Name: fluorescent paper strips for the detection of diesel adulteration with smartphone read-out
Uploaded: 2018-11-09T12:30:00
Description: Watch this Scientific Journal Video about Fluorescent Paper Strips for the Detection of Diesel Adulteration with Smartphone Read-out at JoVE.com

The authors would like to acknowledge the BAM for funding through the focus area Analytical Sciences: https://www.bam.de/Navigation/EN/Topics/Analytical-Sciences/Rapid-Oil-Test/rapid-oil-test.html.

1. Fluorescent Dyes (Figure 1A)
<ol>
	<li>Purchase commercially available 4-DNS and 4-DNS-OH. 
	Note: 4-DNS-COOH is not commercially available and is prepared from 4-DNS-OH as described hereafter.</li>
	<li>Place 50 mg (0.16 mmol) of 2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol, 2 mg (0.016 mmol) of 4-dimethylaminopyridine and 19.2 mg (0.192 mmol) of succinic anhydride in a 10 mL round bottom flask.</li>
	<li>Dissolve the reagents in 2 mL of dry dichloromethane under argon atmosphere.</li>
	<li>Add 11...

<ol>
	<li>Mattheou, L., Zannikos, F., Schinas, P., Karavalakis, G., Karonis, D., Stournas, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+Using+Adulterated+Automotive+Diesel+on+the+Exhaust+Emissions+of+a+Stationary+Diesel+Engine.">Impact of Using Adulterated Automotive Diesel on the Exhaust Emissions of a Stationary Diesel Engine.</a> Global NEST Journal. 8 (3), 291-296 (2006).</li><li>Gawande, A. P., Kaware, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fuel+Adulteration+Consequences+in+India+:+A+Review.">Fuel Adulteration Consequences in India : A Review.</a> Scientific Reviews and Chemical Communications. 3 (3), 161-171 (2013).</li><li>Lam, N. L., Smith, K. R., Gauthier, A., Bates, M. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kerosene:+A+Review+of+Household+Uses+and+their+Hazards+in+Low-+and+Middle-Income+Countries.">Kerosene: A Review of Household Uses and their Hazards in Low- and Middle-Income Countries.</a> Journal of Toxicology and Environmental Health, Part B. 15 (6), 396-432 (2012).</li><li>Chandrappa, R., Chandra Kulshrestha, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Sustainable Air Pollution Management: Theory and Practice. , 305-323 (2016).</li><li>Felix, V. J., Udaykiran, P. A., Ganesan, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fuel+Adulteration+Detection+System.">Fuel Adulteration Detection System.</a> Indian Journal of Science and Technology. 8, 90-95 (2015).</li><li>Meira, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+Adulterants+in+Diesel+by+Integration+of+LED+Fluorescence+Spectra.">Determination of Adulterants in Diesel by Integration of LED Fluorescence Spectra.</a> Journal of the Brazilian Chemical Society. 26 (7), 1351-1356 (2015).</li><li>Klingbeil, A. E., Jeffries, J. B., Hanson, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Temperature-+and+composition-dependent+mid-infrared+absorption+spectrum+of+gas-phase+gasoline:+Model+and+measurements.">Temperature- and composition-dependent mid-infrared absorption spectrum of gas-phase gasoline: Model and measurements.</a> Fuel. 87 (17-18), 3600-3609 (2008).</li><li>Gupta, A., Sharma, R. K., Villanyi, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Air Pollution. , (2010).</li><li>Gruber, J., Lippi, R., Li, R. W. C., Benvenho, A. R. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+Methods+for+Determining+Automotive+Fuel+Composition.">Analytical Methods for Determining Automotive Fuel Composition.</a> New Trends and Developments in Automotive System Engineering. 13, 13-28 (2011).</li><li>Park, D. H., Hong, J., Park, I. S., Lee, C. W., Kim, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Colorimetric+Hydrocarbon+Sensor+Employing+a+Swelling-Induced+Mechanochromic+Polydiacetylene.">A Colorimetric Hydrocarbon Sensor Employing a Swelling-Induced Mechanochromic Polydiacetylene.</a> Advanced Functional Materials. 24 (33), 5186-5193 (2014).</li><li>Haidekker, M. A., Theodorakis, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ratiometric+mechanosensitive+fluorescent+dyes:+Design+and+applications.">Ratiometric mechanosensitive fluorescent dyes: Design and applications.</a> Journal of Materials Chemistry C. 4 (14), 2707-2718 (2016).</li><li>Uzhinov, B. M., Ivanov, V. L., Melnikov, M. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+rotors+as+luminescence+sensors+of+local+viscosity+and+viscous+flow+in+solutions+and+organized+systems.">Molecular rotors as luminescence sensors of local viscosity and viscous flow in solutions and organized systems.</a> Russian Chemical Reviews. 80 (12), 1179-1190 (2011).</li><li>Grabowski, Z. R., Rotkiewicz, K., Rettig, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+Changes+Accompanying+Intramolecular+Electron+Transfer:+Focus+on+Twisted+Intramolecular+Charge-Transfer+States+and+Structures.">Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures.</a> Chemical Reviews. 103 (10), 3899-4032 (2003).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ASTM D975 - 16a, Standard Specification for Diesel Fuel Oils. , (2016).</li><li>Colucci, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Future Automotive Fuels &#8226; Prospects &#8226; Performance &#8226; Perspective. , (1977).</li><li>Lackner, M., Winter, F., Agarwal, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Gaseous and Liquid Fuels. 3, (2010).</li><li>Gotor, R., Tiebe, C., Schlischka, J., Bell, J., Rurack, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+Adulterated+Diesel+Using+Fluorescent+Test+Strips+and+Smartphone+Readout.">Detection of Adulterated Diesel Using Fluorescent Test Strips and Smartphone Readout.</a> Energy &amp; Fuels. 31 (11), 11594-11600 (2017).</li><li>Coskun, A., Akkaya, E. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ion+Sensing+Coupled+to+Resonance+Energy+Transfer:+A+Highly+Selective+and+Sensitive+Ratiometric+Fluorescent+Chemosensor+for+Ag(I)+by+a+Modular+Approach.">Ion Sensing Coupled to Resonance Energy Transfer: A Highly Selective and Sensitive Ratiometric Fluorescent Chemosensor for Ag(I) by a Modular Approach.</a> Journal of the American Chemical Society. 127 (30), 10464-10465 (2005).</li><li>Chang, B. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smartphone-based+Chemistry+Instrumentation:+Digitization+of+Colorimetric+Measurements.">Smartphone-based Chemistry Instrumentation: Digitization of Colorimetric Measurements.</a> Bulletin of the Korean Chemical Society. 33 (2), 549-552 (2012).</li><li>Roda, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smartphone-based+biosensors:+A+critical+review+and+perspectives.">Smartphone-based biosensors: A critical review and perspectives.</a> TrAC Trends in Analytical Chemistry. 79, 317-325 (2016).</li><li>McCracken, K. E., Yoon, J. -. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+approaches+for+optical+smartphone+sensing+in+resource-limited+settings:+a+brief+review.">Recent approaches for optical smartphone sensing in resource-limited settings: a brief review.</a> Analytical Methods. 8 (36), 6591-6601 (2016).</li></ol>

A fluorescent probe, based on a molecular rotor dye that is sensitive to viscosities in the range of those measured for diesel and its different blends with kerosene, was used to obtain simple and efficient test strips for the detection of diesel fuel adulteration. The emission intensity of 4-DNS at 550 nm in various diesel/kerosene blends correlates with a reduction in viscosity when the proportion of kerosene increases. At a temperature of 24 &#176;C, a nonlinear fluorescence quenching of up to 55% was observed for up ...

Fuel adulteration is a serious problem in many different parts of the world, simply due to the enormous relevance of fuel as an energy source. Running engines on adulterated fuel reduces their performance, leads to earlier engine failure and entails environmental pollution1. Increased SOx emissions occur if diesel is adulterated with kerosene that usually contains a higher amount of sulfur2,3. Although the problem exists for decades, sustainable fuel management that uncovers such criminal activity at its point of origin is still rare, because simple and reliable tests for fuel adulteration are largely lacking4. Despite substantial progress in laboratory-based mineral oil analysis in the past decades5,6,7, approaches to on-site measurements are still scarce. Various methods for the use outside of the laboratory have recently been devised, using fiber optics8, field-effect transistors9 or mechano-chromic materials10. Although they overcome some of the drawbacks of conventional methods, robust, user-friendly and portable methods are still lacking largely. Fluorescent viscosity probes based on molecular rotors are an interesting alternative11,12, because mineral oils are comprised of a great variety of hydrocarbons that differ in chain length and cyclicity, being often reflected in different viscosities. Because fuels are complex mixtures without specific lead compounds to act as tracers, the measurement of the change of a macroscopic property like viscosity or polarity seems very promising. The latter can be addressed by fluorescent molecular rotors for which the fluorescence quantum yields depend on environmental viscosity. After photoexcitation, deactivation commonly involves a twisted intramolecular charge transfer (TICT) state, the population of which is determined by the viscosity of its surrounding microenvironment13. Highly viscous solvents hinder molecular rotors to adopt a TICT state, entailing bright emission. In low-viscous solvents, the rotor can much better access the TICT state, accelerating non-radiative decay and thus quenched fluorescence. The addition of kerosene, with a viscosity of 1.64 mm2&#8729;s-1 at 27 &#176;C, to diesel, with respective viscosities of 1.3-2.4, 1.9-4.1, 2.0-4.5 or 5.5-24.0 mm2&#8729;s -1 at 40 &#176;C for grades 1D, 2D, EN 950 and 4D14,15,16, reduces the kinematic viscosity of the mixture and potentially leads to a proportional quenching of the fluorescence of a molecular rotor probe. The family of 4-dimethylamino-4-nitrostilbenes (4-DNS) seemed most promising to us because of their strong fluorescence variation over a kinematic viscosity range of 0.74-70.6 mm2&#8729;s -1. This range matches well with the known values of kerosene and diesel.
We therefore explored the ability of 4DNS, 2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol (4DNSOH) and (E)-4-(2-(ethyl(4-(4-nitrostyryl)phenyl)amino)ethoxy)-4-oxobutanoic acid (4DNSCOOH) to indicate the viscosity of diesel-kerosene mixtures through their fluorescence, depending on intramolecular rotation and finally yielding a rapid test for diesel adulteration with kerosene. The disposable test is easy to use, precise, reliable, cost-effective and dimensionally small. The adsorption of the probes onto the filter paper as a solid support was investigated and the analysis was accomplished with an embedded smartphone-based fluorescence reader. Today, ubiquitously available smartphones are equipped with high-quality cameras, rendering the detection of optical changes such as color and fluorescence straightforward, and paving the way for powerful on-site analyses. We demonstrate here that the measurement of the emission of fluorescent probes adsorbed on paper strips with a smartphone can be used for fraud detection on combustion fuels in a reliable manner17.

<table>
	<tbody>
		<tr>
			<td>4-dimethylamino-4-nitrostilbene (CAS Number: 2844-15-7)</td>
			<td>Sigma-Aldrich</td>
			<td>39255</td>
			<td>4-DNS Dye</td>
		</tr>
		<tr>
			<td>2-[ethyl[4-[2-(4-nitrophenyl)ethenyl]phenyl]amino]ethanol (CAS Number: 122258-56-4)</td>
			<td>Sigma-Aldrich</td>
			<td>518565</td>
			<td>4-DNS-OH Dye</td>
		</tr>
		<tr>
			<td>Whatman&#160;qualitative filter paper, Grade 1</td>
			<td>Sigma-Aldrich</td>
			<td>Z274852</td>
			<td>Test strips support</td>
		</tr>
		<tr>
			<td>Whatman&#160;application specific filter, activated carbon loaded paper, Grade 72</td>
			<td>Sigma-Aldrich</td>
			<td>WHA1872047</td>
			<td>Fuel pre-treatment filters</td>
		</tr>
		<tr>
			<td>Pall reusable in-line filter holders stainless steel, diam. 47&#160;mm</td>
			<td>Sigma-Aldrich</td>
			<td>Z268453&#160;</td>
			<td>Holder pre-treatment filters</td>
		</tr>
		<tr>
			<td>(3-Aminopropyl)triethoxysilane</td>
			<td>Sigma-Aldrich</td>
			<td>919-30-2</td>
			<td>APTES</td>
		</tr>
		<tr>
			<td>4-(Dimethylamino)pyridine</td>
			<td>Sigma-Aldrich</td>
			<td>1122-58-3</td>
			<td>DMAP</td>
		</tr>
		<tr>
			<td>Succinic anhydride</td>
			<td>Sigma-Aldrich</td>
			<td>108-30-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Triethylamine</td>
			<td>Sigma-Aldrich</td>
			<td>121-44-8</td>
			<td>Et3N</td>
		</tr>
		<tr>
			<td>N,N&#39;-dicyclohexylcarbodiimide&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>538-75-0</td>
			<td>DCC</td>
		</tr>
		<tr>
			<td>Stuart Tube Rotators</td>
			<td>Cole-Parmer</td>
			<td>SB3</td>
			<td>Rotator</td>
		</tr>
		<tr>
			<td>FreeCAD</td>
			<td>freecadweb.org</td>
			<td>-</td>
			<td>Freeware - 3D design</td>
		</tr>
		<tr>
			<td>Ultimaker Cura</td>
			<td>Ultimaker</td>
			<td>-</td>
			<td>Freeware - 3D printing</td>
		</tr>
		<tr>
			<td>Android Studio</td>
			<td>Google</td>
			<td>-</td>
			<td>Freeware - App programming</td>
		</tr>
		<tr>
			<td>Renkforce SuperSoft OTG-Mirror Micro-USB Cable 0,15 m</td>
			<td>Conrad.de</td>
			<td>1359890&#160;- 62</td>
			<td>Smartphone setup electronic part</td>
		</tr>
		<tr>
			<td>Black Cord Switch 1 x Off / On</td>
			<td>Conrad.de</td>
			<td>1371835&#160;- 62</td>
			<td>Smartphone setup electronic part</td>
		</tr>
		<tr>
			<td>Carbon Film Resistor 100 &#937;</td>
			<td>Conrad.de</td>
			<td>1417639&#160;- 62</td>
			<td>Smartphone setup electronic part</td>
		</tr>
		<tr>
			<td>492 nm blocking edge BrightLine&#160;short-pass filter</td>
			<td>Semrock</td>
			<td>FF01-492/SP-25</td>
			<td>Filter excitation</td>
		</tr>
		<tr>
			<td>550/49&#160;nm BrightLine single-band bandpass filter</td>
			<td>Semrock</td>
			<td>FF01-550/49-25</td>
			<td>Filter emission</td>
		</tr>
		<tr>
			<td>&#216;1/2&#34; Unmounted N-BK7 Ground Glass Diffuser, 220 Grit</td>
			<td>Thorlabs</td>
			<td>DG05-220</td>
			<td>Diffuser excitation</td>
		</tr>
		<tr>
			<td>LED 465 nm, 9 cd, 20 mA, &#177;15&#176;, 5 mm clear epoxy</td>
			<td>Roithner</td>
			<td>RLS-B465</td>
			<td>LED excitation</td>
		</tr>
	</tbody>
</table>

fluorescent paper strips for the detection of diesel adulteration with smartphone read-out

Three fluorescent molecular rotors of 4-dimethylamino-4-nitrostilbene (4-DNS) were investigated for their potential use as viscosity probes to indicate the content of kerosene in diesel/kerosene blends, a wide-spread activity to adulterate fuel. In solvents with low viscosity, the dyes rapidly deactivate via a so-called twisted intramolecular charge transfer state, efficiently quenching the fluorescence. Measurements of diesel/kerosene blends revealed a good linear correlation between the decrease in fluorescence and the increase of the fraction of the less viscous kerosene in diesel/kerosene blends. Immobilization of the hydroxy derivative 4-DNS-OH in cellulose paper yielded test strips that preserve the fluorescent indicator&#39;s behavior. Combination of the strips with a reader based on a smartphone and a controlling app allowed to create a simple field test. The method can reliably detect the presence of kerosene in diesel from 7 to 100%, outperforming present standard methods for diesel adulteration.

The three structures of the two commercial dyes 4-DNS and 4-DNS-OH and the synthesized dye 4-DNS-COOH contain a stilbene core element substituted with a donor (-NR2) and an acceptor (-NO2) group at both ends, the central double bond constituting the hinge of the so called &#39;molecular rotor&#39; (Figure 1A). The structures differ in amino group substitution pattern with short alkyl groups for 4-DNS, two slightly longer groups including...

Watch this Scientific Journal Video about Fluorescent Paper Strips for the Detection of Diesel Adulteration with Smartphone Read-out at JoVE.com

Fluorescent Paper Strips for the Detection of Diesel Adulteration with Smartphone Read-out

Here, we present a protocol to detect the adulteration of diesel with kerosene using test strips coated with a fluorescent viscosity probe together with a smartphone-based analysis system.

Three fluorescent molecular rotors of 4-dimethylamino-4-nitrostilbene (4-DNS) were investigated for their potential use as viscosity probes to indicate ...

The overall goal of these dipstick assays combining a fluorescent viscosity probe and a smartphone readout is to detect diesel adulteration with kerosene and to detect such frauds and avoid economical damage. This method can help users in resource-limited country to carry out rapid tests according to the WHO ASSURED demands The main advantage of this technique is that it gives a qualitative measurement result in less than one minute and can be performed by untrained personnel without specific equipment requirement. Although the method provides a new tool for the detection of fuel adulteration, it can also be used for other onsite measurement applications, like for instance, explosive detection or water analysis.Prepare one millimolar solutions of the reference dye and dyes 4-DNS, 4-DNS-OH, and 4-DNS-COOH in toluene as described in the text protocol. Cut cellulose strips of 30-by-five millimeters from filter paper. Place approximately 50 of those strips in a sealable five-milliliter vial together with 4.5 milliliters of the desired dye solution.Shake the strips inside the vial with a vertical rotator for 20 minutes at 30 rpm. Then pour the toluene solution out of the vial. Immediately fill with four milliliters of cyclohexane and rotate for one minute at 30 rpm to wash off excess dyes.Repeat this washing operation three times. Following wash, dry the obtained test strips on a filter paper for 10 minutes at room temperature before performing sample pretreatment as described in the text protocol. Purchase a standard five-millimeter epoxy LED at 460 nanometers, a 100-ohm resistor, and a USB on-the-go cable with an on-off switch and a micro USB port.Cut the USB cable on the opposite of the on-the-go side to isolate the red wire powering positive five volts and the black wire corresponding to the ground. Now, cut the black wire of the USB cable and solder the 100-ohm resistor on the back of the switch. Solder the LED anode to the positive five-volt red wire and the LED cathode to the ground black wire.Purchase a diffuser and two filters for the LED and the camera, typically a short-pass filter for the excitation channel and a band-pass filter for the emission collection. 3D print a smartphone case that fits on the smartphone and integrates the different optical parts consisting of a black chamber as described in the text protocol. Also, 3D print a strip holder to hold a reference and a test strip.Implement the excitation channel by placing the LED, the diffuser, and the filter to illuminate the paper strips at an angle of 60 degrees. Implement the reading channel by placing the filter in front of the smartphone CMOS camera. Select the adequate calibration file from the software memory by clicking on the menu button in the upper right corner of the software window.Dip the test strip into the diesel sample for a couple of seconds by holding the test strip with tweezers. Remove excess fuel by padding with a drying paper. Place the test strip inside the strip holder beside the reference strip and introduce the holder into the smartphone case.An image of the strip's fluorescence is then immediately displayed on the smartphone's screen. Press the shoot button to record the fluorescence intensities of test and reference strips. The degree of adulteration is immediately calculated by the internal algorithm and displayed on the screen.To obtain test strips coded with a fluorescence molecular rotor as a viscosity probe, three types of dyes were coded on paper. One candidate, 4-DNS-OH, was found to be the most suitable probe for detecting diesel adulteration with kerosene. The fluorescence of the strips was determined with a smartphone camera after insertion of the strips into a 3D-printed case.The case integrated the strip holder and all necessary optical elements, such as an LED powered directly by the smartphone USB port, filters, and a diffuser. The assay procedure was kept as simple as possible with only a couple of steps, dipping, placing the strip in the holder, starting the LED, and positioning the holder in the case, followed by measurement and analysis. The analysis software averaged all the RGB values of the pixels in predefined spatial areas corresponding to the strips and converted them to fluorescence intensities.Once mastered, this technique can be done within one or two minutes. After watching this video, you should have a good understanding of how such cost-effective, precise, and rapid methods for fuel adulteration should work. It's also interesting forensic solution, for instance, if an untrained authority personnel or consumers should uncover fraud.While attempting this procedure, it's important to remember to choose the adequate calibration files specially when working with any diesel samples of different grades, as they can interact specifically on the strip. Following this procedure, other reference or laboratory methods like GC-FID can be performed in order to validate positive results observed on-field during a screening campaign. So, this technique can pave the way for other researchers to combine fluorescent dipstick assays with embedded smartphone readout systems to provide valuable tools for onsite detection like pollutants in water or other forensic applications.Working with smartphone CMOS alt-detector requires some precautions concerning the outer-wide valence algorithm that is present in most of the devices. Measuring the fluorescence of a reference strip besides the test strip permits correction of such deviation.

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