Acrylic acid sampling techniques

X-ray diffraction has been applied to certain AB cements. For example. Crisp et al. (1979), in a study of silicate mineral-poly(acrylic acid) cements, used the technique both to assess the purity of the powdered minerals employed and to monitor mineral decomposition in mixtures with poly(acrylic acid), in order to indicate whether or not cement formation had taken place. They employed Cu radiation passed through a nickel filter for most of the samples, a seven-hour exposure time was found to be adequate for the development of a discernible diffraction pattern. Samples were identified by reference to published powder diffraction data. 

Ionized gels were acrylic acid-sodium acrylate copolymers. The samples were provided by Norsolor Company. The gels were obtained through an inverse suspension process. In this technique, the aqueous phase, containing an hydrophilic monomer, was dispersed in an organic phase, such as an alicyclic or aliphatic hydrocarbon. 

By a surface imprinting technique, in Zhang H. et al., 2011, a comfX)site imprinted material, on the basis of a MWCNTs-incorporated layer using melamine as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethaciylate as a cross-linker, was synthesized. In this work, the poly(acrylic-acid)-functionalized CNTs were synthesized to increase the diameter of CNTs. Then, the vinyl group was introduced to the surface of poly(acrylic-acid)-functionalized CNTs by an amidation Using Melamine as a template molecule, imprinted CNT composite material was fabricated by a thermal fX)lymeiization. Applied as a sorbent, the imprinted materials were used for the determination of Melamine in the spiked sample by online SPE combined with HPLC. 

In order to obtain quantitative results by HS-GC, the system must be calibrated. Absolute quantitation is not possible. Quantification can be done by the conventional external calibration method with liquids containing the analytes concerned in known concentrations or by means of standard addition. Pausch et al. [958] have developed an internal standard method for solid headspace analysis of residuals in polymers in order to overcome the limitations of external standardisation cfr. Chp. 4.2.2 of ref. [213a]). Use of an internal standard works quite well, as shown in case of the determination of residual hydrocarbon solvent in poly(acrylic acid) using the solid HS-GC-FID approach [959]. In the comparison made by Lattimer et al. [959] the concentrations determined by solid HS-GC exceeded those from either solution GC or extraction UV methods. Solid HS-GC-FID allows sub-ppm detection. For quantitative analysis, both in equilibrium and non-equilibrium conditions, cfr. ref. [960]. Multiple headspace extraction (MHE) has the advantage that by extracting the whole amount of the analyte, any effect of the sample matrix is eliminated the technique is normally used only for method development and validation. 

The apparatus is described and details given of its use with PETP homopolymer, PS/poly(vinyl methyl ether) miscible blend and styrene-styrenesulphonic acid copolymer/ethyl acrylate-4-vinylpyridine copolymer ionomer blend with ionic interactions. Orientation and relaxation curves were obtained for all three samples. It is concluded that the technique is very efficient for obtaining curves with high precision. For these three systems, the relaxation rate increases with temperature. 

Figure 3 Graphical representation of the relative extraction effectiveness of a series of carboxylic acids using 100-pm polydimethylsiloxane (PDMS) and 85-pm polyacrylate (Acrylate) SPME fibers. The acids were dissolved in water at a concentration of 10 ppm each and the solutions were sampled using the headspace technique. The effect of dissolving 25% NaCl in the solutions is also represented. A 3-mL vial containing 1 mL of solution was used for the experiment and the adds were monitored by capillary GC (30 m X 0.25 mm DB-1, 1 p film, flame ionization detection, injector temperature 235°C, split flow 8 mL/min, fiber desorb time 1.0 min).

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