Table 1.

Major endotoxin fragments generated by DART-LTQ (ion trap) MS and proposed chemical formula for different ions with exact mass obtained from an accurate mass Q-TOF MS.

m/z value	Chemical formula	Proposed ion form	Exact m/z value	Mass error (ppm)
117	C5H9O3	[M − H2O − 45]+	117.0565	11.0
127	C6H7O3	[M − 3H2O + H]+	127.0407	9.4
145	C6H9O4	[M − 2H2O + H]+	145.0514	8.6
163	C6H11O5	[M − H2O + H]+	163.0619	7.6
180	C6H14NO5	[M + NH4 − H2O]+	180.0882	5.7
198	C6H16NO6	[M + NH4]+	198.0984	3.3
271	C12H15O7	[N − 4H2O + H]+	271.0840	8.1
289	C12H17O8	[N − 3H2O + H]+	289.0933	2.2
307	C12H19O9	[N − 2H2O + H]+	307.1033	1.4
325	C12H21O10	[N − H2O + H]+	325.1130	−2.4
342	C12H24NO10	[N − H2O + NH4]+	342.1390	−2.9
343	C12H23O11	[N + H]+	343.1240	0.0
360	C12H26NO11	[N + NH4]+	360.1489	−4.6
119	C4H7O4	[M − 60 − H]−	119.0345	0.7
143	C6H7O4	[M − 2H2O − H]−	143.0344	−0.5
161	C6H9O5	[M − H2O − H]−	161.0451	−0.4
179	C6H11O6	[M − H]−	179.0548	−4.5
221	C8H13O7	See SI	221.0650	−7.4
323	C12H19O10	[N − H2O − H]−	323.0970	−2.8
341	C11H21O11	[N − H]−	341.1069	−4.6

Note: m/z values in the first column were obtained from an ion trap MS, while exact m/z values (the fourth column) were acquired from a high resolution accurate mass Q-TOF MS. The peaks listed in the Table can be used as golden standards for the detection of endotoxin in different matrices. M indicates a chemical formula of C₆H₁₂O₆ for monosaccharide; N indicates a chemical formula of C₁₂H₂₂O₁₁ for disaccharide; 45 indicates a loss of COOH, 60 indicates a loss of 2CHOH from hexose. Please see Supporting information (SI) Fig. S3 for the proposed structures of ions m/z 117, m/z 119 and m/z 221.