The 20 g sucrose per mL solution is approximately 20% by weight, The density and refractive index changes for both sucrose and ethanol are alcohol, you could write two equations for the refractive index R I and density begins, the difference between the current density and the baseline density. methods will give the same result if pure sucrose/HFCS content of a solution is measured. Old methods to measure automatic conversion of refractive index / density into Brix degrees or HFCS %. With both There is a direct relationship between density and BRIX. The measured . Direct calculation of BRIX. Less sample. Are the relationships actually linear? For the dependence on the sugar concentration you do expect from first principles (at polarizability α of each contributing species times the number density of said species. Refractive Index of Water and Its Dependence on Wavelength, Temperature, and Density.
Refractive index of sucrose solutions.
Recent studies [ 2 - 4 ] provided the detailed study on the concentration mapping by the measurement of refractive index of liquids.
Temperature coefficient of refractive index can also be used to calculate thermal expansion coefficient [ 24 ]. Several techniques are reported in literature for the measurement of concentration and temperature dependence of refractive index of sugar solution using various techniques [ 2 - 7 ]. Various techniques have been developed to determine the contents of sugar in solutions [ 12 - 14 ].
The techniques are Inter digital Capacitor Sensor to determine the contents of sugar in solution [ 12 ]; optical Coherence Tomography to determine blood glucose concentration in diabetic patients [ 13 ]; Quantification of sugar in soft drinks and fruit juices by Density, refractometry, infrared spectroscopy and statistical methods [ 14 - 16 ] are some of the techniques so far developed. The above mentioned techniques are industrial made instrument used to determine the concentration of sugar in solution.
Such kind of instrument is very expensive and also not available in most laboratories. Materials and Methods Materials Locally constructed equilateral hollow prism, Red and Green Diode laser, He-Ne laser as light sources, digital electronic balance with a good accuracy for mass measurement were used.
Refractometry: Analyzing Results
In addition, different apparatus such as measuring cylinder to measure the volume of water, mercury thermometer to control the temperatures of the solutions and magnetic stirrer with hot plate for heating and mixing the solution.
In addition, deionized water as solvent, locally produced sugar and soft drink beverages Pepsi, Coca, 7up, Sprite, Mirind and Fanta were used as our sample.
Calibration curve developed from the graph of refractive index versus the concentration of the solution. Numerical procedure of fitting the experimental data was carried out by linear curve fitting using origin 8 software. A theory and method for derivation of refractive index have been discussed elsewhere [ 1 - 25 ]. The angle of incidence is responsible for deviation produced in the path of light beam. A monochromatic source of light Red, Green Diode laser and He-Ne laser was allowed to fall at angle of incident on the face of the liquid prism and the angle of minimum deviation was determined for each laser light.
During the measurement the solutions were filtered before pouring into the hollow prism. The hollow prism was also rinsed carefully after every measurement. Each measurement has taken three times. Experimental set up for the measurements of angle of minimum deviation using prism spectrometer. Methods of measuring temperature dependent refractive The temperature dependent refractive indices of the solution measured at the temperatures The solutions were heated using magnetic stirrer with hot plate and its temperature controlled by placing the thermometer inside a solution.
The angle of minimum deviation was measured at the interval of 5 K while the solution is cooling down from highest to lowest temperature.
Calibration curve developed from the graph of refractive index versus temperature of the solution. Soft drink beverage solutions preparation In order to measure the sugar contents in soft drink beverages Pepsi, Coca, 7up, Sprite, Fanta and Mirinda each sample was poured into a beaker and stirred for minutes by magnetic stirrer to remove gases within the samples.
For example, refractometer-based methods have been developed for determining the percentage of sugar in fruits, juices, and syrups, the percentage of alcohol in beer or wine, the salinity of water, and the concentration of antifreeze in radiator fluid. Many industries use refractometer-based methods in quality control applications.
In most cases the refractive index is linearly or nearly linearly related to the percentage of dissolved solids in a solution Figure 2. By comparing the value of the refractive index of a solution to that of a standard curve the concentration of solute can be determined with good accuracy. A much more detailed standard curve for the relationship between the refractive index and the percentage of sucrose is available as a PDF file.
Structural Information The refractive index does not provide detailed information about a molecule's structure, and it is not usually used for this purpose since spectroscopic techniques are much more powerful at revealing details of molecular structure. One structural factor that influences the refractive index of a sample is its polarizability. Substances containing more polarizable "soft" groups e.
See Table 2 below. Effect of polarizable groups on refractive index.