Metrohm 746 VA Trace Analyzer - Manual (Page 7)

Table of contents
746 VA Trace Analyzer / 747 VA Stand
VI
7 Safety, Errors, Troubleshooting,
Diagnosis, GLP
.............................................................................
7-1
7.1 Electrical safety ............................................................................... 7-1
7.2 Safety considerations concerning mercury
.....................
7-2
7.2.1 Properties of mercury .................................................................. 7-2
7.2.2 Toxicity of mercury and its compounds ...................................... 7-3
7.2.3 Handling of mercury .................................................................... 7-3
7.2.4 References dealing with mercury ................................................ 7-5
7.3 Error messages ............................................................................... 7-6
7.3.1 General information on error messages...................................... 7-6
7.3.2 List of error messages ................................................................. 7-7
7.3.3 Instrument initialization .............................................................. 7-29
7.4 Troubleshooting
...........................................................................
7-33
7.4.1 General rules for VA trace analysis............................................ 7-33
7.4.2 Problems with DME/SMDE........................................................ 7-35
7.4.3 Problems with HMDE................................................................. 7-37
7.4.4 Problems with RDE.................................................................... 7-40
7.5 Hardware/software faults in the instruments
or simply the vagaries of the chemistry .......................... 7-42
7.5.1 General ...................................................................................... 7-42
7.5.2 Oxygen in the analysis solution ................................................. 7-42
7.5.3 Unsuitable bridging electrolyte solution
in the reference electrode.......................................................... 7-43
7.5.4 Overcharging of the working electrode ..................................... 7-43
7.5.5 Disturbances at the HMDE through gas formation ................... 7-45
7.5.6 Complex formation .................................................................... 7-46
7.5.7 Peak on highly curved baseline................................................. 7-47
7.5.8 Peak overlapping....................................................................... 7-47
7.5.9 Calibration with chemically non-isoformal standards................ 7-48
7.6 Diagnosis ......................................................................................... 7-49
7.6.1 General ...................................................................................... 7-49
7.6.2 Prepare instrument for diagnostic test ...................................... 7-50
7.6.3 Checking thermal printer ........................................................... 7-50
7.6.4 Checking RS232 interfaces ....................................................... 7-52
7.6.5 Checking control lines ............................................................... 7-52
7.6.6 Checking the keypad................................................................. 7-53
7.6.7 Checking the VA Stand.............................................................. 7-54
7.7 Standard operating procedure in the context of
GLP/ISO 9001 guidelines
.........................................................
7-58
7.7.1 Checking 747 VA Stand with polarogram simulator.................. 7-58
7.7.2 Loading the TESTPb.mth method........................................... 7-60
7.7.3 Preparing the sample solution................................................... 7-60
7.7.4 Performing the determination .................................................... 7-61
7.7.5 Assessment of the determination.............................................. 7-62