Refractive index of oils

Light Tar Oils (benzene and its homologues).—The presence of these oils, which may have D = 0-870-0-945, b.pt. 80-200° and refractive index above 1-5, exerdses a certain influence on the specific gravity, boiling point and refractive index of oil of turpentine. Their presence may also be detected by the test with nitric acid (see paragraph 10 a). 

Point spread function (PSF) If a tiny population of 100 nm fluorescent beads sandwiched between a coverslip and a microscope slide are examined at high resolution (i.e. at 100x objective magnification, 1.4 NA. and in a correctly matched refractive index of oil), it can actually show a tiny set of rings in the horizontal (XY) view (also called an airy disk (see Fig. below). This airy disk cannot be avoided due to diffraction and the wave nature of light. If a specimen is optically sectioned and projected in a vertical (XZ) view (see Fig. xx), a set of concentric rings will flare from the center. When a three-dimensional image of this specimen is collected, a complete point spread function is said to be recorded for each bead. The (PSF)... 

Standard methods for measuring the refractive index of oils and fats are published by IUPAC (standard method 2.102, Paquot Hautfenne, 1987), the American Oil Chemists Society (AOCS Official Method Cc 7-25, Firestone, 1998) and the International Standards Organization (International Standard 1739-1975 (E), ISO, 1975). The last specifically applies to the measurement of the refractive index of the fat from butter, and was developed jointly with the International Dairy Federation and the American Oil Chemists Society. 

PERC (Petroleum Research Center). Refractive index of oils. 2000. Available at http //www.perc.utah. edu/Capabilities/OilChar/RI/index.htm (accessed 22/2/2009). 

Refractive index plays an important role in different fields of chemistry, physics and biology. Knowledge of the refractive index of oil is of critical importance in applications of adulteration of oils and purity (Yunus et al., 2009). 

The solubility of essential oils in water, or in aqueous solutions of other substances is obviously a question of considerable importance in reference to the transference of the oil from one portion of the plant to another, as will be seen in the sequel. From a laboratory point of view, the question has been thoroughly investigated in a number of eases by Umney and Bunker. The following table indicates the results obtained by these observers, the methods adopted by them being (1) the determination of the difference between the refractive index of the dry oil and that of the oil saturated with water, and (2) the determination of the difference between the specific gravity of the dry oil and that of the oil saturated with water —... 

The author has recommended the examination of the last 10 per cent, left on evaporation of the oil on a water-bath, since the heavy artificial esters accumulate in this fraction. The refractive index of this 10 per cent, should not be below 1 5090, and the saponification value should not exceed 190. The following figures (see p. 317) represent nine samples of adulterated oil, all sold as genuine bergamot oil. 

Alcohol and acetone may be detected by their low boiling-point and by the iodoform test. Oils containing alcohol form milky mixtures with water. It may be extracted by washing with water, when the refractive index of the washed oil is found to be distinctly higher than that of the original oil. 

To a solution of 93.8 g of the monoglycol ester in 500 ml of benzene, there are added 55 g of nicotinic acid chloride and 25 g of trimethylemine dissolved in 200 ml of benzene. The solution is stirred gently at a temperature of 60°C for two hours. After this time, the solution is cooled and washed successively with water, dilute hydrochloric acid, dilute ammonia and water until neutrality, it is dried over anhydrous sodium sulfate, and the sol vent Is evaporated under vacuum In this wey llOg of glycol 2-(p-chlorophenoxy)-2-methylpropionate nico-tlnate Is prepared, which represents a yield of 84%. The product is a sllghly yellow oil having a refraction index of no = 1.5422 and which is distilled with decomposition et 214°C at a pressure of 0.3 mm. 

PE). Then, the mixtures were placed in an ultrasonic cleaner for 15 minutes to obtain a uniform mixture oil. The viscosity and the optical refractive index of these base oils and mixture oils were given in Table 7. 

Both recycled and non-recycled essential oils met the standards for specific gravity, angular rotation and refractive index of the Food Chemicals Codex [22] and United States Pharmacopeia [23] for cold-pressed lemon peel oil. Results of gas chromatography analysis show the same compounds and levels in both systems, specially for the oxygenated compounds as citral (neral and geranial). Therefore, recycling the aqueous discharges to the extractor does not cause undesirable modifications. 

The fiber-taper coupling scheme was applied to liquid-immersed water-droplet microsphere resonators by Hossein-Zadeh and Vahala35. The water droplets of diameter 0.5 1 mm were generated by a syringe and immersed in a low refractive immiscible cladding liquid - an index matching oil with a refractive index of 1.3, and trapped on a silica sphere which was fixed to the bottom of a liquid container... 

Uses Determining refractive index of minerals paint diluent dyed hexane is used in thermometers instead of mercury polymerization reaction medium calibrations solvent for vegetable oils alcohol denaturant chief constituent of petroleum ether, rubber solvent, and gasoline in organic synthesis. 

Kizling and coworker [21] suggested that salts in the aqueous phase stabilised w/o HIPEs by two means. First, the Ostwald ripening process is inhibited due to the decreased solubility of the aqueous solution in the continuous oil phase. Secondly, the attractive forces between adjacent aqueous droplets are lowered, as a result of the increase in refractive index of the aqueous phase towards that of the oil phase. When the refractive indices of the two phases are matched, the attractive forces are at a minimum and highly stable, transparent emulsions are formed. The attractive force, A, is given by ... 

In the case of aqueous thin films between oil droplets (Figure 5), the interferometer beam is brought into the microscope through the epi-illumination attachment whereby the objective lens is used to both observe the film and focus the interferometer beam. The contrast of the observed image is much improved in stray light is minimized by positioning a pinhole at the image plan of the epi-illumination device. The thickness calculations remained the same as for the a/w films as the refractive index of the aqueous thin film was the same in both cases. 

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