Electronic Supplementary Material
Electrophoretic separation of acidic and basic proteins in the presence of micromolar ionic liquid
Journal name: Microchimica Acta
Janar Tursen, Aimin Wang, Weidong Qin*
College of Chemistry, Beijing Normal University, No. 19, Xinjiekou Wai Street, Beijing, 100875, P. R. China
*Correspondence:
College of Chemistry, Beijing Normal University, No. 19, Xinjiekou Wai Street, Beijing, 100875, P. R. China, Dr. Weidong Qin
E-mail:
Fax: + 86-10-58802531
1. Effect of alkyl group length of the imidazolium cation
Fig. 1S Effect of alkyl group length of the imidazolium cation. Separations were carried out in the BGE of 200 mM HAc (a) that was added to 50 μM [C4MIm]Br (b), 50 μM [C8MIm]Br (c), 50 μM [C12MIm]Br (d). Samples were injected by siphon of 28 cm × 20 s. Separation voltage, 12 kV; capillary length, 39.5 cm (with effective length of 30 cm); C4D excitation: 75 kHz at 9.8 V. Peak identities and concentrations (in μg mL-1): 1, LZ (100); 2, HSA (100); 3, TF (100); 4, MB (50); 5, TRI (200); 6, HB (150); 7, CL (200). Traces are offset for clarity.
2. Determination of the CMC of [C12MIm]Br
Variation in conductance values as a function of [C12MIm]Br concentration is plotted in Fig. 2S. Line a and b correspond to the concentration range below and above the CMC, respectively. The linear equations of them are:
y=0.053x + 0.643 (a)
y=0.017x + 1.136 (b)
The value of R2 are 0.99919 and 0.95513 for eq. (a) and for eq. (b), respectively. The CMC of [C12MIm]Br is 13.7 mM, as obtained from the equations.
Fig. 2S Variation of conductivity vs. surfactant concentration in 200 mM acetic acid BGE (pH 2.47), experiments were carried out at 25°C.
3. EOF of the IL coated capillary
EOF was determined by the migration time of neutral marker (acetone solution). Fig. 3S shows the influence of IL coating on EOF.
Fig. 3S Influence of IL coating on EOF of the capillary. Separations were carried out in the BGE of 200 mM HAc containing [C12MIm]Br concentration levels in the range of 1-100 μm. The marker was injected by siphon of 28 cm × 5 s. Separation voltage, 12 kV; capillary length, 39.5 cm (with effective length of 30 cm); C4D excitation: 75 kHz at 9.8 V.
4. Protein recovery
Table 1S Recoveries a of proteins (mean ± SD)
IL concentration (μM) / LZ / HSA / TF / MB / TRI / HB / CL0 b / 53.5±0.9 / 36.2±1.0 / 31.6±1.2 / 39.5±0.6 / 51.6±0.9 / 39.2±0.4 / 47.0±0.8
30 c / 97.0±1.0 / 81.4±0.8 / 40.2±1.2 / 46.6±1.1 / 106.3±0.7 / 49.2±1.2 / 54.6±1.1
a Average of three replicates
b BGE contains 200 mM HAc
c BGE contain 200 mM HAc plus 30 μM [C12MIm]Br
5. Influence of [C12MIm]Br concentration on peak heights
Table 2S Influence of [C12MIm]Br concentration on peak heights (mV)
IL concentration (μM)0 / 7 / 15 / 25 / 30 / 40
LZ / 17.67 / 16.85 / 17.50 / 17.04 / 16.28 / 15.79
HSA / 4.54 / 3.53 / 3.29 / 3.98 / 4.74 / 3.67
TF / 0.83 / 1.52 / 1.21 / 1.35 / 1.50 / 1.41
MB / 6.36 / 4.35 / 6.39 / 7.15 / 7.27 / 5.64
TYI / 1.88 / 1.29 / 2.63 / 2.85 / 2.29 / 2.24
HB / 0.06 / 0.03 / 0.81 / 1.18 / 1.79 / 1.55
CL / 0.06 / 0.03 / 0.81 / 1.18 / 1.79 / 1.55
Rh / 3.39 / 2.46 / 4.46 / 5.50 / 5.57 / 3.02
6. Effect of acetic acid concentration
Table 3S Optimization of BGE concentration
Parameters a / HAc concentration (mM)50 / 100 / 200 / 500 / 700 / 1000
LZ / tm / 7.59 / 7.94 / 7.21 / 7.52 / 7.78 / 7.37
W1/2 / 0.38 / 0.4 / 0.27 / 0.22 / 0.23 / 0.23
S/N / 428 / 452.04 / 450.72 / 158.2 / 147.57 / 154.5
HSA / tm / 8.17 / 8.87 / 7.73 / 7.84 / 8.04 / 7.66
W1/2 / 0.11 / 0.51 / 0.32 / 0.18 / 0.17 / 0.14
S/N / 201.56 / 130.28 / 146.6 / 4.37 / 128.22 / 61.58
TF / tm / 9.33 / 10.34 / 8.51 / 8.35 / 9.44 / 8.99
W1/2 / 0.34 / 0.41 / 0.29 / 0.24 / 0.46 / 0.35
S/N / 62.52 / 14.57 / 23.23 / 11.07 / 14 / 16.14
MB / tm / 11.58 / 11.48 / 10.06 / 9.94 / 10.24 / 9.32
W1/2 / 0.69 / 0.68 / 0.7 / 0.42 / 0.4 / 0.33
S/N / 76.9 / 118.46 / 88.56 / 43.09 / 35.35 / 42.67
TRI / tm / 16.5 / 16.89 / 12.43 / 11.56 / 11.9 / 9.74
W1/2 / 0.52 / 0.49 / 0.5 / 0.38 / 0.31 / 0.28
S/N / 41.67 / 79.06 / 85.68 / 12.43 / 20.21 / 42.45
HB / tm / 18.41 / 21.14 / 14.56 / 11.11 / 11.31 / 10.08
W1/2 / 0.61 / 0.6 / 0.63 / 0.37 / 0.34 / 0.37
S/N / 36.57 / 116.29 / 99.4 / 30.19 / 15.97 / 19.93
CL / tm / 26.52 / 27.91 / 16.97 / 13.55 / 13.6 / 11.61
W1/2 / 0.98 / 0.69 / 0.57 / 0.42 / 0.4 / 0.34
S/N / 51.9 / 52.89 / 96.94 / 16.14 / 7.96 / 8.22
t / 26.52 / 27.91 / 16.97 / 13.55 / 13.6 / 11.61
Sum of S/N / 899.12 / 963.59 / 991.13 / 275.49 / 369.28 / 345.49
TR / 38.43 / 36.87 / 17.91 / 7.95 / 7.69 / 5.14
Rt / 0.041 / 0 / 0.666 / 0.877 / 0.881 / 1
RS/N / 0.871 / 0.961 / 1 / 0 / 0.131 / 0.098
RTR / 1 / 0.953 / 0.383 / 0.084 / 0.076 / 0
CRF / 0.637 / 0.638 / 0.683 / 0.32 / 0.363 / 0.366
a tm and W1/2 are given in min