Role of ultrasound irradiation in
analytical chemistry
In the name of god
1
Ultra-sound comprises the region of frequencies between 18 kHz and 100 MHz.
Two different region:
power ultra-sound between 20 and 100 kHz
diagnostic ultra-sound between 1 and 10 MHz
2
Application of ultrasonic energy:
Animal communications
Medicine for fetal imaging
Under-water range founding (SONAR)
Nondestructive testing for metal flaws
Potential source for enhancement of chemical reactivity
3
Vibrations induced by ultrasound
Ultrasonic irradiation of a liquid medium
F is the frequency of the wave
T is the time
PA is the maximum pressure amplitude of the wave
4
Attenuation of Sound in a Liquid Medium
The heating effect is caused by the degradation of acoustic energy due to absorption
I is the intensity at distance d from the ultra-sound source
a is the absorption coefRcient
5
The Phenomenon of Cavitation
cavitation
transient
stable
R m is the radius of the cavity at the moment of collapse
6
Influence of Different Parameters on the Cavitation Process
Liquid medium
Intensity
Hydrostatic pressure
The formation of cavitation bubbles decreases on increasing ultrasonic frequency
7
Instrumentation
Bath sonicator
Probe type sonicator
8
US baths are more widely used, they have two main disadvantages that substantially decrease experimental repeatability and reproducibility:
Lack of uniformity in the distribution of US energy (only a small fraction of the total liquid volume in the immediate vicinity of the US source experiences cavitation)
Decline in power with time
9
Ultrasound energy
extractions of inorganic and organic compounds
slurry dispersion
homogenization
10
Sonochemical reaction
Formation
Growth
Implosive collapse of gas vacuoles in a solution
11
degassing
cleaning
atomization
Measurement condition
Solid and liquid samples
Heterogeneous sample
12
Scheme of US-assisted chemical reactions of analytical interest involving liquid samples.
13
Type of reaction accelerated or improved by US
US is largely used to accelerate formation reactions and also in degradation and hydrolysis.
14
Derivatization reactions
alkylation reactions and acetylation of chlorophenols by acetic anhydride in an alkaline aqueous medium
Example:
15
Oxidation reactions
Example:
Oxidation of organic mercury in urine
Time of reaction
30 min
0.5-8.0 min
Other advantage of US assistance:
US application avoids precipitation of manganese dioxide thanks to both the low concentration of KMnO4required (0.01%), and the denuding effect of US.
16
Example:
Digestion of organic matter for COD determination
study of oils stability
Oxidation reactions
129 hr
shorter than 1 h
17
Hydrolysis reactions
Example:
Carbohydrates
Use of US bath working at 35 kHz to facilitate carbohydrates hydrolysis
18
Great potential of ultrasonic assistance
sample preparation, especially extraction
versatile isolation technique for a broad spectrum of organic substances from a liquid matrix
liquid extraction (LE)
19
US-assisted derivatization coupled to (or simultaneous with) other steps of the analytical process
Discontinuous approaches for US-assisted derivatization coupled to other steps of the analytical process1
Examples of US assistance of several steps within the same method are as follows:
Characterization of the triterpenic fraction in olive leaves2
using the appropriate device (also an US probe in this case) to favor and/or accelerate several steps of the analytical process3
1K.J. Huang, C.Y. Wei, W.L. Liu, W.Z. Xie, J.F. Zhang, W. Wang, J. Chromatogr. A 1216 (2009) 6636
2N. Sánchez-Ávila, F. Priego-Capote, M.D. Luque de Castro, J. Chromatogr. A 1165 (2007) 158
3M. Orozco-Solano, J. Ruiz-Jiménez, M.D. Luque de Castro, J. Chromatogr. A 1217 (2010) 1227
20
Ultrasound-assisted extraction
UALE is the first extraction technique that brings in emulsification caused by US radiation and was first described and used in 1987
In comparison with conventional liquid liquid extraction
Easer and faster
21
New methods were introduced and developed to facilitate sample preparation for analysis
Assisted solvent-free extraction
Microextraction techniques
Methods requiring a micro-volume of solvent
22
The newest modifications of microextraction techniques that apply US are:
US-assisted solid-phase microextraction
US-assisted LLE
US-assisted stir-bar sorptive extraction
US-assisted homogenous liquid-liquid microextraction
US-assisted electro membrane extraction
US-assisted cloud-point extraction
USAEME
USAEME with solidified floating organic-drop microextraction
(SFODME)
US-assisted solvent-bar microextraction
23
Ultrasound-Assisted Extraction for Metal Determination
On of the application areas of ultrasound-assisted extraction
selective extraction of different physicochemical forms of elements for speciation
24
Applications of Ultrasound-Assisted Extraction for Element Speciation
Organometallic species can be extracted without changes in their integrity under suitable extraction conditions
Use of a probe-type sonicator
25
Continuous approaches for US-assisted derivatization coupled to other steps of the analytical process
Continuous approaches for US-assisted solid–liquid extraction and derivatization coupled to other steps of the analytical process
Some examples of the use of these dynamic systems are as follows:
the leaching step assisted by an US probe was performed for determination of colistin in feed1
DUSAE coupled to on-line filtration, solid-phase extraction (SPE), LC separation, post-column derivatization with OPA, and fluorescence detection for the determination of N- ethylcarbamates in soil and food2
In situ derivatization of the target analytes by complex formation with EDTA3
1S. Morales-Mu˜ noz, M.D. Luque de Castro, J. Chromatogr. A 1066 (2005)
2A. Caballo-López, M.D. Luque de Castro, J. Chromatogr. A 998 (2003) 51
3A. Caballo-López, M.D. Luque de Castro, Chromatographia 58 (2003) 257
26
Micro scale US-assisted extraction with in situ derivatization1
USAE–LLE-assisted emulsification–extraction with in situ complex formation
Scheme of USAE–LLE procedures using extractant denser (A) and less dense than the sample (B)
27
Dithizone (H2Dz) is one of the chelating reagents
28
Able to form neutral complexes with a large amount of metals
Making possible transfer to an organic phase
which avoids interferences
Separation/concentration of lead from water samples after determination by either FAAS
J.C. Li, J.W. Zhang, Y.K. Wang, X. Du, J.J. Ma, H.Q. Gao, J. Chem. Soc. Pak. 33 (2011)822
US-assisted emulsification–extraction with in situ ion-pair formation
29
Other chelating agents
Pyrrolidine dithiocarbamate
Added to the polar sample and its complexes are easily extracted into CCl4
simultaneous USAE–LLE of up to 12 metal cations (viz. aluminium, bismuth, cadmium, cobalt, copper, gallium, indium, iron, lead, nickel, thallium and zinc in water) prior to simultaneous determination by ICP–OES
H. Sereshti, V. Khojeh, M. Karimi, S. Samadi, Anal. Methods 4 (2012) 236.
30
2-(5-bromo-2-pyridylazo)-5 diethy-laminophenol
Other chelating agents
forms manganese chelates extractable
into 1-undecanol
The pH plays a unique role on metal-chelate formation, with solidification floating organic drop (SFOD) preceding the determination of Mn by GFAAS
A. Mohadesi, M. Falahnejad, Scientific World J. 2012 (2012), http://dx.doi.org/10.1100/2012/98764
31
US-assisted emulsification–extraction by in situ Azo derivative formation
Bromopyrogollol red
Added to an aqueous sample
For ion-pair formation
Gold and thallium can be complexed by chloride prior to form the ion-pairs with cations of benzyldi-methyltetradecyl ammonium chloride dihydrate, then extracted with 1-undecanol before GFAAS determination
H. Fazelirad, M.A. Taher, Talanta 103 (2013) 375
US-assisted emulsification–extraction with other types of in situ derivatization
32
Enough acidic metal ions
extracted by changing the pH of the sample yielding a hydroxide easy to extract and with very low reagent cost
Chromium and zinc have been extracted into tetrachloroethylene by changing the pH of sample to 11.4 when in contact with the immiscible extractant
H. Sereshti, V. Khojeh, M. Karimi, S. Samadi, Anal. Methods 4 (2012) 236
33
Comparison of ultrasound-assisted extraction with conventional extraction
methods of oil and polyphenols from grape (Vitis viniferaL.) seeds
Ultrasonic Sonochemistry
Ultrasonic Sonochemistry 20 (2013) 1076–1080
Ultrasound-assisted extraction (US)
ultrasonic sonifier equipped with a titanium alloy flat tip probe (13 mm diameter) was used
Grape seed flour
200 mL n-hexane
immersed into a
500 mL beaker containing ice-bath.
30 min ultrasonic
Filtration
34
Soxhlet extraction (S)
crushed grape seed powder (25 g) was continuously extracted with 300 mL n-hexane for 6 h at a maximum temperature of 70C in a Soxhlet apparatus
n-hexane was removed at 50`C
remove the residual n-hexane
35
Kinetics of ultrasound-assisted extraction of total polyphenols (TP), total tannins (TT) total anthocyanins (TA), cinnamic acids (CA) and flavonols (F) from grape seed defatted by Soxhlet.
Effect of Soxhlet extraction and ultrasound-assisted extraction on grape seed oil
36
Polyphenols extraction from defatted grape seeds
Maceration (M)
10 g of grape seed flours defatted by Soxhlet extraction
by ultrasound-assisted extraction (US)
and
mixed with
150 mL of methanol
stirred at room temperature for 12 h
Centrifuged at 3000 rpm for 30 min, at -4`C.
dryness in a rotary vacuum evaporator
37
Ultrasound-assisted extraction (UAE)
10 g of grape seed flours defatted by Soxhlet extraction
by ultrasound-assisted extraction (US)
and
mixed with
150 mL of methanol
sonicated by the ultrasonic probe for 15 min at a temperature lower than 30`C
38
Ultrasound-assisted extraction technique
Conclusions
Very efficient in the extraction of oil from grape seeds
The advantage of the ultrasound, compared to the conventional extraction methods
a lower solvent consumption
a shorter extraction time.
39
Determination of fragrance allergens in indoor air by active sampling followed by ultrasound-assisted solvent extraction and gas chromatography–mass spectrometry
Journal of Chromatography A
Journal of Chromatography A,1217 (2010) 1882–1890
Fragrances are ubiquitous pollutants in the environment, present in the most of household products, air fresheners, insecticides and cosmetics. Commercial perfumes may contain hundreds of individual fragrance chemicals
40
Ultrasound-assisted extraction
volume of 100µLof standard mixtures in acetone
Spiked on 25mg of the adsorbent
(activated Florisil of 60–100µm mesh or Tenax TA of mesh size 60–80
activated overnight in an oven at 130◦C.
evaporation of the solvent
selected volume (1 or 2mL depending on the experiment) of the extractant organic solvent (ethyl acetate or n-hexane) was added to the glass vial
sealed with a headspace aluminum cap furnished with PTFE-faced septum
41
The analytes were extracted from the samples to the organic solvent using an ultrasound bath
Filtration
Analysis
Quantification ions and performance of the GC–MS method
42
GC–MS full scan chromatogram of a standard mixture of the fragrance allergens at 5µgmL−1 in ethyl acetate
43
Conclusions
A very simple and sensitive method to analyze fragrance allergens in indoor air was developed
The study of method performance demonstrated its linearity, quantitative recoveries, and good sensitivity, with LODs≤0.6µgm−3
The analysis of several air samples demonstrated the validity of the proposed method for the analysis of the target compounds in indoor environments
44
Thanks for your attention