Analysis of ε-caprolactam and its cyclic oligomers by high-performance liquid chromatography

Bonifaci, Luisa; Frezzotti, D.; Cavalca, Gianfranco; Malaguti, E.; Ravanetti, Gian Paolo

doi:10.1016/0021-9673(91)85098-z

Cited by 22 publications

(10 citation statements)

References 7 publications

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“…Determined RRFs of PA6 dimer and tetramer from this paper best match those derived from the work of Mori and Takeuchi (1970). In accordance with Barkby and Lawson (1993) and Bonifaci et al (1991), cyclic PA6 dimer exhibits a lower response than cyclic trimer. While hexamer RRF fits with that stated by Barkby and Lawson (1993), determined penta-, hepta-and octamer RRFs are somewhat higher.…”

Section: Relative Response Factors (Rrfs)supporting

confidence: 76%

“…It is obvious that different methods of determining RRFs may lead to different results. RRFs from Guaita (1984) are derived from HPLC calibration curves; those of Mori and Takeuchi (1970), Russo (1981) and Bonifaci et al (1991) are derived from molar extinction coefficients of caprolactam and isolated oligomers, determined by spectro-photometrical measurement. In contrast to all other authors, Guaita (1984) detected caprolactam and oligomers at 205 nm instead of 210 nm.…”

Section: Relative Response Factors (Rrfs)mentioning

confidence: 99%

See 1 more Smart Citation

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

Heimrich

Bönsch

Nickl

et al. 2012

Food Additives & Contaminants: Part A

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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.

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Section: Relative Response Factors (Rrfs)supporting

confidence: 76%

Section: Relative Response Factors (Rrfs)mentioning

confidence: 99%

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

Heimrich

Bönsch

Nickl

et al. 2012

Food Additives & Contaminants: Part A

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“…Because the production of high molecular weight polymers (such as polyamides) is often accompanied by the formation of moderate molecular weight oligomers, 4,5 it not unexpected that such polymers would contain cyclic and open chained oligomers, 6 with oligomers up to the hexamer being reported and quantitated. 6,7 Such oligomers, along with the unreacted monomer, represent the extractable portions of polycondensate polymers. 8 In fact, cyclic oligomers of caprolactam are reportedly present in water extracts of polyamides (e.g., waste solutions associated with nylon-6 production).…”

Section: Introductionmentioning

confidence: 99%

Identification of caprolactam oligomers and related compounds in aqueous extracts of nylon‐6

Jenke

Poss

Sadain

et al. 2005

J of Applied Polymer Sci

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Cyclic oligomers of caprolactam were isolated from a multilayered polyolefin plastic film containing a nylon-6 layer and subsequently characterized. Nylon-6 was extracted with aqueous solutions and the levels of the oligomers were measured in the resulting extracts. Oligomers up to n ϭ 5 were present at high and comparable levels in all the nylon-6 extracts. The levels of the oligomers dropped off rapidly with increased compound size after n ϭ 5, with the heptamer being barely observable in the extract chromatograms. The effect of extracting solution pH on the compound's concentration in the extract was small, except for the monomer, whose accumulation was significantly decreased at low pH.

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“…Calibration data published by Bonifaci et al [17] has been used to calculate these results. The anticipated differences in the migration levels into the food and into the surrounding boiling water are clearly demonstrated.…”

Section: Migration Of Caprolactam and Oligomers In Pouch Samplesmentioning

confidence: 99%

Contaminant migration from food packaging laminates used for heat and eat meals

Lawson

Barkby

Lawson

1996

Analytical and Bioanalytical Chemistry

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EU legislation requires that components from food contact plastics should not migrate significantly into the food. The nature and extent of species migrating from laminated materials used for packaging 'heat and eat' meals have been investigated. Selected target analytes included additives incorporated into the polyolefin, e.g. the Irganox and Irgafos antioxidants, the diisocyanate and polyol residues from the adhesive and oligomeric material from the nylon. The results identified a wide range of migrants arising from each of the individual components of the laminate. Some of the migrants have been identified as precursors of the principal components of the laminate as well as those anticipated from a knowledge of the laminate construction. The levels of migration for those components identified and quantified has been well below the legal limits. Some significant migrant species have been however left unidentified by this investigation.

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Analysis of ε-caprolactam and its cyclic oligomers by high-performance liquid chromatography

Cited by 22 publications

References 7 publications

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

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

Identification of caprolactam oligomers and related compounds in aqueous extracts of nylon‐6

Contaminant migration from food packaging laminates used for heat and eat meals

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