*Fuel Quality Monitoring by Color Detection DOI: http://dx.doi.org/10.5772/intechopen.86531*

*Color Detection*

*3.2.2 Water*

**Figure 13.**

**3.3 Gasoline**

*3.3.1 Methanol*

cable in the field, was described in 3.2.1.

the detergent-dispersant additives they contain.

*Structure of some types of additives available on the market. Source: Santos [53].*

*3.3.2 Detergent-dispersant additives*

ethanol (1:1) complexes [51].

In Brazil, ANP Resolution #19, of 2015, states that hydrous ethanol fuel may contain up to 7.5% water [50]. Giordano et al. have developed a simple, rapid, portable, low-cost method that can be used in the field to indirectly determine water in ethanol fuel. The system is based on a colorimetric reaction between ethanol and ceric oxide (Ce(IV)), as shown in **Figure 13.** When a solution of ammonium cerium (IV) nitrate ([(NH4)2Ce(NO3)6], which is yellow in color, is mixed with ethanol, an intense orangey-red color immediately appears because of the formation of Ce(IV)-

The device is made up of mechanically connected layers of acrylic, a sample reservoir, a light source, and a detector. A solution containing the reagents is added to the reservoir, together with aqueous solutions of ethanol (standards or real samples) prepared at 0.2–5.0% v/v and transferred to the reservoir. The volume introduced is approximately 70 μL. As soon as the solutions are mixed, the reactions

*Colorimetric reaction between the reagent Ce(IV) and ethanol. Adapted from Giordano et al. [51].*

Real samples of ethanol obtained from filling stations in Brazil were tested. The water concentrations were compared with those obtained by Karl Fischer titration (ASTM E203, reference method), and the data obtained by the two techniques were found to be statistically equivalent by Student's t-test, at a 95% confidence level [51, 52].

The method for determining methanol in gasoline containing ethanol, appli-

Gasoline is additized with detergent-dispersant additives, which are designed to reduce the formation of deposits in engines and valves, enhance car engine efficiency, and ensure a cleaner combustion process, all of which has a positive impact on the environment. Although different types of additized gasoline have been available on the market for a long time, there is no reference method for analyzing

**Figure 14** illustrates the structure of some of the additives available on the market.

take place, as indicated by a change in color from yellow to orangey red.

**98**

**Figure 14.**

One factor that hampers the development of analytical methods for detergentdispersant additives is that they are sold as packages, with the additives already dissolved in solvents compatible with the hydrocarbon composition of the fuel, without indicating their respective composition.

Santos et al. have developed two laboratory methods for analyzing detergentdispersant additives in gasoline. One uses thermogravimetry to identify the type of additive in the gasoline, which is then quantified by size-exclusion chromatography with refraction index detector, while the other just uses thermogravimetry [53–55].

d'Avila and Souza have developed a method that can be used in the field for the qualitative and/or semiquantitative identification of detergent-dispersant additives in fuels and lubricating oils. It is based on differences in the chromatographic behavior, in nonpolar stationary phases like silica, of nonpolar fuels and oils that form the basis for lubricants, which, due to their hydrocarbon composition in nonpolar stationary phases like silica, are retained less than detergent-dispersant additives, which are polar. The basicity of amine groups in additives could be used to reveal their position in the chromatography column by the addition of different acid-base indicators, making the presence or absence of the additives in the fuels and lubricating oils unequivocal. The process could be used by customers, inspectors, producers, or even by distributors—i.e., by operators who are not necessarily technically qualified—because of the simplicity of the procedure and the interpretation of the results, as shown in **Figure 15**, for a gasoline additized with ethanol, as is commonplace in Brazil and in many other countries [56]. The stages are:


When the fuel contains a detergent-dispersant additive, a colored ring is formed when the indicator changes color (in **Figure 15** exemplified by bromothymol blue), enabling qualitative identification by the naked eye. Semiquantitative identification may be possible, as the intensity of the color is proportional to the concentration of the additive in the fuel.

### **Figure 15.**

*Stages involved in the qualitative identification of detergent-dispersant additives in fuels, executable in the field. Source: d'Avila et al., 2012 (BR1020120292300/WO2014/075158A1) [56].*
