After the LAMP reaction, a white precipitate of magnesium
pyrophosphate is the subsidiary outcome, but it is
difficult to see with naked eye. The addition of CuSO4
after the LAMP reaction leads to an obvious white deposition
in some tubes, which is clearly seen and stable. The
tubes with a deposition were identified as negative LAMP
reaction (female), while the others without obvious one
were active or positive LAMP reaction (male, Fig. 1b).