DETERMINATION OF BUTANONE CONCENTRATION IN NAIL POLISH REMOVER USING A PROGRAMMABLE MBED CONTROLLER by Prince Ahmed
A Thesis Submitted to the Faculty of
The Harriet L. Wilkes Honors College
in Partial Fulfillment of the Requirements for the Degree of
Bachelor of Arts in Liberal Arts and Sciences
with a Concentration in Chemistry
Wilkes Honors College of
Florida Atlantic University
Jupiter, Florida
May 2018 DETERMINATION OF BUTANONE CONCENTRATION IN NAIL POLISH REMOVER USING A PROGRAMMABLE MBED CONTROLLER by Prince Ahmed
This thesis was prepared under the direction of the candidate’s thesis advisor, Dr. Eugene T. Smith, and has been approved by members of his supervisory committee. It was submitted to the faculty of The Honors College and was accepted in partial fulfillment of the requirements for the degree of Bachelor of Arts in Liberal Arts and Sciences.
SUPERVISORY COMMITTEE:
______Dr. Eugene T. Smith
______Dr. Shree Kundalkar
______Dean Ellen Goldey, Wilkes Honors College
______Date
ii ACKNOWLEDGEMENTS I would like to thank Dr. Eugene T. Smith, my academic and thesis advisor for his patient advice during the course of this project. I would also like to thank Dr. Shree Kundalkar for the task of being my second reader.
iii ABSTRACT Author: Prince Ahmed Title: Determination of Butanone Concentration in Nail Polish Remover Using a Programmable mBed Controller Institution: Wilkes Honors College of Florida Atlantic University Thesis Advisor: Dr. Eugene T. Smith Degree: Bachelor of Arts in Liberal Arts and Sciences Concentration: Chemistry Year: 2018
Scientific identification requires precise and quantifiable discrimination between different volatile substances in real-world samples; affordable, effective and rapid gas chromatography has been crucial towards that end (James, p. 170). In this study, the concentration of butanone (also known as methyl ethyl ketone, MEK) in generic nail polish remover was detected with an analog gas chromatograph fitted with a thermal conductivity detector, and digitally converted for display on a Microsoft Excel worksheet using an mbed LPC 1768 microcontroller. A quantitative measure of butanone in the original sample was obtained through the method of standard addition with deionized water as the analyte, and was found to be 20%. This experiment is appropriate for a quantitative analysis, instrumental methods or possibly a general chemistry course, since students could gain experience with instrumental analysis and the concept of standard addition by using cheap and readily available materials.
iv Table of Contents
1 Introduction...... 1
1.a. A sample chromatogram with labeled dead and retention times...... 1
1.b. Circuit Diagram for a Data Logger...... 4
2 Methods...... 4
2.b. A chromatograph of the elution of a 2:1 mixture of butanone and water...... 5
3 Results and Discussion...... 5
3.a. Baseline corrected chromatographs of nail polish remover samples diluted with water....7
3.b. Standard addition plot of signal intensity versus added water...... 7
4 References...... 8
v List of Figures
Figure 1: A chromatogram with labeled dead and retention times...... 1
Figure 2: Circuit Diagram for a Data Logger...... 4
Figure 3: A chromatograph of the elution of a 2:1 mixture of butanone and water...... 5
Figure 4A: Baseline corrected chromatographs of nail polish remover samples diluted with water...... 7
Figure 4B: Standard addition plot of signal intensity versus added water...... 7
vi Introduction
Chromatography is a method used in analytical and preparative chemistry to separate mixtures. In general, the sample to be examined (called the solute) is allowed to interact with two physically distinct entities— a mobile phase and a stationary phase
(Grob, p. 5). The solute is dissolved in the fluid mobile phase and travels through a stationary phase, with different chemicals in the solute having greater or lesser affinities for the stationary phase. The greater the affinity, the longer it takes for the chemical to be removed, or eluted, from the stationary phase. This time, called the retention time of the chemical, is commonly measured through mass spectrometers, thermal conductivity detectors or flame ionization detectors. This number is a constant for a particular compound under specified conditions of the carrier gas flow rate; the temperatures of the injector, column, and detector; and type of column
(Skoog, p. 865, 872-883). A typical two- tR component chromatogram is shown in Figure 1, tM where the x-axis represents time elapsed and the y- axis represents the signal from the detector. In this experiment, we used gas-liquid partition Figure 1: A sample chromatogram with labeled dead (tM) and retention (tR) times. The first peak has been chromatography to partition our solute and a exaggerated for easier viewing. The dead time would be set to t=0, and the thermal conductivity detector to measure the retention time would be set to t=tR –
tM. elution time.
Gas-liquid partition chromatography (gas chromatography, or GC) was dicovered by Archer Martin and A. T. James in 1954 (James, p. 170). This method separates
1 mixtures using a gaseous mobile phase and a liquid stationary phase on an inert solid support. The liquid can either be coated onto the inside of a column, as in a capillary column, or coated onto small solid particles and packed into a column, as in a packed column. In this experiment, we used a packed column with an outer diameter of 1/8" and a length of one meter, with polyethylene glycol (carbowax) as the stationary phase and pressurized helium gas as the mobile phase.
Gas chromatography can be performed on any species that can at least partially dissolve in the stationary phase and are thermally stable up to a few hundred degrees
Celsius, allowing for a wide range of testable species (Skoog, pp. 862, 887-901). In this experiment we used a Series 400 GOW-MAC Isothermal Gas Chromatograph, which can operate quantitatively up to 300°C (GOW-MAC).
Butanone, also known as methyl ethyl ketone or MEK, is an organic compound
-1 with the formula CH3C(O)CH2CH3. It has a molar mass of 72.11 g·mol , and has a solubility in water of 290 g/L at 20°C (ICSC). Its applications vary, from a solvent for paint removers and glues to a component in the production of paraffin wax (Methyl).
Since butanone is inexpensive and readily available in household products, it is ideal for classroom-scale experiments.
The method of standard addition involves adding known amounts of a standard solution of analyte to a portion of the sample and recording each response to the change in initial conditions. The value of the peak of interest after each successive addition is plotted and extrapolated to the x-intercept to find the analyte concentration in the original sample, as shown in Figure 4B (Skoog, p. 185). Standard addition is useful for samples
2 with complex or unknown interferents that contribute to the analytical signal, which would bias comparisons using calibration curves. In this paper, the peak of interest measures the elution of water, the standard solution is deionized water, and the data was recorded with a data logger powered by an mbed LPC 1768 microcontroller.
A microcontroller is a computer on a chip, an integrated circuit with a processor core, memory, and programmable input/output peripherals (Ahmed). An electronic circuit is composed of individual electronic components (such as operational amplifiers, voltage dividers, and resistors) connected by conductive wires or traces through which electric current can flow. The various electronic components can be used to perform different operations on the provided current; among other things, operational amplifiers can amplify the difference between two input voltages, resistors can reduce current flow, and voltage dividers can divide voltages. The device used here measures the change in voltage over time of the mobile phase, as reported by the gas chromatograph, and converts and amplifies this analog signal to a 0-3.3 V digital signal for use by a computer
(Ahmed).
For reasons of brevity and clarity, the precise technical details for constructing the circuit board and operating the related software will be omitted from this paper, and can be found at kissinstruments.com (Ahmed). This paper assumes that the reader has a functional microcontroller, and the Excel program is scaled so that the full scale of the signal is observed on the Excel spreadsheet. This device features programmable voltage gain and voltage offsets to accomodate different equipment, which can be chosen from a dropdown menu in the Excel spreadsheet (Ahmed). A final operational amplifier acts as a
3 voltage controller to avoid inputting negative voltages, which would destroy the microcontroller (Tran, p. 12). An overview of the circuit used in this experiment is shown in Figure 2, with labeled electrical components.
Figure 2: Circuit diagram for a data logger illustrating the microcontroller, gain control, offset, inputs, instrument amplifiers, power supply, and other electrical components (Ahmed). Methods Gas chromatograms were recorded using a GOW-MAC Series 400 Isothermal
Gas Chromatograph using a 1/8 inch OD x 1 meter polyethylene glycol (carbowax) column and a thermal conductivity detector. The injector, column, and detector were set at 140, 125 and 130°C, respectively; the helium gas flow rate was 20 mL/min. The chromatograph was connected to the mbedLPC 1768 microcontroller, and the microcontroller was connected to a personal computer through a USB port. The computer ran an Excel program which can be found at kissinstruments.com alongside instructions for its use (Smith).
Three vials were prepared, each containing 1000 µL of nail polish remover. Each vial received a different amount of deionized water and was labeled appropriately (e.g.
0% added water, 33% added water, ...). For this experiment, we used 0, 500, and 2000 µL of water. The solutions were then mixed by capping and gently inverting them. Due to
4 clouding agents in the commercial nail polish, the mixtures were left undisturbed at room temperature and pressure for one week to separate the miscible butanone from the immiscible clouding agents. Approximately one µL of each sample was micropipetted using a gastight syringe and injected into the gas chromatograph, taking care to avoid the opaque supernatant in the mixtures. The resulting data from the chromatograph was recorded with an mbedLPC 1768 microcontroller and collated with a Microsoft Excel program, as shown in Figure 3 below.
Figure 3: A chromatograph of the elution of a 2:1 mixture of butanone and water. The peak at 15 seconds represents butanone and the peak at 30 seconds represents other additives. Results and Discussion Typical results for the spike analysis of non-acetone nail polish remover with water are shown in Figure 4A, with baselines set to zero for easier comparison. As the relative concentration of water in each sample increases, the first peak decreases, which identifies the first peak as methyl ethyl ketone and the second peak as other ingredients, including water. The tailing and the slightly decreased retention times on the second peak can be attributed to interactions between the other minor ingredients in the sample and water, as the tailing exists in every sample to various degrees. The second peak height 5 was used to construct a standard addition plot of signal intensity as a function of added water, and the result is shown in Figure 4B. The relative peak heights (P) of the unknown
(u) and the spike (s) are related to the ratio of their concentrations (C) as follows:
푃푢 퐶푢 = 푃푢 + 푠 퐶푢 + 퐶푠 Given the data in Figure 4A, the corresponding concentration of water in the original sample is equal to:
17.22 x = 31.50 2 x + (100%) (3)
x = .8039 = 80.39% As shown above, the concentration of water in the original sample was calculated as 80%, which is close to the value of 82% found by the standard addition plot. The agreement of these independent derivations of the concentration of water demonstrates that this process worked as intended.
6 Figure 4A: Baseline corrected chromatographs of nail polish remover samples diluted with water. Experimental conditions are provided in the text. Each parenthesis denotes the time and value of its nearest peak, in the form (time,value).
Figure 4B: Standard addition plot of signal intensity versus added water. The negative of the x-intercept indicates the original concentration of water in the sample, as a percent total of the entire sample. The standard deviation about the regression (sr) was less than 1 x 10-7, and thus was too small to be shown here.
7 References
Ahmed, P., & Smith, E. T. (n.d.). Data Logger Manual. Accessed April 21, 2018. http://kissinstruments.com/wp-content/uploads/2017/10/KI_DataLogger.pdf.. GOW-MAC Instrument Co. (2009). “Series 400 Isothermal Gas Chromatograph.” SB- 400_1009.Indd. GOW-MAC Instrument Co. Accessed April 20, 2018. https://acs.expoplanner.com/files/acsfall10/ExhibFiles/1038_1700_SB- 400_1009.pdf. Grob, R. L., & Barry, E. F. (2004). Modern Practice of Gas Chromatography (4th ed.). Hoboken, NJ: John Wiley & Sons "ICSC 0179 - METHYL ETHYL KETONE." ICSC 0179 - METHYL ETHYL KETONE. Accessed April 20, 2018. http://www.inchem.org/documents/icsc/icsc/eics0179.htm. James, A. T., & Martin, A. J. (1954). GAS-LIQUID CHROMATOGRAPHY: A Technique for the Analysis and Identification of Volatile Materials. British Medical Bulletin,10(3), 170-176. doi:10.1093/oxfordjournals.bmb.a069416. “Methyl Ethyl Ketone (2-Butanone).” 2018. Methyl-Ethyl-Ketone.pdf. Accessed April 20, 2018. https://www.epa.gov/sites/production/files/2016-09/documents/methyl- ethyl-ketone.pdf. Skoog, D. A., Holler, F. J., Crouch, S. R., & West, D. M. (2014). Fundamentals of analytical chemistry (9th ed.). Australia: Brooks/Cole. Smith, E. T. (n.d.). Curriculum resources for Educators. Accessed April 20, 2018. http://kissinstruments.com/sample-page/. Tran, N. (2016, August 8). Development of a Microcontrolled pH Meter. Accessed April 21, 2018. http://chemeducator.org/bibs/0021001/21160143.html.
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