YC/T 207-2014 "Determination of Solvent Residues in Tobacco Papers by Headspace-Gas Chromatography/Mass Spectrometry" (hereinafter referred to as "New Standard") was released on December 24, 2014 and officially implemented on January 15, 2015. The 8-year old standard YC/T 207-2006 "Determination of Volatile Organic Compounds in Cigarette Strips and Box Packaging Paper" (headspace-gas chromatography) (hereinafter referred to as "the old standard") was simultaneously invalidated.
Solvent residue is a testing program generally carried out by various cigarette printing companies and material manufacturers. Some enterprises have used headspace-gas chromatography mass spectrometry before the release of the new standard, and have been using headspace-gas chromatography. The companies that are testing are under pressure from instrument upgrades.
According to our company's testing experience in the past two years, we believe that the new standard is a major change to the old standard. The most important change is that the detection method is upgraded from headspace-gas chromatography to headspace-gas chromatography/mass spectrometry. While improving the detection limit and sensitivity of the test method, it also puts forward higher professional requirements for the testers. In order to help the industry to further understand the changes in the new version of the standard, as well as the testing work that needs to be focused on, this article will explain and analyze as follows.
Change Description
1. Adjust the detection name
The new version of the standard adjusts the name of the test to "headspace-gas chromatography/mass spectrometry for the determination of solvent residues in cigarette paper."
2. Adjust the scope of application
The new version of the standard has been adapted to the scope of application, adding paper for cigarettes such as tipping paper and liner paper.
3. Modify the test indicators
(1) The new standard is in the old standard benzene, toluene, ethylbenzene, (o-, m-, p-) xylene, ethanol, isopropanol, n-butanol, acetone, 4-methyl-2-pentanone, butanone, Based on the detection of cyclohexanone, ethyl acetate, n-propyl acetate, n-butyl acetate, isopropyl acetate and propylene glycol methyl ether, styrene, methanol, n-propanol and 1-ethoxyl groups were added. 9-propanol, 2-ethoxyethyl acetate, 2-ethoxyethanol, dimethyl succinate, dimethyl glutarate and dimethyl adipate The name of methyl ether was changed to 1-methoxy-2-propanol, a total of 25 typical detection indicators.
(2) Based on the above 25 typical test indicators (3.2.1), 3.2.2 proposes the concept of “other solvent residue standardsâ€, which is determined by the qualitative analysis results of cigarette paper (6.1.2).
Therefore, the new version of the standard has increased the detection index compared with the old version of the standard, and changed the detection index to open type, which is divided into typical solvent residues (25 items) and other solvent residues (not fixed).
4. Modify the instrument detection method
The instrument detection method change is the core change of the new standard. The detection method is upgraded from headspace-gas chromatography (GC-FID) to headspace-gas chromatography/mass spectrometry (GC-MS).
GC-FID and GC-MS are two common detection methods, each with advantages and disadvantages.
(1) Qualitative analysis. GC-FID uses the retention time to characterize the compound to be tested, while GC-MS is characterized by the retention time of the target compound and the abundance ratio of the target compound. The qualitative reliability is greatly improved compared with GC-FID. Basically, it can effectively avoid the false positive problem that GC-FID is prone to occur.
(2) Detection limit and limit of quantitation. Compared to GC-FID, GC-MS can achieve lower detection and quantitation limits.
(3) Linear range. The linear range of GC-FID is about 106, while the linear range of GC-MS is only 103, that is, the range of accurate quantitation of GC-MS is much smaller than that of GC-FID.
(4) Instrument operation. The hardware and software operations of GC-MS are more complicated than GC-FID, and the requirements for inspectors are also higher.
(5) Instrument status. GC-FID is basically static, and GC-MS is dynamic, which means that its instrument state is always changing dynamically, and monitoring needs to be strengthened.
5. Adjust the standard solution to prepare the concentration
The standard solution concentration of the new standard is adjusted according to the actual residue of the test compound, and the highest concentration and the lowest concentration are reduced from 625 times to 100 times, which is more favorable for obtaining better linearity on the basis of strengthening the detection specificity.
6. Increase quality control
(1) Blank test ( 6.2.2 ). The blank test is one of the conventional quality control methods in the field of chemical detection. The blank test can effectively eliminate the abnormality of the detection data caused by blank pollution.
(2) Quality control samples ( 6.2.1 ). A standard working solution of medium concentration should be determined after 20 sample tests. If the measured value differs from the original value by more than 5%, the standard working curve should be re-made.
Through the quality control sample, the system deviation can be effectively identified, and if necessary, the standard working curve can be re-created to ensure accurate detection data.
Key Analysis
1. Standard curve linear
Since the linear range of GC-MS is much smaller than GC-FID, when using GC-MS, the linearity of some of the compounds to be tested is difficult to meet the standard requirement of R2 ≥ 0.995.
In this regard, on the one hand, it is necessary to strengthen the skill training of the inspectors, on the other hand, it is necessary to set the instrument parameters reasonably according to the characteristics and actual state of the respective instruments (the new standard is based on the headspace parameters established by the Agilent G1888, and the current Agilent 7697A and The headspace parameter settings of other brands are different. In addition, the GC-MS of different brands and models have different sensitivity, so the instrument parameters need to be set reasonably, and the experiment is repeated until the standard requirements are fully met.
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