Acrylic acid Analytes

Brandt [200] has extracted tri(nonylphenyl) phosphite (TNPP) from a styrene-butadiene polymer using iso-octane. Brown [211] has reported US extraction of acrylic acid monomer from polyacrylates. Ultrasonication was also shown to be a fast and efficient extraction method for organophosphate ester flame retardants and plasticisers [212]. Greenpeace [213] has recently reported the concentration of phthalate esters in 72 toys (mostly made in China) using shaking and sonication extraction methods. Extraction and analytical procedures were carefully quality controlled. QC procedures and acceptance criteria were based on USEPA method 606 for the analysis of phthalates in water samples [214]. Extraction efficiency was tested by spiking blank matrix and by standard addition to phthalate-containing samples. For removal of fatty acids from the surface of EVA pellets a lmin ultrasonic bath treatment in isopropanol is sufficient [215]. It has been noticed that the experimental ultrasonic extraction conditions are often ill defined and do not allow independent verification. 

Acrylic acid (AA) and methacrylic acid (MAA) (purchased from Merck) are freed from inhibitor on a neutral aluminium oxid column and distilled. Acrylamide (AM) from Kebo, Stockholm, is recrystallized once from chloroform solution before use. Other monomers of analytical grade were purchased from Merck and used as received crotonic acid (CA), tiglic acid (TA), 3-methyl crotonic acid (3-MCA), and a-methyl cinnamic acid (oi-MCia) (Table 1). Benzophenone (analytical grade, Kebo) and acetone (spectroscope grade, Merck) were used as supplied. 

Analysis for Poly(Ethylene Oxide). Another special analytical method takes advantage of the fact that poly (ethylene oxide) forms a water-insoluble association compound with poly (acrylic acid). This reaction can be used in the analysis of the concentration of poly(ethylene oxide) in a dilute aqueous solution. Freshly prepared poly (acrylic acid) is added to a solution of unknown poly(ethylene oxide) concentration. A precipitate forms, and its concentration can be measured turbidimetrically. Using appropriate calibration standards, the precipitate concentration can then be converted to concentration of poly(ethylene oxide). The optimum resin concentration in the unknown sample is 0.2—0.4 ppm. Therefore, it is necessary to dilute more concentrated solutions to this range before analysis (97). Low concentrations of poly(ethylene oxide) in water may also be determined by viscometry (98) or by complexation with KI3 and then titration with Na2S203 (99). 

The pyrolysate of polyacrylic-/nfer-nef-polysiloxane copolymer contains as main fragment molecules pyrolysis products similar to those of poly(butyl acrylate) and of poly(dimethylsiloxane (see Figure 6.7.8. and Section 16.1). The identification of fragments that would indicate sequences of other comonomers or any molecular connections between the two types of comonomer units was not possible. Other copolymers with acrylic acid as comonomer were studied using analytical pyrolysis. Among these are copolymers with special properties such as the copolymer with the formula shown below ... 

We chose 2-chlorotrityl chloride resin for the attachment of acrylic acid, because in solution-phase chemistry the best results have been obtained by using aryl acrylates or (erf-butyl acrylates [21], In addition to DABCO (1,4-diazabicyclo [2.2.2]octane) - the most common tertiary cyclic amine for this type of reaction - we also used the more reactive 3-quinuclidinol (3-hydroxy-quinuclidine, 3-HQN) for the Baylis-Hillman reaction with aldehydes. We used 26 different aldehydes and obtained good to excellent purities, as determined by analytical HPLC. 

There are two possibilities for converting polymer-bound 3-hydroxy-2-methylidene propionic acids into 2-diethoxy-phosphorylmethyl acrylic acids. One is the treatment of these substrates with diethyl chlorophosphite and Et3N followed by an Arbuzow rearrangement. The other method, which resulted in higher purities [28], is the reaction of acetylated 3-hydroxy-2-methylidene propionic acids with triethylphosphite in DMF for 5 h at 60°C (Fig. 6.12). Table 6.6 shows the variation of the aldehydes in this reaction. All compounds were analyzed by ES-MS and analytical HPLC. 

On the other hand, we reexamined in detail the ring size of the cyclic structural units of poly-AA s by means of IR, 1H-NMR, and C-NMR spectroscopy these analytical procedures were applied to the structural analysis of poly-AA, the poly(acrylic acid) derived from hydrolysis of the poly-AA, and the poly(methyl acrylate) obtained by subsequent esterification of the poly(acryl-ic acid) in comparison with the corresponding model polymers of five- or six-membered ring structure. Then, we investigated in detail the effects of polymerization conditions on the ring size of poly-AA s, i.e., on the intramolecular addition modes in the cyclopolymerization of AA since five- or six-membered ring anhydride structure can be formed via intramolecular hh or ht addition of the uncyclized radical to the internal double bond(22,23). 

Liquid-liquid extraction of short-chain organic acids, ketoacids, or dicarboxylic acids result in low and often unreproducible extraction yields due to the hydrophilic character of the analytes. However, some authors report reproducible results for short-chain acids at mg/1 concentrations after liquid-liquid extraction at pH 2, although extraction yields remain low. Note also that organic solvents, namely diethylether, may be contaminated with organic acids. An unusual variation in liquid-liquid extraction is the use of tri-n-octylphosphine oxide (TOPO) in methyl-tert-butylether (MtBE) to enhance extraction yields, e.g., of acrylic acid in marine waters and of organic acids in aqueous solutions obtained from air collection chambers." TOPO s very low solubility in water and its high polarity make it suitable for extraction of polar compounds. The extraction yield for acrylic acid was 40% and its detection limit after derivatization with pentafluorobenzyl bromide was estimated to be 3 nM. ... 

All inorganic salts used as supporting electrolytes were of analytical grade. The monomers acrylamide (Feinchemie Sebnitz), acrylic acid (Fluka), methylenediacrylamide (Merck), methacrylamide (Roehm) and its cationic form trimethylammoniumpropylmeth-acrylamide-chloride (Roehm) as well as methacrylic acid (Roehm) were of pure grade. 

Lattimer RP (2003) Pyrolysis mass spectrometry of acrylic acid polymers. Journal of Analytical and Applied Pyrolysis 68-69 3-14. 

Impurities in the solvent may also be curable of fluorescing. For example, acrylonitrile, acrolein, and acrylic acid impurities and their adducts with mobile phase components will fluoresce under the prefer conditions. This also happens when trifluoroacetic acid is a mobile phase modifier and amine impurities are in the mobile phase. The result is the appearance of spurious chromatographic peaks. As in UV absorbance techniques, these peaks are of variable size when a gradient is used and the size of the peak is directly proportional to the amount of solvent pumped onto the column between gradients. If such solvent combinations are used, then it is recommended that the fluorescence output of the solvent mixture be monitored prior to analytical use. 

The monomer acrylic acid (AA), comonomer maleic acid (MA), initiator ammonium per sulfate (APS) and crosslinker N,N -methylenebisaciylamide (NMBA) of analytical grade were purchased from Hi Media, Mumbai, India. The chemical structures of these materials were as given in scheme l(a-e). Potassium lydroxide (KOH) used for neutralization of AA was procured from Merck, India. Methylene blue (MB) for adsorption study was purchased from Spectrum chemicals. 

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