melts. 

The hydrochloride salt is stirred with 200 gm of ice water, and concentrated aqueous ammonia is added dropwise while maintaining a temperature between 0° and 20°C, until the pH of the aqueous phase reaches 8. The mixture is stirred for an additional hour at 10°-20°C. The solid product is filtered off, washed with 100 ml of cold water, and air-dried at 25o-30°C yield 14.5 gm (85%), m.p. 128o-130°C dec. In an attempt to recrystallize a sample of this product, it decomposed. 

Crystallization was followed by analyzing the solid product quantitatively by x-ray powder diffraction. Prepared mixtures of a standard sample of mordenite and the amorphous substrate of mordenite composition were used to establish a calibration curve for the quantity of mordenite based on the summation of x-ray peak intensities. For zeolites A and X, the unreacted aluminosilicate gel was used to prepare mixtures with standard samples of zeolites A and X for quantitative phase identification. 

Al-containing SBA mesoporous solid was prepared as reported 9 mL tetraethyl orthosilicate (TEOS) and the calculated amount of aluminum tri-tert-butoxide, in order to obtain a well defined Si/Al ratio equal to 10, were added to 10 mL of HC1 aqueous solution at pH=1.5 water. This solution was stirred for over 3 h and then added to a second solution containing 4 g triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EO20PO70EO20 Aldrich) in 150 mL of HC1 aqueous solution at pH=1.5 at 313 K. The mixture was stirred for another 1 h and allowed to react at 373 K for 48 h. The solid product was filtered, dried at 373 K, and finally calcined in air flow (9 L h 1) at 823 K for 4 h with a heating rate of 24 K h"1. The SBA-15 was prepared according to the literature [11]. In what follows, the samples are denoted AlSBA and SBA, respectively. 

The white crystalline solid product is pure enough for the next step, but an analytical sample is recrystallized as follows. A sample (0.45 g) is dissolved in dry dichloromethane (5 mL) and the solution is filtered through a 2-mL glass filter with 25- to 50-p porosity. The solution is then diluted with methanol (3 mL) and the dichloromethane is carefully distilled off on a steam bath. Crystallization begins almost immediately on cooling. After 2 h at room temperature, the mixture is placed in the freezer ( — 25°C) for 15 h. The mixture is filtered through a 2-mL glass filter with 25- to 50-p porosity and the white crystalline solid is washed with three 5-mL portions of methanol... 

The condensation reaction was carried out in a stirred 50 cm3 glass flask under a reflux condition. The reaction temperature was maintained by a heated silicon oil bath surrounding the reactor, and measured by a mercury thermometer immersed into the reaction mixture. After the reaction, the solid product and catalyst were separated from the reaction solution by filtration. The product was dissolved in ethyl acetate and separated from the catalyst particles by another filtration. The product was washed by water and then dried over MgS04. Analysis of the product was made with a 1IPLC (Waters 990) equipped with a —Porasil column. A 30% ethyl acetate in hexane was used as an eluent. The conversion of IICHO, the limiting reactant, was calculated from the isolated solid product. The selectivity was calculated by comparing the peak area of the main product with that for an authentic 4,4 —MDU sample. 

All the as-synthesized samples ofTi-MWW-PI and Ti-MWW-HM showed the XRD patterns totally consistent with those of the lamellar precursor of MWW topology, generally designated as MCM-22(P) [64, 65], Upon calcination at 803 K, all the samples were converted into the porous three-dimensional (3D) MWW structure with good quality. The amount of B incorporated into the produds was in the Si/B range 11-13, which is far lower than that in the gel with a Si/B ratio of 0.75. In contrast, there was little difference in the Si/Ti ratios between the gel and the solid product, except for the gel of Si/Ti = 100, indicating that the synthesis system is very effedive for Ti incorporation. 

This method has a number of positive features it may be applied to most supercritical fluids with critical temperatures close to ambient deposition of the solid product occurs in a controlled manner, if necessary under an inert atmosphere and the high pressure "stabilizing" conditions are maintained right up to the point of precipitation. The precipitated solid product may then be analysed and characterised by other off-line spectroscopic techniques. In our example, the 13C-NMR spectrum of the solid material, redissolved in d8-toluene, shows the same resonances as those observed with a genuine sample of Cr(CO)4(C2H4)2. 

The technical feasibility of such an approach is demonstrated in Table IV, where data obtained on a sample of Illinois No. 5 seam cleaned coal from an Illinois Basin operating mine was processed by supercritical extraction. The cleaned coal had a total sulfur content of 1.5 % processing this physically cleaned coal for 1 hour at 350C in methanol with 5% K0H reduced the total sulfur concentration to 0.75 % The solid product, which retained 56 % of the original volatile matter concentration, exhibited a value of 1.1 lb SC / million BTU, thus meeting the existing new performance standard of 1.2 lb SO2/ million BTU. 

The reaction flask is cooled to —78°C., and a 1.05-g. (13.8-mmole) sample of trimethylphosphine, measured as a gas, is introduced. The colorless solution wrhich forms is allowed to warm to room temperature and is stirred for an hour. Solvent is removed slowly under vacuum, and the white solid which remains is pumped for one hour under high vacuum. Dry nitrogen is admitted, and the flask is removed from the vacuum line. The solid product is broken up with a spatula and washed from the flask with ether. It is collected by filtration, washed with 50 ml. of ether in small portions, and allowed to air-dry in the hood for half an hour. Yield is 3.5 g. (87%). The white salt is pure [H2B P(CH8)8 2]+I as judged by its infrared spectrum, but it has a strong trimethylphosphine odor. 

The water slurry of SP-300 was acidified to pH 2 with 10% HCL to obtain two forms of precipitates one was lumpy and the other was powder-like. After separation from the solution, each form of precipitate was dried. The former was designated as fraction I and the latter, fraction J. The solid product from SP-300 was acidified, separated from the solution and dried. Then the product was extracted with pyridine at room temperature with a solvent/sample ratio of 10. The soluble portion was called fraction K. Thus SP-300 was divided into four fractions fractions I, J, K, and Pyridine-Insoluble. Likewise, SP-320 was divided into four fractions fractions I Jf, K, and Pyridine-Insoluble. Figure 1 summarizes the procedures used in the preparation of all CDL products. Elemental compositions, molecular weight, nuclear magnetic resonance and infrared spectra were obtained for each major fraction. Details of the preparation of specific fractions of HVL-P and solubilization products and analyses can be found elsewhere (13,14). 

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