Analytical Separations PDF

Analytical Separations 1 Concept Map Showing Some Common Separating Technique 2 Common Separation Techniques 3 4 5 Magnetic separation 6 7 8 9 10 Filtration...

Analytical Separations 1 Concept Map Showing Some Common Separating Technique 2 Common Separation Techniques 3 4 5 Magnetic separation 6 7 8 9 10 Filtration 11 12 Is a technique used for the separation of particles from a solution according to their size, shape, density, viscosity of the medium and rotor speed. 13 Types of centrifugues Microcentrifuges Small Benchtop Centrifuges Research Applications: Cellular Biology, Microbiology, Genomics / Molecular Biology, Proteomics, Biochemistry, Pharmaceutical Studies. Clinical Applications: Clinical Chemistry, Clinical Microbiology, Hematology, Immunology, Clinical Studies. General Purpose Centrifuges Large Capacity Centrifuges Provide reproducible separations for high‐throughput applications such as blood banking and bioprocessing. 14 Superspeed Centrifuges Ultracentrifuges Separation of macromolecules/ligand Allow you to collect binding kinetic studies, micro-organism, cellular separation of various debris, larger cellular lipoprotein fractions from plasma and deprotonisation organelles and of physiological fluids for precipitated proteins. amino acid ananlysis. 15 16 Simple distillation Fractional distillation 17 18 19 20 21 22 23 The bases of separation for the different types of separation techniques 24 Solid-Phase Microextraction (SPME) SOLVENTLESS EXTRACTION High sensivity Reproducibility Solventless nature Sampling/isolation/enrichment into one step Fast, easily automated 25  Solid-Phase Microextraction (SPME) SOLVENTLESS EXTRACTION Little sample manipulation Drawbacks Shorter analysis time Lot-to-lot variation Wide range of sampling techniques Sensibility against organic ▪ Field solvents ▪ On site Limited range of stationary ▪ Air sampling phases 26 27 28 Sampling VOMs Extraction GC-qMS SPME Optimization parameters Fibre Extraction time Extraction temperature Ionic strength pH Sample volume 29 Microextraction in Packed Syringe (MEPS) MEPS Analytical Procedure UHPLC to barrel PTFE sealing ring frits MEPS packed eVol - MEPS bed end plug needle 30  QuEChERS Tomato, garlic, onium, red Transfer 10g sample + Centrifugation pepper, green pepper, carrot, 10mL solvent to a for 5min beetroot and brocolli 50mL tube Transfer 2mL to 2mL tube containing150mg Filter (0.22m) Resuspend in 100L MgSO4 + 25 mg PSA + and inject mobile phase 25 mg C18 31 32 33 34 35  recolhido para análise. Retenção recolha 36 Extractions 1.) Definition The transfer of a compound from one chemical phase to another - The two phases used can be liquid-liquid, liquid-solid, gas-solid, etc - Liquid-liquid is the most common type of extraction Immiscible [ S ]2 K= liquids [ S ]1 - The partitioning of solute s between two chemical phases (1 and 2) is described by the equilibrium constant K K is called the partition coefficient 37 Extractions 2.) Extraction Efficiency The fraction of moles of S remaining in phase 1 after one extraction can be determined - The value of K and the volumes of phases 1 and 2 need to be known V1 q= (V1 + KV2 ) where: q = fraction of moles of S remaining in phase 1 V1 = volume of phase 1 V2 = volume of phase 2 K = partition coefficient The fraction of S remaining in phase 1 after n extractions is n  V1  qn =   ( ) Assumes V2 is constant  1V + KV2  38 Extractions 4.) Example #1: Solute A has a K = 3 for an extraction between water (phase 1) and benzene (phase 2). If 100 mL of a 0.01M solution of A in water is extracted one time with 500 mL benzene, what fraction will be extracted? Solution: First determine fraction not extracted (fraction still in phase 1, q): n 1  V1   100 mL  qn =   =   = 0.062 = 6.2%  (V1 + KV2 )  100 mL + ( 3 )  ( 500 mL )  The fraction of S extracted (p) is simply: p = 1 − q = 1 − 0.062 = 0.938 = 93.8% 39  ANALYTICAL SEPARATIONS Extractions 4.) Example #2: For the same example, what fraction will be extracted if 5 extractions with 100 mL benzene each are used (instead of one 500 mL extraction)? Solution: Determine fraction not extracted (fraction still in phase 1, q): n 5  V1   100 mL  qn =   =   = 0.00098 = 0.98%  (V1 + KV2 )  100 mL + ( 3 )  ( 100 mL )  The fraction of S extracted (p) is: p = 1 − q = 1 − 0.00098 = 0.99902 = 99.902% Note: For the same total volume of benzene (500 mL), more A is extracted if several small portions of benzene are used rather than one large portion 40