Greisinger GMH 3511 Set pH measurement equipment 605215 用户手册
产品代码
605215
H70.0.21.6C-01
Operating Manual GMH 3511
page 14 of 14
13 Notes A: temperature influence on pH buffer solutions
GPH buffer capsules for 100 ml buffer solution
Capsules for do-it-yourself mixing – unopened capsules can be stored a long time (approx. 3 years)
T [°C]
10
20
25
30
40
GREISINGER GPH 4.0
3.99
3.99
4.01
4.01
4.03
GREISINGER GPH 7.0
7.06
7.01
7.00
6.99
6.98
GREISINGER GPH 10.0
10.18
10.06
10.01
9.97
9.89
GREISINGER GPH 12.0
12.35
12.14
12.00
11.89
11.71
PHL buffer solutions in dosing bottles 250 ml
Buffer solutions are ready for use, with dosing volume of 20 ml - 25 ml
T [°C]
10
20
25
30
40
GREISINGER PHL 4,0
(pH 4.01 +/- 0.015 @25°C)
(pH 4.01 +/- 0.015 @25°C)
4.02
4.00
4.01
4.01
4.01
GREISINGER PHL 7,0
(pH 7.00 +/- 0.015 @25°C)
(pH 7.00 +/- 0.015 @25°C)
7.06
7.02
7.00
6.99
6.97
GREISINGER PHL 10,0
(pH 10.01 +/- 0.030 @25°C)
(pH 10.01 +/- 0.030 @25°C)
10.18
10.07
10.01
9.97
9.89
14 Notes B: preparation of pH buffer solutions
General information on pH buffer solutions
The actual characteristic curve of pH electrodes deviates from the ideal characteristic. Thus the electrodes have to
be calibrated before initial operation and thereafter at regular intervals to get accurate measuring values.
At least a 2-point calibration is required to get the parameters ‘offset’ and ‘slope’. Two different buffer solutions are
necessary for this.
A 1-point calibration only affects the ‘offset’ whereas ‘slope’ is assumed to be the ideal value of -59.2 mV/pH. A
device calibrated only at 1 point assures only accurate measuring values at a range close to the buffer value.
Buffer capacity β
The pH value of a buffer solution changes only very little when small amounts of acids or bases are added. The
buffer capacity β and the dilution influence dpH are values to measure this capability. The buffer capacity β is the
amount of a strong acid or base that has to be added to 1 liter of the buffer solution in order to change its pH value
by 1. The dilution influence dpH is the change of the pH value of the buffer solution when it is diluted with pure
water at a ratio of 1 to 1.
Typical values for buffer capacity and dilution influence are: β = 0.03; dpH = 0.05
Please consider when choosing buffer solutions: date of expiry
Unopened and well stored buffer capsules (GPH) can be stored for a very long time in contrast to ready to use or
self prepared buffer solutions. Caution with alkaline buffers: they age comparatively fast if opened (i.e. at air). The
buffer gets more acid, because carbon dioxide from air is dissolved.
How to prepare calibration buffers of standard GPH series (capsules)
1. Fill 2 plastic bottles with 100 ml distilled water each.
2. Open pH 7 capsule (green) carefully (turn one half of the capsule while pulling and make sure not to
spill any of the powder); put content (including both capsule parts) into one of the bottles.
3. Put content of pH 4 capsule (orange) (or pH 10, blue) and both capsule parts into a second bottle..
The capsule shell will color the liquid in the respective color:
orange = pH4.01; green = pH7.00; blue = pH10.01
Make sure to prepare buffer solutions in time as they can only be used after at least 3 hours.
Shake well before use.
The actual characteristic curve of pH electrodes deviates from the ideal characteristic. Thus the electrodes have to
be calibrated before initial operation and thereafter at regular intervals to get accurate measuring values.
At least a 2-point calibration is required to get the parameters ‘offset’ and ‘slope’. Two different buffer solutions are
necessary for this.
A 1-point calibration only affects the ‘offset’ whereas ‘slope’ is assumed to be the ideal value of -59.2 mV/pH. A
device calibrated only at 1 point assures only accurate measuring values at a range close to the buffer value.
Buffer capacity β
The pH value of a buffer solution changes only very little when small amounts of acids or bases are added. The
buffer capacity β and the dilution influence dpH are values to measure this capability. The buffer capacity β is the
amount of a strong acid or base that has to be added to 1 liter of the buffer solution in order to change its pH value
by 1. The dilution influence dpH is the change of the pH value of the buffer solution when it is diluted with pure
water at a ratio of 1 to 1.
Typical values for buffer capacity and dilution influence are: β = 0.03; dpH = 0.05
Please consider when choosing buffer solutions: date of expiry
Unopened and well stored buffer capsules (GPH) can be stored for a very long time in contrast to ready to use or
self prepared buffer solutions. Caution with alkaline buffers: they age comparatively fast if opened (i.e. at air). The
buffer gets more acid, because carbon dioxide from air is dissolved.
How to prepare calibration buffers of standard GPH series (capsules)
1. Fill 2 plastic bottles with 100 ml distilled water each.
2. Open pH 7 capsule (green) carefully (turn one half of the capsule while pulling and make sure not to
spill any of the powder); put content (including both capsule parts) into one of the bottles.
3. Put content of pH 4 capsule (orange) (or pH 10, blue) and both capsule parts into a second bottle..
The capsule shell will color the liquid in the respective color:
orange = pH4.01; green = pH7.00; blue = pH10.01
Make sure to prepare buffer solutions in time as they can only be used after at least 3 hours.
Shake well before use.