Acetonitrile versus Propylene Carbonate Listed as VOC Not listed as - PowerPoint PPT Presentation

Acetonitrile versus Propylene Carbonate  Listed as VOC  Not listed as VOC  Toxic  Readily biodegradable  Flammable  Not flammable  Acetonitrile shortage  Available as highly (economic crisis) purified solvent

Comparative properties Characteristics ACN PC MeOH EtOH CAS no. 75-05-8 108-32-7 67-56-1 64-17-5 Type of solvent Polar aprotic Polar aprotic Polar protic Polar protic Mw 41.04 102.09 32.04 46.07 Molecular dipole moment (D) 3.92 4.90 1.70 1.69 Dielectric constant 35.94 64.90 32.66 24.55 Hansen solubility parameters – Dispersive -  D 15.3 20.0 15.1 15.8 Polar -  P 18.0 18.0 12.3 8.8 Hydrogen bonding -  H 6.1 4.1 22.3 19.4 Hildebrand solubility parameter  T 24.3 27.3 29.6 26.5 Boiling point ( o C) 81.6 241.7 64.7 78.0 Melting point ( o C) -45.0 -49.2 -97.8 -113.9 Density g/cm 3 0.781 1.205 0.7918 0.789 Experimental Log K ow -0.34 -0.41 -0.77 -0.31 Water solubility Fully miscible 240 g/L Fully miscible Fully miscible Viscosity / 25 o C (cps) 0.36 2.4 0.59 1.1 Vapor pressure kPa/20 o C 9.7 0.017 12.8 5.83 Flash point o C 2 132 11 13 Auto ignition temperature ( o C) 524 455 385 365 Lower flammable limit (LFL) - % 4 1.7 6 3.5 Upper flammable limit (UFL) - % 16 32.5 36.5 19 Oral LD50 rat mg/kg 2460 29100 5600 15010 Dermal LD50 rabbit mg/kg 980 20001 15800 19999 Inhalation LC50 rat ppm 4 h 17100 >50000 64000 124700 Acute LC50 Daphnia 48 hrs mg/mL 3600 > 10000 3289 6386 HMIS Health 2 1 2 2 HMIS Flammability 3 1 3 3 HMIS Physical hazards 0 0 0 0 Exempt VOC (acc. 40 CFR 51.100) No Yes No No readily readily Biodegradability ~ 40% / 10 days > 80% / 10 days biodegradable biodegradable

Miscibility Solv. A = EtOH:H 2 O Solv. B = EtOH:PC Solv. A / PC H 2 O / Solv. B 1:9 1:9 1:4 1:4 3:7 3:7 2:3 2:3 1:1 1:1 3:2 3:2 7:3 7:3 4:1 4:1 9:1 9:1 EtOH 0% 10% 20% 30% EtOH 0% 10% 20% 30% fully miscible fully miscible immiscible immiscible a) H 2 O / EtOH = 7/3 (v/v) and PC b) PC / EtOH = 7/3 (v/v) and H 2 O

Pressure Drop Stationary ECLIPSE XDB C18 Phase 15 cm L x 4.6 mm i.d. x 5  m d.p. 10 cm L x 2.1 mm i.d. x 3.5  m d.p. 5 cm L x 4.6 mm i.d. x 1.7  m d.p. Dimensions 25 o C 25 o C 60 o C Temperature Flow Rate 0.8 mL/min 0.25 mL/min 1.0 mL/min Pressure drop ratio (P alternative organic modifier /P ACN ) % Org. Mod. ACN/(PC+EtOH) ACN/PC ACN/(PC+EtOH) ACN/PC ACN/(PC+EtOH) ACN/PC 10 1.1 (82.9*) 2.0 1.2 (95.0) 2.1 1.1 (111.5) 1.7 20 1.3 (84.5) 2.0 1.3 (97.0) 2.0 1.3 (114.5) 1.7 30 1.6 (82.4) 2.1 1.6 (94.0) 2.1 1.5 (113.5) 1.8 40 2.0 (78.0) 2.3 2.1 (89.0) 2.3 1.7 (109.5) 2.0 50 2.4 (71.8) 2.6 2.4 (82.0) 2.6 2.0 (103.0) 2.2 60 2.8 (64.0) 2.9 2.8 (73.0) 3.0 2.3 (95.0) 2.5 70 3.2 (55.0) 3.4 3.3 (62.6) 3.5 2.7 (85.0) 2.9 80 3.8 (45.0) 4.1 3.9 (51.8) 4.2 3.0 (74.5) 3.4 90 4.3 (37.2) 5.1 4.5 (41.5) 5.3 3.5 (63.7) 4.3 100 5.3 (26.0) 9.2 4.7 (34.4) 8.0 3.8 (56.8) 6.3 * Pressure drop (bar) measured on using ACN/water mobile phases in the given conditions.

Pressure Drop (example) 260 Eclipse XDB C18 150*4.6 mm 5 um Flow rate 0.8 mL/min 240 Temperature 25 o C 220 200 Pressure drop (bar) 180 160 140 120 100 80 ACN 60 PC+EtOH 40 PC 20 0 10 20 30 40 50 60 70 80 90 100 % Organic Solvent

Experimental parameters / Retention data Chromatographic Column: Purosphere Star C18e 7.5 cm L x 4 mm i.d. x 3  m d.p. Column dimensions: 25 o C Column temperature: Mobile Phase Solvent A: aqueous 0.1% HCOOH (for acidic compounds) Solvent A’: aqueous 50 mM boric acid at pH=9 with NaOH (for alkaline compounds) Solvent A’’: water (for neutral compounds) Solvent B: acetonitrile Solvent A (or A’ or A’’) / Solvent B = 7/3 Solvent a: water/ethanol = 7/3 (v/v) with 0.1% HCOOH (for acidic compounds) Solvent a’: water/ethanol = 7/3 (v/v) with 50 mM boric acid at pH=9 with NaOH (for alkaline compounds) Solvent a’’: water/ethanol = 7/3 (v/v) (for neutral compounds) Solvent b: propylene carbonate Solvent a (or a’ or a’’) / Solvent b = different volumetric ratios Elution: isocratic Flow rate: 0.5 mL/min 5  L Injection volume:

Retention data  = 238 nm Lovastatic Acid Fenofibric Acid Nicergoline mAU Diltiazem Simvastatic Acid Carbamazepine mAU  = 220 nm 50% ACN 50% ACN 35% PC 35% PC 0 2 4 6 8 min 10 12 14 16 2 4 6 min 8 10 12 14 Toluene Fluoranthene  = 254 nm Fluorene mAU 60% ACN 40% PC 2.5 5 7.5 10 12.5 15 17.5 20 min

Retention data 2.000 y = -2.7975x + 5.7034 ACN R 2 = 0.9989 1.800 PC + EtOH 1.600 1.400 1.200 log (tR) Toluene 1.000 0.800 0.600 0.400 y = -3.1801x + 6.4259 0.200 R 2 = 0.9891 0.000 0.000 0.500 1.000 1.500 2.000 2.500 log (%org)       ACN Org log( t ) B log(% ACN ) A log( t ) b log(% Org ) a R R     ACN Org t t ; % Org 0 . 7 % PC 30 R R

Retention data 80.0 y = 1.3685x - 36.701 R 2 = 0.9999 70.0 60.0 50.0 %PC 40.0 y = 1.3139x - 33.631 30.0 R 2 = 0.9997 20.0 y = 1.357x - 34.713 Averages R 2 = 0.9998 Toluene 10.0 Fenofibric Acid y = 1.4345x - 41.759 R 2 = 1 Diltiazem 0.0 0 10 20 30 40 50 60 70 80 90 % ACN  ( A a ) B     b b % PC [( 1 / 0 . 7 ) 10 (% ACN ) ] ( 30 / 0 . 7 )

Buffer concentration 14 12 Retention Time (min) 10 Carbamazepine Diltiazem 8 Nicergoline 6 4 2 0 100 / 0 50 100 0 50 100 150 200 C buffer (mM) Acetonitrile Propylene carbonate Salting-out effects (especially for last eluting peaks)!

Buffer concentration 10000 Carbamazepine Diltiazem 9000 Nicergoline 8000 N 7000 6000 5000 4000 100 / 0 50 100 0 50 100 150 200 Acetonitrile C buffer (mM) Propylene carbonate Loss of efficiency when using PC?

Buffer concentration 1 Carbamazepine 0.95 Diltiazem Nicerdoline 0.9 0.85 Peak Symmetry 0.8 0.75 0.7 0.65 0.6 0.55 0.5 100 / 0 50 100 0 50 100 150 200 C buffer (mM) Acetonitrile Propylene carbonate No significant loss in peak symmetry when using PC!

Van Deemter curves 30.0 Simvastatic acid (ACN) Fluoranthene (ACN) Simvastatic acid (PC) 25.0 Fluoranthene (PC) 20.0 HETP (um) 15.0 10.0 5.0 0.0 0.00 5.00 10.00 15.00 20.00 25.00 u (cm/min) Low optimal flow rates when using PC!

Thermodynamic Aspects 3.000 Fenofibric Acid ACN Toluene Simvastatic Acid y = 1090.5x - 2.9537 2.500 R 2 = 0.9943 Fluorene Fluoranthene 2.000 y = 980.91x - 2.2741 R 2 = 0.9955 ln (k) y = 506.74x - 0.4084 1.500 R 2 = 0.943 y = 1310.7x - 2.4373 R 2 = 0.9966 1.000 y = 1690.8x - 3.1192 R 2 = 0.9986 0.500 0.000 0.00310 0.00315 0.00320 0.00325 0.00330 0.00335 0.00340 0.00345 0.00350 1/T Van’t Hoff plots with ACN as organic modifier!

Thermodynamic Aspects 3.000 Fenofibric Acid PC y = 1191.1x - 2.8826 Toluene R 2 = 0.9967 Simvastatic Acid 2.500 Fluorene y = 1037.6x - 2.1934 Fluoranthene R 2 = 0.9983 2.000 y = 366.76x + 0.6339 R 2 = 0.7229 y = 1224.8x - 2.0723 ln (k) R 2 = 0.9962 1.500 y = 1447.5x - 2.4518 1.000 R 2 = 0.9965 0.500 0.000 0.00310 0.00315 0.00320 0.00325 0.00330 0.00335 0.00340 0.00345 0.00350 1/T Van’t Hoff plots with PC/EtOH as organic modifier!

Thermodynamic Aspects Fenofibric Simvastatic Parameter Toluene Fluorene Fluoranthene Solvent Acid Acid B (slope of the van’t ACN 1090.5 980.9 506.7 1310.7 1690.8 Hoff plot) PC 1191.1 1037.6 366.8 1224.8 1447.5 A (intercept of the ACN -2.9537 -2.2741 -0.4084 -2.4373 -3.1192 van’t Hoff plot) PC -2.8826 -2.1934 0.6339 -2.0723 -2.4518 r xy (correlation coeff. of ACN 0.9971 0.9977 0.9711 0.9983 0.9993 the van’t Hoff plot) PC 0.9983 0.9991 0.8502 0.9981 0.9982 ACN -9067 -8156 -4213 -10898 -14058  H 0 (J) PC -9903 -8627 -3049 -10184 -12035 ACN -16.9 -11.3 4.2 -12.6 -18.3  S 0 (J) PC -17.8 -12.1 11.4 -11.1 -14.2 ACN -4022 -4796 -5478 -7133 -8603  G 0 (25 o C) (J) PC -4589 -5021 -6452 -6878 -7788 No essential changes in the thermodynamics of the partition process arises when PC+EtOH are used instead ACN as organic modifier of the mobile phase!

Sensitivity (UV)  = 254 nm  = 254 nm 0.9 mAU mAU 0.5 0.85 0.45 0.8 0.4 0.75 0.35 0.7 0.3 0.65 0.25 S/N = 3.51 S/N = 8.61 0.6 0.2 0.55 0.15 0.5 0.1 Fluorene ACN Fluorene PC min min 10.2 10.4 10.6 10.8 11 11.2 11.4 10.8 11 11.2 11.4 11.6 11.8 12 No addition to the mobile phase!

Sensitivity (UV)  = 238 nm mAU  = 238 nm mAU 0.2 0 -0.1 0.15 -0.2 0.1 -0.3 -0.4 0.05 S/N = 5.52 S/N = 7.44 -0.5 -0.6 0 -0.7 -0.05 Lovastatic Acid ACN -0.8 Lovastatic Acid PC min 9.2 9.4 9.6 9.8 10 min 8.8 9 9.2 9.4 9.6 9.8 10 10.2 Acid addition (HCOOH) to the mobile phase!