Table 1.

Characteristic peaks of REEs in MPT-MS.

REEs	Natural isotopes (%)	Dominant peak band in MPT-MS (m/z)		Normalized intensity of corresponding peaks		Assignment
		+modea	−modeb	+mode	−mode	+mode	−mode
Y	89Y (100)	267	337	1	1	[Y(NO3)2·3H2O]+	Y(NO3)4 −
La	138La (0.09)	—	—	—	—	[La(NO3)2·3H2O]+	La(NO3)4 −
	139La (99.91)	317	387	1	1
Ce	136Ce (0.19)	—	—	—	—	[Ce(NO3)2·3H2O]+	Ce(NO3)4 −
	138Ce (0.25)	—	—	—	—
	140Ce (88.48)	318	388	1	1
	142Ce (11.08)	320	390	0.112	0.1205
Pr	141Pr (100)	337	389	1	1	[Pr(NO3)2·4H2O]+	Pr(NO3)4 −
Nd	142Nd (27.13)	320	390	1	1	[Nd(NO3)2·3H2O]+	Nd(NO3)4 −
	143Nd (12.18)	321	391	0.419	0.458
	144Nd (23.80)	322	392	0.8401	0.8714
	145Nd (8.30)	323	393	0.3002	0.325
	146Nd (17.19)	324	394	0.624	0.638
	148Nd (5.76)	326	396	0.181	0.2247
	150Nd (5.64)	328	398	0.1712	0.217
Sm	144Sm (3.1)	322	392	0.138	0.1253	[Sm(NO3)2·3H2O]+	Sm(NO3)4 −
	147Sm (15.0)	325	395	0.5887	0.5767
	148Sm (11.3)	326	396	0.4112	0.4368
	149Sm (13.8)	327	397	0.501	0.5395
	150Sm (7.4)	328	398	0.2562	0.2911
	152Sm (26.7)	330	400	1	1
	154Sm (22.7)	332	402	0.8472	0.8318
Eu	151Eu (47.8)	329	399	0.916	0.9148	[Eu(NO3)2·3H2O] +	Eu(NO3)4 −
	153Eu (52.2)	331	401	1	1

^a10 mg/L standard solutions were used.

^b0.5 mg/L standard solutions were used.