pH group 7.06 positive 7.18 positive 7.30 positive 7.30 positive 7.31 positive 7.32 positive 7.33 positive 7.34 positive 7.36 positive 7.36 positive 7.40 positive 7.41 positive 7.43 positive 7.48 positive 7.49 positive 7.53 positive 7.55 positive 7.57 positive 7.55 no-resp 7.70 no-resp 7.73 no-resp 7.75 no-resp 7.75 no-resp 7.77 no-resp