Determinations phthalates

Koch HM, Rossbach B, Drexler H, Angerer J (2003) Internal exposure of the general population to DEHP and other phthalates - determination of secondary and primary phthalate monoester metabolites in urine. Environ Res 93 177-185... 

Liss GM, Albro PW, Hartle RW, Stringer WT (1985) Urine phthalate determinations as an index of occupational exposure to phthalic anhydride and di(2-ethylhexyl) phthalate. Scand J Work Environ Health 11 381-387... 

De Qrsi, D., L. Gagliardi, R. Porra, et al. 2006. An environmentally friendly reversed-phase hquid chromatography method for phthalates determination in nail cosmetics. Anal. Chim, Acta 555 238-241. 

Interpreting the results of phthalate determinations in soil may be rather difficult. Even if blank values are really under control, phthalate contents, especially DEHP, may be caused by some artefacts, even the presence of pieces of plastics in the sample. If large samples have been pre-treated by milling, such an artefact may be difficult to recognise. Therefore, a different strategy should be considered and taking a number of small size samples that can be visually inspected may be a better choice. In any case the analyst should have a close look at the contents of the sample container in taking the required portion for... 

Concerning the phthalate determination, the number of publications dealing with these compounds shows their great interest and their widespread presence in many consumer products and the environment. Specifically, in the case of the determination of phthalates in cosmetic products, several analytical methods for the identification and determination at the level of pg mL and ng mL have been published. The most commonly used techniques are liquid chromatography (LC)... 

When standardizing a solution of NaOH against potassium hydrogen phthalate (KHP), a variety of systematic and random errors are possible. Identify, with justification, whether the following are systematic or random sources of error, or if they have no effect. If the error is systematic, then indicate whether the experimentally determined molarity for NaOH will be too high or too low. The standardization reaction is... 

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. 

Plasticizers can be classified according to their chemical nature. The most important classes of plasticizers used in rubber adhesives are phthalates, polymeric plasticizers, and esters. The group phthalate plasticizers constitutes the biggest and most widely used plasticizers. The linear alkyl phthalates impart improved low-temperature performance and have reduced volatility. Most of the polymeric plasticizers are saturated polyesters obtained by reaction of a diol with a dicarboxylic acid. The most common diols are propanediol, 1,3- and 1,4-butanediol, and 1,6-hexanediol. Adipic, phthalic and sebacic acids are common carboxylic acids used in the manufacture of polymeric plasticizers. Some poly-hydroxybutyrates are used in rubber adhesive formulations. Both the molecular weight and the chemical nature determine the performance of the polymeric plasticizers. Increasing the molecular weight reduces the volatility of the plasticizer but reduces the plasticizing efficiency and low-temperature properties. Typical esters used as plasticizers are n-butyl acetate and cellulose acetobutyrate. 

Another interface for RPLC-GC is the programmed-temperature-vaporization (PTV) system, an interesting application of which is the determination of phthalates... 

The structure of phthalate dioxygenase reductase that transfers electrons directly from NADPH to phthalate dioxygenase has been determined by X-ray crystallography (119). In class II or class III dioxygenases, the ferredoxin obligately transfers electrons from the reductase to the terminal dioxygenase (64a) it can be either a Rieske-type ferredoxin or a ferredoxin containing a 4-cysteine coordinated [2Fe-2S] cluster. 

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. 

A titration requires a solution whose concentration is known. In Example the NaOH solution used as the titrant was known to be 0.1250 M. A titrant of known concentration is known as a standard solution, and the concentration of such a solution is determined by a standardization titration. In a standardization titration, the solution being titrated contains a known amount of acid or base. An excellent acid for standardization is potassium hydrogen phthalate, KHCg H4 O4. This substance, a carboxylic acid that contains one weakly acidic hydrogen atom per molecule, is easily obtained as a highly pure solid. A known number of moles can be weighed on an... 

C04-0157. As a final examination in the general chemistry laboratory, a student was asked to determine the mass of Ca (0H)2 that dissolves in 1.000 L water. Using a published procedure, the student did the following (1) About 1.5 mL of concentrated HCl (12 M) was added to 750 mL of distilled water. (2) A solution of KOH was prepared by adding approximately 1.37 g KOH to 1.0 L distilled water. (3) A sample of potassium hydrogen phthalate (185.9 mg) was dissolved in 100 mL of distilled water. Titration with the KOH solution required 25.67 mL to reach the stoichiometric point. (4) A 50.00-mL sample of the HCl solution prepared in step 1 was titrated with the KOH solution. The titration required 34.02 mL of titrant to reach the stoichiometric point. (5) The student was given a 25.00-mL sample of a saturated solution of Ca (0H)2 for analysis. Titration with the HCl solution required 29.28 mL to reach the stoichiometric point. How many grams of calcium hydroxide dissolve in 1.00 L of water ... 

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],... 

For direct determination of plasticisers in PVC the sample was dissolved in THF, and phthalate or phosphate plasticisers were measured from absorbance at 240 and 275 nm or 257, 262 and 268 nm, respectively... 

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