Login Registrieren

Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

Chapter 30: Q. 29-9 (page 792)

List the advantages and any disadvantages of SFE compared to liquid-liquid extractions.

Short Answer

Expert verified

Supercritical fluid extraction is more expensive than liquid-liquid extraction but has more advantages.

Step by step solution

01

Given information

Explain the advantages and disadvantages of supercritical fluid extraction as compared to liquid-liquid extraction needs.

02

Step 2. Advantages of supercritical fluid extraction as compared to liquid-liquid extraction needs

The results collected from SFE are quicker as compared to liquid-liquid extraction.
The strength of solvent can be adjusted by adjusting the pressure and temperature in SFE.
The recovery of analytes from the analyzed samples is easy in SFE.
The characteristics of solvent used in SFE are less price or cost, no harm, and chemically stable.

03

Disadvantages of supercritical fluid extraction as compared to liquid-liquid extraction needs

The cost of instruments to perform SFE is very high and cannot be initially spendable.
In working with SFE, the applied pressure should be very high.

Therefore, supercritical fluid extraction is far much better than liquid-liquid extraction.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

In an interesting paper, Zheng and coworkers (J. Zheng, L. T. Taylor, J. D. Pinkston, and M. L. Mangels, J. Chromatogr. A, 2005, 1082, 220, DOI: 10.1016/j.chroma.2005.04.086) discuss the elution of polar and ionic compounds in SFC.

(a) Why are highly polar or ionic compounds usually not eluted in SFC?

(b) What types of mobile-phase additives have been used to improve the elution of highly polar or ionic

compounds?

(c) Why is ion-pairing SFC not often used?

(d) Why are ammonium salts sometimes added as mobile-phase modifiers in SFC?

(e) The authors describe an SFC system that uses mass spectrometry (MS) as a detector. Discuss the

interfacing of an SFC unit to a mass spectrometer. Compare the compatibility of SFC with MS to that

of HPLC and GC with MS.

(f) The authors studied the effect of column outlet pressure on the elution of sodium 4-dodecylbenzene

sulfonate on three different stationary phases with five mobile-phase additives. What effect was

observed, and what was the explanation for the effect?

(g) What elution mechanisms were considered by the authors?

(h) Which mobile-phase additive gave the fastest elution of the sulfonate salts? Which provided the

longest retention times?

(i) Did a silica column give results similar to or different from a cyano bonded-phase column?

For supercritical carbon dioxide, predict the effect that the following changes will have on the elution time in an SFC experiment:

(a) Increasing the flow rate (at constant temperature and pressure)

(b) Increasing the pressure (at constant temperature and flow rate)

(c) Increasing the temperature (at constant pressure and flow rate)

A certain inorganic cation has electrophoretic mobility of $5.27 \times 10^{- 4} {cm}^{2} s^{- 1} V^{- 1}$ . This same ion has a diffusion coefficient of $9.5 \times 10^{- 6} {cm}^{2} s^{- 1}$ .If this ion is separated from other cations by CZE with a

data-custom-editor="chemistry" $50.0 cm$ capillary, what is the expected plate count N at applied voltages of

(a) data-custom-editor="chemistry" $10.0 kV$ ?

(b) data-custom-editor="chemistry" $20.0 kV$ ?

(c) data-custom-editor="chemistry" $30.0 kV$ ?

What is the principle of micellar electrokinetic capillary chromatography? How does it differ from CZE?

Doxorubicin ( $D O X$ ) is a widely used anthracycline that has been effective in treatments of leukemia and breast cancer in humans (A. B. Anderson, C. M. Ciriaks, K. M. Fuller, and E. A. Ariaga, Anal. Chem., $2003, 75, 8, D O I : 10.1021 / a c 020426 r)$ . Unfortunately, side effects, such as liver toxicity and drug resistance, have been reported. In a recent study, Anderson et al. used laser-induced fluorescence ( $L I F$ ) as a detection mode for $C E$ to investigate metabolites of $D O X$ in single cells and subcellular fractions. The following are results similar to those obtained by Anderson et al. for quantifying doxorubicin by $L I F$ . The $C E$ peak areas were measured as a function of the $D O X$ concentration to construct a calibration curve.

( $a$ ) Find the equation for the calibration curve and the standard deviations of the slope and intercept. Find the $R^{2}$ value.

( $b$ ) Rearrange the equation found in part ( $a$ ) to express concentration in terms of the measured area. ( $c$ ) The limit of detection ( $L O D$ ) for $D O X$ was found to be $3 \times 10^{- 11} M$ . If the injection volume was $100 p L$ , what was the $L O D$ in moles?

( $d$ ) Two samples of unknown $D O X$ concentration were injected and peak areas of $11.3$ and $6.97$ obtained. What were the concentrations and their standard deviations?

( $e$ ) Under certain conditions, the $D O X$ peak required $300 s$ to reach the $L I F$ detector. What time would be required if the applied voltage were doubled? What time would be required if the capillary length were doubled at the same applied voltage?

( $f$ ) The capillary used in part ( $e$ ) under normal conditions had a plate count of $100000$ . What would $N$ be if the capillary length were doubled at the same applied voltage? What would $N$ be if the applied voltage were doubled at the original capillary length?

( $g$ ) For a $40.6 - c m$ -long capillary of inside diameter $50 µ m$ , what would the plate height be for a capillary with $N = 100, 000$ ?

( $h$ ) For the same capillary as in part ( $g$ ), what is the variance $σ^{2}$ of a typical peak?

See all solutions

Recommended explanations on Chemistry Textbooks

Ionic and Molecular Compounds

Read Explanation

Chemical Analysis

Read Explanation

The Earths Atmosphere

Read Explanation

Making Measurements

Read Explanation

Kinetics

Read Explanation

Chemical Reactions

Read Explanation

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free