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Electronic Supplementary Material for
Utilization of deep eutectic solvents as novel mobile phase additives for
improving the separation of bioactive quaternary alkaloidsTing Tana,b, Mingliang Zhangc, Yiqun Wana,b* and Hongdeng Qiuc,*
a State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, Chinab School of chemistry, Nanchang University, Nanchang 330031, China
c Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province,
Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
*Corresponding author. Tel.:+86 931 4968877; fax: +86 931 8277088; E-mail: [email protected] (H. Qiu). [email protected]
(Y. Wan)
Fig. S1. The picture of DESs used in this work.
Characterization
Chemical composition was characterized by Fourier Transform Infrared Spectroscopy (FTIR)
(IFS 66v/s) (Bruker, Germany). The peaks in the fingerprint region (400-1300 cm -1) indicate that
hydrogen bonds were formed [49]. DESs displayed the characteristic peaks of –OH between 3000
cm-1 and 3500 cm-1.
Differential Scanning Calorimetry (DSC) was carried out by a DSC 822e (Mettler Toledo,
Switzerland) equipped with a Brookfield DV-III Ultra programmable rheometer and the value was
listed in Table 1.
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Fig. S2. Characterization of DES-1
Fig. S3. Effect of DESs in acetonitrile (a) and methanol (b), containing (a) 32 : 68 (v/v) MeCN : 1%
DES-1 (pH 3.3) and (b) 32 : 68 (v/v) MeOH : 1% DES-1 (pH 3.3). Peaks: 1, CopC; 2, Sang; 3,
BerbC and 4, Chel. Flow-rate: 1.0 mL min-1. Detection: UV 345 nm. Column: C18. Temperature: 30
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°C. Injection volume: 10 μL.
Preparation of 1-butyl-3-methylimidazolium chloride ionic liquid.
1-Methylimidazolium (8.21 g) and 1-chlorobutane (10.20 g) were mixed in a round-bottom
flask under N2. The reaction mixture was stirred at 70 °C for 72 h.
With comparison purposes, the separation result of DESs as mobile phase additives for
quaternary alkaloids was compared with commonly used IL. When adding 0.25% IL to water as
mobile phase additive, baseline separation (Fig. S4b) was obtained, and the retentions of four
analytes were slightly shorter than using DES-1.
Fig. S4. Separation of four QAs including CopC (1), Sang (2), BerbC (3) and Chel (4) with mobile
phase 32 : 68 (v/v) for (a) MeCN : 0.25% DES-1 (pH 3.3) and (b) MeCN : 0.25% 1-butyl-3-
methylimidazolium chloride aqueous solution (pH 3.3).
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Fig. S5. Effect of temperature on the retention time of analytes in C18 column.
Table S1. Analytical performance of QAs (n=3).
Quanterary
alkaloids
Linear range
(μg mL-1)
Linear equation r LOD
(μg mL-1)
LOQ
(μg mL-1)
Precision
RSD (%)
Repeatability
RSD (%)
CopC 0.10-25.0 Y=17177x+11421 0.9988 0.008 0.030 2.03 2.38
Sang 0.10-25.0 Y=19623x+6247.6 0.9992 0.020 0.060 0.95 1.86
BerbC 0.10-25.0 Y=32773x+14073 0.9992 0.006 0.020 0.37 1.01
Chel 0.10-25.0 Y=18258x+6407.1 0.9994 0.010 0.050 1.81 2.99
Notes: Y, peak area; x, concentration of QAs; r, correlation coefficient; LOD, limit of detection; LOQ, limit of
quantitation.
Table S2. Recoveries of BerbC in Lanqin Chinese herbal oral solution and BerbC tablet.
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Sample Found
(μg mL-1)
Spiked
(μg mL-1)
Detect
(μg mL-1)
Recovery
(%)
RSD
(%)
Lanqin Chinese herbal solutiona 5.75
1 6.69 99.1 2.64
5 9.86 91.7 1.70
7 11.8 92.5 2.85
BerbC tabletb 0.56
0.25 0.74 91.4 1.89
0.50 0.96 90.6 0.60
1.5 2.02 98.1 2.16
Notes: a, 10 fold diluted Lanqin Chinese herbal solution; b, one tablet was dissolved in 50 L deioned water.
Effect of DESs on the column stability
At the very beginning of the experiment, 80 : 20 (v/v) MeOH : H2O was used to balance the C18
column for 4 hours, four reference reagents including uracil, toluene, benzene and naphthalene were
injected 10 μL into HPLC-UV, under the detection conditions of flow-rate 1.0 mL min -1, 30 °C, 254
nm. The C18 column was used throughout the whole optimization of alkaloids separation and sam-
ple analysis. After experiment, for comparison purposes, four reference reagents were detected
again under the same condition. Identical experiments were carried out on C8.
Table S3. Performance of C18 and C8 column stability.
C18 C8
Before experiment After experiment Before experiment After experiment
RT(min) N (/m) P(Mpa) RT(min) N (/m) P(Mpa) RT(min
)
N (/m) P(Mpa) RT(min) N (/m) P(Mpa)
Uracil 1.75 11728 7.6 1.76 11945 7.6 1.80 15881 5.6 1.80 15806 5.6
Toluene 3.22 28189 3.23 28351 3.32 45200 3.32 45295
Benzene 4.11 31096 4.12 31204 4.07 53648 4.07 53843
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Naphthalene 4.92 34150 4.93 34230 4.48 59088 4.48 59185
Note: N, theoretical plate number; P, back pressure.
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