LCK 653 method which is based on dimethyl-p-phenylenediamine
reacting with dissolved hydrogen sulphide to form an intermediate
compound which turns into leucomethylene blue. Leucumethylene
blue is oxidized to methylene blue by iron(III) ions. The methylene
blue concentration was then measured optically by photometer.
Carbonate was similarly analyzed using the Lange LCK388 method
which is based on dissolved carbon dioxide reacting with indicator
(not specified by manufacturer) to generate a specific colour. The
resulting colour change was then measured optically.
Statistical analysis of the results was performed with PASW Statistics
18 computer program. Normality of the acquired data was
checked with One-Sample Kolmogorov-Smirnov Test. T-Test (Student’s
t-distribution) for equality of means was performed for
the data and 95% significance level was used to interpret the results
(risk level a = 0.05).