Paraffin test

The older technique for this purpose (Ref 8), variously referred to as the paraffin test, the paraffin-glove test, the dermal nitrate test, and the diphenylamine test, had been abundantly shown to be unreliable, was no longer accepted in most US courts, and was now seldom used by good crime investigation laboratories... 

In 1935, the American Federal Bureau of Investigation pointed out that the test was not specific and had reservations about its use.118 Other evaluations of the technique proved it to be completely unreliable as an indicator of FDR. Common substances such as tobacco, tobacco ash, fertilizers, certain pharmaceuticals, certain paints, and urine also give positive results.119120 In addition a number of oxidizing agents such as chlorates, bromates, iodates, permanganates, chromates, vanadates, molybdates, antimony(V), and ferric salts also give a reaction.121,122 At the Interpol Conference in Paris in 1968 it was officially concluded that the paraffin test should no longer be used.123... 

The oil must pass the solid paraffin test at 0°C (this is essentially a cloud point test) by remaining clear at this temperature. This is established in the dewaxing step. 

Acrylonitrile content of the synthetic light liquid paraffin sample solution for extraction with water Weight of Ught liquid paraffin sample extracted with 2 x250 ml of water Weight of acrylonitrile present in light liquid paraffin test solution Weight of acrylonitrile recovered in fractions of azeotropic distillation, pg Mean recovery of acrylonitrile in first two fractions obtained by azeotropic distillation... 

The mechanical properties of waxes and solid paraffins are of considerable importance for most applications and numerous tests have been developed for characterizing the hardness, the brittleness, and resistance to rupture. 

For medicinal or food grade white oils, a very high purity is required. This is controlled by tests analogous to food-grade paraffins ... 

Characteristics for food-grade paraffins Codex test French pharmacopoeia... 

Specifications and test methods for paraffins and waxes. There are no French specifications for these products, but only the customs ... 

Group VI. Concentrated sulphuric acid provides a simple test for the diflferentiation inter alia between (a) saturated paraffin and cyclic hydrocarbons and also simple aromatic hydrocarbons and (b) unsaturated hydrocarbons. 

As a general rule flasks and similar vessels should be heated in an air bath (compare Fig. II, 5, 3). A glycerol bath may be employed for temperatures up to 140° the glycerol is subsequently removed from the outside of the vessel by washing with water. Medicinal liquid paraffin may be used for temperatures up to about 220° hard hydrogenated cotton seed oil, Silicone fluids or fusible metal may be employed when higher temperatures are required. Small test-tubes and centrifuge tubes... 

The test formulation contains 100 parts of PVC (Fikentscher K = 65), 1.2 parts of paraffin wax, 0.6 parts of calcium stearate, and 0.4 parts of methyitin-based stabilizers. 

Pour-Point Depressants. The pour point of alow viscosity paraffinic oil may be lowered by as much as 30—40°C by adding 1.0% or less of polymethacrylates, polymers formed by Eriedel-Crafts condensation of wax with alkylnaphthalene or phenols, or styrene esters (22). As wax crystallizes out of solution from the Hquid oil as it cools below its normal pour point, the additive molecules appear to adsorb on crystal faces so as to prevent growth of an interlocking wax network which would otherwise immobilize the oil. Pour-point depressants become less effective with nonparaffinic and higher viscosity petroleum oils where high viscosity plays a dominant role in immobilizing the oil in a pour-point test. 

Bitumen Insoluble in Paraffin Maphtha (AASHPO T46). This test designated by the American Association of State Highway and Transportation Officials (AASHTO) is used to indicate the content of naphtha-insoluble asphaltenes in an asphalt. Other solvents such as / -heptane (ASTM D3279), / -hexane, and / -pentane have been substituted for the naphtha solvent. 

Toxicity. The acute toxicity of chlotinated paraffins has been tested ia a range of animals and was found to be very low (4). A comprehensive study (5) demonstrated that the toxicity of chlotinated paraffins was related to carbon chain length and to a lesser degree chlorine content. The shorter chain-length chlotinated paraffins were more toxic than the longer chain chlotinated paraffins. 

The acute toxicity of chlorinated paraffins to mammals, binds, and fish is very low (8), but over longer periods of exposure certain chlorinated paraffins have proved to be toxic to some aquatic species. However, the very low water solubility of chlorinated paraffins has made studies on aquatic species complicated. Laboratory experiments in which the chlorinated paraffins had been artificially solubilized showed only the short-chain grades to be toxic at low concentration other longer-chain grades showed no adverse effects on the majority of aquatic species tested. The degree of solubilization achieved in the laboratory is unlikely ever to be experienced in the environment and is of doubtful environmental relevance (9). 

It is important to note that simulated distillation does not always separate hydrocarbons in the order of their boiling point. For example, high-boihng multiple-ring-type compounds may be eluted earher than normal paraffins (used as the calibration standard) of the same boiling point. Gas chromatography is also used in the ASTM D 2427 test method to determine quantitatively ethane through pentane hydrocarbons. 

Pure Commercial Benzene, obtained from coal-tai naphtha, should distil w lthin one degiee (80—Si ), and solidify completely when cooled to 0°. Other tests are as follow s shaken with concentrated sulphuric acid for a few minutes, the acid should not darken, and a drop of bromine water should not be immediately decolourised. A single distillation over a few small pieces of sodium, which absorb any traces of water, is usually a sufficient purification. If the benzene impart a brown or black colour to the sulphuric acid, it must be repeatedly shaken with about 20 per cent, of the acid until the lattev becomes only slightly yellow on standing. This is done in a stoppered separating funnel, and after shaking fora few minutes the mixture is allow ed to settle, and the low er layer of acid diawn off. The benzene is then shaken tw o 01 three times with water to free it from acid, carefully separated from the aqueous layer, and left in contact with fused calcium chloride until the liquid becomes clear. It is then decanted, frozen in ice, and any liquid (carbon bisulphide, paraffins) carefully drained off, and die benzene finally distilled over sodium. 

The pour point represents the lowest temperature at which the liquid fuel will pour. This is a useful consideration in the transport of fuels through pipelines. To determine the pour point, an oil sample contained in a test tube is heated up to 115°F (46°C) until the paraffin waxes have melted. The tube is then cooled in a bath kept at about 20°F (11°C) below the estimated pour point. The temperature at which the oil does not flow when the tube is horizontally positioned is termed the pour point. 

The aniline clo d point is a measure of the paraffinicity of a fuel oil. A high value denotes a highly paraffinic oil while a low value indicates an aromatic, a naphthenic, or a highly cracked oil. The flash point represents the temperature to which a liquid fuel can be heated before a flash appears on its surface upon exposure to a test flame under specified conditions. A knowledge of the flash point is needed to ensure safe handling and storage without fire hazards. 

The pour point of a crude oil or product is the lowest temperature at which an oil is observed to flow under the conditions of the test. Pour point data indicates the amount of long-chain paraffins (petroleum wax) found in a crude oil. Paraffinic crudes usually have higher wax content than other crude types. Handling and transporting crude oils and heavy fuels is difficult at temperatures helow their pour points Often, chemical additives known as pour point depressants are used to improve the flow properties of the fuel. Long-chain n-paraffins ranging from 16-60 carhon atoms in particular, are responsible for near-ambient temperature precipitation. In middle distillates, less than 1% wax can be sufficient to cause solidification of the fuel. ... 

For a highly paraffinic (waxy) feed, the sample should be heated to about I20 F (49°C) before immersing the hydrometer for testing. Heating ensures that the wax is melted, eliminating erroneous readings. 

In the previous examples, the feed characterizing correlations in Chapter 2 are used to determine composition of the feedstock. The results show that the feedstock is predominantly paraffinic (i.e., 61.6% paraffins. 19.9% naphthenes, and 18.5% aromatics). Paraffinic feedstocks normally yield the most gasoline with the least octane. This confirms the relatively high FCC gasoline yield and low octane observed in the test run. This is the kind of information that should be included in the report. Of course, the effects of other factors, such as catalyst and operating parameters, will also affect the yield structure and will be discussed. 

In the 1880 s, the Fr prepd and tested a series of paraffined nitrocelluloses (Refs 1 2), Several mixts were prepd by incorporating various amts of paraffm (5 to 20%) into hot, wet NC, followed by extrusion into cartridges... 

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