2-Cyclopentyl-cyclopentanone

Fig.1 Relative peak areas and standard deviations after triplicate headspace extractions of 100-ng 2-cyclopentyl-cyclopentanone standard. Extraction time and temperature was 30 min at 80 °C. Fiber material PA = polyacrylate PDMS = polydimethylsUox-ane CW/DVB = carbowax/divinylbenzene PDMS/DVB = polydimethylsUoxane/divinyl-benzene, CAR/PDMS = carboxen/polydimethylsiloxane. Reprinted from [66] with permission of Elsevier. Elsevier (2004)...

Fig. 2 The 45-min headspace extractions of 2-cyclopentyl-cyclopentanone from 1 to 1000 mg polyamide 6.6 at 80 °C using a PDMS/DVB fiber. The dynamic range was linear when the sample size was between 1 and 100 mg. Reprinted from [67] with permission of Elsevier. Elsevier (2004)...

In addition to the equilibrium reached after 12 h of incubation, two equilibrium-like states were observed during the first 60 min of extraction [66]. It was proposed that the equilibrium-like shape of the extraction profile, found during the first 30 min of extraction, represents the equilibrium between the readily available free 2-cyclopentyl-cyclopentanone on the surface of the polyamide 6.6 powder, the headspace and the SPME-fiber. The second equilibrium-like state probably represents equilibrium for the 2-cyclopentyl-cyclopentanone originally present inside the polyamide 6.6 powder, at a close distance to the outer surface. The equihbrium-like shape of the recovery profile may lead to an erroneous selection of extraction conditions, which in turn would lead to erroneous quantitation. The long equilibrium time reflects the need for rapid methods to estimate the volatile content under non-equihbrium conditions. 

A method for extraction of 2-cyclopentyl-cyclopentanone from polyamide 6.6 by MAE was developed to quantitate the amount of 2-cyclopentyl-cyclo-pentanone in the polyamide 6.6 samples [66] and to validate a MHS-SPME method for extraction of 2-cyclopentyl-cyclopentanone [67]. The method was optimized with respect to the type of solvent, extraction temperature, extraction time and sample-to-solvent ratio. Chloroform and methanol were evaluated as extracting solvents. After extraction at 90 °C for 30 min the highest recovery was achieved using methanol as a solvent. This is attributed to the better compatibility between polar polyamide 6.6 and polar methanol, which gives good swelHng of the polyamide 6.6 matrix and more effective extraction of analyte. The effect of extraction time on the recovery of 2-cyclopentyl-cyclopentanone was studied by extracting 1.0 g of... 

The effect of sample amount, extraction temperature, incubation time and addition of a displacer on the measured amount of 2-cyclopentyl-cy-clopentanone in polyamide 6.6 and the characteristics of the corresponding linear regression lines are shown in Table 1 [67]. Changing the sample amount from 50 to 75 mg did not significantly influence the measured amount of 2-cyclopentyl-cyclopentanone. The extraction temperature, however, strongly influenced the measured amount. After MHS-SPME at 50 °C, the measured concentration of 2-cyclopentyl-cyclopentanone was 0.47 xg/g. At 80 °C and 120 °C, the measured concentrations were 3.90 p.g/g and 96.07 xg/g, respectively. The very low correlation coefficient of 0.686 obtained at 120 °C immediately indicates that the measurement is invalid. At 50 °C and... 

To validate the developed MHS-SPME method, the concentration of 2-cyclopentyl-cyclopentanone in five different polyamide 6.6 samples was measured by MHS-SPME and the results were compared to the concentrations determined by the previously developed MAE method [67]. In general, the amounts determined by MHS-SPME and MAE agreed well. However, the concentrations determined by MHS-SPME were up to 30% higher than the concentrations measured after MAE. As it was shown that the developed MHS-SPME method eliminated the matrix effects, it is likely that the con-... 

The content of volatiles in polymers is routinely assessed by the polymer producing and processing industry. Generally, HS-GC is used under non-equilibrium conditions and absolute contents are not measured. The performance of HS-SPME, compared to traditional HS, for assessing the 2-cyclopentyl-cyclopentanone content in polyamide 6.6 under non-equiUb-rium conditions was evaluated by extracting the analyte from five polyamide 6.6 samples using traditional HS and HS-SPME at 80 °C and 120 °C [66]. The influences of different parameters on the extractions were studied. Table 2 shows the amount of 2-cyclopentyl-cyclopentanone extracted from five polyamide 6.6 samples using traditional HS extraction and HS-SPME at 80°Cand 120 °C. 

Under non-equilibrium conditions, sample size, extraction temperature and extraction method (HS or HS-SPME) strongly affected the amount of 2-cyclopentyl-cyclopentanone emitted from polyamide 6.6 [66]. The amount... 

Fig. 6 Chromatograms of extractions from virgin and recycled polyamide 6.6 after 25 h of thermo-oxidation at 100 °C. Identity of the peaks is 1 = cyclopentanone, 2 = 2-methylpyridine, 3 = pentanoic acid, 4 = butanamide, 5 = 2-ethylcyclopentanone, 6 = 2,4,6-trimethylpyridine, 7 = pentanamide, 8 = 3-(l-methylethyl)pyridine, 9 = 2-butylpyridine, 10 = N,N-hexamethylenebisformamide, 11 = 2-butylcyclopentanone, 12 = glutarimide, 13 = l-propyl-2,5-pyrrolidinedione, 14 = 2-pentylcyclopentanone, 15 = caprolactam, 16 = azepane-2,7-dione, 17 = 2-cyclopentyl-cyclopentanone, 18= l-butyl-2,5-pyrrolidinedione, 19 = l-pentyl-2,5-pyrrolidinedione, 20 = 2-butyl-3,5-dimethylethylpyridine, L1-L7 = linear C13-C17 alkanes and alkenes from lubricant, = silicone from septa used to seal vials. Reprinted from [65] with permission of John WUey Sons, Inc. John Wiley Sons, Inc (2002)...

Cyclopentanone and four cyclopentanone derivatives were identiUed 2-ethyl-cyclopentanone, 2-butyl-cyclopentanone, 2-pentyl-cyclopentanone and 2-cyclopentyl-cyclopentanone [65]. At the beginning of oxidation, i.e. after 25 h of ageing, 2-cyclopentyl-cyclopentanone was the most abundant compound in the extractions from both virgin and recycled material, hi contrast to the other compounds extracted, the amoimt of cyclopentanones and espe-... 

Fig. 11 Decrease in extractable amoimt of 2-cyclopentyl-cyclopentanone from virgin and recycled polyamide 6.6 diming thermo-oxidation at 100 °C. Reprinted from [65] with permission of John Wiley Sons, Inc. John Wiley Sons, Inc (2002)...

Strong interactions between the polar matrix and polar analytes may lead to extremely long equilibrium times and errors in quantitation even when the MHS technique is used. In these cases, a displacer may be added to break the interactions between the matrix and analyte. Polar 2-cyclopentyl-cyclopentanone could be quantitatively determined in polar polyamide 6.6 by MHS-SPME if water was added as a displacer to break the hydrogen bonding between 2-cyclopentyl-cyclopentanone and polyamide. The addition of water also significantly reduced the equilibrium time. A correlation was found between the amount of 2-cyclopentyl-cyclopentanone emitted from polyamide 6.6 and the total amount of 2-cyclopentyl-cyclopentanone in the material. This correlation enables rapid assessment of the 2-cyclopentyl-cy-clopentanone content using headspace techniques under non-equilibrium conditions. The analysis time is significantly reduced if the polymer samples are milled to a powder prior to extraction. 

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