Study of a Simulated Moving Bed (SMB) Preparative Liquid Chromatographic Appliance and Technology 1 Melinda Nagy, 1 Zoltán Molnár, 1 László Hanák, 1 János Argyelán, 1 Tibor Szánya, 2 Antal Aranyi, 2 Krisztina Temesvári 1 University of Veszprém, Department of Chemical Engineering, H-8201 Veszprém, Hungary 2 Richter Gedeon Rt., H-1475 Budapest 10, Hungary 1 e-mail: menagy@freemail.hu 2 e-mail: a.aranyi@richter.hu Abstract The simulated moving bed (SMB) technique is one of the newest method among the preparative chromatographic technologies. This technique is widely used in pharmaceutical industry, in analytical chemistry, in separating biotechnology and anywhere else, where other methods fail to achieve high purity in the product. We can optimize the efficiency of the separation with changing the operation parameters. The main goal is to get the highest quality along the highest productivity. Introduction For the laboratory tests we make the plans of a 4-columned equipment; each column is 25 cm long and the inner diameter is 1 cm. We separated two steroid isomers on YMC S-50 silica-gel adsorbent. We analyzed the effect of the concentration changing of the fresh eluent to the efficiency of the separation. The quality and other specific physical data of the product was determined by gaschromatographic measurements. Using the collected results we created a mathematical model and a computer program for this SMB method. The model is using the physical and chemical data of the chemicals, and the theoretical plate number of the column. These data were determined by other classical measurement techniques. Methodology SMB is a continuous liquid chromatographic separation technique using multiple columns, to achieve a quasi-stationary concentration profile while we change the flowing of the steady-phase the opposed moving eluent and the point of the inflow and outflow step-by-step. Investigation of adsorbent charge We determined the specific surface and pore size distribution of the YMC S-50 silica-gel with ASAP- 2000 equipment (Table 1.) and we made scanning electron microscopy photo (Fig. 1.). Table 1. Determine of BET specific surface Fig. 1. SEM photo of adsorbent Adsorbent YMC S-50 Surface of BET 798.6 m 2 /g BJH pore volume 1.7nm < d pore < 00nm 1.18 cm /g Average pore size of BJH 5.4026 nm
Equilibrium measurements Determination of the acetone s and A and B steroid s (Fig..) adsorption equilibrium data (Fig.2.) were done in a dichloromethane-silica-gel system. The measurement was done by the Gedeon Richter Rt. on a YMC S-50 silica-gel, acetone, dichloromethane system at 20 C temperature. The examination made by analytical HPLC with multistage frontal saturation. q acetone (g / g s ilic a g el) 0,6 0,5 0,4 0, 0,2 0,1 Fig.2. Adsorption equilibrium of the acetone EQULIBRIUM MEASUREMENTS (Frontal adsorption - desorption method) ACETONE in Dichloromethane YMC-S-50 silicagel, 20 C measurements of G. R. q acetone (g/g) measured q acetone (g/g) calculated 0 200 400 600 800 1000 c acetone (g/dm eluent) q A, q B (g/g silicagel) Fig.. Adsorption equilibrium of the A and B steroid 0,18 0,16 0,14 0,12 0,1 8 6 4 2 0 Steroid A, B adsorption, YMC - S - 50 silicagel in 50:50 v/v% acetone-dichloromethane, 20 C, measurements of G. R. q A measured (g/g) q B measured (g/g) 0 10 20 0 40 c A, c B (g/dm eluent) We used the following Langmuir constants during the calculations: = 1.54 g silicagel * a Acetone = 10.6 g silicagel * a B = 0.001517 mg aceton b Acetone = 0.02675 mg B b B = 22.55 g silicagel * a A = 0.06640 mg A b A Determination of the Number of Theoretical Plates (NTP) and Height of Equivalent Theoretical Plate (HETP) We poured YMC S-50 silica-gel into the SUPELCO chromatographic column (D in =1 cm, L= 25cm) with a charge loader vibrator. The mass of the charge is 8 g. The air was removed from the column by a LMIM D-167 pump and an acetone:dichloromethane (1:1) mixture. We put Rheodyne injection cock on the input of the column with 100 µl loop. We connected a Waters UV detector to the output of the column, where we detected the changing of the impulses of the 0.2 %v/v acetophenone in elunet and dichloromethane on 00 nm wavelength. We evaluated the retention time density function with the triangle method: 2 tr NTP = (Fig.4.) σ NTP Number of Theoretical Plates t R retention time σ scatter L HETP = (Fig.5.) NTP HETP High of Equivalent Theoretical Plate L charge length
Fig.4. NTP measurement Fig.5. Determination of HETP NTP / 25cm 2000 1800 1600 1400 1200 1000 800 600 400 200 0 NTP - HETP measurements ID=1 cm L=25cm column 8 g YMC - S - 50 silicagel NTP - YMC - acetone - DKM /50:50 v/v%/ Dichloromethane y = 1640,x -0,6059 R 2 = 0,9452 Injection:100µl 2%V/V acetophenone/ eluent y = 1522,4x -0,707 R 2 = 0,969 0 2 4 6 8 10 12 14 B cm /min HETP,mm 1,2 1,0 0,8 0,6 0,4 0,2 HETP measurements YMC-aceton-DKM/1:1/ Injektálás:100µl *1600=160ml /2%V/V acetofenon y = 0,1178x 0,707 R 2 = 0,969 Injektálás:100µl *1600=160ml y = 0,1146x 0,6059 R 2 = 0,9452 0 5 10 15 20 25 B dm /min liquid concentration (g/dm ) 4,5 4,5 2,5 2 1,5 1 0,5 0 The simulation data of the frontal adsorption desorption (Calculation KROM N software with solvent adsorption desorption) Input data of the software Number of components: k = Column inner diameter: ID=0.75 cm Column length: L=42 cm Free volume coefficient: EPS= 0.8018 cm liquid free volume/ cm column Feed: B=2.47 cm /min Bulk density: Langmuir constants: (same as on page 2) Sample feeding time: 55 min (15.85 cm ) Sample concentration: c Acetone =96 mg/cm ROH= 0.4045 g silicagel/cm column c B =4 mg/cm c A =1 mg/cm Eluent concentration: c Acetone =96 mg/cm c B =c A =0 mg/cm End of elution time: Printing time: NTP=400 112 min 2.5 min Frontal adsorption-desorption measurement compare with simulation We poured YMC S-50 silica-gel into the SUPELCO chromatographic column (D in =1 cm, L= 25cm) with a charge loader vibrator. The air was removed from the column by a LMIM D-167 pump and an acetone:dichloromethane (1:1) mixture. During the frontal adsorption we fed 5 g (A+B)/dm (B 80 m/m%, A 20m/m%) mixture at 20 C with a 2.47 cm /min volume flow rate into the upper part of the column. We finished the feeding of A and B steroid after 55 min ( 15 cm liquid), then lead pure eluent (1:1 v/v% acetone:dichloromethane) with a 2.85 cm /min volume flow rate into the column. We determined the concentration of the samples with analytical gaschromatographic measurement (Fig.6. and Fig.7.). Fig.6. and Fig.7. Frontal adsorption-desorption measurement of the steroids and acetone 50 % v/v acetone 50 % v/v DKM 4 g B/dm 1 g A/dm Steroid concentration in function of volume 15 cm 50% v/v acetone, 50% v/v dichloromethane Measured "B" Measured "A" Calculated "B" Calculated "A" 0 50 100 150 200 250 00 v (cm ) Acetone concentration (mg/cm ) 405 400 95 90 85 80 Acetone concentration in function of volume Measured acetone conc. Calculated acetone conc. 0 50 100 150 200 250 V (cm )
Planning (Fig.8.) and making SMB equipment (Fig.9.) We assembled the four-columned, four-sectored, open eluent loop SMB preparative chromatographic equipment from the following parts: Stand from stainless steel 4 pieces Preparative HPLC column, stainless steel, D in = 10mm, L= 250mm (SUPELCO) 5 pieces Four-way cock stainless steel (VALCO) 4 pieces Liquid distributor 4-way 4 pieces Liquid distributor 1+6-way Open-close cock, stainless steel, high-pressure (VALCO) 4 pieces Gilson type HPLC pump 2 pieces non-return valve, stainless steel, high-pressure 10 m acid-resistant capillary Fig.8. The flowchart of SMB Fig.9. The SMB equipment The simulation data of the gradient SMB SMB KROM N Software with solvent adsorption desorption Input data of the software Number of components: k = Column inner diameter: ID=1 cm Column length: L=25 cm Number of columns: N=4 Free volume coefficient: EPS= 0.8018 cm liquid free volume/ cm column Feed: F=1.5 cm /min Fresh eluent: S=7. cm /min Extract: E=6.2 cm /min Raffinate: R=2.6 cm /min Bulk density: ROH= 0.045 g silicagel/cm column Langmuir constants: (same as on page 2) Feed concentration: mg acetone Fresh eluent concentration: = 96 mg B = 4 c F acetone c F B mg A = 1 c F A c = c mg B or A = 0 S S B A Measurements SMB 7 SMB1 SMB5 SMB 6 Acetone v/v % 40 50 60 70 c S Acetone (mg acetone/cm liquid) 16.8 96 475.2 554.4
yield % productivity (mg B/g silicagel min) m/m % Eluent consumption (cm eluent / mg B) 100 90 80 70 60 50 40 0 10 98,0 96,0 94,0 92,0 9 88,0 86,0 84,0 82,0 8 0,25 0,2 0,21 0,19 0,17 0,15 0,1 0,11 9 7 5 Number of Theoretical Plates: NTP=200 for a 25 cm column Switching time: 22.5 min Calculation time: 585 min The results of the gradient SMB measurements compare with simulation Results of the gradient SMB Purity of components 4 5 6 7 Yield of components Productivity of technology Eluent consumption 1,80 1,60 1,40 1,20 1,00 0,80 0,60 0,40 0,20 Yield % m/m % productivity (mg A/g silicagel min) Eluent consumption (cm eluent / mg A) 100 90 80 70 60 50 40 0 10 9 8 7 6 5 4 2 1 0,10 9 8 7 6 5 4 2 1 0 Results of the gradient SMB Purity of components 12,0 1 Yield of components Productivity of technology acetone v/v% 8,0 6,0 4,0 2,0 Eluent consumption
Results and Conclusions Changing the acetone concentration of the fresh eluent between 40 70 % v/v in DKM according to the Morbidelli triangle the extract and raffinate concentrations change as well. Over 60 % v/v acetone in dichloromethane the B in raffinate is under 99.9% m/m required purity, under 45 % v/v acetone in dichloromethane the A in extract is under 99.9% m/m required purity. The optimum concentrations are between 45-60 % v/v acetone in dichloromethane. The new computer programmes (KROM-N, SMB-KROM-N with solvent adsorption-desorption) gave proper results at the working point (50-50 % v/v acetone in dichloromethane). The difference between the measured and calculated concentrations in dichloromethane until 40% v/v or increasing up-to 70% v/v in dichloromethane. The conclusion is that the authors have to modify the model parameters in the next future. References (1) M. Miron, T. Szanya, L. Hanak, J. Argyelan, Gy. Marton: Mathematical modelling of displacement chromatography, Hung..J.of Ind. Chem. Vol.2. pp. 29-298. (1995) (2) S. Kovats, B. Csukas, A. Aranyi, E. Pozna.: Structural modelling of chromatographic processes I.: Hung. J. of Ind. Chem. Vol.26. pp. 44-5. (1998) () T. Szanya, J. Argyelan, S. Kovats, L. Hanak: Separation of steroid compounds by overloaded preparative chromatography with precipitation in the fluid phase, J. of Chrom.A. 908(2001), 265-272 (4) G. Guiochon, S. Golshan-Shirazi, A.M.Katti: Fundamentals of preparative and non-linear chromatography, Acad. Press, New York, Acknowledgement The research was financed by the Cooperation Research Center, Chemical Engineering Institute of the Veszprém University, upon the request of Gedeon Richter Rt. The authors express their thanks to these institutions.