Differentiation of Polyamide 6, 6.6, and 12 Contaminations in Polyolefin-Recyclates Using HPLC Coupled to Drift-Tube Ion-Mobility Quadrupole Time-of-Flight Mass Spectrometry

Abstract

Recycling is a current hot topic with a focus especially on plastics. The quality of such plastic recyclates is of utmost importance for further processing because impurities lead to a reduction thereof. Contaminations originating from other polymers are highly problematic due to their immiscibility with the recyclate, leading to possible product failures. Therefore, methods for the determination of polymer impurities in recyclates should be investigated. In this paper, an approach for the identification of three different polyamide grades (polyamide 6, 6.6, and 12) is presented, applicable for the analysis of polyolefin-recyclates. An HPLC equipped with a drift-tube ion-mobility QTOF-MS was used for the identification and differentiation of compounds originating from the polyamides, which were then used as markers. These marker compounds are specific for each type and can be identified by their corresponding value of the collision cross section (CCS). After a simple sample preparation, all three types of polyamides were identified within one measurement. In particular, the problematic differentiation of polyamide 6 and 6.6 was easily made possible.

High-Throughput Characterization and Optimization of Polyamide Hydrolase Activity Using Open Port Sampling Interface Mass Spectrometry

“…PA manufacture results in the entrainment of a mixture of monomeric starting material and cyclic oligomers with various degrees of polymerization (Figure a,b). , These compounds leach out as water or other solvents permeate the polymer. Single PA6 and PA66 pellets were submerged in separate vials with 150 μL of buffer and incubated at 65 °C for 16 h before removal of the pellets.…”

“…Spectra are consistent with previous reports using ESI-MS, except greater proportions of [M + K] + and [M + Na] + adducts are observed here. 15,31 Salt adducts are not surprising, given that potassium phosphate buffer is not completely removed prior to analysis. Caprolactam cyclic oligomers peaked at the cyclic trimer (C 3 ) and ranged up to the cyclic hexamer (C 6 ).…”

“…Assays for determination of hydrolysis or degradation of PA are typically conducted using thin-layer chromatography (TLC), gel permeation chromatography (GPC), or high-performance liquid chromatography (HPLC) workflows. ,− These workflows are able to quantitatively measure oligomer distributions but require prior dissolution of solid PA using costly solvents. Due to the nature of chromatography, a single run can take many minutes to acquire, which limits throughput.…”

Oligomer composition and content in regenerated PA6 fiber and its effect on properties

“…In addition to providing accurate molecular weight information, this method enabled separation based on their shape and size. 25,26 As shown in Figure 1, the oligomers were efficiently separated by LC-TOF-MS, with λ = 200 nm as the detection wavelength. According to the corresponding mass spectra (Figure 2), low-molecular-weight compounds, such as the monomer (C1) and the cyclic dimer to cyclic nonamer (C2, …, C9) were extracted by dissolution and precipitation, whereby C2, C1, C3, and C4-C9 were eluted in sequence.…”

Molecular Structure Characterization of Micro/Nanoplastics by 193 nm Ultraviolet Photodissociation Mass Spectrometry

“…There are many types of PA analogues prepared by different types of polymerization monomers and synthetic routes, resulting in the high structure diversity of PA MNPs. 48 It is difficult to unambiguously discriminate the backbone connectivity differences of PA analogues just by oligomer MW detection. Therefore, we tried to discriminate the sequence details of PA MNP analogues S5).…”