| 摘要 |
1,153,784. Micro-biological testing. STANDARD OIL CO. July 27, 1966 [July 28, 1965], No.33824/66. Heading C6F. An indicator composition for viable microorganisms comprises an aqueous solution of nutrient salts, a normally liquid hydrocarbon and at least one triphenyl monotetrazolium chloride, particularly 2, 3, 5-triphenyl [2H] tetrazolium chloride and 1, 4, 5-triphenyl tetrazolium chloride. Formulations of nutrient salts are disclosed. The hydrocarbon may be a jet fuel, a diesel fuel, a kerosine or a home heating oil, but is preferably either a distillate fuel at least 30% of which boils above 400‹F. and not more than 15% of which boils below 250‹F., or a mixture of 90% by volume of n-dodecane and 10% of n-hexadecane. Other hydrocarbon products and pure hydrocarbons are also mentioned. The reduction of the tetrazolium chlorides to a red coloured formazan by the living micro-organisms usually takes between 12 and 72 hours; the colour change may, however, be accelerated by enriching the nutrient salts with other specified ingredients to increase the metabolic activity of the micro-organisms or by the addition to the composition, when pure hydrocarbons are employed, of minor amounts of the corresponding alcohol or aldehyde e.g. dodecanal in the case of dodecane. When the indicator composition is employed for field testing for the presence or absence of viable micro-organisms in hydrocarbon fuels and water bottoms associated therewith, the hydrocarbons in the composition may correspond to those present in the fuel, provided they are relatively olefin-free. The examples disclose test procedures on commercial turbine fuels employing: (i) the indicator composition, and (ii) the indicator composition together with a biocide such as a mixture of dioxaborinanes, pink or red colourations being obtained in the former series. It is ascertained from further experiments disclosed that certain other tetrazolium salts are unsuitable. The tests were carried out in serum bottles provided with a split rubber stopper receiving a needle portion of a syringeneedle unit, and a crimpable sealing ring. |
