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MaxiDirect_2c 03/2010
1.1 Methods
Notes:
1. For photometric determination of pH values only use PHENOL RED tablets in black
printed foil pack and marked with PHOTOMETER.
2. Water samples with low values of Alkalinity-m (below 35 mg/l CaCO
3
) may give wrong
pH readings.
3. pH values below 6.5 and above 8.4 can produce results inside the measuring range.
A plausibility test (pH-meter) is recommended.
4. The accuracy of the colorimetric determination of pH values depends on various
boundary conditions (buffer capacity of the sample, salt contents etc.).
5. Salt error
Correction of test results (average values) for samples with salt contents of:
Indicator
Salt content
Phenol red
1 molar
– 0.21
2 molar
– 0.26
3 molar
– 0.29
The values of Parson and Douglas (1926) are based on the use of Clark and Lubs
buffers. 1 Mol NaCl = 58.4 g/l = 5.8 %
Содержание Maxi Direct
Страница 1: ...Photometer System axi GB Instruction manual ...
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Страница 9: ...7 MaxiDirect_2c 03 2010 Part 1 Methods ...
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Страница 125: ...123 MaxiDirect_2c 03 2010 1 1 Methods Notes 1 Some solids may not dissolve 2 Conversion mg l NO3 mg l N x 4 43 3 N NO3 ...
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Страница 187: ...185 MaxiDirect_2c 03 2010 1 1 Methods Notes 1 If Sulfate is present a cloudy solution will appear ...
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