Electronic Supplementary Material
Direct analysis of biogenic amines in water matrix bymodified capillary zone electrophoresis with18-crown-6
Wen-li LiJin-yuan GeYa-li Pan Qing-cui ChuJian-nong Ye*
Department of Chemistry, EastChinaNormalUniversity, Shanghai 200062, China
CE-AD equipment and conditions
A ±30 kV high-voltage dc power supply (Shanghai Institute of Applied Physics, Shanghai, China, provided a voltage between the ends of the capillary. The inlet end of the capillary was held at a positive potential and the outlet end was maintained at ground. The separation was performed in a fused-silica capillary (90 cm × 25 μm id × 360 μm od, Polymicro Technologies, Phoenix, AZ, USA, provided by Zhengzhou Inno-Tech Co., Ltd., In order to avoid contact between the operator and the high voltage and assure the safety of the CE-AD system, the entire capillary, the buffer reservoirs for CE and all electrodes were enclosed in a Plexiglas box.
A three-electrode electrochemical cell consisting of a 300 µm diameter copper-disc working electrode, a platinum auxiliary electrode and a saturated calomel electrode (SCE) as the reference electrode, was used in combination with a BAS LC-3D amperometric detector (Bioanalytical System, West Lafayette, IN, USA, The design of AD was based on the end-column approach and has been described previously [34]. Before use, the surface of the copper-disc electrode was polished with emery sand paper, sonicated in twice distilled water, and then positioned carefully opposite the capillary outlet with the aid of an Oriel Corp. Model 14901 micropositioner (Stratford, CT, USA, All samples were injected electrokinetically without preconcentration, applying 14 kV for 12 s. Data acquisition and analysis were preformed using HW-2000 software package, Version 2.21 (Shanghai Qianpu Software Co., Ltd., China, The conversion expression between voltage (mV) unit of the instrumental readout and current (nA) unit of AD instrument is “1 mV=0.04958 nA”.
Fig. S1 Molecular structures of Spm, Spd, Cad, His, Phe, Tyr and Try.
Fig.S2Effect of the separation voltage on migration time of analytes. Fused-silica capillary: 25 μm i.d. × 90 cm; working electrode: 300 μm diameter copper-disc electrode; working electrode potential: +650 mV (vs. SCE); running buffer: 180 mmol.L-1 18-crown-6 / 20 mmol.L-1 acetate buffer solution (pH 3.6); separation voltage: 14 kV; injection time: 12 s (at 14 kV); concentrations of seven BAs: 1.0×10-5 g.mL-1, each;
Fig.S3Effect of the injection time on peak area of analytes. Experimental conditions were the same as in Fig.S2.
Table S1The regression equations, linearity and LODs of seven BAsa(n=3)
Analytes / Regression equation / Correlation coefficient / Linear range(µg.mL-1) / Detection limit (ng.mL-1)
Slop / Intercept
Spm / 1422.9 / 485.0 / 0.9953 / 50.0 - 0.1 / 21.7
Spd / 1302.6 / 257.6 / 0.9993 / 50.0 - 0.1 / 20.2
His / 2466.1 / 600.1 / 0.9976 / 20.0 - 0.1 / 10.1
Cad / 1588.6 / -28.3 / 0.9990 / 20.0 - 0.1 / 16.4
Phe / 306.43 / 156.8 / 0.9985 / 100.0 - 0.1 / 42.6
Tyr / 599.9 / 565.5 / 0.9975 / 50.0 - 0.1 / 28.4
Try / 346.43 / 189.8 / 0.9977 / 100.0 - 0.1 / 36.4
aCZE-AD conditions were the same as those in Fig. S2.
Table S2 The results of recovery on analyzing BAs with No.4 sewage sample a (n=3)
Analytes / Added amount (µg.mL-1)10.0 / 5.0 / 2.0
Spm / 83.6 (1.4)b / 95.4 (0.6) / 91.3 (2.8)
Spd / 93.6 (1.6) / 81.4 (3.0) / 86.3 (2.6)
His / 81.6 (0.6) / 92.9 (1.5) / 83.9 (1.9)
Cad / 94.1 (3.2) / 96.1 (2.4) / 95.4 (1.9)
Phe / 92.0 (0.3) / 90.1 (1.0) / 91.6 (1.4)
Tyr / 89.7 (0.6) / 99.6 (0.5) / 71.6 (1.1)
Try / 101.0 (1.0) / 100.3 (2.9) / 77.8 (2.8)
a CZE-AD conditions were the same as in Fig. S2.
b RSD% of the assay results.
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*Correspondence:Department of Chemistry, EastChinaNormalUniversity, 3663 North Zhongshan Road, Shanghai 200062, China
E-mail: (QC Chu) or (JN Ye)
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