Fibre optics phenol

Scorsone E., Christie S., Persaud K.C., Simon P., Kvasnik F., Fibre-optic evanescent sensing of gaseous ammonia with two forms of a new near-infrared dye in comparison to phenol red, Sensor. Actual. B-Chem. 2003 90 37-45. 

Reagents used include 500 ml concentration sulphuric acid in an automatic dispenser (5 ml volume), 500 ml 5% phenol solution and standard sucrose solution (lOmg/lOOml). Select a series of 15 X 18 mm glass test tubes which are clean and free from dust or cellulose fibres. In the first step take 0.1 ml of 80% ethanol extract and add 0.9 ml of water, simultaneously adding 1 ml of 5% phenol. Pump a jet of 5 ml of concentrated sulphuric acid to the central part of the sample and mix (Carefiil this step is potentially dangerous, and solution comes to the boil.) A face mask must be worn, and acid must be added behind the screen in the fume hood. Measure the optical density at 490 nm when the tubes have cooled, and standardize the procedure with standard of sucrose (5-70 pg per tube). The amount of ethanol soluble sugar in kernels of Nonpareil almond is between 2.5 and 3.5mg/g. 

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