Comparison of high-performance liquid chromatography and supercritical fluid chromatography using evaporative light scattering detection for the determination of plasticizers in medical devices

Limitation of the migration of plasticizers from medical devices through treatment with low-pressure cold plasma, polydopamine coating, and annealing

Poly(vinyl chloride) (PVC) is widely used in the manufacture of medical devices. The plasticizers added to PVC are potentially toxic for humans, likely to migrate, and thus unintentionally administered to patients. The objective of the present study was to reduce the migration of plasticizer (1,2-cyclohexanedicarboxylic acid, diisononylester (DINCH) or trioctyltrimellitate (TOTM)) from PVC by implementing a three-step surface treatment process: (i) pretreatment with low-pressure argon cold plasma, (ii) polydopamine coating, and (iii) post-treatment with cold plasma exposure or thermal treatment at 140 °C. Samples were then characterized in terms of the water contact angle (WCA) and the aspect in scanning electron microscopy. Plasticizer migration (n = 5) was measured using an HPLC technique with ultraviolet detection and found to depend on the treatment and the plasticizer. Plasticized PVC was hydrophobic, with a measured mean ± standard deviation WCA of 96.7 ± 3.6° for PVC-DINCH and 110.2 ± 5.8° for PVC-TOTM. Plasma post-treatment and thermal post-treatment were respectively associated with a mean decrease in migration of 38.3 ± 1.9% for DINCH and 61.5 ± 4.4% for TOTM. Our results are promising with regard to limiting the migration of plasticizers into the patient's blood and thus enabling the development of safer medical devices.

Columns in analytical-scale supercritical fluid chromatography: From traditional to unconventional chemistries

Within this review, we thoroughly explored supercritical fluid chromatography (SFC) columns used across > 3000 papers published from the first study carried out under SFC conditions in 1962 to the end of 2022. We focused on the open tubular capillary, packed capillary, and packed columns, their chemistries, dimensions, and trends in used stationary phases with correlation to their specific interactions, advantages, drawbacks, used instrumentation, and application field. Since the 1990s, packed columns with liquid chromatography and SFC-dedicated stationary phases for chiral and achiral separation are predominantly used. These stationary phases are based on silica support modified with a wide range of chemical moieties. Moreover, numerous unconventional stationary phases were evaluated, including porous graphitic carbon, titania, zirconia, alumina, liquid crystals, and ionic liquids. The applications of unconventional stationary phases are described in detail as they bring essential findings required for further development of the supercritical fluid chromatography technique.

Investigating the use of unconventional temperatures in supercritical fluid chromatography

The use of unorthodox temperatures, ranging from -5 °C up to 80 °C, have been thoroughly investigated in supercritical fluid chromatography. To this purpose, an initial evaluation of the kinetic and thermodynamic performance has been made with a set of 4 analytes eluting at different percentages of organic co-solvent in the mobile phase (3%-10% - 45%-80%). The van Deemter plots have demonstrated how, at low organic modifier presence, the use of low temperatures did not necessarily translate into worse performance, while high temperatures could pose more issues due to the poor handling of the super/subcritical mobile phase by the chromatographic system. With important percentages of co-solvent, however, high temperatures were fundamental in ensuring better profiles of the van Deemter plots, compared to low temperatures. Pressure plots have demonstrated that gradients reaching elevated percentages of organic modifiers can also be used on stationary phases packed with sub 2 μm silica particles if high temperatures are employed. The thermodynamic evaluation, made via the analysis of van't Hoff plots, indicates the presence of three retention behaviors happening in UHPSFC when switching from high to low temperatures, depending on the co-solvent percentage needed to elute one analyte. Finally, an assessment of the stationary phase stability at high temperatures was performed: the retention times variabilities recorded were minimal (RSD < 2.5%), as well as the peak widths and inlet column pressures were somewhat constant throughout the analyses. In the second part of this study, a focus on potential applications benefiting from such unconventional temperatures has been made. A series of challenging analytes have experienced better chromatographic resolution at either high or low temperatures, providing therefore a potentially interesting tool to analysts during the chromatographic method development process. In conclusion, the UV sensitivity at different temperatures was also taken into consideration, with no significant impact on the quality of the UV signal under any condition.

An update on the hazard of and exposure to diethyl hexyl phthalate (DEHP) alternatives used in medical devices

The use of the plasticizer diethyl hexyl phthalate (DEHP) in PVC medical devices is being questioned due to its potential reprotoxic effects in patients exposed as a result from migration from the device. This article reviews new information on migration and toxicity data of eleven alternative plasticizers that have previously been evaluated by the Danish EPA and the EU SCENIHR (Scientific Committee on Emerging and Newly Identified Health Risks). The new toxicity data did not justify the reconsideration of the critical NOAELs as established by SCENIHR and Danish EPA. The dataset on oral toxicity studies is rather complete for most substances; however, in particular for reproductive toxicity and endocrine disruption, data gaps still exist for many alternatives. Toxicity data on intravenous exposure are lacking and these are essential to conclude on hazard characteristics of alternatives that are poorly absorbed via the oral exposure route. Migration data are emerging for a few alternatives but still sparse for the majority of the alternatives. Taking all data on migration and toxicity in consideration, 1,2-cyclohexanedicarboxylic acid, diisononylester (DINCH), and tris(2-ethylhexyl)benzene-1,2,4-tricarboxylate display a more favorable profile compared to DEHP. For these promising alternatives, a risk assessment for use in medical devices should be conducted. As a next step, we recommend the (further) generation of relevant migration data and, where needed, relevant toxicity data for the alternative substances, in order to be able to conduct a benefit-risk analysis of DEHP and the alternatives as obligatory in the new European Union Medical Device Regulation.

Identification and quantification by 1H nuclear magnetic resonance spectroscopy of seven plasticizers in PVC medical devices

Medical devices are generally made of polyvinyl chloride plasticized by six authorized plasticizers as alternatives to di-(2-ethylhexyl)-phthalate (DEHP) classified as reprotoxic class 1b. These are acetyl tri-n-butyl citrate (ATBC), di-(2-ethylhexy) adipate (DEHA), di-(2-ethylhexyl) terephthalate (DEHT), di-isononyl cyclohexane-1,2-dicarboxylate (DINCH), di-isononyl phthalate (DINP), and tri-octyl trimellitate (TOTM). The main objective of this study was to propose a new method using ¹H NMR spectroscopy to determine and quantify these seven plasticizers in PVC sheets, standard infusion tubings, and commercially available medical devices. Two techniques were compared: dissolution in deuterated tetrahydrofuran and extraction by deuterated chloroform. Plasticizer ¹H NMR spectra were very similar in both deuterated solvents; dissolution and extraction provided similar results. The sensitivity of this method enabled us to detect and quantify the presence of minor plasticizers in PVC. In nine commercially available samples, the major plasticizer was identified and quantified by ¹H NMR. In six samples, one, two, or three minor plasticizers were identified and also quantified. DEHP was detected in only one tubing. NMR is therefore very convenient for studying plasticizers contained in medical devices. Only small quantities of solvents and sample are required. It is not necessary to dilute samples to enter a quantification range, and it is sufficiently sensitive to detect contaminants.

Analysis of plasticizers in PVC medical devices: Performance comparison of eight analytical methods

A wide variety of medical devices (MDs) used in hospitals are made of flexible plasticized polyvinylchloride (PVC). Different plasticizers are present in variable amounts in the PVC matrix of the devices and can leach out into the infused solutions and may enter into contact with the patients. The ARMED¹ project aims to assess the migration of these plasticizers from medical devices and therefore the level of exposure in patients. For the first task of the project, eight methods were developed to directly detect and quantify the plasticizers in the PVC matrix of the MDs. We compared the overall performances of the analytical methods using standardized and validated criteria in order to provide the scientific community with the guidance and the technical specifications of each method for the intended application. We have shown that routine rapid screening could be performed directly on the MDs using the FTIR technique, with cost-effective analyses. LC techniques may also be used, but with limits and only with individual quantification of the main plasticizers expected in the PVC matrix. GC techniques, especially GC-MS, are both more specific and more sensitive than other techniques. NMR is a robust and specific technique to precisely discriminate all plasticizers in a MD but is limited by its cost and its low ability to detect and quantify plasticizer contamination, e.g. by DEHP. All these results have been confirmed by a real test, called the " blind test " carried out on 10 MD samples.

Transcriptome profiling and pathway analysis of hepatotoxicity induced by tris (2-ethylhexyl) trimellitate (TOTM) in mice

Tris (2-ethylhexyl) trimellitate (TOTM) is commonly used as an alternative plasticizer for medical devices. But very little information was available on its biological effects. In this study, we investigated toxicity effects of TOTM on hepatic differential gene expression analyzed by using high-throughput sequencing analysis for over-represented functions and phenotypically anchored to complementary histopathologic, and biochemical data in the liver of mice. Among 1668 candidate genes, 694 genes were up-regulated and 974 genes were down-regulated after TOTM exposure. Using Gene Ontology analysis, TOTM affected three processes: the cell cycle, metabolic process and oxidative activity. Furthermore, 11 key genes involved in the above processes were validated by real time PCR. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that these genes were involved in the cell cycle pathway, lipid metabolism and oxidative process. It revealed the transcriptome gene expression response to TOTM exposure in mouse, and these data could contribute to provide a clearer understanding of the molecular mechanisms of TOTM-induced hepatotoxicity in human.