31 2 2012 2 FENXI CESHI XUEBAO Journal of Instrumental Analysis Vol. 31 No. 2 127 ~ 132 - * 730070 PB - Eu - 3 8 min 0. 025 ~ 10 0. 025 ~ 25 0. 05 ~ 10 mg /L 3 1. 00 mg /L 3 6 RSD 4. 5% 0. 95% 3 101%~ 111% O657. 8 TQ460. 72 doi 10. 3969 /j. issn. 1004-4957. 2012. 02. 002 A 1004-4957 2012 02-0127 - 06 Separation and Determination of Ephedrine Pseudoephedrine and Methylephedrine by Capillary Electrophoresis with Electrochemiluminescence Detection MA Yong-jun * LI Qiong-lin WANG Wei-feng ZHOU Min HE Chun-xiao LIU Jing Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province College of Chemistry & Chemical Engineering Northwest Normal University Lanzhou 730070 China Abstract Using an ionic liquid of p-vinylbenzyltriethylammonium chloride as separating additive a novel method for the simultaneous determination of methylephedrine ME ephedrine E and pseudoephedrine PE was developed by capillary electrophoresis coupled with electrochemiluminescence detection using PB - Eu chemically modified electrode as working electrode. The effect factors such as detection potential types and acidity of separation buffer on the separation efficiency were investigated. Under the optimized conditions three analytes were separated well in 8 min. Good relationships r 2 0. 999 1 between peak area and concentrations of analytes ME 0. 025-10 mg /L E 0. 025-25 mg /L PE 0. 05-10 mg /L were established over three orders of magnitude. The synthetic samples containing three alkaloids in a level of 1. 00 mg / L were determined. The RSDs of peak area and migration time were less than 4. 5% and 0. 95% respectively. The method was successfully used in the determination of the three alkaloids in pharmaceutical preparations and Chinese herbal Ma-Huang with recoveries of 101% - 111%. Key words capillary electrophoresis electrochemiluminescence ionic liquid alkaloid Ephedrine E Pseudoephedrine PE Methylephedrine ME 1 1 2011-09 - 19 2011-10 - 22 096RJZA117 * Tel 0931-7971533 E - mail mayj@ nwnu. edu. cn
128 31 3 2 1 Fig. 1 Molecular structures of ephedrine E pseudoephedrine PE and methylephedrine ME 3-4 5 6-13 14-15 16 17 - - - 18-19 6 9 10 11-12 ILs 20-22 - 1 1. 1 Ru bpy 3 Cl 2 6H 2 O 99. 95% Aldrich 171241-200506 171237-200505 171247-200301 1. 00% MPI-A SK2200HP CHI832 40 cm 50 μm i. d. PB-10 Eu - PB Φ = 0. 5 mm 23-24 KCl Ag /AgCl 1. 2 ECL 5 mmol /L Ru bpy 2 + 3 100 mmol /L ph 8. 8 0. 005 mol /L 0. 015 mol /L 10% 0. 2% ph 9. 5 10 kv 10 s 16 kv 850 V 0. 01 mol /L NaOH 3 3 10 min 5 h 5 mmol /L Ru bpy 2 + 3 2 min 0. 22 μm 1. 3 100 2 1. 045 g 10. 0 ml 60 min 10. 0 ml 1 2
2-129 100 ml 1 000 0. 22 μm Ⅰ 2 100 ml 3 0. 010 0 g 10 ml 1. 00 g /L 4 h 4 0. 50 ml 100 mmol /L ph 8. 8 1. 50 ml 100 mmol /L 1. 00 ml 2. 00 ml 1. 0% 10 ml 2 2. 1 3 Ru bpy 2 + 3 2 a Ru bpy 2 + 3 2 b Ru bpy 2 + 3 Ru bpy 2 + 3 Ru bpy 2 + 3 2 c Ru bpy 2 + 3 b c Ru bpy 2 + 3 Ru bpy 2 + 2 3 Fig. 2 Cyclic voltammograms of Ru bpy 2 + 3 and Ru bpy 3 + 3 Ru bpy 2 + 3 coexisting with E Ru bpy 3 + 3 a. bare Pt electrode b. modified Pt electrode c. modified Pt electrode in the presence of E c Ru bpy 2 3 + 2. 5 mmol /L c E 0. 1 mmol /L 100 mmol /L ph 9. 5 phosphate buffer scan rate 100 mv /s 2. 2 2. 2. 1 CE - ECL ECL 1. 12 ~ 1. 24 V ECL 1. 24 V ECL Ru bpy 2 + 3 1. 05 V 1. 24 V ECL 25 Cl - 1. 24 V 2. 2. 2 ph ECL 19 ph ph 8. 2 9. 0 3 ECL ph 3 ECL ph 8. 8 OH - ph ph 8. 8
130 31 2. 2. 3 Tris - H 3 PO 4 Na 2 B 4 O 7 - HCl ph 3 ECL 3 0. 005 mol /L 0. 015 mol /L ph 9. 4 ~ 9. 6 3 ECL ph ECL 3 3 3 ph 9. 5 Fig. 3 Effect of ionic liquid concentration in separating buffer solution on the separability of three alkaloids 2. 2. 4 3 21 3 3 3 10% 3 10% 10% 3 0. 2% 3 3 3 4 4 0. 02 mol /L 4 Fig. 4 Electropherograms of E PE and ME standard solution in two kinds of separating buffer A 0. 02 mol /L Na 2 HPO 4 - NaH 2 PO 4 B 0. 005 mol /L 1. 5 8 min Na 2 HPO 4 - NaH 2 PO 4 + 0. 015 mol /L borate sodium + 10% acetonitrile + 0. 2% ionic liquid 1. ME 2. E 3. PE 2. 2. 5 10 12 14 16 18 kv 3
2-131 16 kv CE - ECL ECL 6 8 10 12 14 s 6 8 10 12 14 kv 10 s 10 s 10 s 10 kv 2. 3 3 1 r 2 0. 999 1 3 3 5. 7 ~ 8. 7 μg /L 3 1. 00 mg /L 6 RSD 4. 0%~ 4. 3% 5. 0%~ 5. 9% 0. 14%~ 0. 94% Table 1 1 Linear ranges regression equations correlation coefficients and detection limits of ME E and PE Compound Linear rangeρ / mg L - 1 Regression equation r 2 Detection limitρ / μg L - 1 E 0. 025 ~ 2. 50 Y = 5. 52 10 10 ρ - 4. 52 10 3 0. 999 5 7. 5 2. 50 ~ 25 Y = 1. 30 10 10 ρ - 1. 06 10 5 0. 999 4 PE 0. 05 ~ 2. 50 Y = 9. 77 10 10 ρ - 1. 86 10 3 0. 999 7 8. 7 2. 50 ~ 10 Y = 3. 51 10 10 ρ + 1. 57 10 5 0. 999 6 ME 0. 025 ~ 1. 00 Y = 2. 30 10 10 ρ - 2. 25 10 2 0. 999 2 5. 7 1. 00 ~ 10 Y = 1. 21 10 10 ρ + 1. 01 10 4 0. 999 1 Y peak area ρ concentration of analyte mg /L 2. 4 3 1. 49 12. 8 0. 456 g /kg 2 3 0. 12 1 2 2 Table 2 n = 3 Spiked recoveries of E PE and ME in Chinese herbal Ma - Huang n = 3 Compound Added ρ / mg L - 1 Recovery R /% RSD s r /% E 0. 10 0. 20 104 109 1. 6 1. 7 PE 0. 20 0. 40 107 101 1. 9 1. 6 ME 0. 10 0. 20 111 108 3. 0 2. 8 Ⅰ No 090311 No 09120673 5. 25 mg / 86. 8 mg / 5 mg / 90 mg / 3 -
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