Chromatograms column

Total variance measured from chromatogram = column variance + variance due to instrument volumes + variance due to electronic response time... 

Fig. 29. Influence of column length on gradient elution of SAN copolymers through iso-octane/THF. Column packing material Polygosil 60-5 silica in both cases, do = 6 nm dP = 5 pm. Upper chromatogram column 55x4.6 mm, lower one column 150x4.6 mm. (The lower chromatogram is from the same run as the dashed line in Fig. 28.) Injection 60 pg in 30 pi THF [124]...

CH2C12 used in an early version of the process Typical HPLC chromatogram Column Ci8 Novapak (or equivalent)... 

Figure 9.5. LSC gradient elution chromatogram. Column 50 cm x 5 mm i.d. Bio-Sil A. Flow 0.5 mL/min. Sample 10 mg in 50 p,L. Reprinted with permission from R. P. W. Scott and P. Kucera, Anal. Chem. 1973, 45, 749. Copyright 1973, American Chemical Society.

FIGURE 4-4. Two approaches to the separation of polynuclear aromatics, (a) Reverse-phase separation of isomeric 4-ring polynuclear aromatics using a gradient of 70/30 (v/v) to 100/0 (v/v) acetonitrile/water as shown beneath the chromatogram. Column C,g detection at 254 nm. (b) Normal-phase separation of aromatic hydrocarbons. Column /uPorasil (silica, 10 /urn) 3.9 mm ID x 30 cm (2 columns) mobile phase hexane flow rate 8 mL/min. (Fig. 4-4b reproduced from reference 1 with permission.)... 

FIGURE 14-4. Separation of aspirin reaction mixture on a high-efficiency column. Reaction times are noted on the chromatograms. Column juBondapak Ci8 (10 /u,m) 3.9 mm ID x 15 cm. Flow 1 mL/min. Mobile phase MeOH/4% HOAc in H20 (37/ 75). Detector UV at 254 nm Sample 10 /uL of aspirin solution. (Note Actual separation will depend upon the quality of the mobile phase and column packing.)... 

HS is generally recalcitrant to any analytical approach, and its chemical structure can only be analyzed after it is broken into low molecular weight compounds by some kinds of degradation. Among the various methods, pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) is currently most commonly used, in which HS is thermally degraded by pyrolysis, the pyrolysate is separated by a gas chromatogram column, and identihed by mass spectrometry. 

FIGURE 14.2-6 Preparation of pure cis- and rrans-l. 3-pentadiene. (ti) Analysis of the feedstock. Column diameter = j in., 6 m long packed with 80-100 mesh Chromosorb P coated with 10% 2.2 oxydipropio-nitrile temperature 30°C. (1) isoprene (2) rrans-1,3-pentadiene (3) c/s-l,3-pentadiene (4) cyclopenta-diene. (b) Preparative chromatogram. Column diameter = 4 cm, 4 m long packed with 20% squalane on 60-80 mesh Chromosoib P temperature 35°C, helium flow-rate 3 L/min (5 cm/s). Injection 4 mL every 20 min. The isoprene of one injection is eluted at about the same time as the cyclopentadiene of the previous injection, (c) Analysis of the trans-l,3-pentadiene prepared (purity 99.8%, cyclopentadiene —1.5 ppm). Reproduced from the Journal of Chromatographic Science by permission of Preston Publications, Inc. 

Figure 1.9 Predicted (a) and experimental (b) chromatograms. Column Zorbax SB CIS 50 x 2.1 mm, 1.8 jLm, mobile phase A methanol-buffer 5-95 VN% (buffer 10 mM phosphate + 0.1% triethylamine, pH 6.7), mobile phase B methanol-buffer 80-20 VA % (buffer 10 mM phosphate + 0.1% triethylamine, pH 6.7), gradient elution (initial 0% B, at 0.7 min 0% B, at 3.1 min 65% B and 100% B at 10 min), flow 0.5 mL/min (p = 531 bar), column temperature 30 C, injection volume 3 jlL, detection 230 nm, analytes basic drug API and its related impurities and degradation products (1) peak of light stress origin (unknown) (2) 1-naphtol (3) duloxetine (4) duloxetine-3-isomer impurity (5) dimethyl-duloxetine impurity, and (6) duloxetine impurity A. Reprinted from Fekete, S. Fekete, J. Molnar, 1. Ganzler, K. J. Chromatogr A. 2009, 1216 7816-7823. Copyright (2009), with permission from Elsevier.

The simulated distillation method uses gas phase chromatography in conjunction with an apolar column, that is, a column where the elution of components is a function of their boiling points. The column temperature is increased at reproducible rate (programed temperature) and the area of the chromatogram is recorded as a function of elution time. 

Typical chromatogram obtained with a sebaconitrile column (mixture ofrefe rence containing LPG components). 

In another procedure, the column of adsorbent is not removed from the glass tube. Tlie developed chromatogram is treated either with a... 

Purification of anthracene. Dissolve 0-3 g. of crude anthracene (usually yellowish in colour) in 160-200 ml. of hexane, and pass the solution through a column of activated alumina (1 5-2 X 8-10 cm.). Develop the chromatogram with 100 ml. of hexane. Examine the column in the hght of an ultra-violet lamp. A narrow, deep blue fluorescent zone (due to carbazole, m.p. 238°) will be seen near the top of the column. Immediately below this there is a yellow, non-fluorescent zone, due to naphthacene (m.p. 337°). The anthracene forms a broad, blue-violet fluorescent zone in the lower part of the column. Continue the development with hexane until fluorescent material commences to pass into the filtrate. Reject the first runnings which contain soluble impurities and yield a paraffin-hke substance upon evaporation. Now elute the column with hexane-benzene (1 1) until the yellow zone reaches the bottom region of the column. Upon concentration of the filtrate, pure anthracene, m.p. 215-216°, which is fluorescent in dayhght, is obtained. The experiment may be repeated several times in order to obtain a moderate quantity of material. 

Column Efficiency. Under ideal conditions the profile of a solute band resembles that given by a Gaussian distribution curve (Fig. 11.1). The efficiency of a chromatographic system is expressed by the effective plate number defined from the chromatogram of a single band. 

A solute s capacity factor can be determined from a chromatogram by measuring the column s void time, f, and the solute s retention time, (see Figure 12.7). The mobile phase s average linear velocity, m, is equal to the length of the column, L, divided by the time required to elute a nonretained solute. 

Examples of the application of size-exclusion chromatography to the analysis of proteins. The separation in (a) uses a single column that in (b) uses three columns, providing a wider range of size selectivity. (Chromatograms courtesy of Alltech Associates, Inc. Deerfield, IL). 

Size-exclusion chromatography can be carried out using conventional HPLC instrumentation, replacing the HPLC column with an appropriate size-exclusion column. A UV/Vis detector is the most common means for obtaining the chromatogram. 

In capillary electrophoresis the conducting buffer is retained within a capillary tube whose inner diameter is typically 25-75 pm. Samples are injected into one end of the capillary tube. As the sample migrates through the capillary, its components separate and elute from the column at different times. The resulting electrophero-gram looks similar to the chromatograms obtained in GG or HPLG and provides... 

Although aimed at the introductory class, this simple experiment provides a nice demonstration of the use of GG for a qualitative analysis. Students obtain chromatograms for several possible accelerants using headspace sampling and then analyze the headspace over a sealed sample of charred wood to determine the accelerant used in burning the wood. Separations are carried out using a wide-bore capillary column with a stationary phase of methyl 50% phenyl silicone and a flame ionization detector. 

This experiment focuses on developing an HPLG separation capable of distinguishing acetylsalicylic acid, paracetamol, salicylamide, caffeine, and phenacetin. A Gjg column and UV detection are used to obtain chromatograms. Solvent parameters used to optimize the separation include the pH of the buffered aqueous mobile phase, the %v/v methanol added to the aqueous mobile phase, and the use of tetrabutylammonium phosphate as an ion-pairing reagent. 

This experiment describes the quantitative analysis of the asthma medication Quadrinal for the active ingredients theophylline, salicylic acid, phenobarbital, ephedrine HGl, and potassium iodide. Separations are carried out using a Gi8 column with a mobile phase of 19% v/v acetonitrile, 80% v/v water, and 1% acetic acid. A small amount of triethylamine (0.03% v/v) is included to ensure the elution of ephedrine HGl. A UV detector set to 254 nm is used to record the chromatogram. 

In this experiment students analyze an artificial RNA digest consisting of cytidine, uridine, thymidine, guanosine, and adenosine using a Cjg column and a mobile phase of 0.4% v/v triethylammonium acetate, 5% v/v methanol, and 94.6% v/v water. The chromatogram is recorded using a UV detector at a wavelength of 254 nm. 

Using the chromatogram shown here, which was obtained on a 2-m column, determine values for t w, 4, k N, and H. 

The chromatogram in Problem 4 was obtained on a 2-m column with a column dead time of 50 s. How long a column is needed to achieve a resolution of 1.5 What height of a theoretical plate is needed to achieve a resolution of 1.5 without increasing the length of the column ... 

A typical TIC chromatogram from an analysis of peptides resulting from enzymatic digest of myoglobin. The peaks represent individual peptides eluting from an LC column and being mass measured by a spectrometer coupled to it through a dynamic-FAB inlet/ion source. 

Typical (a) gas and (b) liquid chromatograms. The charts show amounts (y-axis) of substance emerging from a column versus time (x-axis). The time taken (measured at the top of a peak) for a substance to elute is called a retention time. 

Schematic diagram showing the injection of a mixture of four substances (A, B, C, D) onto a GC column, foliowed by their separation into individuai components, their detection, and the dispiay (gas chromatogram) of the separated materiais emerging at different times from the coiumn.

---