Slope .Problems - Thermo Scientific Orion 2111LL User Manual

Slope Problem
Low Slope
Thermo Scientific Orion 2111LL Sodium Monitor User Guide
ROSS and the COIL tradedress are trademarks of Thermo Fisher Scientific Inc. US Patent 6,793,787
Less .than .45 .mV
• . Check .electrode .function, .etch .electrode, .recalibrate, .if .continues .to .
read .low, .replace .electrode . .
• . Check .electronics .to .read .mV .input .correctly . . .Use .electronic .test .kit .
(Cat . .No . .180029) .procedure .for .checking .electronics .function . .
• . Background .concentration .too .high .for .standards .used .
. Ion-selective .electrodes .(ISEs) .can .be .shown .as .DC-voltage .sources .with .
50 .to .1000 .Mohm; .a .very .high .output .impedance . . .ISEs .respond .to .
ion .concentration .changes .with .a .voltage .change .of .approximately .60 .
mV/decade .for .monovalent .ions .as .sodium . . .Knowing .electrode .and .
instrument .parameters .like .offset .potential, .slope, .etc ., .allows .testing .of .
various .instruments .by .applying .a .known .mV-voltage .
Input Signal
0 mV
- 1000 mV
+ 1000 mV
• . Standards .contaminated .or .incorrectly .made . . .Verify .fresh .standards . .
• . Standard .1 .and .standard .2 .interchanged .– .Check .values .on .standards . .
• . Standard .1 .value: .19 .1 .ppm
• . Standard .2 .value: .192 .ppm
• . If .using .custom .standard, .verify .values .for .each .addition .
• . pH .adjustment .is .not .correct . . .Check .level .and .flow .for .DIPA .reagent . .
Replace .DIPA .if .contamination .or .level .is .less .than .50 .mL . .Refer .to .
Chapter II, Installation of Reagent & Diffusion Tubing .
• . Standard .1 .and .standard .2 .added .in .wrong .sequence . .Refer .to . .
Chapter IV, Calibration .
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Expected Reading: ± (0 .5 mV + 0 .%)
- 0.5 mV to + 0.5 mV
-1001.5 mV to – 998.5 mV
+ 998.5 mV to + 1001.5 mV
Troubleshooting
VI-9