Kromatografi Kolom Sederhana Bergerak / aliran karena gaya grafitasi ↓ Pemilihan fase diam + fase gerak ↓ Kepolaran ↓ Pita-pita kromatogram ↓ Terbentuk fraksi-fraksi ↓ Dianalisis dengan KLT / KK↓
Pengisian Kolom Fase diam Pasir Kapas / glass wool pengisian kolom homogen fase diam ukuran sama fase diam bentuk homogen bebas gelembung udara Tehnis : fase diam + pelarut → bubur (f. gerak)
Klasifikasi Sistem Kromatografi UmumTehnik Spesifik Fase diamKeseimba ngan 1. K. Cair (LC) LLC LSC IEC Cair pd padatan Padatan Resin Partisi Absorbsi Tukar ion 2. K. Gas (GC) GLC GSC Gas terikat Cair pd padatan Padatan Partisi Absorbsi P / A
LIQUID COLUMN CHROMATOGRAPHY A sample mixture is passed through a column packed with solid particles which may or may not be coated with another liquid. With the proper solvents, packing conditions, some components in the sample will travel the column more slowly than others resulting in the desired separation.
How does reverse phase chromatography compare to normal phase chromatography ?
Normal Phase Column Chromatography … The stationary phase is POLAR The more polar component interacts more strongly with the stationary phase The more polar component moves more slowly. The non-polar component moves more rapidly.
Reverse Phase Chromatography… Silica is alkylated with long chain hydrocarbon groups, using 18 carbons long. This is usually referred to as C-18 silica.
Reverse Phase Column Chromatography…. The stationary phase (column packing) is now NON-POLAR Non-polar compounds will move more slowly because they are attracted to the column packing. The more polar component moves more quickly down the column. Polar solvents, such as water and methanol are used in reverse phase chromatography Used mainly in columns, such as HPLC
LIQUID SOLID CHROMATOGRAPHY Si - O - H Normal phase LS Reverse phase LS Silica Gel The separation mechanism in LSC is based on the competition of the components of the mixture sample for the active sites on an absorbent such as Silica Gel.
LIQUID-LIQUID CHROMATOGRAPHY ODPN (oxydipropionylnitrile) Normal Phase LLC Reverse Phase LLC NCCH 3 CH 2 OCH 2 CH 2 CN(Normal) CH 3 (CH 2 ) 16 CH 3 (Reverse) The stationary solid surface is coated with a 2nd liquid (the Stationary Phase) which is immiscible in the solvent (Mobile) phase. Partitioning of the sample between 2 phases delays or retains some components more than others to effect separation.
ION-EXCHANGE CHROMATOGRAPHY SO 3 - Na + Separation in Ion-exchange Chromatography is based on the competition of different ionic compounds of the sample for the active sites on the ion-exchange resin (column-packing).
Types of Ion Exchange Resins Type of Exchanger Functional Exchanger GroupTrade Name Cation Strong AcidSulfonic acid (-SO 3 - H + )Dowex 50; Amberlite IR 120 Weak acidCarboxyclic acid (-CO 2 - H + )Amberlite IRC 50 Anion Strong baseQuaternary ammonium ion (- NR 3 + OH - ) Dowex 1; Amberlite IRA 400 Weak baseAmine group (-NH 3 + OH - )Dowex 3; Amberlite IR 45
Chromatography Conditions associated with each kind of chromatography Ion exchange chromatography Organic cation exchange resins involve crosslinked polystyrene containing either SO 3 - or COO - functional groups with an associated cation Organic anion exchange resin involve crosslinked polystyrene containing NH 3 + functional groups with an associated anion The affinity of dissolved ions for the resin varies with the ion and the composition of the solution
nRzSO 3 – H + + M n+ (RzSO 3 ) n M + nH + nRzCO 2 – H + + M n+ (RzCO 2 ) n M + nH + nRzNR 3 + OH - + A n- (RzNR 3 ) n A + nOH -
MECHANISM OF ION-EXCHANGE CHROMATOGRAPHY OF AMINO ACIDS SO 3 - 3 - Na + COO - H 3 N + Na + COOH H 3 N + pH2 pH4.5 Ion-exchange Resin
Some Applications of Ion Exchange Chromatography Purifications a mixed bed cation-anion exchanger remove salts (ex CaCl 2 ) from water by exchanging them for H 2 O :Deionization of water Concentrations The concentration of trace elements in seawater. Analytical Separations Separations of metal ions and amino acid or halide ions
SIZE EXCLUTION CHROMATOGRAPHY Gel-Permeation Chromatography is a mechanical sorting of molecules based on the size of the molecules in solution. Small molecules are able to permeate more pores and are, therefore, retained longer than large molecules.
SIZE EXCLUTION CHROMATOGRAPHY Molecules that can penetrate the gel particles are separated based on size and shape. Others pass straight through the column. Gel filtration chromatography : mobile phase is water. Gel permeation chromatography : mobile phase is an organic solvent. Sephadex is popular molecular-sieve material 4 the separation of proteins.
PARAMETER PEMISAHAN DALAM KROMATOGRAFI KOLOM 1. KAPASITAS Kapasitas menggambarkan kemampuan fase diam dalam menahan analit. Jika waktu tambat lama, berarti kapasitasnya besar. 2. SELEKTIVITAS Selektivitas menggambarkan kemampuan fase diam untuk dapat memisahkan suatu campuran senyawa. Semakin besar nilai , campuran senyawa semakin terpisah. 3. RESOLUSI Resolusi menggambarkan kemampuan kolom dalam memisahkan campuran senyawa 4. JUMLAH PLATE TEORITIS Jml pelat teoritis N, dalam kolom dapat diketahui dari hasil kromatogram. 5. TINGGI PLATE TEORITIS = H HETP = High Equivalent to A Teoritical Plate Adl : ukuran yang menunjukkan ruang yg ditempati oleh setiap pelat teoritis.panjang kolom
Adjusted Retention Time t r = retention time t m = min. time for unretained mobile phase to travel through column In GC t m is the time CH 4 takes to travel through the column Relative Retention Capacity Factor
Nilai R yg baik > 1,5. Jika R = 1 masih tjd tumpang tindih di antara kedua puncak 2% Untuk memperbaiki R : 1. memperbesar tR = t2 – t1 kolom diperpanjang jumlah fase diam diperbesar manipulasi faktor pemisahan pengoptimalan suhu pilih f.d dan f.g yang cocok 2. Memperkecil lebar puncak, W pilih ukuran fase diam kecil (halus) dan pengisian dalam kolom diperbaiki (seragam dan kompak. Kecepatan alir fase gerak optimum Kurangi dead space dalam kolom Kurangi jumlah sampel Diameter kolom diperkecil.
Resolution w = peak width at the baseline between tangents drawn to the steepest parts of the peak w 1/2 = measured at ½ the peak height
A peak with a retention time of 407 s has a width at the base of 13 s. A neighboring peak is eluted at 424 s with a width of 16 s. Find the resolution for these two components.
Chromatography Chromatographic column theory of packed columns The effect of column efficiency and column selectivity on resolution Poor resolution because of poor column efficiency Good resolution because of good column efficiency, although column selectivity is not great Good resolution because of good column selectivity, although column efficiency is poor Poor resolution because of poor column selectivity, although column efficiency is good
Theories of Elution Chromatography some zone broadening zone separation
Plate height: constant of proportionality between the variance ( 2 ) of the band and the distance traveled (x) Smaller plate height = narrow peaks = better separations Plate height (H) Number of plates (N)
A solute with a retention time of 407 s has a width at the base of 13 s on a column 12.2 m long. Find the plate height and number of plates. L = column length
N is the number of theoretical plates is the relative retention of two peaks k’ 2 is the capacity factor for the more retained component k’ av is the average capacity factor for both components
Remember that variance is additive but standard deviation is not
Applications of Chromatography Qualitative Analysis Quantitative Analysis Analyses Based on Peak Height Analyses Based on Peak Areas Calibration and Standards The Internal Standard Method The Area Normalization Method