Quantification of sulfur-containing substances in petroleum benzene
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Quantification of sulfur-containing substances in petroleum benzeneI. Reagents and instruments
Methanol (analytical grade or chromatographic grade)
Thiophene
Carbon disulfide
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°C
Chromatography column: FFAP
Gas flow rates: Hydrogen: 90 ml/min; Air: 100 ml/min
Split ratio: 20:1 (column flow rate: 1 ml/min)
III. Determination of the minimum detection limits for carbon disulfide and thiophene
1. Preparation of standard solutions
(1) Solution A: Weigh 1.3615 grams of thiophene and 1.017 grams of carbon disulfide 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 and 10.17 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 and 0.1017 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 and 1.017 ug/ml, respectively. (4) Transfer 1 ml, 2.5 ml, and 5 ml respectively from solution C into 10 ml volumetric flasks No. 1, No. 2, and No. 3, 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): 10.136, 150.1017, 20.340, 40.254, 330.680, 750.5085. Solution C: 1.3615, 1.017. (5) Solution D: 5 ml of Solution B was transferred into a 100 ml volumetric flask, diluted to the mark with methanol, and mixed well before use. The concentrations were 6.8075 μg/ml and 5.085 μg/ml, respectively. Sampling was carried out once the instrument had stabilized, and the results were as follows: Sample number, Thiophene (peak area), Carbon disulfide (peak area); Spectrum number: Sample 1 – not detected, not detected; Standard sample 20060427001 – not detected, 14.06; Standard sample 20060427002 – 7.58, 25.83; Standard sample 20060427003, Solution C – 39.20, 123.52; Standard sample 20060427004, Solution D – 982.40, 3253.79. The actual spectra are provided separately (under these conditions, the lowest detection limit for thiophene is 0.68 ppm, and for carbon disulfide it is 0.25 ppm). IV. Preparation of the calibration curve: A standard curve was prepared using the spectra of Sample 3, Solution C, and Solution D. The correlation coefficients obtained were r_thiophene = 0.98878 and r_carbon disulfide = 0.98926. V. Analysis of samples: Under stable instrument conditions, the sulfur content in the samples was determined, with the external standard method being used to quantify the sulfur compounds present in those samples. The test results showed that no carbon disulfide or thiophene was detected in the petroleum benzene. Coking benzene contains high levels of carbon disulfide and thiophene