Phthalates, analysis

The sample extract may be analyzed by GC or GC/MS. A 2- to 5-pL aliquot of the extract is injected into a GC and the phthalates are detected by an electron capture detector, a flame ionization detector (FID), or a photoionization detector. Some of the chromatographic packed or capillary columns that may be used for the phthalate analysis are hsted below ... 

Phthalates are widely produced and used and due to their ubiquity, can be found everywhere, including common laboratory equipment and reagents. In consequence, the main problem in phthalate analysis is external contamination coming from the sampling and sample preparation procedure and even the chromatographic analysis. 

In most of the applications of LLE to phthalate analysis, extraction was performed in discontinue mode using separatory funnels. Table 28.5 summarizes some applications of this technique to phthalate analysis.In most cases, the volume of sample extracted is large (from O.I to 5 I). Frequently, samples are acidified and NaCI is added to favor the transfer of the analytes into the organic solvent. The solvents most frequently used are dichloromethane and hexane. In most cases, the extracts are dried with anhydrous sodium sulphate and concentrated to achieve high sensitivity. Nevertheless, the concentration factor is limited due to the presence of trace levels of phthalates in commercially available solvents, even in solvents for trace analysis. In consequence, accurate determinations below O.I /rg/I are questionable with this extraction technique. The extracts obtained are usually analyzed without a cleanup step. 

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. 

Phthalate esters were analyzed in several kinds of environmental solid matrices such as soils, sediment of different origins (mainly marine sediments), and sewage sludge. Some applications of phthalate analysis of solid matrices are summarized in Table... 

Van de Vyver, D. (2012), Efficient phthalate analysis , year report Centexbel 2012. Available from http //www.centexbel.be/files/publication-pdf/jaarverslag2012.pdf http //www. 

In this experiment the overall variance for the analysis of potassium hydrogen phthalate (KHP) in a mixture of KHP and sucrose is partitioned into that due to sampling and that due to the analytical method (an acid-base titration). By having individuals analyze samples with different % w/w KHP, the relationship between sampling error and concentration of analyte can be explored. 

The widespread usage of phthalates in flexible PVC has resulted in many investigations being made of their concentration in the environment. Unfortunately the ubiquitous presence of phthalates in laboratory chemicals and equipment has caused problems in the analysis of very low concentrations of phthalates in environmental samples and has led to erroneously high levels being reported. 

The other analytical methods necessary to control the typical specification given in Table 5 are, for the most part, common quality-control procedures. When a chemical analysis for purity is desired, acetylation or phthalation procedures are commonly employed. In these cases, the alcohol reacts with a measured volume of either acetic or phthalic anhydride in pyridine solution. The loss in titratable acidity in the anhydride solution is a direct measure of the hydroxyl groups reacting in the sample. These procedures are generally free from interference by other functional groups, but both are affected adversely by the presence of excessive water, as this depletes the anhydride reagent strength to a level below that necessary to ensure complete reaction with the alcohol. Both procedures can be adapted to a semimicro- or even microscale deterrnination. 

Potassium hydrogen phthalate [877-24-7] M 204.2. Crystd first from a dilute aqueous solution of K2CO3, then H20(3mL/g) between 100° and 0°. Before being used as a standard in volumetric analysis, analytical grade potassium hydrogen phthalate should be dried at 120° for 2h, then allowed to cool in a desiccator. 

T. Hyotylainen, K. Grob, M. Biedermann and M-L. Riekkola, Reversed phase HPLC coupled on-line to GC by the vaporizer/precolumn solvent split/gas dischar ge analysis of phthalates in water , 7. High Resolut. Chromatogr. 20 410-416 (1997). 

Figure 12.10 Microcolumn SEC-LC analysis of an acrylonitrile-butadiene-styrene (ABS) teipolymer sample (a) SEC ti ace (b) EC ti ace. SEC conditions fused-silica column (30 cm X 250 mm i.d.) packed with PL-GEL (50 A pore size, 5 mm particle diameter) eluent, THE at a flow rate of 2.0 mL/min injection size, 200 nL UV detection at 254 nm x represents the polymer additive fraction (6 p-L) tr ansferred to EC system. EC conditions NovaPak CIS Column (15 cm X 4.6 mm i.d.) eluent, acetonitrile-water (60 40) to (95 5) in 15 min gradient flow rate of 1.5 mL/min detection at 214 nm. Peaks identification is follows 1, styrene-acrylonitrile 2, styrene 3, benzylbutyl phthalate 4, nonylphenol isomers 5, Vanox 2246 6, Topanol 7, unknown 8, Tinuvin 328 9, Irganox 1076 10, unknown. Reprinted with permission from Ref. (14).

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... 

RR spectra of the Rieske protein from T. thermophilus (TRP) and of phthalate dioxygenase from Burkholderia cepacia (PDO) have been reported by Kuila et al. (66, 67), and those of the Rieske protein from Sulfolobus sp. strain 7 tentatively called sulredoxin by Iwasaki et al. (68). Although no complete analysis is yet available, several conclusions can be drawn from these spectra, in comparison to the spectra of proteins containing a 4-cysteine coordinated [2Fe-2S] cluster (Table VI). 

X-ray absorption spectroscopy has been performed on the isolated Rieske protein from bovine heart mitochondrial bc complex 69) as well as on the Rieske-type cluster in Burkholderia cepacia phthalate dioxygenase (PDO) (72). The analysis performed by Powers et al. 69) was significantly hampered by the fact that the presence of two histidine ligands was not fully recognized therefore, only the results obtained with the dioxygenase where the mononuclear iron has been depleted will be considered here. Table VII gives a comparison of the distances obtained from the fit of the EXAFS spectra assuming an idealized Rieske model and of the distances in the crystal structures... 

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 ... 

Example 5.4.4.2a. Differential analysis of integral data for synthesis of dioctyl phthalate... 

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. 

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. 

The main features of PC are low cost, need for small sample amount, high level of resolution, ease of detection and quantitation, simplicity of apparatus and use, difficult reproducibility (because of variation in fibres) and susceptibility to chemical attack. Identification of the separated components is facilitated by the reproducible Rj values. Detection methods in PC have been reviewed [368]. Fluorescence has been used for many years as a means of locating the components of a mixture separated by PC or TLC. However, also ATR-IR and SERS are useful. Preparative PC is unsuitable for trace analysis because filter paper inevitably contains contaminants (e.g. phthalate esters, plasticisers) [369]. For that purpose an acceptable substitute is glass-fibre paper [28]. 

Figure 4.22 Analysis of dialkyl phthalates using 3-pm 100 A PS/DVB columns. After Meehan and Saunders [758]. Reproduced by permission of International Scientific Communications...

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