抄録
A flow injection analysis (FIA) system with turbidimetric determination for cell counting was developed. Similar to the McFarland’s method, the present work is based on the proportionality between the turbidimetric signals obtained for barium sulfate suspension and cell suspension. In spite of differences in physical properties, it was possible to establish a correlation between the two systems. The analytical curves for both species presented the following equations: S = 0.0087Csulfate + 0.0005 for sulfate calibration and S = 4.8 x 10-11 CS.cerevisiae - 0.0018 for Saccharomyces cerevisiae, thus, the correlation between the two systems was: CS.cerevisiae = 1.0875 Csulfate + 0.0023. The results obtained, using the proposed procedure, were compared with results obtained in the Neubauer Chamber and there was no significant difference at confidence level of 95% (paired t-test). The proposed technique presented a limit of detection equal to 2.37 x 108 cell L-1. The main advantages of the FIA system were high sample throughput and good precision; both parameters proved to be better than conventional counting system into Neubauer Chamber. The method was also tested to monitor the cells growth and showed satisfactory results.
