ASIA summary

The text, "Bepaling van de concentratie limoneen in bar soap", Guus de Jong, Vera de Kleijne, Emmy Spierings (2016), describes a method for determing the concentration limoneen in bar soap. D-limonene is a fragrance and flavouring that is used in different products. The smell of D-limonene is very strong and it is dependent on the chiral composition. In the peel are a lot of chemical compounds and there is the characteristic odor in particular. (S)-limonene smells like a lemon and (R)-limonene smells like an orange.

Soap is made by means of saponification, a chemical process. This process needs a fat and a sodium hydroxide solution. When there is water added to the process, then the sodium hydroxide solution can separate the fats in alcohols, potassium- and sodium salts. Soap molecules have a hydrophobic tail and a hydrophilic head, because soap molecules have these properties it can form micelles. The hydrophobic tail will surround the fat particle; therefore it will dissolve in water.

Gas chromatography is a technique that can separate different molecules in one solution. This separation is dependent on the polarity of the components and the adhesion to the mobile- and stationary phase. The mobile phase is a carrier gas and is inert. This carrier gas takes the compounds though the column to the detector. There are two inject methods, split and splitless. The spit method split the injected solution in two parts, one part goes though the column and the other part is waste. The splitless method doesn’t split the injected solution; all the injected solution goes though the column. Another application is the auto sampler, this is an automatically injector.

This technique can have two sorts of columns, a capillary column or a packed column. When the sample is on the column it will spread over the mobile- and stationary phase dependent on the polarity of the compounds. Also there a two options for the temperature, the temperature can be kept constant or there can applied a temperature programme. For the quantification of the unknown compound there are two methods, the intern- and extern standard.

For this research, several experiments were conducted. A sample preparation was needed before any measurements could be done. For the sample preparation the limonene had to be extracted from the solid soap, using acetone. For the analysis of the amount of limonene, three different GC settings were used. The settings with a temperature programme of 5 degrees centigrade per minute and a splitless injection appeared to give the best results.The concentration limonene according to these settings was 0,00241%

The limonene concencatrion in the barsoap was 0,00241%.