YC/T 373-2010Determination of benzene, toluene, ethylbenzene and xylene in polypropylene fiber tow and polypropylene fiber tow filter rod - Gas chromatography-mass spectrometry method (English PDF)

4.1 Reagents

4.1.1 N-hexane (C6H14), Super Pure grade or pesticide residue grade.

4.1.2 N-pentane (C5H12), chromatographic grade.

4.1.3 Benzene (C6H6), purity >=99%.

4.1.4 Toluene (C7H8), purity >=99%.

4.1.5 Ethylbenzene (C8H10), purity >=99%.

4.1.6 O-xylene (o-C8H10), purity >=99%.

4.1.7 M-xylene (m-C8H10), purity >=99%.

4.1.8 P-xylene (p-C8H10), purity >=99%.

4.1.9 2-hexanone (internal standard), if other substances are used as internal standard, the applicability shall be verified.

4.2 Preparation of internal standard solution

4.2.1 Internal standard stock solution: weigh 0.1 g of 2-hexanone (4.1.9)

(accurate to 0.1 mg) in a 50 mL volumetric flask; use n-hexane (4.1.1) to dilute to the mark; mix well, to obtain an internal standard stock solution whose concentration is 2 mg/mL. Seal and store the internal standard stock solution in a refrigerator at 0 °C ~ 4 °C; the validity period is 3 months.

4.2.2 Internal standard solution: accurately pipette 2.5 mL of internal standard

stock solution (4.2.1) into a 50 mL volumetric flask; use n-hexane (4.1.1) to dilute to the mark; mix well to obtain an internal standard solution whose concentration is 100 µg/mL. Seal and store the internal standard solution in a refrigerator at 0 °C ~ 4 °C; the validity period is 1 month.

4.3 Preparation of standard solution

4.3.1 Mixed standard stock solution: respectively weigh 0.1 g of benzene (4.1.3), toluene (4.1.4), ethylbenzene (4.1.5), o-xylene (4.1.6), m-xylene (4.1.7), p- xylene (4.1.8) (accurate to 0.1 mg) in the 100 mL volumetric flasks; use n- hexane (4.1.1) to dissolve them and dilute to the mark; mix well, to obtain the mixed standard stock solution, of which the concentration of each component is 1 mg/mL, respectively. Seal and store the mixed standard stock solution in a refrigerator at 0 °C ~ 4 °C; the validity period is 3 months.

4.3.2 Mixed standard solution: use n-hexane (4.1.1) to gradually dilute the

mixed standard stock solution (4.3.1) to obtain a mixed standard solution whose concentration is 5 µg/mL. Formulate this solution when needed.

Perform selective ion scanning on the standard working solution; calculate the peak area ratio of benzene, toluene, ethylbenzene, and xylene in each standard solution to the internal standard 2-hexanone; draw the standard working curve of concentration-to-peak area ratio of benzene, toluene, ethylbenzene and xylene. The standard working curve shall be straight line relationship; the correlation coefficient shall be R2 >0.99.

A standard working curve shall be made for each test. After every 20 samples, add a medium-concentration standard working solution. If the measured value differs from the original value by more than 10%, the standard working curve shall be made again.

6.5 Sample determination

Measure the sample solution (6.2) according to the instrument test conditions;

repeat the measurement twice for each sample. At the same time, make a set of blanks for each batch of samples.