Table 3.

Inter-lot and intra-lot variability in microcystin (MC) contamination in Aphanizonemon flos-aquae containing blue-green algal dietary supplements as determined by protein phosphatase inhibition assay (PPIA) and liquid chromatography tandem mass spectrometry (LC-MS/MS). LC-MS/MS values represent the average for duplicate analyses (n = 2) run on separate days.

Original Purchase				Second Purchase				Different Lot
Sample Number	Forma	PPIA (μg/g MC)	LC-MS/MS (μg/g MC)	Sample Number	Forma	PPIA (μg/g MC)	LC-MS/MS (μg/g MC)
1	Powder	2.8	3.0	59	Tablet	1.2	0.90	Yesb
3	Capsule	1.2	1.4	60	Capsule	0.26	–	Yes
4	Tablet	1.1	1.4	61	Tablet	0.82	1.2	Yes
9	Tablet	0.95	1.2	62	Tablet	1.3	1.2	Yes
10	Capsule	0.92	0.80	63	Powder	0.29	–	Yesb
7	Powder	0.97	1.0	64	Powder	0.86	0.86	No
11	Capsule	0.89	0.68	65	Capsule	0.80	0.71	No
14	Capsule	0.56	0.60	66	Capsule	0.64	0.66	No
19	Capsule	0.38	–	67	Capsule	0.42	–	No

“–” Only samples ≥0.50 μg/g by PPIA were confirmed by LC-MS/MS.

^aAll of these products contained AFA as the only active ingredient.

^bNote that these products, from the same manufacturer, were different lots but also in different product forms.