CFll Range
Analysis is based on integration of particle size and fluorescence characterisation of individual particles in complex particulate backgrounds i.e. the sample matrix. Particle size is determined by electrical flow impedance through an orifice (volume displacement is the most accurate means of determining the size of a particle). As individual particles transit the orifice they are exposed to laser excitation and emission of fluorescence is indicative of a viable cell (figure 1). The level of fluorescence is a measure of the physiological state of the cell i.e. its metabolic activity.
A single analysis therefore yields the following data:
- Presence and concentration, of particles in the selected (microbial) size range(s)
- Quantification of the number of viable cells
- Physiological status
Sample analysis
The sample is presented to the CellFacts II instrument in batches of 120, 8 or single samples. Once a batch of samples has been presented to the instrument, analysis is automatic, the instrument performs all necessary liquid handling and washing procedures. Approximately thirty samples are analysed per hour. An advanced cluster analysis algorithm is used to distinguish and detect the presence of yeast and bacteria even in heavily particulate backgrounds. Post-analysis interpretation of data by the operator is not required. However the optional CFII View software allows the operator a manual view of measured data if required.
The data output is for the presence or absence of bacteria and yeast above a specified threshold (e.g. one yeast per two ml of sample). Following analysis of each test sample the instrument algorithm displays whether the sample is clean (green) or contaminated (red). Contaminated samples also display the number of viable organisms present in the sample at the time of analysis.
