How to use
1. Inoculation: Each sample is inoculated with three different inoculation amounts decreasing by 10 times, and 5 bags of paper strips are inoculated with each inoculation amount, for a total of 15 bags of paper strips. For clean water samples (using paper strips with product number 060030), the total amount of water sample inoculated is 55.5mL, 5 bags of 10mL water sample volume paper strips, each bag is inoculated with 10mL water sample, 10 pieces of 1mL water sample volume paper strips, 5 of which are inoculated with 1mL of water sample, and the other 5 bags are inoculated with 1mL of 1:10 diluted water sample. For contaminated water samples (using paper strips with product number 060070), 5 bags of 1mL diluted water samples with 3 different dilutions are inoculated. The inoculated water sample should be evenly dripped on the paper strips, and the paper strips should be fully soaked and absorbed by the water sample, and then gently smoothed on the outside of the plastic film bag with your hand, marked, and placed vertically in a constant temperature incubator for incubation with the bag opening facing up. 2. Culture: When testing for total coliform bacteria, observe the results after culturing at 36-38 for 18~24h; when testing for fecal coliform bacteria, observe the results after culturing at 44.5±0.5 for 18~24h 3. Interpretation of results: (1) If red spots or red halos appear on the paper and the surrounding area turns yellow, it is positive. (2) If the entire paper turns yellow without red spots or red halos, it is positive. (3) If part of the paper turns yellow without red spots or red halos, it is negative. (4) If red spots or red halos appear on the purple background of the paper, but the surrounding area does not turn yellow, it is negative. (5) If there is no change on the paper, it is negative. 4. Result report: According to the number of positive paper discs with different inoculation amounts, check the corresponding MPN table (see Appendix B of HJ 755-2015), convert and report the total coliform group or fecal coliform group in 1L water sample according to formula (1): Formula (1): C = 100 × M / Q C-total coliform group or fecal coliform group concentration in water sample (MPN / L) M-MPN value obtained by checking the MPN table (MPN / 100mL) Q-actual maximum inoculation volume of water sample (mL) 100- is 10 × 10mL, where 10 converts the unit of MPN value MPN / 100mL to MPN / L, and 10mL is the maximum inoculation volume in the MPN table. 5. Result expression: The test result retains two significant figures. When it is greater than or equal to 100, it is expressed in scientific notation. The unit of the result is MPN / L. The average value is calculated by geometric mean.
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