Table 5: Robustness study in the analysis of ECD.

ParameterStandard curve of coal(1)QCcoal (2)
Linear least squares regression equationCorrelation coefficient ( )Sulfur weight (%)Recovery yield (%)(3)

Dosing time (sec)90Y = 1.544 × 10−6X + 3.394 × 10−30.99923.14 ± 0.06102.36 ± 2.58
120Y = 1.615 × 10−6X + 4.747 × 10−30.99933.13 ± 0.07101.91 ± 2.30
150Y = 1.604 × 10−6X + 7.508 × 10−40.99993.05 ± 0.1099.17 ± 2.84

Temperature of combustion tube (°C)1120Y = 1.605 × 10−6X + 8.215 × 10−40.99973.13 ± 0.06102.01 ± 1.85
1150Y = 1.615 × 10−6X + 4.747 × 10−30.99933.13 ± 0.07101.91 ± 2.30
1180Y = 1.586 × 10−6X + 1.126 × 10−30.99853.03 ± 0.0398.68 ± 1.14

Temperature of reduction tube (°C)850Y = 1.621 × 10−6X + 9.226 × 10−50.99973.12 ± 0.06102.01 ± 1.75
900Y = 1.615 × 10−6X + 4.747 × 10−30.99933.13 ± 0.07101.91 ± 2.30
950Y = 1.649 × 10−6X − 1.288 × 10−30.99963.00 ± 0.0297.97 ± 0.87

(1)Standard curves were constructed by the coal concentration range of 1.01 to 3.49 mg.
(2)Data are expressed as average ± SD, .
(3)Recovery yield (%) = Sulfur(mg)exp/Sulfur(mg)nominal  × 100%.