Soil and sediments. Determination of dioxins. Isotope dilution high resolution gas chromatography-high resolution mass spectrometry (2)

Six, analysis and testing

(1) Instrument conditions (for reference only, can be adjusted appropriately according to the actual instrument)

1.

Injection port: temperature is 280℃, column flow (constant flow mode) is 1.

2.

Resolution: greater than 10000 (the resolution needs to be tuned to higher than 10000 before each sample analysis), solvent delay time is 20 minutes, electron bombardment source: EI, EI source temperature: 280℃, SIM scanning mode, transmission line temperature: 280 ℃

(2) Qualitative quantitative ion and toxicity equivalent

EI source is used to analyze the retention time of each compound, the quantitative qualifier ion used and the toxicity equivalent are shown in Table 7-10

Table 7-10 Retention time and quantitative qualitative ion of each compound

(3) Calibration curve

Take five standard solutions of EPA-1613CS1, EPA-1613CS2, EPA-1613CS3, EPA-1613CS4, and EPA-1613CS5, directly inject the sample for analysis, and quantify with the internal standard relative response factor method.

Where Q _es —— the absolute amount of the internal standard substance extracted in the standard solution, pg;

Q _s ——the absolute amount of the compound to be tested in the standard solution, pg;

A _s ——the sum of the peak areas of the monitored ions of the compounds to be tested in the standard solution;

A _{es ——the} sum of the peak areas of the monitored ions extracted from the internal standard substance in the standard solution

Similarly, calculate the relative response factors RRF _rs and RRF _{ss of the} injection internal standard relative to the extracted internal standard and the extracted internal standard relative to the sampling internal standard according to equations (3) and (4), respectively

Where Q _rs —— the absolute amount of the internal standard substance injected in the standard solution, pg;

Q _{es ——the} absolute amount of the internal standard substance extracted in the standard solution, pg;

A _{es ——the} sum of the peak areas of the monitored ions extracted from the internal standard substance in the standard solution;

A _{rs ——the} sum of the peak areas of the monitored ions of the injected internal standard substances in the standard solution

Where Q _es ——-the absolute amount of the internal standard substance extracted in the standard solution, pg;

Q _{ss ——the} absolute amount of the internal standard substance sampled in the standard solution, pg;

A _{ss ——the} sum of the peak areas of the monitored ions of the internal standard substances sampled in the standard solution;

A _{es ——the} sum of the peak areas of the monitored ions extracted from the internal standard substance in the standard solution

(4) Sample determination

The sample after pretreatment is measured under the same conditions as the calibration curve, and quantification is performed based on the peak area