Mass Spectrometry & Spectroscopy
Analysis of Acetaldehyde and Limonene in Recycled PET Using an HS-GC/MS System
Sonja Wischnewsky, Shimadzu Europa
One environmental problem threatening the Earth is plastic waste. Packaging waste accounts for 20-30% of household waste by weight and 60% by volume.
In particular, due to the light weight and durability of polyethylene terephthalate (PET), which is widely used for beverage bottles and various other containers, various methods for reusing PET are being considered. In Japan, 96.7% of PET bottles are collected and 88.5% are recycled, on the other hand, only about 40% are recycled in Europe and about 20% in the United States [1].
For recycling PET, recycling companies in Japan have been implementing their own quality measurements. One example is a method based on using a gaschromatograph massspectrometer (GC-MS) system. GC-MS systems can be used to identify component peaks for qualitative and quantitative analysis of target substances, even for samples that contain many contaminants that make identifi cation diffi cult.
It is known that acetaldehyde can easily remain in PET containers that contained water beverages, and limonene that contained citrus-based beverages. This article describes an example of using a GCMS-QP™ 2020NX system with a HS-20 NX unit (Figure 1) for qualitative and quantitative analysis of acetaldehyde and limonene in PET bottles.
Analytical conditions The conditions for GCMS analysis with HS are listed in Table 2. Table 2: Analytical Conditions. Oven Temperature
Sample Line Temperature Transfer Line Temperature Vial Stirring Vial Volume
Vial Heat-Retention Time Vial Pressurization Time Vial Pressure Loading Time:
Needle Flush Time Injection Volume Load Equilib. Time:
Figure 1. GCMS-QP™2020 NX + HS-20 NX System Sample Preparation
Six types of samples with different pretreatment states were prepared. Sample types included pellets and freeze-ground pellet powder obtained from a recycler, two types of PET bottles that contained commercially marketed bottled water, and one PET bottle type each that contained lemon tea and orange juice. Each type of sample was sealed inside an HS vial. The state and quantity of each sample are indicated in Table 1.
Table 1. Information about Each Pretreated Sample. *1 PET sample provided by a recycling company (identical samples in pellet and powder state) *2 PET bottles for commercial beverages (lightly washed with water and cut with scissors)
Sample
Pellets *1 Powder *1 Water *2 Water *2
Lemon tea *2 Orange Juice *2 State
Pellets Powder
Cut into pieces with scissors Cut into pieces with scissors Cut into pieces with scissors Cut into pieces with scissors
Quantity 5 g
0.5 g 1 g 1 g 1 g 1 g
Model Column
Column Temp Injection Mode Split Ratio
Carrier Gas Control Linear Velocity
Ion Source Temperature Interface Temperature Acquisition Mode SCAN Range SIM
Event Time
Analytical Conditions [HS-20 NX] 80°C
150°C 150°C Off
20 mL 30 min 0.5 min
80 kPa (He) 0.5 min 5 min 1 mL
0.1 min [GC] GCMS QP 2020 NX
SH-PolarWax (0.25 mm ID x 30 m x d.f. = 0.5 µm)
40°C with 10°C/min to 250°C (21 min) Split 1:20
Constant linear velocity mode (He) 30 cm/sec
[MS]
200°C 250°C
SCAN/SIM (Simultaneus) m/z 10 to 250
m/z 43, 29, 42 (Acetaldehyde); m/z 136, 68, 93 (D-Limonene)
0.3 sec
INTERNATIONAL LABMATE - APRIL 2023
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