surfactant
surfactant (%)
α-Lipoic acid (%)
metal (M)
M
2+
/α-Lipoic acid
CO
3
2-
/M
2+
appearance
blank
0
1
Mg
0.5
-
s
0
1
Mg
0.25
-
s
0
1
Ca
0.5
-
s
0
1
Ca
0.25
-
s
Polyoxyethylene (20) stearyl eter
1
1
Mg
0.5
0.2
t
2
1
Mg
0.5
0.2
t
5
1
Mg
0.5
0.2
t
5
1
Ca
0.5
0.2
s
8
1
Ca
0.5
0.2
s
8
1
Mg
0.5
0.2
t
10
1
Ca
0.5
0.2
s
10
1
Ca
0.25
0.2
t
10
0.5
Ca
0.5
0.2
s
10
0.5
Ca
0.25
0.2
t
Polyoxyethylene (60) hydrogenated castor oil
10
1
Ca
0.5
0.2
s
10
1
Ca
0.25
0.2
t
10
0.5
Ca
0.5
0.2
s
10
0.5
Ca
0.25
0.2
t
sucrose laurate
5
1
Mg
0.5
0.2
t
10
0.5
Ca
0.5
0.2
s
10
0.5
Ca
0.25
0.2
t
t=transparent; s=separate
Table 2
: Influence of nonionic surfactants, divalent cations (Ca
2+
, Mg
2+
) and a divalent anion (CO
3
2-
) on appearance of the solution containing α-lipoic acid.
