Table 4.

Matrix effect estimated via matrix factors of ZNS and IS and IS normalized matrix factor.

DBS
	MFZNS * %	MFIS * %	MFZNS/MFIS %	MP <Cc> * µg/mL	MP CZNS RSD, %	MA <Cc> µg/mL	MA CZNS RSD, %	CZNS bias, %
low QC 0.375 µg/mL	110.11	108.26	101.72	0.417	3.73	0.409	4.33	2.85
medium QC 3.75 µg/mL	91.55	91.02	100.58	4.19	2.51	4.15	6.61	0.90
high QC 19 µg/mL	99.12	95.41	103.89	21.19	4.24	20.63	5.31	2.70
n	3
DPS
	MFZNS * %	MFIS * %	MFZNS/MFIS %	MP <Cc> * µg/mL	MP CZNS RSD, %	MA <Cc> µg/mL	MA CZNS RSD, %	CZNS bias, %
low QC 0.750 µg/mL	102.26	99.44	102.84	0.832	2.25	0.804	7.27	3.58
medium QC 7.5 µg/mL	93.92	96.62	97.21	8.17	4.77	8.41	1.16	−2.84
high QC 38 µg/mL	100.11	102.30	97.86	40.91	6.14	41.91	3.09	−2.39
n	3

MF_ZNS—Matrix factor of ZNS calculated by dividing average peak area of ZNS in matrix-present sample (MP P_zns) with average peak area of ZNS in matrix-absent sample (MA P_zns), then multiplied by 100 to express as percentage value—MP P_zns/MA P_zns × 100; MFIS—Matrix factor of IS calculated by dividing average peak area of IS in matrix-present sample (MP P_is) with average peak area of IS in matrix-absent sample (MA Pis), then multiplied by 100 to express as percentage value—MP Pis/MA Pis ×100; MF_ZNS/MF_IS—IS normalised MF, calculated by dividing the MF of the ZNS by the MF of the IS and multiplying by 100 to express as percentage value; MP <Cc>—average ZNS concentration calculated for matrix-present samples; MA <Cc>—average ZNS concentration calculated for matrix-absent samples; MP C_ZNS RSD,%—percentage coefficient of variation for ZNS concentration calculated at certain QC level for both batches of matrix in matrix-present samples; MA C_ZNS RSD,%—percentage coefficient of variation for ZNS concentration calculated at certain QC level in matrix-absent samples; C_ZNS bias%-percentage deviation of ZNS concentration determined in the matrix-present samples relative to ZNS concentration determined in matrix-absence sample, calculated by dividing deviation of the average ZNS concentration obtained in matrix-present samples from average ZNS concentration obtained in matrix-absent samples, with ZNS determined in matrix-absent samples—((MP <Cc> − MA <Cc>)/MA <Cc>) × 100; n—number of replicates per each QC level; * average values calculated by considering all individual values at each QC level obtained from the both batches of each matrix in the case of the matrix-present samples and all individual values at each QC level for the matrix-absent samples.