Eluent and flow rate

Fig. 3-142. Separation of guanylurea. -Separator column, eluent, and flow rate see Fig. 3-140 detection UV (215 nm) injection volume 50 pL solute concentration 100 mg/L guanylurea (sulfate salt).

Fig. 8-11. Anion analysis of a waste water from the isopropanol synthesis. — Separator column IonPac AS3 eluent and flow rate see Fig. 8-8 detection suppressed conductivity injection 50 pL waste water (1 5000 diluted).

Sample Ion Column(s) Eluent and Flow Rate Inj. Vol. (/il) Detection Comments References... 

Isocratic In chromatography, conditions in which the eluent and flow rate do not change during the separation. 

Figure 4.55 Analysis of guanylurea. Separator column, eluent and flow rate see Figure 4.54 detection UV (215nm) injection volume 50pL peak 100mg/Lguanylurea (sulfate salt) (1).

Figure 12.8 Mia ocolumn size exclusion chromatogram of a styrene-aaylonitrile copolymer sample fractions ti ansfeired to the pyrolysis system are indicated 1-6. Conditions fused-silica column (50 cm X 250 p.m i.d.) packed with Zorbax PSM-1000 (7p.m 4f) eluent, THF flow rate, 2.0 p.L/min detector, Jasco Uvidec V at 220 nm injection size, 20 nL. Reprinted from Analytical Chemistry, 61, H. J. Cortes et al, Multidimensional chromatography using on-line microcolumn liquid chromatography and pyrolysis gas chromatography for polymer characterization , pp. 961 -965, copyright 1989, with peimission from the American Chemical Society.

The instruments for polymer HPLC except for the columns (Section 16.8.1) and for some detectors are in principle the same as for the HPLC of small molecules. Due to sensitivity of particular detectors to the pressure variations (Section 16.9.1) the pumping systems should be equipped with the efficient dampeners to suppress the rest pulsation of pressure and flow rate of mobile phase. In most methods of polymer HPLC, and especially in SEC, the retention volume of sample (fraction) is the parameter of the same importance as the sample concentration. The conventional volumeters— siphons, drop counters, heat pulse counters—do not exhibit necessary robustness and precision [270]. Therefore the timescale is utilized and the eluent flow rate has to be very constant even when rather viscous samples are introduced into column. The problems with the constant eluent flow rate may be caused by the poor resettability of some pumping systems. Therefore, it is advisable to carefully check the actual flow rate after each restarting of instrument and in the course of the long-time experiments. A continuous operation— 24h a day and 7 days a week—is advisable for the high-precision SEC measurements. THE or other eluent is continuously distilled and recycled. 

The concentrations of benzaldehyde, the mixed product, and benzoin and the enantiomeric excesses (revalues) were determined by chiral-phase HPLC with a photodiode array detector. Chiral-phase HPLC was performed on a Chiracel OD-H (Daicel, Diisseldorf, Germany) using isohexane/isopropanol (90 10) as eluent, a flow rate of 0.5 mL min and a column oven at 40 °C. The retention time for benzaldehyde was 10.2 min, for the mixed product DMA-HPP 15.1 and 16.4 min, for the (S)-benzoin 20.3 min, and for the (R)-benzoin 28.5 min. 

Subsequent work by Petersen et al. also used TRU-Resin columns with a HPIC instrument however, the effects of column length were investigated and a 3-cm length was selected.61 Other parameters such as resin size and flow rate were examined, and eluent compositions were studied to minimize the use of oxalic acid. Decreased oxalic acid concentrations reduced the frequency of instrument cleaning. In the final scheme, the Np and Am were eluted in hydrochloric acid, followed by Pu and Th together as tetravalent species in a gradient that added oxalic acid. Last to elute was U. Coelution of Pu and Th was considered satisfactory because isobaric interferences between these elements was not a problem. 

The separation was carried out at ambient temperature with a solution of D20/acetonitrile-d3 (60 40, v/v) as eluent. A flow rate of 1.5 pl/min was applied and the injection was performed by filling up the 5 xl injection loop with the black beetles extract and switching on the valve for 90 s under a back-pressure of about 478 psi. 

Eluent pump flow rate of 35-40% (161-184ml IT1), maintained system pressure between 500 and 700psi. Both the sample and regeneration pumps were operated at 50% flow rate (230ml IT1). 

The original soybean oil (SBO), the processed soybean oil under similar conditions without catalyst (SBO control), and polymers of soybean oil (PSBO) were dissolved in THF. Molecular weights and molecular weight distribution were measured by GPC with a differential refractive index detector using THF as an eluent. The flow rate was 1.00 mL/min at 40 C. The injection volume was 100 pL. Linear polystyrene standards (Polymer Laboratories (PL), Mn = 580-lOOK, Mw/Mn = 1) were used for calibration of molecular weights of all polymers of PSBO. 2 PL gel 3 pm mixed E columns (300 mm x 7.5 mm) in series were used to resolve the samples. 

Fig. 2.10. Enantiomer separation factor (a) and specific surface area versus the level of MAA in the monomer mixture for the chromatographic resolution of D,L-PA on an L-PA imprinted polymer using acetonitrile as inert solvent. Eluent 5% acetic acid in acetonitrile. Column temperature 80°C and flow rate 0.2 ml/min. From Sellergren [12],...

In a uniform colonm the isothermal retention volume V is related to eluent-gas flow rate F, column length L, and average band velocity (dzjdtXy, by the expression... 

Fig. 1 Polystyrene, PSt, and poly (ethylene glycol), PEG, calibration curves obtained on PL Gel column set (Mixed C, 10 A, 5 X 10 A, and 10 A). Eluent THE flow rate 1 mL/min temperature 40°C. Inset SEC elution profiles of poly(ethylene glycol)s (PEGs) at the same analysis conditions.

Fig. 3-32. Separation of the sodium salts of various anions on silica coated with crown ether polymers. - Stationary phase dibenzo-18-crown-6 eluent water flow rate 1 mL/min detection direct conductivity solute concentrations 0.7 ppm Na2S04, 0.1 ppm NaCI 1 ppm Nal, 4 ppm NaSCN, and 8 ppm NaHC03 (taken from [37]).

Fig. 3-136. Separation of alkali metal ions on silica modified with poly(benzo-15-crown-5). - Eluent water flow rate 1 mL/min detection direct conductivity injection volume 1 pL solute concentrations 13.6 g/L LiBr, 14.4 g/L NaBr, 26.2 g/L KBr, 36.4 g/L RbBr, and 34 g/L CsBr (taken from [38]).

Fig. 3-137. Dependence of the retention of monovalent cations on the ionic strength of the eluent for sodium, ammonium, and potassium. - Separator column IonPac CS1 eluent HC1 flow rate 2.3 mL/min detection suppressed conductivity.

Fig. 4-9. Illustration of the influence of the acid concentration in the mobile phase on the separation of sulfate and oxalate. - Separator column IonPac ICE-AS1 eluent HCI flow rate 0.8 mL/min detection suppressed conductivity.

Fig. 4-15. Simultaneous separation of alcohols and aldehydes on IonPac ICE-AS1. - Eluent water flow rate 1 mL/min detection RI injection volume 50 pL solute concentrations 100 ppm each of glyoxal (1), glycerol (2), formaldehyde (3), ethylene glycol (4), glutaric dialdehyde (5), methanol (6), ethanol (7), 2-propanol (8), and 1-propanol (9).

Figure 4.1. Three potential approaches to perform simultaneous, suppressed, and non-suppressed detection. (a) Split stream approach. DD, dummy dispersion device suppressed detector, D , nonsup-pressed detector. Restrictors R1 and R2 are adjusted to provide the same residence time and flow rate in each of the branches, (b) Single column approach. D precedes the suppressor, (c) NaOH introduction approach. A small constant quantity of NaOH is introduced after D no restriction is placed on eluent NaOH concentration [4].

Chromatography of Ribonuclease on IRC-50 (XE-64) Carboxylic Acid Cation Exchange Resin. This was carried out by the method of Hirs, Moore, and Stein (15) using a column of XE-64, 0.9 cm. in diameter and 30 cm. in length with 0.2M sodium phosphate (pH 6.17) as eluent. The flow rate was 5 ml. per hour. 

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