A Salting-out Liquid-Liquid extraction (SALLE) for the analysis of caprolactam and 2,4-di-tert butyl phenol in water and food simulants. Study of the salinity effect to specific migration from food contact materials.

Caprolactam and 2,4-di-tert-butyl phenol (2,4-DTBP) are substances typically found in some food contact materials (FCMs). They are known to often migrate into food, and are difficult to analyse in liquid food simulants using GC. In this work a simple salting-out Liquid-Liquid Extraction (SALLE) for the analysis of both substances in water and the official food simulant A (10 % v/v ethanol, Regulation (EU) No. 10/2011) is presented. The method, which included analytical determination by GC-MS, was optimized and validated to ensure sufficient analytical quality. The method's LOQs allowed the proper quantification of caprolactam at its EU legislative limit (15 mg kg-1). For 2,4-DTBP the method also revealed good sensitivity, although no official limits have been established yet. Linear regression coefficients (R2) were in all cases higher than 0.999, and recoveries ranged from 87 % and 95% for caprolactam and 2,4-DTBP, respectively. Precision was also acceptable, with the RSDs (%) below 12 %. The method proved to be adequate to be used for routine analysis. The presence of salt during migration of caprolactam and 2,4-DTBP was also investigated in this work. Polyamide/polyethylene FCM multilayer films have been tested with water and simulant A, containing different amounts of NaCl (up to 15 % m/v), and applying different migration conditions (temperature and time). The results indicated that salinity plays an important effect on the migration of caprolactam, with the presence of salt reducing its migration in case of water and increasing it in case of simulant A. These preliminary results seem to indicate that migration testing should consider not only the well-known fatty content of a food, but also its salinity content, as it may end up affecting drastically the migration of polar substances.

Microplastic contamination in Penaeid shrimp from the Northern Bay of Bengal.

Microplastic pollution has received increased attention recently due to potential threat to marine biota and human health. This study reports microplastic (MP) content in brown shrimp (Metapenaeus monocerous) and tiger shrimp (Penaeus monodon) inhabiting in the shallow and offshore waters of the Northern Bay of Bengal, Bangladesh. Gastrointestinal tract (GT) of shrimps (n = 150) were examined for MPs following alkali digestion, microscopic observation and chemical analysis by micro-Fourier Transformed Infrared Spectroscope (µFTIR). A total of 33 and 39 MP items were found in P. monodon and M. monocerous, averaging 3.40 ±â€¯1.23 and 3.87 ±â€¯1.05 items/g GT, respectively. Among various shapes, types and colours of MP, filament (57-58%), fiber (32-57%) and black (48-51%) were dominant amongst the various particles identified. Tiger shrimp had high numbers (23 items) of larger size fractions of MPs (1-5 mm) but brown shrimp had high numbers (15 items) of smaller MPs (250-500 µm), and µ-FTIR data confirmed 13 particles of polyamide-6 and 6 particles of rayon polymers. These results provide a baseline of MP contamination in seafood from Bangladesh that should be useful for future monitoring efforts.

[Determination of the key impurity in caprolactam produced from a combined process by gas chromatography-mass spectroscopy].

Caprolactam (CPL) is an important chemical raw material. Because even trace level contaminations in CPL can directly influence the polymerization and the resulting properties of fibers, the CPL monomer must be very pure. In this study, gas chromatography with a flame ionization detector (GC/FID) and gas chromatography mass spectroscopy (GC-MS) techniques were developed to determinate the key impurities in CPL using a novel process which characterized the ultraviolet (UV) absorption rates of the samples. The GC-MS results indicated that the major impurity had a relative molecular mass of 188 and was qualitatively characterized as 1,2,3,4,6,7,8,9-octahydrophenazine. Considering the reaction conditions and properties of the substances in the reactor, we speculated that the octahydrophenazine may have originated from a Neber rearrangement, which is a side-reaction of the Beckmann rearrangement. The impurity contains strong chromophores and severely impacted the UV absorption rate of the CPL product. Therefore, during CPL production, the concentration of octahydrophenazine must be strictly controlled.

Interlaboratory Study on Caprolactam Test for Food-Contact Nylon Products.

The Japanese Food Sanitation Law sets a limit on the migration level of caprolactam for food-contacting nylon products. Here, we carried out an interlaboratory study in twenty laboratories to evaluate the performance of the official GC-FID test method and a GC-MS method as an alternative test method to the official method. Each laboratory quantified caprolactam in three test solutions in 20% ethanol as blind duplicates using GC-FID or GC-MS. The official method (GC-FID with absolute calibration) gave trueness, repeatability (RSDr) and reproducibility (RSDr) values of 96-97%, 3.3-5.4% and 4.0-6.7%, respectively. These values met the target criteria (trueness: 80-110%, RSDr: 10%, RSDr: 25%). The performance of the method was further improved by the introduction of heptalactam as an internal standard. As for GC-MS method, some values of the RSDr exceeded 10% when absolute calibration was used. However, when an internal standard was introduced, the trueness, RSDr and RSDr of GC-MS method were all acceptable at 94-96%, 2.0-4.4% and 7.0-9.4%, respectively. Therefore, GC-MS with an internal standard is available as an alternative test method to the official method.

Exposure study to examine chemosensory effects of ɛ-caprolactam in healthy men and women.

CONTEXT: ε-Caprolactam is an important industrial chemical with a relatively low human toxicity; of importance is the irritations that occur after exposure to ε-caprolactam as aerosols or vapors. OBJECTIVE: The aim of this study was to examine symptoms and objective effects, which occur on the mucous membranes of the eyes and the upper respiratory tract. METHODS: A total of 52 healthy volunteers (26 women and 26 men, aged between 19 and 50 years) were exposed by random to different ε-caprolactam concentrations (0.05, 0.5 and 5.0 mg/m³) and the control condition (0.0 mg/m³) for 6 h on four consecutive days. Eye blinking frequency, tear film break-up time, eye redness, nasal flows and resistance, olfactory function as well as total protein and interleukin-8 in nasal lavage fluid were determined daily before, during and after exposure. Questionnaires were used to record both subjective symptoms and personality factors. RESULTS: There were no significant specific effects on the subjective and objective endpoints examined. Statistical analysis yielded no evidence of concentration-response relationships. Evaluation of olfactory symptoms showed that the duration of the stay in the chamber and not the ε-caprolactam concentration was decisive for the perception of "impure air". Personality factors had no significant influence on the reported symptoms. CONCLUSIONS: Exposure to ε-caprolactam concentrations of 5.0 mg/m³ at maximum for 6 h did not cause chemosensory effects on the upper respiratory tract or eyes of healthy volunteers. Therefore, the concentration of 5.0 mg/m³ corresponds to the No Observed Adverse Effect Level (NOAEL).

Brush head composition, wear profile, and cleaning efficacy: an assessment of three electric brush heads using in vitro methods.

OBJECTIVE: The objective of this research was to evaluate a current store brand (SB) brush head for composition/physical characteristics, Wear Index (WI), and cleaning efficacy versus the previous SB brush head refill design (SB control) and the Oral-B Precision Clean brush head (positive control, PC). METHODS: This research consisted of three parts: 1) Analytical analysis using Fourier Transform Infrared (FT-IR) spectrometry to evaluate the chemical composition of the current SB brush head bristles relative to the SB control. In addition, physical parameters such as bristle count and diameter were determined. 2) Wear Index (WI) investigation to determine the Wear Index scores of in vitro-aged brush heads at four weeks (one month) and 13 weeks (three months) by a trained investigator. To "age" the brush heads, a robot system was used as a new alternative in vitro method to simulate aging by consumer use. 3) Robot testing to determine the cleaning performance of in vitro-aged brush heads, comparing one month-aged current SB brush heads with the SB control (one and three months-aged) and the PC brush heads (three months-aged) in a standardized fashion. RESULTS: 1) FT-IR analysis revealed that the chemical composition of the current and control SB refill brush heads is identical. In terms of physical parameters, the current SB brush head has 12% more bristles and a slightly oval brush head compared to the round brush head of the SB control. 2) Wear Index analysis showed there was no difference in the one month-aged current SB brush head versus the one month-aged SB control (1.67 vs. 1.50, p = 0.65) or versus the three months-aged PC brush head (1.67 vs. 1.50, p = 0.65). The one month-aged current SB brush head demonstrated statistically significantly less wear than the three months-aged SB control (1.67 vs. 2.67, p = 0.01). 3) Analysis of cleaning efficacy shows that the one month-aged current SB brush head had improved cleaning performance over the one month-aged SB control brush head (p < 0.05), despite no statistically significant difference in wear. Both the one month-aged current and control SB brush heads showed statistically significantly lower cleaning performance compared to the three months-aged PC brush heads (p < 0.01). CONCLUSION: While the current SB brush head showed improved cleaning over the SB control, it demonstrated significantly lower durability and cleaning in comparison to the PC brush head. Dental professionals should be aware of these differences, both in durability and in cleaning performance, when recommending brush heads to their patients.

Influence of PA6 nanocomposite films on the stability of vacuum-aged beef loins during storage in modified atmospheres.

A masterbatch of polyamide 6 (PA6) containing dispersed nanoclays, was used to fabricate a novel multilayer film for vacuum packed meat. Performance of the nanocomposite was compared to a control PA6 multilayer and a high barrier commercial film. Addition of nanoclays improved oxygen barrier properties, UV-blocking capability and stiffness. Beef loins were vacuum-aged using the three films for 0 7, 14 and 21 days at 2°C. After each ageing time, beef steaks were packaged in commercial trays and high oxygen atmosphere and stored at 4°C for 9 days. Beef quality parameters and gas content were studied during display time in MAP (1, 3, 6 and 9 d). Beef quality parameters were not influenced by the packaging materials used during ageing and the performance of nanocomposites was comparable to high barrier films. Ageing had a positive impact on the stabilization of redness up to day 6 in MAP. Thereafter, oxymyoglobin content and oxidation levels were negatively influenced by ageing.

Analytical tools for identification of non-intentionally added substances (NIAS) coming from polyurethane adhesives in multilayer packaging materials and their migration into food simulants.

Adhesives used in food packaging to glue different materials can provide several substances as potential migrants, and the identification of potential migrants and migration tests are required to assess safety in the use of adhesives. Solid-phase microextraction in headspace mode and gas chromatography coupled to mass spectrometry (HS-SPME-GC-MS) and ChemSpider and SciFinder databases were used as powerful tools to identify the potential migrants in the polyurethane (PU) adhesives and also in the individual plastic films (polyethylene terephthalate, polyamide, polypropylene, polyethylene, and polyethylene/ethyl vinyl alcohol). Migration tests were carried out by using Tenax(®) and isooctane as food simulants, and the migrants were analyzed by gas chromatography coupled to mass spectrometry. More than 63 volatile and semivolatile compounds considered as potential migrants were detected either in the adhesives or in the films. Migration tests showed two non-intentionally added substances (NIAS) coming from PU adhesives that migrated through the laminates into Tenax(®) and into isooctane. Identification of these NIAS was achieved through their mass spectra, and 1,6-dioxacyclododecane-7,12-dione and 1,4,7-trioxacyclotridecane-8,13-dione were confirmed. Caprolactam migrated into isooctane, and its origin was the external plastic film in the multilayer, demonstrating real diffusion through the multilayer structure. Comparison of the migration values between the simulants and conditions will be shown and discussed.

Cyclic oligomers in polyamide for food contact material: quantification by HPLC-CLND and single-substance calibration.

Cyclic oligomers are the major substances migrating from polyamide (PA) food contact materials. However, no commercial standards are available for the quantification of these substances. For the first time the quantification of cyclic oligomers was carried out by HPLC coupled with a chemiluminescence nitrogen detector (CLND) and single-substance calibration. Cyclic monomer (MW = 226 Da) and dimer (MW = 452 Da) of PA66 were synthesised and equimolar N detection of CLND to synthesised oligomers, caprolactam, 6-aminohexanoic acid (monomers of PA6) and caffeine (a typical nitrogen calibrant) was proven. Relative response factors (UVD at 210 nm) referring to caprolactam were determined for cyclic PA6 oligomers from dimer to nonamer, using HPLC-CLND in combination with a UVD. A method for quantification of cyclic oligomer content in PA materials was introduced using HPLC-CLND analysis and caffeine as a single nitrogen calibrant. The method was applied to the quantification of cyclic PA oligomers in several PA granulates. For two PA6 granulates from different manufacturers markedly different oligomer contents were analysed (19.5 versus 13.4 g kg⁻¹). The elution pattern of cyclic oligomers offers the possibility of identifying the PA type and differentiating between PA copolymers and blends.

The effect of Ce doped in Ti/SnO(2)-Sb(2)O(3)/SnO(2)-Sb(2)O(3)-CeO(2) electrode and its electro-catalytic performance in caprolactam wastewater.

Ti/SnO(2)-Sb(2)O(3)/SnO(2)-Sb(2)O(3)-CeO(2) anodes were prepared by brush coating with high temperature oxidation. The anodes were characterized by X-ray diffractometer (XRD), scanning electron microscope and cyclic voltammetry. The surface of the electrode shows more compact and exist shallower mud cracks than the others by coating with 1% Ce to the surface of Ti/SnO(2)-Sb(2)O(3) electrode. The XRD patterns show that as-prepared electrodes are SnO(2) and TiO(2). The electrode with 1% Ce dopant shows the highest efficiency in the electrolysis of caprolactam wastewater. The oxygen evolution potential is about 1.75 V, the removal rate of chemical oxygen demand is 50%, and the biochemical oxygen demand is 353 mg/L for 5 h at a current of 0.12 A.

[Migration of monomers and primary aromatic amines from nylon products].

Migration of 2 kinds of monomer and 21 kinds of primary aromatic amines (PAAs) from 21 kinds of nylon products such as turners, ladles and wrap film were determined. Samples were classified as regards materials by mean of pyrolysis-GC/MS. One sample was classified as nylon 6, 15 samples as nylon 66 and three samples as nylon 6/66 copolymers, while two samples were laminate of nylon 6 with polyethylene or polypropylene. All of the nylon 66 samples contained a small amount of ε-caprolactam (CPL), which is the nylon 6 monomer. Migration levels of monomers and PAAs at 60°C for 30 min into 20% ethanol were measured by LC/MS/MS. CPL was detected at the level of 0.015-38 µg/mL from all samples, excluding one wrap film sample, and 1,6-hexamethylenediamine was detected at the level of 0.002-0.013 µg/mL from all nylon 66 samples and one nylon 6/66 sample. In addition, 0.006-4.3 µg/mL of 4,4'-diaminodiphenylmethane from three samples, 0.032-0.23 µg/mL of aniline from four samples, 0.001 µg/mL of 4-chloroaniline from two samples, and 0.002 µg/mL of 2-toluidine and 0.066 mg/mL of 1-naphthylamine from one sample each were detected. The migration levels at 95 or 121°C were about 3 and 10 times the 60°C levels, respectively.

Effect of gamma irradiation on caprolactam migration from multilayer polyamide 6 films into food simulants: development and validation of a gas chromatographic method.

A GC method to determine caprolactam in water, 15% ethanol, and olive oil food simulants was developed and validated. Linear ranges varied from 0.96 to 642.82 microg/mL for water, 0.64 to 800.32 microg/mL for 15% ethanol, and 1.06 to 1062.34 microg/g for olive oil, with correlation coefficients higher than 0.999. Method precision studies showed RSD values lower than 5.45%, while method accuracy studies showed recovery from 72 to 111% for all simulants. The effect of gamma irradiation on caprolactam migration from multilayer polyamide 6 (PA-6) films intended for cheese into water, 15% ethanol, olive oil, and 3% acetic acid simulants was also studied. For migration assay, non-irradiated and irradiated (12 kGy) films were placed in contact with the simulant and exposed at 40 degrees C for 10 days. The validated method was used to quantify caprolactam migration from multilayer PA-6 films into the simulants, which ranged from 1.03 to 7.59 mg/kg for non-irradiated films, and from 4.82 to 11.32 mg/kg for irradiated films. Irradiation caused almost no changes in caprolactam levels, with the exception of olive oil, which showed an increase in the caprolactam level. All multilayer PA-6 films were in accordance with the requirements of the legislation for caprolactam migration.

Identification and migration of degradation compounds from irradiation of multilayer polyamide 6 films for meat foodstuffs and cheese.

The aim of this work was to identify the degradation compounds produced during irradiation of multilayer polyamide 6 (PA-6) films and to study their migration into water and 95% ethanol food simulant. After irradiation of multilayer PA-6 films at 3, 7 and 12 kGy, degradation compounds were extracted using solid-phase microextraction, for which the time and temperature of extraction and stirring were optimized, and identified by gas chromatography-mass spectrometry. Caprolactam, 2-cyclopentylcyclopentanone and aldehydes, among other compounds, were identified in the headspace of the films. Polydimethylsiloxane was considered the best fiber for extraction. The optimum conditions of time, temperature and stirring to extract the compounds were 20 min, 80 degrees C and 225 rpm. For validation purposes, the compounds were quantified in water and 95% ethanol and the results showed high sensitivity, good precision and accuracy. Migration of compounds from irradiated and non-irradiated multilayer PA-6 films into water and 95% ethanol food simulants was carried out at 40 degrees C for 10 days. The method was efficient for the quantification of decaldehyde, 2-cyclopentylcyclopentanone and caprolactam that migrated from multilayer PA-6 films into food simulants.

Isolation of the epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin.

epsilon-Caprolactam has high COD and toxicity, so its discharge to natural water and soil systems may lead to an adverse environmental effect on water quality, endangering public health and welfare. This investigation attempts to isolate epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene (ABS) resin. The goal is to elucidate the effectiveness of isolated pure strain and ABS mixed strains in treating epsilon-caprolactam from synthetic wastewater. The results reveal that Paracoccus versutus MDC-3 was isolated from the wastewater treatment system manufactured with ABS resin. The ABS mixed strains and P. versutus MDC-3 can consume up to 1539mg/l epsilon-caprolactam to denitrify from synthetic wastewater. Complete epsilon-caprolactam removal depended on the supply of sufficient electron acceptors (nitrate). Strain P. versutus MDC-3, Hyphomicrobium sp. HM, Methylosinus pucelana and Magnetospirillum sp. CC-26 are related closely, according to the phylogenetic analyses of 16S rDNA sequences.

[The hygiene estimation of polyamide shells safety for the sausage products]. / Gigienicheskaia otsenka bezopasnosti poliamidnykh obolochek kolbasnykh izdelii.

The investigation of polyamide shells, contrasting according to the level of penetration and layering, named as "Amitan", "Amiflex T", "Amismok" were carried out. It was stated that in terms of technological process of cooked meats production modeling the studied polyamide shells meet the requirements of hygiene safety.

Method of test and survey of caprolactam migration into foods packaged in nylon-6.

An analytical method for the determination of the nylon-6 monomer caprolactam in foods is described. The foodstuff was extracted with ethanol: water (1:2) containing capryllactam as internal standard and the extract was defatted using hexane. The extract was analysed by liquid chromatography coupled with mass spectrometry. The test method was calibrated down to 0.7 mg kg(-1). The repeatability of the method was good, with a relative standard deviation of 9% at the 15 mg kg(-1) level. The method was demonstrated to be accurate in an independent external check sample exercise. The new method was applied to the analysis of 50 retail foodstuffs packaged in nylon-6. Caprolactam was detected and confirmed in nine of the 50 food samples, in the range 2.8-13 mg kg(-1). The presence of caprolactam was indicated in a further 15 samples, in the range 0.8-11 mg kg(-1), but these samples did not meet all of the five confirmation criteria applied. All migration levels (both confirmed and unconfirmed) were below the European specific migration limit for caprolactam, which is 15 mg kg(-1). The average migration for all 50 samples, setting non-detectables at half the limit of detection, was 2.6 mg kg(-1) with a standard deviation of 3.1 mg kg(-1) (n = 50). All samples found to contain detectable levels of caprolactam migration were for applications involving heating the food in the packaging. They were packs of, for example, sausage meat for which the food would have been heat processed in the nylon casing, or they were nylon pouches for heating foods by boiling, microwaving or roasting.

Endgroup-based separation and quantitation of polyamide-6,6 by means of critical chromatography.

Polyamide-6,6 is a polycondensation product from the two monomers adipic acid and 1,6-hexamethylenediamine. Depending on the reacted amount of these monomers, different ratios of amine and carboxylic acid endgroups can be formed. Besides linear chains, cyclic polyamides will also be formed. Using critical chromatography, polyamide-6,6 can be separated independently of molar mass. Retention is based solely on endgroup functionality. It is demonstrated that high-molecular-mass polyamide-6,6 (Mw approximately 20,000-30,000) can be separated using this approach. The separation was optimized by using different parameters, such as percentage modifier, temperature and pressure. The concentration of phosphoric acid was used for selective retention of the different endgroup functionalities. Using this property, a new method called critical gradient chromatography was performed where the mobile phase changes from a weak to a strong solvent with respect to the endgroup functionality, while retaining the critical conditions of the backbone unit. Quantification using UV detection is discussed.

Separation and quantification of the linear and cyclic structures of polyamide-6 at the critical point of adsorption.

The linear and cyclic structures of polyamide-6 were separated by liquid chromatography at critical conditions (LCCC) and identified with different mass spectrometric (MS) techniques and quantitated by LCCC with evaporative light-scattering detection (ELSD). Electrospray ionization MS was not suitable to identify the higher cyclic structures. For this purpose, matrix-assisted laser desorption ionization time-of-flight MS performed better and cyclic and linear structures were oligomerically resolved and separately identified in the mass spectrometer. The highest cyclic structure present and detected was the cyclic pentacontamer. It could be demonstrated that cyclic and linear oligomers follow different ionization and fragmentation routes/patterns. Quantification with ELSD of the components separated by LCCC using a universal calibration curve or an iterative procedure was developed. An area correction to account for different peak widths of coeluting components improves precision and accuracy of the calibration curve and improves quantitation accuracy for the samples analyzed. With these corrected values, no molecular mass dependency was observed for the cyclic and linear structures. Under critical conditions, the linear and cyclic structures of polyamide-6 were separated, identified and quantified.

Electrospray and matrix-assisted laser desorption/ionization mass spectral characterization of linear single nylon-6 oligomers.

Synthetic nylon-6 single molecular mass oligomers were studied by matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry. These oligomers, considered as model compounds for the study of nylon-6 polymers, gave good mass spectrometric results using both MALDI and ESI. In spite of the gentle nature of both techniques, the MALDI and ESI spectra showed evidence of end-group cleavage from the oligomer chains. MALDI-MS was found to give similar fragmentation patterns for all of the oligomer samples. An increase in doubly charged ion signals with increasing oligomer mass was observed in the ESI mass spectra, as was end-group fragmentation. Signals from oligomer clusters were observed in ESI-MS for the dimer, tetramer and hexamer, most likely due to non-covalent bonding among the low-mass oligomer molecules.