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Six, analysis and testing
(1) Reference conditions of gas chromatography (for reference only, can be adjusted appropriately according to the actual instrument)
Temperature rotation of the injection port: 280℃
Carrier gas: nitrogen, purity ≥99.
The chromatographic column connected to the forward inlet is an auxiliary qualitative chromatographic column, and the other conditions of the qualitative analysis are the same as those of the forward inlet analysis
(2) Calibration curve
The dilution solvent is n-hexane, and the standard series (such as 0.
Table 3-3 Toxaphene quantitative peak retention time
7.
(1) Qualitative target compound
Qualitatively based on the retention time of each component of the standard material
(2) Quantitative calculation
The target compound was quantified by an external standard method, and the mass concentration of the target compound in the leachate ρ(uL) was calculated according to formula (1)
ρ=ρ x ×(V x /V i ) (1)
Where ρ x — the mass concentration of the target compound calculated from the calibration curve, ug/L;
V x —Concentrated constant volume of the extract, mL;
V i — sampling volume of leaching solution, mL
8.
(1) Use the linear fitting curve to calibrate, the correlation coefficient should be greater than or equal to 0.
(2) Before analyzing each batch of samples (up to 10 samples), check the calibration curve with the mass concentration of the middle point of the calibration curve.
(3) Each batch of samples (up to 10 samples) should be a laboratory blank, and the mass concentration of the target compound in the experimental blank should be less than the detection limit of the method
(4) Each batch of samples (up to 10 samples) should be subjected to at least one parallel determination, and the relative deviation of the parallel sample determination results should be within 30%
(5) Each batch of samples (up to 10 samples) should be spiked with actual samples at least once
Nine, matters needing attention
(1) The solvents and reagents used in the experiment have a certain degree of toxicity, so the sample pretreatment process should be carried out in a fume hood, and the operator should do his own protection work
(2) The rotary evaporation should not be too fast and the vacuum degree should not be too low, otherwise it will affect the recovery rate of toxaphene
.
(3) The sampling amount of the leaching solution can be appropriately reduced according to the content of the target substance.
The leaching solution should be extracted immediately, otherwise it should be stored in a refrigerator at 4°C
.
(4) The emulsification of the extract can be broken by mechanical separation or centrifugation
.
(5) Double columns should be used for qualitative analysis of detected samples, and the accuracy of the results should be judged based on the recovery rate of standard addition
.