*3.3.2 Detergent-dispersant additives*

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 the detergent-dispersant additives they contain.

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

**99**

**Figure 15.**

syringe

tion of the additive in the fuel.

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

without indicating their respective composition.

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,

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:

1.Extraction of the ethanol from the gasoline with a saline aqueous solution, as described in Brazilian standard NBR13992, which is available and executable at all fuel distribution stations to easily determine the ethanol content in the gasoline

2.Continuous introduction of gasoline without ethanol in the column made of a Pasteur pipette containing a polar adsorbent (e.g., silica), using a hypodermic

3.Addition of an alcoholic solution of different acid-base indicators, followed by the addition of ethanol to remove any excess, revealing the presence of additive in the column due to the "turning" of the indicator and its change of color because of

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 concentra-

*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].*

the change in pH caused by the presence of the additive in the column

**Figure 14.** *Structure of some types of additives available on the market. Source: Santos [53].*
