Table 2.

Top m/z features matching chlorinated isotope patterns

m/za	Retention time (s)	Identity	Isotopesb	Adjusted r2	β coefficient	P-value
206.8750	81.3	Trichloroacetic acidc	M + 2, M + 4	0.76	9.87	3.1E-55
224.8456	88.4	Trichloroethanold	M + 2	0.68	8.37	1.0E-43
264.8338	78.7	Unknown	M + 2, M + 4	0.55	7.16	9.8E-32
332.8201	83.3	Unknown	M + 2, M + 4	0.43	5.69	3.9E-23
280.8067	88.5	Unknown	M + 2, M + 4	0.41	5.08	1.2E-21
324.7895	77.2	Unknown	M + 2	0.39	5.55	7.2E-21
340.7621	77.1	Unknown	M + 2, M + 4	0.32	4.11	7.1E-16
274.8629	84.8	Unknown	M + 2	0.29	4.01	2.4E-15
392.7587	86.1	Unknown	M + 2	0.20	4.14	3.2E-10
380.7691	52.6	Unknown	M + 2, M + 4	0.16	0.08	2.6E-04

Regression parameters for the monoisotopic mass only are listed. Regression results for all features with FDR ≤ 20% are provided in Supplementary Text 2, available as Supplementary data at IJE online.

^aMass-to-charge ratio.

^bM + 2 = ³⁷Cl (+1.9971); M + 4 = ³⁷Cl₂ (+3.9941).

^cDetected as +2Na-H adduct form.

^dDetected as +2K-H adduct form.