Phthalate esters, determining

In addition to EPA procedures, other agencies and organisms such as the U.S. Department of Energy (DOE), the American Public Health Association (APHA), NIOSH and OSHA have issued standard procedures for dealing with phthalate ester determination. 

List of Phthalate Esters Determined and Their Physicochemical Properties... 

The phthalate esters are one of the most widely used classes of organic esters, and fortunately they exhibit low toxicity (82). Because of the ubiquitous nature of phthalates, many iavestigations have been conducted to determine their toxicides to marine life as well as ia mammals (83—85). Generally, phthalates are not absorbed through the skin and are not very potent when inhaled. The phthalates become less toxic as the alcohol group increases in molecular weight. For example, dimethyl phthalate has an oral LD q (mouse) of 7.2 g/kg, whereas di(2-ethylhexyl) phthalate shows an oral LD q (rat) of greater than 26 g/kg. 

Fatoki, O.S. and Ogunfowokan, A.O. (1993). Determination of Phthalate ester plasticizers in the Aquatic environment of Southwestern Nigeria. Environment International 19, 619-623. 

SPE has been applied to phthalate esters (plasticisers in PVC), polar pesticides (agricultural usage) and for other continuous pollution monitoring problems and environmental analyses [272]. For these applications SPE has largely displaced LLE as the preferred technique for the preparation of liquid samples, e.g. EPA method 506 is concerned with the determination of phthalates and adipate esters in drinking water. 

C12 to C20, primarily Ci6 to ( is), used as surface lubricants in the manufacture of food-contact articles. The method, which uses ethyl palmitate (Eastman Chemicals No. 1575 Red Label) as an internal standard, has been validated at 200 ppm total FAME [185]. Other FAME standards (methyl palmitate, methyl stearate, methyl oleate, methyl linoleate and methyl linolenate) are available (Applied Science Laboratories) [116], Worked out examples of additive determinations are given in the Food Additives Analytical Manual [116], which also describes a great many of indirect food additives, such as BHA, BHT, TBHQ, l-chloro-2-propanol, DLTDP, fatty acid methyl esters, w-heptyl-p-hydroxybenzoate, propyl-gallate, sodium benzoate, sodium stearoyl-2-lactylate, sorbitol and phenolic antioxidants. EPA methods 606 and 8060 describe the CGC separation of phthalate esters (direct injection) (cf. Figure 4.2). 

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],... 

Penalver A, Pocurull E, Borrull F, Marce RM (2000) Determination of phthalate esters in water samples by solid-phase microextraction and gas chromatography with mass spectro-metric detection. J Chromatogr A 872(1-2) 191-201... 

Determination of Phthalate Esters in Municipal and Industrial Discharges using LLE and GC... 

Lin Z-P, Ikonomou MG, ling H, Mackintosh Ch, Gobas FAPC (2003) Determination of phthalate ester congeners and mixtures by LC/ESI-MS in sediments and biota of an urbanized marine inlet. Environ Sci Technol 37 2100-2108... 

Phthalate Esters (Method 606). These compounds are extracted with methylene chloride, concentrated, and solvent exchanged to hexane for Florisil or aluminum oxide column cleanup and EC-GC determination by using a mixed phase columnn of 1.5 SP-2250 and 1.95 SP-2401. This method is essentially the same as that for or-ganochlorine pesticides. 

To determine whether the plasticizer was functioning as solvent, attempts were made to extract the analyte (salicylic acid) with liquid diethyl phthalate. The distribution ratio for this extraction was negligibly small. This finding indicated that the PVC polymer rather than the phthalate ester plasticizer served as the solvent. 

A manufacturing precast for producing ortho-phthalate otters derived from alkyl acid ortho-phthalatos and olefins has boon developed and demonstrated on the pilot plant scale. Process variables Include choice of reactants, stoichiometry, reaction kinetics, recycle of recovered materials and the fate of the perchloric add catalyst. Seme physical properties of the ortho-phthalate esters have been determined and severed of the esters have been evaluated as plasticizers for polyvinyl chloride. The composite data show that the acid-olefin esterification process provides commercially acceptable plasticizers for polyvinyl chloride. 

Diffusive samplers have also been developed to determine SVOCs but there have been relatively few studies to date. An example is the passive flux sampler developed by Fujii et al. (2003) to determine the rate of emission of phthalate esters from materials. The sampler consisted of a circular metal disc containing activated carbon particles held within an inert matrix of PTFE. The sampler was placed on the material under test giving a diffusion length of 0.5 or 2 mm depending upon the design and adsorbed phthalate esters were extracted from the sampler with toluene and determined by GC-MS. 

Phthalate esters Diethyl phthalate, di-n-octyl phthalate Separated on a C-18, or C-8, reverse phase high temperature bonded silica column and UV detection at 254 nm also determined by gel permeation chromatography... 

Because PCBs produce multiple peaks, extra care should be taken to identify the genuine peaks from any other contaminants, such as phthalate esters, sulfur or chlorinated pesticides, and herbicides, to avoid any false positive inference. The following steps should be taken for the qualitative determination ... 

Lopez-Jimenez, F.J., S. Rubio, and D. Perez-Bendito. 2005. Determination of phthalate esters in sewage by hemimicelles-based sohd-phase extraction and hquid chromatography-mass spectrometry. Anal. Chim. Acta 551 142-149. 

Mori [20] has identified and determined very low levels of phthalate esters in river water using reversed phase high performance liquid chromatography using an ultraviolet detector. Phthalates were extracted with n-hcxanc and the uncleaned or concentrated extracts were injected into three chromatographic systems, these being cross-linked porous beads (Shodex HP-225, Showa Penko Co.), porous polymer beads and polystyrene GPC gel. The eluants were respectively / -hexane (system A) and methanol (system B), and chloroform (system C). 

Takeda et al. [4] studied the migration behaviour of phthalate esters in micellar electrokinetic chromatography with and without the addition of butyl alcohol. This procedure was applied to the determination of phthalate esters in environmental waters. 

DEHP exposure of humans might result from intravenous administration of blood that has been stored in plastic containers, or through hemodialysis. Under situations such as these, in which DEHP is introduced directly into the blood, it is possible to evaluate exposure by measuring blood DEHP concentrations. DEHP metabolites, MEHP and phthalic acid, are also measured in the blood to determine exposure from medical products or devices (Barry et al. 1989 Sjoberg and Bondesson 1985). If the total amount of phthalate is to be monitored, the phthalate esters are first de-esterified (Liss et al. 1985). Techniques that measure total phthalic acid are not specific for DEHP exposure since other alkyl phthalic acid esters that are used as plasticizers will also produce phthalic acid after de-esterification. 

Limited information was located regarding possible interactions of DEHP with other chemicals in humans. Urinary measurements of the monoester metabolites of seven common phthalates in 289 adults from the U.S. population, determined using the selective and sensitive analytical approach discussed in Section 3.8.1 (Biomarkers Used to Identify or Quantify Exposure to DEHP), showed detectable levels of monoethyl phthalate (95th percentile concentration, 3,750 ppb), monobutyl phthalate (294 ppb), monobenzyl phthalate (137 ppb), 2-ethylhexyl phthalate (21.5 ppb), cyclohexyl phthalate (8.6 ppb), isononyl phthalate (7.3 ppb), and octyl phthalate (2.3 ppb), reflecting exposure to DEHP, dibutyl phthalate, benzyl butyl phthalate, di-(2-ethylhexyl) phthalate, dicyclohexyl phthalate, di-isononyl phthalate, and dioctyl phthalate, respectively (Blount et al. 2000a). Considering evidence such as this which indicates that co-exposure to multiple phthalates can occur, as well as the likelihood that many of these compounds exert effects via a common mechanism of action, there is a potential for interactions between DEHP and other phthalate esters. 

Application of LC-MS/MS techniques to the analysis of phthalate ester metabolites in urine have also been developed. For example, Blount et al. (2000b) have developed an assay to quantify the monoester metabolites (including MEHP) of eight phthalate diesters in urine, utilizing HPLC coupled with atmospheric pressure chemical ionization and tandem mass spectrometric (APCI-MS/MS) detection techniques. Urine samples were treated with -glucuronidase to release the free phthalate monoesters followed by a two-step solid phase extraction procedure. After evaporative concentration of the eluant, the analytes in the purified samples are further separated on a phenyl reverse phase HPLC column and quantified by APCI-MS/MS, following careful optizimation of the APCI-MS/MS instrument. The limits of detection for MEHP were determined to be 1.2 ng/ml urine with recovery efficiencies of between 78 and 91%. 

Giam CS, Chan HS, Neff GS. 1975. Sensitive method for determination of phthalate ester plasticizers in open-ocean biota samples. Anal Chem 47 2225-2228. 

Waldock MJ. 1983. Determination of phthalate esters in samples from the marine environment using GC-MS. ChemEcol 1 261. 

Liang, P., Xu, J., Li, Q. Application of dispersive liquid-liquid microextraction and high-performance liquid chromatography for the determination of three phthalate esters in water samples. Anal. Chim. Acta 609, 53-58 (2008)... 

Russell, D.J., McDuffie, B., Fineberg, S. (1985) The effect of biodegradation on the determination of some chemodynamic properties of phthalate esters. J. Environ. Sci. Health A20, 927-941. 

The alkaline hydrolysis of phthalate diesters has been fit to the Taft-Pavelich equation (Eq. 9). Dimethyl phthalate (DMP) hydrolyzes to phthalic acid (PA) in two steps DMP + H20->MMP + CH30H and MMP + H20- PA + CH30H. The first step is about 12 times faster than the second, and nearly all the diester is converted to the monoester before product PA is formed. Other diesters are assumed to behave similarly. An LFER was obtained from rate measurements on five phthalate esters (Wolfe et al., 1980b). The reaction constants, p and S, were determined by multiple regression analysis of the measured rate constants and reported values of cr and Es for the alkyl substituents. The fitted intercept compares favorably with the measured rate constant (log kOH = — 1.16 0.02) for the dimethyl ester (for which a and s = 0 by definition). Calculated half-lives under pseudo-first-order conditions (pH 8.0, 30°C) range from about 4 months for DMP to over 100 years for di-2-ethylhexyl phthalate. 

Determination of the components of industrial effluents (Castillo et al. 1997) that included phthalate esters, 4-nonylphenol, pen-tachlorophenol, 2-methylbenzenesulfonamide, and tetramethyl-thiourea. 

Penalver, A., PocumU, E., Borrull, F., and Marce, R. M., Determination of phthalate esters in water samples hy solid-phase microextraction and GC with mass spectrometric detection, J. Chromatogr. A, 872, 191-201, 2000. 

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