PREVIOUS TREATMENTS OF THE SAMPLE (1)

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1 Theme 02. PREVIOUS TREATMENTS OF THE SAMPLE (1) 1599-ENVIRONMENTAL ANALYTIC METHODS Grade in Environmental Sciences Course Second Semester Professors: Miguel A Sogorb (msogorb@umh.es) y Jorge Estévez (jorge.estevez@umh.es) Department: Applied Biology PREVIOUS TREATMENTS OF THE SAMPLE (1) INDEX: 1 2 LIQUID-LIQUID EXTRACTION 3 SOXHLET EXTRACTION 4 5 REFERENCES 1

2 Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. 2

3 THE DISSOLUTION OF SOLID SAMPLES IS FACILITATED BY: Warming Agitation Ultrasounds Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. 3

4 DIGESTION: HUMID ROUTE DRIED ROUTE (calcination or incineration) FUSION CHEMICALS USED FOR DIGESTION BY HUMID ROUTE Dissolution Properties Use Hydrochloric acid (38% w/w) Acid Metals that oxidize easier than the hydrogen Nitric acid (70% w/w) Oxidant Metals that do not react with HCl; oxidized substances (Ag + ; Hg 2+ ; Pb 2+...) Hydrofluoric acid (49% w / w) Perchloric acid (70% w/w) Sulfuric (98.3% w/w) Form stable fluorides Strong oxidizer High point boiling ( 340 C) Silica and silicates; used in combination with other acids Metals (DO NOT USE WITH REDUCERS AGENTS!) Metals; it destroys the organic matter Sodium hydroxide Strong base Aluminum and oxides of Sn, Pb, Zn, Cr 4

5 DRIED ROUTE (calcination or incineration) Sample is heated in an electric oven (muffle) or microwave. The treatment destroys organic matter and preserves inorganic one. Calcination or incineration are usually combined with wet digestion. Sample + Melting chemical Heat MELTING DIGESTION Solid at room T, oxidant, strong acid or base Melted material Soluble en common solvents Melting chemical Properties Use Sodium carbonate Basic Silicates, sulfates insoluble Sodium hydroxide Basic Oxides and sulfides; minerals Sn, Zn, Cr, Zr Sodium peroxide Basic and oxidant Minerals of Sb, Sn, Mo, V, Cr, chromed steel Potassium pyrosulfate Acid Oxides of Fe, Co, Ni, Cr, Ti, W, Al, steel 5

6 Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. Trypsin Enzymatic Glucuronidase Deproteinization Aryl sulfatase Ammonium sulfate Chemistry Perchloric acid Aluminum hydroxide 6

7 Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. DIGESTION AND DISSOLUTION ASSISTED BY MICROWAVE The electromagnetic field causes the water molecules rotation and the movement of electrons in the metallic materials Radiation of 2450 MHz Teflon or silica containers Caution with acid + metal mixtures 7

8 DIGESTION AND DISSOLUTION ASSISTED BY MICROWAVE Pictures taken from: 40-vessels-microwave-digestion-system-microwave-extractionsystem html Dissolution of solid samples. Digestion. Deproteinization. Digestion and dissolution assisted by microwave. Ultrasound-assisted dissolution. 8

9 ULTRASOUNDS T ~ 5000 K P > 1000 atm Agitation PREVIOUS TREATMENTS OF THE SAMPLE (1) INDEX: 1 2 LIQUID-LIQUID EXTRACTION 3 SOXHLET EXTRACTION 4 5 REFERENCES 9

10 LIQUID-LIQUID EXTRACTION DECANTATION FUNNEL LIQUID-LIQUID EXTRACTION A ac A org x (A y ) ac y (A x ) org K = [A org] [A ac ] K = [ (A x) org ]y [(A y ) ac ] x 10

11 LIQUID-LIQUID EXTRACTION [A ac ] n = Concentration of A remaining in the aqueous solution. V ac = Volume of the aqueous solution. n = number of extractions. Vac [Aac] n = ( Vorg x K + V ac ) n x [A ac ] 0 V org = Volume of organic solvent. [A ac ] 0 = Initial concentration of analyte in the aqueous solution. K = Distribution constant (partition coefficient). LIQUID-LIQUID EXTRACTION Let s imagine we want to extract the content in xenobiotic A of 100 ml of aqueous solution with a total volume of 200 ml of organic solvent. It is supposed a partition coefficient (K) of 2. n = 1; V org = 200 ml, 20% of A remains in the aqueous layer. n = 2; V org = 100 ml, 11% of A remains in the aqueous layer. n = 4; V org = 50 ml, 6.25% of A remains in the aqueous layer. n = 5; V org = 40 ml, 5.2% of A remains in the aqueous layer. n = 10; V org = 20 ml, 3.4% de A of A remains in the aqueous layer. 11

12 LIQUID-LIQUID EXTRACTION 1) The distribution coefficient for the xenobiotic X between an organic solvent and H2O is 85. Calculate the concentration of X in the aqueous layer remaining after the extraction of 50 ml of an aqueous solution of X at 1.0 x 10-3 M concentration with the following amounts of organic solvent: a) 50 ml, b) two portions of 25 ml; c) five portions of 10 ml. 2) Which is the minimum distribution coefficient needed to remove 99% of a xenobiotic from 50 ml of water with a) 25 ml of organic solvent, b) and five extractions with 10 ml of organic solvent?. PREVIOUS TREATMENTS OF THE SAMPLE (1) INDEX: 1 2 LIQUID-LIQUID EXTRACTION 3 SOXHLET EXTRACTION 4 5 REFERENCES 12

13 SOXHLET EXTRACTION Animation with extractor Soxhlet in: ns/sox.mov SOXHLET EXTRACTION ADVANTAGES Very effective DISADVANTAGES Slow High consumption of solvent 13

14 PREVIOUS TREATMENTS OF THE SAMPLE (1) INDEX: 1 2 LIQUID-LIQUID EXTRACTION 3 SOXHLET EXTRACTION 4 5 REFERENCES. Supercritical fluid: Substance under temperatures and pressures above its critical point Supercritical point of CO 2 : 31,2 C 73,8 bar 14

15 THE SUPERCRITICAL FLUIDS HAVE DENSITIES AND DIFFUSIVITIES SIMILAR TO THE LIQUIDS AND VISCOSITIES COMPARABLE TO THOSE OF THE GASES DENSITY (g/ml) VISCOSITY (poise) DIFFUSIVITY (cm 2 /s) Gas ~10-3 ( ) x Supercritical fluid ( ) x 10-3 ( ) x 10-4 Liquid (03-2.4)x 10-2 ( ) x 10-5 ADVANTAGES OF CO 2 AS SUPERCRITICAL FLUID: Critical point easy to reach. No toxic, no explosive no inflammable. Chemically inert. Easy to obtain with great purity. Economic. OTHER SUPERCRITICAL FLUIDS USED AS EXTRACTORS: NH 3 (toxic and not totally inert) N 2 O (explosive) 15

16 APPLICATIONS OF SUPERCRITICAL EXTRACTION WITH CO 2 Excellent for extraction of low polar species as: alkanes, terpenes, polycyclic aromatic hydrocarbons, PCBs, pesticides, fats. Good for extraction of moderately polar species as: aldehydes, esters, alcohols It does not work well with polar or very polar analytes, for which modifiers as NH 3 or N 2 O should be added. SUPERCRITICAL FLUIDS EXTRACTOR (1) = Gas container (2) = Pressure pump (3) = Inlet valve (4) = Extraction chamber (5) = Block heater (6) = Outlet Valve (7) = Capillary restrictor (8) = Collection vial 16

17 EXTRACTION CARTRIDGES The sample should occupy most of the volume. The extraction chambers should be inert and capable of withstanding supercritical condition (normally are made with stainless steel) CAPILLARY RESTRICTORS 17

18 METHODS OF WITHDRAWAL OF THE EXTRACT LIQUID TRAP. CRYOGENIC TRAP. SOLID PHASE ADSORBENT. MANNERS OF APPLICATION OF THE SUPERCRITICAL FLUIDS EXTRACTION DYNAMIC EXTRACTION. 18

19 SUPERCRITICAL FLUIDS EXTRACTOR (1) = Gas container (2) = Pressure pump (3) = Inlet valve (4) = Extraction chamber (5) = Block heater (6) = Outlet Valve (7) = Capillary restrictor (8) = Collection vial MANNERS OF APPLICATION OF THE SUPERCRITICAL FLUIDS EXTRACTION DYNAMIC EXTRACTION. STATIC EXTRACTION. 19

20 SUPERCRITICAL FLUIDS EXTRACTOR (1) = Gas container (2) = Pressure pump (3) = Inlet valve (4) = Extraction chamber (5) = Block heater (6) = Outlet Valve (7) = Capillary restrictor (8) = Collection vial MANNERS OF APPLICATION OF THE SUPERCRITICAL FLUIDS EXTRACTION DYNAMIC EXTRACTION. STATIC EXTRACTION. ON-LINE EXTRACTION. 20

21 SUPERCRITICAL FLUIDS EXTRACTOR (1) = Gas container (2) = Pressure pump (3) = Inlet valve (4) = Extraction chamber (5) = Block heater (6) = Outlet Valve (7) = Capillary restrictor (8) = Collection vial MANNERS OF APPLICATION OF THE SUPERCRITICAL FLUIDS EXTRACTION DYNAMIC EXTRACTION. STATIC EXTRACTION. ON-LINE EXTRACTION. OFF-LINE EXTRACTION. 21

22 SUPERCRITICAL FLUIDS EXTRACTOR (1) = Gas container (2) = Pressure pump (3) = Inlet valve (4) = Extraction chamber (5) = Block heater (6) = Outlet Valve (7) = Capillary restrictor (8) = Collection vial APPLICATIONS OF THE EXTRACTION WITH SUPERCRITICAL FLUIDS Extraction of pesticides, PCBs, polycyclic aromatic hydrocarbons, vitamins, flavors, etc. in biological samples. Extraction of triazine pesticides, PCBs in sediment, soil, plant leaves, powder. Extration of dibenzodioxins, dibenzofurans, anthraquinone, hydrocarbons in rocks. Extraction of additives in polymers. 22

23 APPLICATIONS OF THE EXTRACTION WITH SUPERCRITICAL FLUIDS Material Extracted product Solvent Coffee grains Hops flowers Tobacco Yolk Aromatic spices and herbs Biological tissues Wood Oleaginous grains Activated carbon, catalysts Soil, stream sediment Aqueous solutions Polymer solutions Aqueous solutions of proteins Electronic components, optical fibers Tar Petroleum Caffeine Hop extract Nicotine Cholesterol Essential oils Lipids Lignin Oil Pollutants Pesticides Phenols Polystyrene BSA Fats Aromatic fractions Heavy fractions CO 2 /H 2 O CO 2 CO 2 CO 2 CO 2 CO 2 Alcohols CO 2 CO 2 CO 2 CO 2 CO 2 /surfactant CO 2 /surfactant CO 2 Toluene Pentane PREVIOUS TREATMENTS OF THE SAMPLE (1) INDEX: 1 2 LIQUID-LIQUID EXTRACTION 3 SOXHLET EXTRACTION 4 5 REFERENCES 23

24 REFERENCES SOGORB MA y VILANOVA E. (2004). Preparación de muestras. In: TÉCNICAS ANALÍTICAS DE CONTAMINANTES QUÍMICOS. Aplicaciones toxicológicas, medioambientales y alimentarias. Editorial Díaz de Santos. pp: ISBN: All pictures in this presentation, except when otherwise was indicated, were taken from the above stated reference. 24