Comparison of methods for quantitative analysis of additives in low-density polyethylene using supercritical fluid and enhanced solvent extraction

Analysis of potential migrants from plastic materials in milk by liquid chromatography-mass spectrometry with liquid-liquid extraction and low-temperature purification

A simple and fast analytical method was developed for the determination of six UV stabilizers (Cyasorb UV-1164, Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, and Tinuvin 1577) and five antioxidants (Irgafos 168, Irganox 1010, Irganox 3114, Irganox 3790, and Irganox 565) in milk. For sample preparation liquid-liquid extraction with low-temperature purification combined with centrifugation was used to remove fats, proteins, and sugars. After the cleanup step, the sample was analyzed with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). External standard and matrix calibrations were tested. External calibration proved to be acceptable for Tinuvin P, Tinuvin 234, Tinuvin 326, Tinuvin 327, Irganox 3114, and Irganox 3790. The method was successfully validated with matrix calibration for all compounds. Method detection limits were between 0.25 and 10 μg/kg. Accuracies ranged from 93 to 109%, and intraday precisions were <13%.

Analytical methods for the determination of DEHP plasticizer alternatives present in medical devices: a review

Until 2010, diethylhexylphthalate (DEHP) was the plasticizer most commonly used to soften PVC medical devices (MDs), because of a good efficiency/cost ratio. In flexible plasticized PVC, phthalates are not chemically bound to PVC and they are released into the environment and thus may come into contact with patients. The European Directive 2007/47/CE, classified DEHP as a product with a toxicity risk and restricted its use in MDs. MD manufacturers were therefore forced to quickly find alternatives to DEHP to maintain the elasticity of PVC nutrition tubings, infusion sets and hemodialysis lines. Several replacement plasticizers, so-called "alternative to DEHP plasticizers" were incorporated into the MDs. Nowadays, the risk of exposure to these compounds for hospitalized patients, particularly in situations classified "at risk", has not yet been evaluated, because migrations studies, providing sufficient exposure and human toxicity data have not been performed. To assess the risk to patients of DEHP plasticizer alternatives, reliable analytical methods must be first developed in order to generate data that supports clinical studies being conducted in this area. After a brief introduction of the characteristics and toxicity of the selected plasticizers used currently in MDs, this review outlines recently analytical methods available to determine and quantify these plasticizers in several matrices, allowing the evaluation of potential risk and so risk management.

Development of Supercritical Fluid Extraction Coupled to Comprehensive Two-dimensional Supercritical Fluid Chromatography (SFE-SFC×SFC)

Supercritical fluid extraction was coupled to comprehensive two-dimensional supercritical fluid chromatography with conventional packed columns. With this system, three modes of operations were feasible, such as SFE-SFC, SFCxSFC, and SFE-SFCxSFC. The operations for valve switching and data acquisition were automated using in-house software. In order to evaluate the present system, SFE-SFC for polymer additives in polypropylene, SFCxSFC for a mixture of benzene derivatives with different polarities, and SFE-SFCxSFC for styrene oligomers in polystyrene were performed. With SFE-SFCxSFC, diastereomers were resolved for linear tetramers and pentamers as well as trimers with the tetraline moiety.

Spectrofluorimetric determination of phenyl-β-naphthylamine used as rubber antioxidant

Phenyl-beta-naphthylamine (PBN) used as rubber antioxidant was found to have native fluorescence. A spectrofluorimetric method for determination of PBN in multicomponent mixtures of polymer additives is described. The apparent excitation and fluorescence wavelengths used are 348 and 413.5 nm, respectively. Maximum fluorescence intensity is obtained by irradiating PBN dissolved in ethanol, at room temperature. The fluorescence varies linearly with the concentration of PBN in the range of 0.04-4 microg mL(-1). The accuracy and precision of the method are reported.

Determination of residual styrene monomer in polystyrene granules by gas chromatography–mass spectrometry

Polystyrene is widely used in formulations intended for children use. The main problem with this plastic is the residual styrene, which can migrate from the product, and therefore, be in contact with children. The acute toxicity of styrene is well known, raising the need of an efficient and fast method of analysis for this compound. Several extraction methods have been evaluated and compared for the determination of residual styrene monomer in polystyrene granules used in toys: supercritical fluid extraction (SFE), microwave-assisted extraction (MAE), Soxhlet extraction, headspace emission and dissolution-precipitation. The analyte was subsequently detected by gas chromatography (GC) with MS detection. The results indicated that the most efficient method was dissolution-precipitation giving even higher extraction efficiency than SFE. For validating the method, PS samples spiked with known quantities of styrene at three concentration levels were prepared to calculate the extraction recovery. The founded validation data proved the suitability of the proposed method.

Analysis of low-molar-mass materials in commercial rubber samples by Soxhlet and headspace extractions followed by GC–MS analysis

Very tight regulations apply to materials used for pharmaceutical packaging and for administering drugs. In this paper, we describe a simple and reliable procedure involving both gas- and liquid-phase extraction steps followed by an analysis step to identify the low-molar-mass materials in commercial-rubber samples. Representative commercial rubbers, that could be used for pharmaceutical packaging, have been selected and cryogenically powdered. Headspace and Soxhlet extractions have been carried out and the key parameters are discussed. The obtained extracts have been analyzed by gas chromatography (GC)-mass spectrometry (MS). More than 100 compounds have been detected and identified. Headspace allowed to extract the more-volatile compounds, whereas Soxhlet extraction recovered less-volatile compounds, but induced a loss of the volatile ones. Thus, both extraction techniques are required to fully characterize the low-molar-mass compounds present in rubber.

Determination of antioxidant migration levels from low-density polyethylene films into food simulants

An analytical method for the determination of specific migration levels of phenolic antioxidants from low-density polyethylene (LDPE) into food simulant has been developed. The screening and response surface experimental designs to optimize the liquid-liquid extraction (LLE) of these antioxidants have been tested and the analyses have been carried out by reversed-phase high-performance liquid chromatography (HPLC) coupled with ultraviolet diode-array detector. The procedure developed has been applied to specific migration tests in different commercial LDPE films. The considered antioxidants have not been found upper the legislation limits although Ethanox 330 and Irgafos 168 have been found at trace level.

Collection in analytical-scale supercritical fluid extraction

This review is a comprehensive summary of available collection techniques in supercritical fluid extraction (SFE), with emphasis on which parameters are especially important for a successful analyte collection. Environmental, biological and agricultural applications, including several types of sample matrices and analyte groups, are discussed with respect to choice of collection mode and optimization of collection conditions. This review also includes discussions about collection when a modifier is used or when the sample contains large amounts of fat or water, as well as possibilities to achieve enhanced selectivity.