1. Field of the Invention
The present invention generally concerns both colorimetric detection of water and alcohol in gasoline, but also includes a volumetric determination of alcohol if present in fuels commonly known as "gasohols." Additionally, the tests are also applicable to a variety of liquid hydrocarbons for detection of water and/or alcohol therein. Moreover, they are believed environmentally safe.
2. Prior Art
Alcohol is fastly becoming a familiar component of gasolines known as gasohols wherein the alcohol content is often found to be as much as 10%, and in some specialty fuels it can approach nearly 100%. Although ethanol is most often the alcohol of choice, other alcohols such as methanol or tertiary butanol are sometimes added to gasoline or even used as fuels themselves for various reasons. In this regard the propensity of alcohols to absorb water from the environment has long been known where it is theoretically possible to find as much as 10% disbursed water in alcohol which would translate into about 1% water disbursed in gasohols containing 10% alcohol. The adverse effects of excessive water in a fuel system cannot be overstated as ranging from corrosion to poor engine performance, and accordingly over the past 30 years of prior art in the field there have been various methods described for detecting water and/or alcohol in engine fuels.
For example, in U.S. Pat. No. 2,968,940 (1961), Feldman, et. al., describes a method to detect 30 parts per million disbursed water in jet aircraft fuels (the "go-no go" limit) by adding one-half gram of a mixture of sodium o-cresolsulfonphthalien and barium carbonate to 100 cc's of jet fuel, shaking it, allowing the powder to settle and noting its color. Although several common additives were found not to interfere, none of these included alcohols in the concentration normally found in gasohols.
In U.S. Pat. No. 3,505,020 (1970), Caldwell, et. al., discloses an improved mixture of methylene violet or fuchsia (3-amino-7(dimethylamino)-5-phenylphenazinium chloride) and an absorbent from the Group II metals, such as calcium carbonate, to detect 30 parts per million disbursed water in jet fuels but without reference to the presence or absence of alcohol therein.
In U.S. Pat. No. 4,070,154 (1978), Mascher, et. al., discloses a colorimetric test for as little as 0.1% alcohol in jet aircraft fuels (the ice formation inhibitors) by an emulsion reagent of sodium vanadiate, 8-hydroxyquinoline, water, acetic acid and an organic solvent. Because water is part of his reagent it was not intended to detect water in the fuel.
In U.S. Pat. No. 4,608,345 (1986), Feldman, et. al., describes a colorimetric test for detecting small amounts (1%) of alcohol in gasoline using a variety of alcohol soluble-hydrocarbon insoluble dyes with an absorbent from the Group II metals, such as calcium carbonate, however since the absorbent is non-selective, water must first be removed from the fuel by treating with a drying agent.
In U.S. Pat. No. 4,676,931 (1987), I first proposed forming colored hydrates to detected disbursed water in fuels by adding an anhydrous powder which, when shaken with the fuel, would remove only the water so that the presence of alcohol would not interfere with the test. The preferred anhydrous powder was cupric sulfate because it formed two colored-hydrated crystals, light blue and dark blue, depending upon the amount of water present, however a few problems were found using this test under actual field conditions.
First, it was found very difficult to measure a small amount of the powder into a test vial in the field. Secondly, it was also nearly impossible to keep the anhydrous powder dry because every time its container was opened the powder absorbed water vapor from the air and became discolored prior to use. Thirdly, a relatively large fuel sample was required for enough sensitivity where disposal of the sample after the test became increasingly difficult with the advent of environmental regulations. And lastly, the formation of the blue hydrated crystals was always somewhat masked by the usual yellowish hue of various fuels. Accordingly, and in view of the above problems, it was felt that a method be developed that would specially detect water and/or alcohol in the presence or absence of the other with smaller fuel samples of about five cc's to facilitate their easy disposal with relatively safe and inexpensive chemicals. The present invention addresses that need.