Table 3: Precision and accuracy in the analysis of QC samples and ECD in ECD Kit.

DayStandard curve(1)Sulfur weight (%)(2)Recovery yield (%)
Dynamic range of sulfur (mg)Linear least squares regression equationCorrelation coefficient ( )QCcoalQCcoalQCECD (3)

10.033 –0.104Y = 1.615 × 10−6X + 4.747 × 10−30.99933.13 ± 0.07 (2.25%)102.08 ± 2.29
10.031–0.105Y = 1.623 × 10−6X + 1.741 × 10−30.99893.10 ± 0.02 (0.60%)100.89 ± 0.60
20.034–0.107Y = 1.634 × 10−6X + 1.034 × 10−30.99943.08 ± 0.04 (1.21%)100.15 ± 1.21
3 0.033–0.106 Y = 1.576 × 10−6X + 4.202 × 10−3 0.9996 3.18 103.79102.78
(QC-L)
100.00
(QC-M)
102.08
(QC-H)

(1)Standard curves of coal.
(2)Content percentage of sulfur in coal standard: 3.07% (w/w); data are expressed as average ± SD (%R.S.D.), .
(3)Purity of ECD: 97.53%; compositions of ECD QC samples (QC-L, QC-M, and QC-H) were shown in Table 2.