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TOGS 9000 and System Components
The TOGS 9000 is a single sample microprocessor controlled, isothermal spectronic device (ISD) with all of the benefits of the Aquasure PRO 3000 plus the ability to conduct quantitative analysis using Fluorometric, Colorimetric & Nephlometric Detection, and data storage and communications capability, even from remote areas, without a computer.
TOGS 9000 Detection Systems
The TOGS 9000 Features Three Detection Systems Operating Simultaneously during Incubation - all done automatically and non-intrusively.
Fluorometric Detection for E.coli
The fluorigenic enzyme substrate such as 4-methylumbelliferyl -β-D-glucuronide (MUG) when hydrolyzed by the GUD from e.coli produces the fluorescing compound 4-methylumberlliferone (4MU). The, e.coli present in the sample multiplies and interacts with the MUG present in the medium, during incubation which in turn releases the 4MU into the solution. This fluorogen when subjected to UV radiation at ~ 360 nm re-emits the energy absorbed in the form of light radiation (~ 450 nm). The emitted radiation thus has a different but longer wavelength than the absorbed radiation (the fluorescence effect). The emission is random and non-directional. Thus it can be measured at any angle. As the number of e.coli increases, the intensity of the fluorescence emission increases. Low levels of emission intensity are measured accurately and provide an early indication of the presence of e.coli in sample.
Colorimetric Detection for Total Coliform
The chromogenic enzyme substrate such as X-GAL is converted by the enzyme produced by coliforms into the indigo-blue chromophore. During the incubation period, coliforms present in the sample multiply and interact with the X-GAL present in the medium, which in turn releases the indigo dye into the solution. This chromophore when subjected to radiation at ~ 680 nm absorbs the energy. The unabsorbed (transmitted) radiation is measured using an appropriate photo detector. As the number of coliforms increases, the intensity of the transmitted radiation reaching the detector decreases. Low levels of absorption are measured accurately and provide an early indication of the presence of coliforms in sample.
Nephelometric Detection for Total Bacteria
Turbidity is used as a measure of the presence of total bacteria in water samples. During the course of the incubation the transparent growth medium progressively becomes more cloudy and opaque indicating the growth of bacteria in the sample. The increasing turbidity during incubation is monitored using an optical spectroscopic detection technique.
Similar to the colorimetric and fluorometric detection systems, simultaneous to incubation the turbidity produced by the active bacteria present in the fluid sample is measured, as the bacteria present in the sample multiplies and interacts with the nutrient substrate, which in turn produces suspended particles (turbidity) in the solution.
When subjected to incident radiation, these suspended particles scatter the light energy in all directions. The scattered radiation has the same wavelength as that of the incident radiation and is detected at any angle (Nephelometric). As the number of bacteria increases, the turbidity increases, and the intensity of the scattered radiation increases. Using a light source and the appropriate detector, low levels of scattered light intensity are accurately measured thus providing early indication of the presence of bacteria (total) in the sample.
This way total bacteria count can be determined in a water sample using a nutrient growth media. With the use of an X-GAL/MUG reagent, the turbidity produced during the early stages of the growth period is solely attributed to the presence of coliforms as no other bacteria interfere by producing turbidity. Therefore the turbidity measurement can also be used as confirmatory test for coliforms & e.coli measurement.
Unique Features of the TOGS System