in the separation of these 8 organic herbicides using HPLC in two different modes: Isocratic elution and gradient elutions. Stationary phase is C18 and the eluent is water-acetonitril (ACN) mixture as presneted in the figure. Rate is the same (1ml/min, Temperature is the same 35 C). i) Compare both the isocratic elution and gradient elution in this experiment. ii) explain why component 8 comes at 30 min in gradient elution without peak tailing while it appears at ~ 65 min in isocratic elution as shoeter and wider peak with tailing.

in the separation of these 8 organic herbicides using HPLC in two different modes: Isocratic elution and gradient elutions. Stationary phase is C18 and the eluent is water-acetonitril (ACN) mixture as presneted in the figure. Rate is the same (1ml/min, Temperature is the same 35 C). i) Compare both the isocratic elution and gradient elution in this experiment. ii) explain why component 8 comes at 30 min in gradient elution without peak tailing while it appears at ~ 65 min in isocratic elution as shoeter and wider peak with tailing.

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter33: High-performance Liquid Chromatography

Section: Chapter Questions

Problem 33.12QAP

See similar textbooks

Similar questions

An HPLC method was developed for the separation and determination of ibuprofen in blood samples. A 3.00 mL blood sample dissolved in 70.00 mL solvent was prepared and 10.0 mL was injected into the HPLC. Standard ibuprofen solutions were also run.Calculate the ibuprofen present in the 3.00 mL blood sample The following data were obtained. Table po itoo: Ibuprofen concentration, mg/ml0.50 1.0 2.0 3.0 Blood sample Peak area (Right column)5.29.617.419.911.4
3. a. Briefly explain why internal standardization method is useful inanalytical chemistry?b. Why does a response factor of an instrument’s detector need to becalculated?
Thin‑layer chromatography (TLC) can be used as a preliminary identification method for many amphetamine‑type stimulants (ATS). Using a 0.25 mm thick silica gel stationary phase and a 98.5:1.5 methanol:concentrated ammonia mobile phase, a spot was observed to have traveled 3.52 cm when the solvent front traveled 8.81 cm. What is the retardation factor (?F)for the compound that composes this spot?
kindly prepare an assignment on Application of HPLC in Drug Analysis: one page show name of the drug, dosage form, extraction step, type of column, separation parameters e.g., flow rate, mobile phase, detection wavelength and run time. Submit before 05.11.
Vitamin C Analysis, a student accidentally puts 1.0 g of sodium bicarbonate (NaHCO3) solid into the vitamin sample solution for trial #1 instead of 0.5 g as the procedure instructs. How does this procedural change impact the calculated milligrams of ascorbic acid in the sample?
A 0.0200 gram blood sample was decomposed by a microwave digestion technique followed by dilution to 100.0 mL in a volumetric flask. Aliquots of the sample solution were treated with a lead complexing reagent and water as follows: Solution 1: 10.0 ml blood sample + 20.0 mL complexing agent + 30.0 mL H20. Solution 2: 10.0 ml blood sample + 20.0 mL complexing agent + 26.0 mL H20 + 4.00 mL of 78 ppb Pb2+ standard. The resulting solutions were analyzed by UV/Vis at 375 nm. Absorbance for solution 1 = 0.155 and for solution 2 = 0.216. Calculate the concentration of lead (ppb) in the original sample.
Gradient elution used in HPLC. How is the gradient created for a reverse-phase HPLC experiment over the course of the run? A)Increase the pH of the mobile phase. B)Decrease the pH of the mobile phase. C)Increase the vapor pressure of the analytes by increasing the temperature. D)Increase mobile phase polarity by increasing the fraction of polar solvent in a binary mobile phase. E)Decrease mobile phase polarity by mixing with a less polar solvent to better compete with the nonpolar stationaryphase. Plz explain properly why statement is not correct
Gradient elution used in HPLC. How is the gradient created for a reverse-phase HPLC experiment over the course of the run? A)Increase the pH of the mobile phase. B)Decrease the pH of the mobile phase. C)Increase the vapor pressure of the analytes by increasing the temperature. D)Increase mobile phase polarity by increasing the fraction of polar solvent in a binary mobile phase. E)Decrease mobile phase polarity by mixing with a less polar solvent to better compete with the nonpolar stationaryphase.
A young researcher was evaluating a standard method for determining the methylmercury content in blue fin tuna using high performance liquid chromatography (HPLC). She determined the standard deviation (?)(s) for the method to be 0.440.44 ppb and assumed that ?s was a good approximation of ?σ . As a test, she used this method to evaluate the methylmercury content in a National Institutes of Standards and Technology (NIST) standard and determined the unknown amount to be within 0.210.21 ppb (?)(μ) of the known mean with 99% probability. How many replicate measurements of the NIST standard did the researcher perform?
(please answer all questions) 5-30. When marking the sample line on a TLC plate, why is it inadvisable to use a ball-point pen? 5-31. A series of dyes is separated by TLC. The data are given below. Calculate the Rf value for each dye. 5-32. Why is it important not to let the level of the elution solvent in a packed chromatographic column drop below thetop of the solid-phase adsorbent? 5-33. What are some advantages of using column chromatography to purify reaction products in the microscalelaboratory? 5-34. Discuss the similarities and dissimilarities of TLC, paper, and column chromatography. 5-35. Discuss the similarities and dissimilarities of HPLC and gas chromatography. 5-36. (a) What are the main advantages of using flash chromatography?(b) How can TLC be used in connection with flash chromatography? 5-37. Using the information presented on the right, please identify and explainwhich spot has an Rf value of 0.5.
prepare an assignment on Application of HPLC in Drug Analysis(Amiloride): one page show name of the drug, dosage form, extraction step, type of column, separation parameters e.g., flow rate, mobile phase, detection wavelength and run time
Three students did a chromatography experiment, where Rf = distance of solute / distance of solvent. What could be the possible errors why student 3 had results that are quite far from that of students A and B?