Table 4: Stability study of QC samples analysis.

DayStandard curveRecovery yield (%)(1)
Dynamic range of sulfur (mg)Linear least squares regression equationCorrelation coefficient ( )QCcoal (2)QCECD (3)

10.032–0.105Y = 1.627 × 10−6X + 4.149 × 10−30.9994101.10 ± 0.9496.02 ± 2.33
20.033–0.103Y = 1.629 × 10−6X + 2.390 × 10−30.999499.82 ± 0.9098.48 ± 1.96
30.031–0.105Y = 1.609 × 10−6X + 2.608 × 10−30.9997101.72 ± 2.00102.31 ± 1.63

(1)Data are expressed as average ± SD, .
(2)QCcoal: 2.05 ± 0.05 mg of coal QC samples (S = 3.07%, w/w) were analyzed.
(3)QCECD: 7.52 ± 0.03 mg of ECD QC samples (ECD = 3.61%; S = 0.58%, w/w) were analyzed.