Quantification of sulfur-containing substances in benzene chloride
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Quantification of sulfur-containing substances in benzene chlorideI. Reagents and instruments
Methanol (analytical grade or chromatographic grade)
Thiophene, carbon disulfide, 2,5-dichlorothiophene
GC6890 (with FPD detector equipped with an S-filter and an automatic sampler)
II. Analysis conditions:
Vaporization chamber: 200°C
Detection chamber: 200°C
Auxiliary temperature: 200°C
Column temperature: 60–100°C (programmed temperature rise)
Chromatography column: FFAP
Gas flow rates: Hydrogen: 90 ml/min; Air: 100 ml/min
Split ratio: 20:1 (column flow rate: 2 ml/min)
III. Determination of the minimum detection limits for carbon disulfide, thiophene, and 2,5-dichlorothiophene
1. Preparation of standard solutions
(1) Solution A: Weigh 1.3615 grams of thiophene, 1.017 grams of carbon disulfide, and 1.0148 grams of 2,5-dichlorothiophene respectively, place them in a 100 ml volumetric flask, dilute to the mark with methanol, and mix well for later use. The concentrations are 13.615 mg/ml, 10.17 mg/ml, and 10.148 mg/ml respectively. (2) Solution B: Transfer 1 ml from Solution A into a 100 ml volumetric flask, dilute to the mark with methanol, mix well, and set aside for use. The concentrations are 0.13615 mg/ml, 0.1017 mg/ml, and 0.10148 mg/ml respectively. (3) Solution C: Transfer 1 ml from Solution B into a 100 ml volumetric flask, dilute to the mark with methanol, mix well, and set aside for use. The concentrations are 1.3615 ug/ml, 1.017 ug/ml, and 1.0148 ug/ml respectively. (4) Transfer 1 ml, 2.5 ml, and 5 ml respectively from solution C into 10 ml volumetric flasks numbered 4, 5, and 6, dilute to the mark with methanol, mix well, and set aside for use. The concentrations are as follows: Number, Thiophene (ug/ml), Carbon disulfide (ug/ml), 2,5-Dichlorothiophene (ug/ml): 40.13, 61.50, 101.70, 101.48, 50.34, 040.25, 430.25, 3760.68, 0750.50, 850.50, 47. Solution C: 1.36, 151.01, 71.01, 48. Solution D: 5 ml of Solution B was transferred into a 100 ml volumetric flask and diluted to the mark with methanol; after mixing, it was set aside for use. The concentrations are 6.8075 ug/ml, 5.085 ug/ml, and 5.074 ug/ml respectively. (6) Solution E: Transfer 1 ml from Solution B into a 10 ml volumetric flask, dilute to the mark with methanol, mix well, and set aside for use. The concentrations are 13.615 ug/ml, 10.17 ug/ml, and 10.148 ug/ml respectively. (7) Solution F: Transfer 5 ml from Solution B into a 10 ml volumetric flask, dilute to the mark with methanol, mix well, and set aside for use. The concentrations are 68.075 ug/ml, 50.85 ug/ml, and 50.74 ug/ml respectively. 2. Sampling was carried out when the instrument was stable. The results of sampling are as follows: Sample number, Thiophene (area), Carbon disulfide (area), 2,5-Dichlorothiophene (peak area). Spectrum number: Sample 4 – not detected, not detected, not detected; Sample 20060501001 – not detected, 11.03, not detected; Sample 20060501002 – 16.16, 23.36, 14.59; Sample 20060501003 – Solution C: 61.95, 88.84, 17.47; Sample 20060501004 – Solution D: 732.47, 1491.84, 144.65; Sample 20060501005 – Solution E: 2986.47, 7149.55, 533.63; Sample 20060501006 – Solution F: 8627, 171.79, 3233.51, 2030.7. The detailed spectra are attached separately. (Under these conditions, the lowest detection limit for thiophene is 0.68 ppm, for carbon disulfide it is 0.25 ppm, and for 2,5-dichlorothiophene it is 0.5047 ppm.) IV. Preparation of calibration curves: Standard curves were prepared using the spectra of Sample 3, Solution C, and Solution D. The correlation coefficients obtained were: r for thiophene = 0.9855, r for carbon disulfide = 0.9915, r for 2,5-dichlorothiophene = 0.9947. V. Analysis of samples: Under stable instrument conditions, the sulfur content in the samples was determined, and the amount of sulfur-containing substances in the samples was quantified using the external standard method. Test results: Thiophene, carbon disulfide, and 2,5-dichlorothiophene were not detected in petroleum-grade chlorobenzene; thiophene and carbon disulfide were not detected in coking-grade chlorobenzene, while the content of 2,5-dichlorothiophene was relatively high