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Table 1 Rate constants and t90 values for thiamine in solutions of TMN and TClHCl

From: Effect of pH and concentration on the chemical stability and reaction kinetics of thiamine mononitrate and thiamine chloride hydrochloride in solution

pH Vitamin salt form Acid Concentration (mg/mL) Reaction kinetics 25 °C 40 °C 60 °C 70 °C 80 °C
3 TMN HNO3 1 kobs (day−1) 0.00243 ± 5e-5C 0.0082 ± 5e-4B 0.0250 ± 6e-4C
R2 0.9894 0.9340 0.9897
t90 (days) 43.3 ± 0.9a 12.9 ± 0.7c 4.2 ± 0.1e
20 kobs (day−1) 0.00251 ± 6e-5C 0.0061 ± 4e-4B 0.0207 ± 8e-4C
R2 0.9847 0.9206 0.9710
t90 (days) 42 ± 1ab 17 ± 1a 5.1 ± 0.2cd
HCl 1 kobs (day−1) 0.00253 ± 9e-5C 0.0084 ± 4e-4B 0.0253 ± 5e-4C
R2 0.9664 0.9598 0.9920
t90 (days) 42 ± 2abc 12.5 ± 0.5c 4.17 ± 0.09e
20 kobs (day−1) 0.00249 ± 7e-5C 0.0069 ± 4e-4B 0.0208 ± 3e-4C
R2 0.9817 0.9349 0.9950
t90 (days) 42 ± 1ab 15.2 ± 0.9b 5.06 ± 0.08d
TClHCl HNO3 1 kobs (day−1) 0.00246 ± 5e-5C 0.0068 ± 4e-4B 0.0177 ± 6e-4C
R2 0.9893 0.9283 0.9829
t90 (days) 42.8 ± 0.9ab 15.4 ± 0.9b 6.0 ± 0.2b
20 kobs (day−1) 0.00268 ± 8e-5C 0.0068 ± 3e-4B 0.0160 ± 4e-4C
R2 0.9783 0.9657 0.9900
t90 (days) 39 ± 1cd 15.5 ± 0.6b 6.6 ± 0.2a
HCl 1 kobs (day−1) 0.00275 ± 6e-5C 0.0088 ± 4e-4B 0.0245 ± 6e-4C
R2 0.9896 0.9584 0.9918
t90 (days) 38.3 ± 0.8d 12.0 ± 0.5c 4.3 ± 0.1e
20 kobs (day−1) 0.00259 ± 9e-5C 0.0068 ± 3e-4B 0.0195 ± 6e-4C
R2 0.9674 0.9638 0.9837
t90 (days) 41 ± 1bcd 15.5 ± 0.6b 5.4 ± 0.2c
6 TMN HNO3 1 kobs (day−1) 0.00111 ± 4e-5B 0.00149 ± 6e-5C 0.022 ± 1e-3C 0.043 ± 2e-3B 0.122 ± 4e-3B
R2 0.9712 0.9446 0.9330 0.9518 0.9883
t90 (days) 95 ± 3c 70. ± 3b 4.7 ± 0.3e 2.5 ± 0.1d 0.86 ± 0.03f
20 kobs (day−1) 0.0058 ± 4e-4A 0.023 ± 2e-3A 0.31 ± 3e-2A 0.43 ± 6e-2A 0.48 ± 4e-2A
R2 0.9261 0.9431 0.9312 0.8945 0.9464
t90 (days) 18 ± 1d 4.6 ± 0.4c 0.34 ± 0.03f 0.24 ± 0.03e 0.22 ± 0.02g
HCl 1 kobs (day−1) 0.00067 ± 5e-5B 0.00133 ± 7e-5C 0.0196 ± 7e-4C 0.040 ± 1e-3B 0.129 ± 5e-3B
R2 0.8943 0.9199 0.9771 0.9820 0.9803
t90 (days) 160 ± 10a 79 ± 4a 5.4 ± 0.2e 2.63 ± 0.09d 0.82 ± 0.03f
20 kobs (day−1) 0.0058 ± 3e-4A 0.023 ± 2e-3A 0.29 ± 3e-2AB 0.40 ± 5e-2A 0.44 ± 6e-2A
R2 0.9259 0.9434 0.9238 0.9051 0.8809
t90 (days) 18 ± 1d 4.6 ± 0.4c 0.37 ± 0.03f 0.26 ± 0.03e 0.24 ± 0.03g
TClHCl HNO3 1 kobs (day−1) 0.00080 ± 3e-5B 0.00129 ± 5e-5C 0.019 ± 1e-3C 0.046 ± 1e-3B 0.098 ± 8e-3BC
R2 0.9616 0.9621 0.9422 0.9918 0.9244
t90 (days) 131 ± 5b 82 ± 3a 5.5 ± 0.3e 2.28 ± 0.05d 1.08 ± 0.09f
20 kobs (day−1) 0.0058 ± 4e-4A 0.015 ± 2e-3B 0.26 ± 4e-2B 0.39 ± 5e-2A 0.43 ± 7e-2A
R2 0.8974 0.8154 0.8243 0.8890 0.8289
t90 (days) 18 ± 1d 6.8 ± 0.9c 0.41 ± 0.06f 0.27 ± 0.04e 0.24 ± 0.04g
HCl 1 kobs (day−1) 0.00102 ± 6e-5B 0.00136 ± 5e-5C 0.019 ± 1e-3C 0.047 ± 1e-3B 0.107 ± 3e-3BC
R2 0.9156 0.9576 0.9334 0.9896 0.9903
t90 (days) 103 ± 6c 77 ± 3ab 5.4 ± 0.3e 2.25 ± 0.06d 0.99 ± 0.02f
20 kobs (day−1) 0.0058 ± 4e-4A 0.016 ± 2e-3B 0.25 ± 4e-2B 0.38 ± 5e-2A 0.42 ± 6e-2A
R2 0.8957 0.8263 0.8293 0.9076 0.8621
t90 (days) 18 ± 1d 6.7 ± 0.9c 0.41 ± 0.06f 0.27 ± 0.03e 0.25 ± 0.04g
  1. t90 indicates time when 90% of the initial concentration of thiamine remains
  2. Uppercase superscript letters denote statistical significance of kobs within a temperature (down columns)
  3. Lowercase superscript letters denote statistical significance of t90 within a temperature (down columns)
  4. Standard error of the slope was used for statistical calculations