Page 21 - Shimadzu Journal vol.7 Issue1

Environmental Analysis

Determination of short chain chlorinated paraffins (SCCPs)
using comprehensive two-dimensional gas chromatography
coupled with mass spectrometry

3
1
3
2
1
3
Yun Zou Naoki Hamada Yuki Hashi Liang Dong Wenlong Yang Pengjun Xu Shan Niu 3
1 Shimadzu China MS Center, Shimadzu (China) Co. LTD., Beijing, China, 100020
2 Shimadzu China R&D Division, Shimadzu (China) Co. LTD., Shanghai, China, 200052
3 National Research Center for Environmental Analysis and Measurement, Beijing, China, 100029
Introduction
Chlorinated paraffins (CPs) are known as a group of synthetic 13 C labeled 1,5,5,6,6,10-hexachlorodecane used as an internal
chlorinated n-alkanes. They are widely used in industries related to standard (ISTD) was purchased from Cambridge Isotope Laboratories
metalworking fluids, sealants, rubbers, textiles and so on . According (Andover, USA). The commercial CP products were bought from three
[1]
to the carbon chain length, CPs are divided into short chain chlorinated industries. In factory A CP products are classified according to
paraffins (SCCPs; C10-C13), medium chain chlorinated paraffins (MCCPs; chlorination degree. Samples noted as CP-42, CP-52, and CP-70
C14-C17), and long chain chlorinated paraffins (LCCPs; C18-C30) . SCCPs indicate the approximate chlorine content of 42%, 52%, and 70% by
[1]
received more attention because of their persistence, bioaccumulation, weight. On the samples CP-B and CP-C collected from factory B and C,
potential for long-range environmental transport and toxicity . respectively, neither chlorination degree nor carbon chain length is
[1]
Stockholm Convention has listed SCCPs in Annex A of persistent labeled. CP products were dissolved into cyclohexane and diluted into
organic pollutants (POPs) . certain concentrations. After that CP solutions were mixed with ISTD
[2]
CP production is rising in China year by year . The contribution of before measurements.
[3]
SCCPs among CP products is unclear . It is necessary to clarify the
[4]
SCCP concentration levels in Chinese commercial CP products. Results and discussion
For the instrumental analysis of SCCPs, one-dimensional gas
chromatography is commonly used for separation, and mass Two-dimensional gas chromatogram of the mixture of SCCP standards
spectrometry in selected ion monitoring (SIM) mode is widely used as with ISTD under the optimal analytical condition was shown in Fig 1. 4
[3]
the detector . However, one-dimensional gas chromatography Events were divided according to carbon chain lengths in order to
coupled with mass spectrometry has the disadvantage on SCCPs and clearly integrate peak volume of every congener. In each carbon chain
MCCPs separation since some of the congeners those share the similar length group, the congener with less chlorine substitution eluted
nd
st
quantitative or qualitative ions have the overlapped retention times . earlier in both 1 column and 2 column. 24 congeners could be
[5]
Comprehensive two-dimensional gas chromatography (abbreviated to separated clearly in the two-dimensional gas chromatogram.
GCxGC hereinafter) is a promising tool for better analyzing SCCPs. A quantification method using the calibration between total response
In this study, an analytical method using GCxGC coupled with mass factor (RF) and chlorine (Cl) content was developed by Reth et al.
[7]
spectrometry (GCxGC-MS) on the quantification of SCCPs was (2005) and widely used in SCCPs quantification . The calculations of
developed. The SCCP concentrations in Chinese commercial CP both RF and Cl content are based on the integrated peak volumes of
products were measured. Moreover, the SCCPs congeners’ relative quantitative ions of 24 congeners. RF-Cl content calibration curves of
contributions of above samples were also described. thirteen chlorine content levels of SCCPs standards were established.
Unlike the previous researches, there were two linear correlations
obtained in different Cl content ranges (Fig. 2). The first calibration
Materials and methods
ranged between Cl content of 0.585 and 0.636. Total response factor
The SCCP measurement was performed on comprehensive was well calibrated with Cl content (R = 0.9544) with the equation of
2
two-dimensional gas chromatography couples with triple quadrupole RF = 212.92 x (Cl content) - 122.14. The second calibration was
mass spectrometry (GCxGCMS-TQ8040; Shimadzu, Kyoto, Japan). obtained in the range of 0.635-0.651 of Cl content. The calibration
GCxGC thermal modulator (Zoex Corp., Houston, TX, USA) was fitted equation was RF = 1395.1 x (Cl content) – 872.59 with R of 0.9736.
2
to GC instrument. The capillary column set was the combination of These two calibration curves were used in the quantification of SCCPs
one non-polar column and one moderately polar column. The first in CP products.
column was a 15 m InertCap 5MS/Sil fused silica capillary column (0.25
mm i.d., 0.1 µm thickness of 5% phenyl and 95%
polysilphenylene-siloxane film; GL Sciences Inc., Tokyo, Japan). The
second column was a 2.5 m BPX-50 fused silica capillary column (0.1
mm i.d., 0.1 µm thickness of 50% phenyl polysilphenylene-siloxane
film; SGE Analytical Science, Melbourne, Australia).
Negative chemical ionization (NCI) was used as ionization source for
SCCP measurement. It has an advantage of enhancing the sensitivity of
dominant fragment ions since little ion fragmentation could occur in
NCI source . Methane was the reagent gas. In SIM mode, a pair of
[6]
ions including one quantitative ion and one qualitative ion were
selected for 24 SCCP congeners as well as the ISTD. Two-dimensional
data processing was conducted using ChromSquare Ver. 2.2
(Shimadzu, Kyoto, Japan). Fig. 1 2D chromatogram of SCCP standards and ISTD.
Three SCCP mixtures (C10-C13 containing different chlorine contents of
51.5%, 55.5%, and 63%; 100 ng/µL solutions in cyclohexane; 100%
pure) were purchased from Dr. Ehrenstorfer (Augsburg, Germany). The

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