Bioanalytical screening of low levels of dioxins and dioxin-like PCBs in pig meat (pork) for checking compliance with EU maximum and action levels using highly sensitive “third generation” recombinant H4L7.5c2 rat hepatoma cells

Environmental Sciences Europe

Table 5 Initial validation: linear regression on BEQ/TEQ results from bioanalytical screening of 30 “blank” pig meat (pork) samples spiked around MLs and ALs, for PCDD/Fs and DL-PCBs followed by calculation of the respective cut-off concentrations [18, 22]

Parameter	Unit	Symbol	PCDD/Fs (ML)	PCDD/Fs (AL)	DL-PCBs	PCDD/Fs + DL-PCBs
Number of calibration levels		c	5	5	5	5
Number of replicates per level		m	6	6	6	6
Number of calibration points		n	30	30	30	30
Calibrated range	pg TEQ/g fat	R	0.09–1.99	0.09–1.99	0.07–1.03	0.16–3.02
Slope, calibration line		b	0.913	0.913	0.578	0.795
Standard error of the slope		s_b	0.065	0.065	0.044	0.048
Y-intercept, calibration line	pg BEQ/g fat	a	0.022	0.022	0.180	0.212
Standard error of the y-intercept	pg BEQ/g fat	s_a	0.077	0.077	0.027	0.086
Coefficient of correlation		r	0.9354	0.9354	0.9280	0.9518
Critical value for r (df = n − 2, p = 0.05, two-sided)		crit_r	0.3610	0.3610	0.3610	0.3610
Square coefficient of correlation		r²	0.8750	0.8750	0.8612	0.9060
GC/HRMS decision limit^a	pg TEQ/g fat	DL	1.2	0.90	0.60	1.50
BEQ concentration at DL	pg BEQ/g fat	y_DL	1.1	0.84	0.53	1.40
Mean recovery^b at ML, or AL		%	84.2	82.2	92.1	86.9
Residual standard deviation^c	pg BEQ/g fat	s_yx	0.2261	0.2261	0.0774	0.3186
Relative s_yx at y_DL (precision^c)	%	s_yx,rel	20.3	26.8	14.7	18.0
Cut-off concentration	pg BEQ/g fat	y_Cut-off	0.83	0.56	0.43	1.1
Maximum level	pg TEQ/g fat	ML	1.0	–	–	1.25
Action level	pg TEQ/g fat	AL	–	0.75	0.50	–

^aML, or AL, plus the expanded measurement uncertainty U (here: U = 20%)
^bAfter correction for the blank BEQ level and the apparent recovery of a reference sample spiked at ML, or AL
^cWithin-laboratory reproducibility conditions