Phthalates, extraction

Serum samples and autopsy specimens were examined from two infants with congenital diaphragmatic hernia who had received life support with extracorporeal membrane oxygenation (ECMO). The serum levels of di(2-ethylhexyl) phthalate after 14 and 24 days of ECMO support were 26.8 and 33.5 mg/L respectively, and levels of 3.5, 1.0 and 0.4 mg/kg di(2-ethylhexyl) phthalate were found in liver, heart and testicular tissues, respectively, and trace quantities were found in the brain. The rate of di(2-ethylhexyl) phthalate extraction from the model PVC circuits was linear with time (rate, 3.5 and 4.1 mg/L per hour). The exposure to di(2-ethylhexyl) phthalate for a 4-kg infant on ECMO support for 3-10 days was estimated to be 42-140 mg/kg (Shneider et al., 1989). 

One of the first applications of SPME to phthalate analysis was the development of a method for the extraction of DEP from water. The final analysis was done by LC-UV. Different parameters were optimized including four types of fibers. Carbowax-template resin (CW-TRP) and polydimethylsiloxane-divinylbenzene (PDMS-DVB) were found suitable to perform phthalate extraction. The other two fibers, polyacrylate (PA) and polydimethylsiloxane (PDMS), were discarded due to low response and broad peaks, respectively. Samples were extracted at room temperature by direct exposition of the fiber to the sample, previously enriched with 25% of NaCl. The linearity achieved was good from 5 to 50 /rg/1. Higher concentrations show a lost of linearity that could suggest the saturation of the fiber coating. Detection limit was 1 ng/ml. 

Tick s second law of diffusion was used to model removal of plasticizer from packaging films using different solvents to simulate the extracting action of food products. Good agreement between the model and the experiment was obtained. The rate of di-(2-ethylhexyl) phthalate extraction depends on its content in PVC (for 50% plasticizer, the extraction rate was 30 g m h" and for 35% plasticizer in formulation, the extraction rate was 2.3 g m h" This is an example of mutual (cooperative) diffiisioa The plasticizer is replaced by solvent. In another study of cooperative diffusion of DOP in dilute solution of polystyrene, a temperature decrease to the neighborhood of the glass transition temperature had profound effect on solvent mobility and thus on the diffusion proeess. Further theoretical discussion of mutual diffusion can be found elsewhere. ... 

Plasticizers. Monomeric (mol wt 250—450) plasticizers (qv) are predominantiy phthalate, adipate, sebacate, phosphate, or trimeUitate esters. Organic phthalate esters like dioctyl phthalate (DOP) are by far the most common plasticizers in flexible PVC. Phthalates are good general-purpose plasticizers which impart good physical and low temperature properties but lack permanence in hot or extractive service conditions and are therefore sometimes called migratory plasticizers. Polymeric plasticizers (mol wt up to 5000 or more) offer an improvement in nonmigratory permanence at a sacrifice in cost, low temperature properties, and processibiHty examples are ethylene vinyl acetate or nitrile polymers. 

The method of detecting dimethylterephthalate (DMTP), dibuthyl-phthalate (DBP) and diocthylphthalate (DOP) in aqueous extract is based on their extraction with an organic solvent (hexane) and subsequent concentration using gas-liquid chromatography and an electron-absorbing detector. The detection limit is 0.05 mg/dirf for DMTP and DBP, and 0,01 mg/dm for DOP. 

Methyl-2-pentanol [108-11-2] M 102.2, b 131-132", d 0.810, n 1.413. Washed with aqueous NaHC03, dried and distd. Further purified by conversion to the phthalate ester by adding 120mL of dry pyridine and 67g of phthalic anhydride per mole of alcohol, purifying the ester and steam distilling it in the presence of NaOH. The distillate was extracted with ether, and the extract was dried and fractionally distd. [Levine and Walti 7 Bio/ Chem 94 367 1931],... 

All PVC plasticisers have a solubility parameter similar to that of PVC. It appears that differences between liquids in their plasticising behaviour is due to differences in the degree of interaction between polymer and plasticiser. Thus such phosphates as tritolyl phosphate, which have a high degree of interaction, gel rapidly with polymer, are more difficult to extract with solvents and give compounds with the highest brittle point. Liquids such as dioctyl adipate, with the lowest interaction with polymer, have the converse effect whilst the phthalates, which are intermediate in their degree of interaction, are the best allround materials. 

Certain higher phthalates are also available. For example, ditridecyl phthaiate and di-isodecyl phthaiate are used in high-temperature cable insulation, the former having the better high-temperature properties. Because of its greater hydrocarbon nature than DIOP, di-isodecyl phthaiate has lower water extract-ability and is used, for example, with epoxidised oils in baby-pants. 

The thin-layer technique (CA 60, 6691) utilizes aliquots of proplnt ether extract (I) and the ether soln (II) of a known mixt. II consists of nitrates of glycerol and glycol, di-Bu or di-Et phthalates, Et or Me centralites, DNT, and diphenylamine. The chromatoplates are made of 85 15 silica gel and plaster of Paris. These plates, containing spots of I and 11, are developed with 1 1 C6H6-petroleum ether, then sprayed with specific detectors by color. The method is much quicker and easier than chemical analysis and simpler than infrared spectroscopy and column chromatography... 

Metabolites may also play a role in the association of the substrate with humic and fulvic acid components. Two illustrations are given (a) naphth-l-ol, an established fungal metabolite of naphthalene, may play a role in the association of naphthalene with humic material (Burgos et al. 1996) and (b) it has been shown that C-labeled metabolites of [9- C]-anthracene including 2-hydroxyanthracene-3-carboxylate and phthalate were not extractable from soil with acetone or dichloromethane, and required alkaline hydrolysis for their recovery (Richnow et al. 1998). 

In the biocatalytic system, a second organic phase consisting of bis(2-ethyUiexyl)phthalate and containing the substrate is added at a phase ratio of 1 1. This procedure enables in situ product extraction and protects the microbial cells from toxic effects of the substrate and... 

In the framework of the phthalate controversy Wilkinson and Lamb [109] used various in vitro methods in which known amounts of soft PVC materials were shaken, stirred, impacted, or otherwise mechanically agitated in some type of simulated saliva under controlled conditions (T, f), and the saliva extracted into hexane for analysis. Shaking-flask (liquid-liquid) extraction was also used for the solvent extraction of nonionic surfactants of the general type R0(CH2CH20) H (where R... 

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. 

MAE has also been used for the extraction of adipate plasticisers from PVC [464]. The efficiency of MAE depends on the kind of solvent, the temperature achieved and the heating time. The final temperature reached depends on the microwave power, number of vessels and irradiation time. Higher recovery values than SEE were reported for both phthalate and adipate. Other reports on microwave-assisted solvent extraction have appeared [465-467]. 

Work is in progress to validate the MAE method, proposed for EPA, in a multi-laboratory evaluation study. Nothing similar has been reported for additives in polymeric matrices. Dean el al. [452] have reviewed microwave-assisted solvent extraction in environmental organic analysis. Chee et al. [468] have reported MAE of phthalate esters (DMP, DEP, DAP, DBP, BBP, DEHP) from marine sediments. The focus to date has centred on extractions from solid samples. However, recent experience suggests that MAE may also be important for extractions from liquids. 

RPLC-PDA is frequently used for quality control, such as the determination of free Irganox 1098 in PA4.6 (at 278 nm after dissolution/precipitation), of free Irganox 1010/1076 in PP (at 278 nm after extraction with MTBE, thus avoiding dissolution of polymer waxes), of Luperco 802 in PP (at 218 nm, after extraction with HCC13), and of Tinuvin 122 in HDPE (at 225 nm as diol). The advantages of the use of HSLC over conventional LC in QC of plastics and additives have been demonstrated, e.g. for AOs in PE, mixed phthalate esters and residual terephthalic acid in PET and partially cured epoxy resins [557],... 

More problems are encountered with plasticisers because most extracts from polymer compositions are mixtures and, when separated by TLC, the amount of the individual fractions is often too small for convenient examination by 1H 1-NMR spectroscopy. Moreover, the original plasticisers themselves are often mixtures. For example, tricresyl (tritolyl)phosphate is based on mixed cresols, while most of the higher phthalate esters are based on complex mixtures of alcohols. 

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