Name: fizzy extraction of volatile organic compounds combined with atmospheric pressure chemical ionization quadrupole mass spectrometry
Uploaded: 2017-07-14T13:00:00
Description: Watch this Scientific Journal Video about Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry at JoVE.com

We would like to thank the Ministry of Science and Technology of Taiwan (grant number: MOST 104-2628-M-009-003-MY4) for the financial support of this work.

This protocol assumes that all the steps are performed according to the relevant laboratory safety regulations. Some of the steps use commercial instruments - in those cases, manufacturer guidelines need to be followed. When handling toxic chemicals, MSDS guidelines need to be followed. The custom-made equipment4 must be operated cautiously; especially, when handling pressurized gases and live electric wiring.
1. Preparation of Standard Solution
<ol>
	<li>Prepare 6.2 ...

<ol>
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Several smart ways to deliver samples to a mass spectrometer were developed in the studies conducted during the past three decades (e.g., references8,9,10,11,12,13,14). One of the goals of those studies was to simplify preparation of samples for analysis. To achieve that goal, vario...

Various phenomena observed in nature and daily life are linked to gas-liquid phase equilibriums. Carbon dioxide is dissolved in soft and alcoholic drinks under elevated pressure. When a bottle of such a fizzy drink is opened, the pressure drops down, and gas bubbles rush to the liquid surface. In this case, effervescence improves organoleptic properties of beverages. The release of gas bubbles is also the main cause of decompression sickness ("the bends")1. Due to sudden decompression, bubbles form in divers' bodies. The persons suffering from the decompression sickness are treated in hyperbaric chambers.
Gas bubbles have various applications in analytical chemistry. Notably, sparging methods rely on passing gas bubbles through liquid samples to extract volatile compounds2. For example, a method called "purge-closed loop" is combined with gas chromatography to enable rapid analysis of dissolved volatiles3. While sparging can continuously extract volatiles over time, it does not confine them in space or time. The released gas-phase species need to be trapped, and-in some cases-concentrated by applying a temperature program or using sorbents. Thus, there is a need to introduce new on-line sample treatment strategies, which could reduce the number of steps, and-at the same time-concentrate volatile analytes in space or time.
To address the challenge of extracting volatile compounds from liquid samples, and performing analysis on-line, we recently introduced "fizzy extraction"4. This new technique takes advantage of the effervescence phenomenon. Briefly, a carrier gas (here, carbon dioxide) is first dissolved in the sample by applying overpressure and stirring the sample. Then, the sample chamber is decompressed abruptly. The sudden decompression leads to formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the mass spectrometer, producing signals in the time domain. Because the release of the analyte species is confined to a short period of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios.
The pressures involved in the fizzy extraction process are very low (~150 kPa)4; much lower than in supercritical fluid extraction5 (e.g., &#8805;10 MPa). The technique does not require the use of any special consumable items (columns, cartridges). Only small volumes of solvents are used for dilution and cleaning. The extraction device can be assembled by chemists with medium technical skills using widely available parts4; for example, open-source electronic modules6,7. Fizzy extraction can be coupled on-line with modern mass spectrometers equipped with atmospheric pressure chemical ionization (APCI) interface. Because gas-phase extracts are transferred to the ion source, operation of fizzy extraction does not substantially contaminate vulnerable parts of the mass spectrometer.
The purpose of this visualized experiment article is to guide the viewers on how to implement fizzy extraction in a simple analytical task. While the core of the fizzy extraction system is as described in our previous report4, several improvements have been introduced to make the operation more straightforward. A microcontroller equipped with an LCD screen shield has been incorporated into the system to display the key extraction parameters in real time. All the functions are programmed in the microcontroller scripts, and there is no longer a need to use an external computer to control the extraction system.

<table border="0" cellpadding="0" cellspacing="0" width="963">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Water</td>
			<td style="width:197px;">Fisher</td>
			<td style="width:160px;">W6212</td>
			<td style="width:191px;">Diluent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Ethanol</td>
			<td style="width:197px;">Sigma-Aldrich</td>
			<td style="width:160px;">32221-2.5L</td>
			<td>Diluent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">(R)-(+)-Limonene</td>
			<td style="width:197px;">Sigma-Aldrich</td>
			<td style="width:160px;">183164-100ML</td>
			<td>Standard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Carbon dioxide</td>
			<td style="width:197px;">ChiaLung</td>
			<td>n/a</td>
			<td>Carrier gas</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Cellulose tissue, Kimwipes Kimtech</td>
			<td style="width:197px;">Kimberly-Clark</td>
			<td>34120</td>
			<td>Used for cleaning</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Triple quadrupole mass spectrometer</td>
			<td style="width:197px;">Shimadzu</td>
			<td style="width:160px;">LCMS-8030</td>
			<td>Detection system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">Atmospheric pressure chemical ionization interface</td>
			<td style="width:197px;">Shimadzu</td>
			<td style="width:160px;">Duis</td>
			<td>Ion source</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">20-mL screw top headspace glass vial with septum cap</td>
			<td style="width:197px;">Thermo Fisher Scientific</td>
			<td style="width:160px;">D-52379</td>
			<td>Sample vial</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">LabSolutions software</td>
			<td style="width:197px;">Shimadzu</td>
			<td>n/a</td>
			<td>version 5.82</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">PeakFit software</td>
			<td style="width:197px;">Systat Software</td>
			<td>n/a</td>
			<td>version 4.12</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:415px;">OriginPro software</td>
			<td style="width:197px;">OriginLab</td>
			<td>n/a</td>
			<td>version 8</td>
		</tr>
	</tbody>
</table>

fizzy extraction of volatile organic compounds combined with atmospheric pressure chemical ionization quadrupole mass spectrometry

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to the gas phase, and efficiently transferred to a detection system. Fizzy extraction takes advantage of the effervescence phenomenon. First, a carrier gas (here, carbon dioxide) is dissolved in the sample by applying overpressure and stirring the sample. Second, the sample chamber is decompressed abruptly. Decompression leads to the formation of numerous carrier gas bubbles in the sample liquid. These bubbles assist the release of the dissolved analyte species from the liquid to the gas phase. The released analytes are immediately transferred to the atmospheric pressure chemical ionization interface of a triple quadrupole mass spectrometer. The ionizable analyte species give rise to mass spectrometric signals in the time domain. Because the release of the analyte species occurs over short periods of time (a few seconds), the temporal signals have high amplitudes and high signal-to-noise ratios. The amplitudes and areas of the temporal peaks can then be correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. The advantages of fizzy extraction include: simplicity, speed, and limited use of chemicals (solvents).

At the beginning, the fizzy extraction system is tested with a standard solution. Subsequently, the real sample and real sample spiked with standard are analyzed. The areas of the temporal peaks of extraction events are correlated with concentrations of the analytes in the liquid samples subjected to fizzy extraction, which enables quantitative analysis. Here, we performed double standard addition to demonstrate quantitative capabilities of the technique (Figure 7</st...

Watch this Scientific Journal Video about Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry at JoVE.com

Fizzy Extraction of Volatile Organic Compounds Combined with Atmospheric Pressure Chemical Ionization Quadrupole Mass Spectrometry

Fizzy extraction is a new laboratory technique for analysis of volatile and semivolatile compounds. A carrier gas is dissolved in the liquid sample by applying overpressure and stirring the sample. The sample chamber is then decompressed. The analyte species are liberated to the gas phase due to effervescence.

Chemical analysis of volatile and semivolatile compounds dissolved in liquid samples can be challenging. The dissolved components need to be brought to ...

The overall goal of this extraction procedure is to liberate volatile compounds from a liquid sample and to transfer these compounds to the mass spectrometer for detection. This method can help answer key questions in the field of science or environmental chemistry field such as what volatile compounds are present in beverages or waste water. The main advantage of this technique is that it's fast and conducted online with mass spectrometry detection.I first had the idea for this method when I opened a bottle of carbonated drink on a sunny day. The bubbles of carbon dioxide released the aroma of the drink. I felt we could easily reproduce this process in the laboratory.To begin this procedure, prepare a stock solution of limonene in ethanol by mixing 10 microliters of limonene with 990 microliters of ethanol. To prepare the real sample, first squeeze fresh lime fruit on a kitchen squeezer to obtain lime juice. Next, mix two milliliters of lime juice in 500 microliters of ethanol.Add LC-MS grade water to a final volume of 10 milliliters and shake the volumetric flask thoroughly. Transfer the prepared sample of diluted lime juice to a 20 milliliter screw top head space glass vial with septum cap. Now, prepare a spiked sample by mixing two milliliters of lime juice, 10 microliters of the limonene stock solution, and 490 microliters of ethanol.Add LC-MS grade water to a final volume of 10 milliliters and shake the volumetric flask thoroughly. Connect a carbon dioxide gas cylinder to the gas supply inlet of a fizzy extraction system. Open the valve in the gas regulator.Then set the output pressure to 1.5 bar. Following this, connect the extraction chamber outlet to the ion source inlet. Then connect the fizzy extraction system to a 12 volt power supply.Set up the data acquisition software of a triple quadropole mass spectrometer connected to the fizzy extraction system. Set the desolvation line temperature to 250 degrees Celsius and the flow rate of drying gas to 15 liters per minute. Then select the MS data acquisition method file.Check that the collision voltage is minus 20 volts, the precursor ion master charge ratio is 137, and the fragment ion master charge ratios are 81 and 95. Then click on the Start Single Run button. Place a sample vial in the fizzy extraction system by using the screw mount.Press the start button on the LCD shield of the fizzy extraction system. While the automated fizzy extraction process is proceeding, observe development of ion signals on the screen of the triple quadropole mass spectrometer. Carbon dioxide is pressurized in the simple Then the simple chamber is decompressed which leads to effervescence.After the fizzy extraction process is complete, unscrew the sample vial from the system. Wipe the sample stirring spindle with cellulose tissue. Then wash the spindle with ethanol and wipe it with cellulose tissue.After switching off the power supply, disconnect the fizzy extraction outlet tube from the ion source. Then close the valve of the gas cylinder and disconnect the gas tubing. Export extracted ion currents for the master charge ratio 81 from the triple quadropole mass spectrometer's data acquisition software to ASCII files.First, click on Select Folder and choose the data file. Click on the File tab, select Export Data and select Export Data as ASCII. Select Output File, select the file path, and click on Open.Then select MS Chromatogram(MC)To import the data into the peak integration software and measure the peak areas, select the option Import from the File tab. Open the data file, click on the Yes button, and select the data in the X and Y columns. Then click on OK and select the option Auto Fit Peaks One Residuals.Now, fit the extraction peak semi-automatically making sure that the fitted curve follows the experimental data points. Select the options List Peak Estimates and then ASCII Editor. Copy the fitting results to clipboard.To input the peak areas in data analysis software, first input the peak area values in the Y column and the concentration values in the X column. Under the Plot tab, select Symbol and Scatter. Then select Fitting and Fit Linear from the Analysis tab.The temporal peak areas of extraction events are correlated with concentrations of the analytes in the liquid sample subjected to fizzy extraction which enables quantitative analysis. In this experiment, double standard edition was performed to demonstrate the quantitative capabilities of the technique. A plot relating temporal peaks areas with the concentration of limonene standard added to the diluted lime juice sample is shown here.Based on the obtained slope and intercept values, the concentration of limonene in the diluted lime juice sample was 8.51 times 10 to the minus five moles per liter. After multiplying by the dilution factor, the concentration of limonene in the original lime juice sample was 4.26 times 10 to the minus four moles per liter. Once mastered, this technique can be done in less than 10 minutes if it is performed properly.While attempting this procedure, it's important to remember to set the experimental parameters correctly. After watching this video, you should have a good understanding of how to set up fizzy extraction equipment and perform extractions of real samples. Don't forget that working with compressed gas can be extremely hazardous and precautions such as wearing safety goggles should always be taken while performing this procedure.

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