Instrumental operation: ICS 3000

Transcription

1 Instrumental operation: ICS 3000 Scope The scope of this document is to present an overview of the Dionex Ion Chromatography System (ICS) 3000 and to provide the reader with guidelines for standard operations, routine maintenance and simple trouble shooting. Detailed instrument description can be found in Dionex Reference Library (CD- ROM) which contains all relevant and specific manuals. Instrument overview The Dionex ICS 3000 system is designed for ion chromatography (IC). It is compatible with high salt and alkaline solvents and therefore fittings, tubings and interior of the system is made of PEEK (polyether ether ketone) to prevent corrosion. It consists of a dual pump system with four channels on each pump. It is capable of operating two columns with two different detectors at the same time and is equipped with a pulsed amperometry detector (PAD) and a conductivity detector. In practice, the common use currently will be one column at a time and primarily on Pump 1 and the PAD detector which will be described here. The PAD is based on electrochemical detection and is in general superior for detection of carbohydrates that are traditionally difficult to detect. The system also includes an eluent generator, which can be used when ultra pure eluents are needed. In practice, the eluent generator has limitations that make it difficult to use for many applications and it will therefore be bypassed for most applications. The principle of the conductivity detector is that changes in conductivity is measured and interpreted as analytes. This requires the installation of an ion suppressor prior to the conductivity detector, which will suppress the inherently high conductivity coming from the eluents. Figure 1 shows an instrument overview. As opposed to many other HPLC systems, the system should be operated with more or less constant flow to avoid detrimental salt precipitations in the pump, column and detector. If the flow will be stopped for a prolonged time period make sure to replace salt containing eluents in all lines with e.g. 50% methanol (also to avoid microbial growth). HPLC systems are delicate equipment and should be handled accordingly. Regularly check the status of the instrument, preferably on a daily basis and always be careful when operating. Eluents should ALWAYS be prepared from fresh top quality water (Milli-Q/18.2 MΩ cm) and preferably sample preparation should also be made based on this water quality. The chromatographic system is controlled by a computer installed with Chromeleon 7 software (hereafter CM) version for instrument control and data handling. All commands and instrument handlings goes through this software.

2 The system consists of 5 compartments/modules: 1. Autosampler 2. Dual pump 3. Eluent generator 4. Column compartment (lower part) 5. Detector compartment (upper part) Figure 1: General system appearance of the ICS-3000

3 Window for starting and stopping Instrument Controller. Can be closed after use. Icon informing about Instrument Controller status. Green: Controller running. White with red cross: Controller stopped. Figure 2: Instrument Controller. Software unit that controls communication between computer and HPLC. Must be running at all times when system is operated. Communication between the computer (CM) and the HPLC is controlled by the Instrument Controller Software found under the Start Menu/Programs/Chromeleon/Service Manager. Alternatively, double click the Chromeleon Icon in the Windows task bar to open the Instrument Controller (figure 2)or right click and select start Chromeleon Instrument Controller. When the HPLC is to be controlled/operated the Instrument Controller must be running. Starting and stopping is done by pressing the command Start/Stop Instrument Controller (figure 2). The window can be closed afterwards. The Instrument Controller does not start automatically after a computer restart and it should therefore be checked that it is running, before starting operation. In the operating software (CM) each module has its own operational screen, which may be found as tabs in the top of the window (figure 3).

4 Overview Autosampler PAD detector Pump Queue System 1 PAD electrochemical detection Switching between Instrument and Data panel Figure 3: Module and system overview from controlling software Chromeleon 7. Unmarked tabs: DC ; Detector compartment. EGC1 ; Eluent generator. Audit ; Audit trail logging every event in the system. Startup ; Programmed system startup (not recommended to use unless you know what you re doing). Operating the pump The internals of the dual pump system is depicted in figure 4. The lower half of the compartment is Pump 1 and the upper half is Pump 2. The pumps are operated at flow rates between 0 and 10ml/min and max pressure is 5000 psi. Each pump is connected to four eluent channels (A, B, C and D). A Rear Seal Wash system is installed to periodically flush the backside of the pump heads in order to avoid salt precipitations and corrosion. Wash setting may be Interval, Automatic or Off. Correct setting is Interval, but the rear seal wash solutions needs to be changed on a weekly basis and consists of 20% methanol/ethanol (figure 4). Note dates of change in the equipment logbook.

5 Figure 4: Internals of Dual Pump. Pump 2 is placed in the upper half of the compartment, Pump 1 in the lower half. Note the screw valve at position 3 is the purge valve on Pump 2. Equivalent purge valve on Pump 1 found in the same position. Position 11 is the rear seal wash reservoir which should be changed on a weekly basis (20% methanol or ethanol). Preparing eluents The eluents for ion chromatography are crucial for good performance and the chromatography (column) is extremely sensitive to contaminations in the eluents. It is therefore of outmost importance that extra care is taken when eluents are prepared. Remember that the lifetime of eluents for ion chromatography is also very short compared to other types of chromatography. The biggest risk of contamination is dissolution of carbonate in the eluents and this occurs when eluents are exposed to atmospheric air. This carbonate accumulates on the columns stationary phase and reduces separation capacity and carbonate has a higher push effect as mobile phase then the others regularly applied. It is impossible to completely avoid carbonate contamination but with the proper precautions it can be minimized and allow a certain lifetime of the eluents (max. 48 hours for top performance). This includes that

6 headspace in the eluent bottles must be saturated with nitrogen to minimize the amount of carbon dioxide. Nitrogen is delivered by a nitrogen generator via a restriction valve and distributed between three of the four channels (channel D does not get nitrogen supply). Three different eluents are made to accommodate the range of analytical methods and all three are changed every time new eluents are prepared. The eluents are always prepared in the same way and always placed on the following channels: Channel A: 0.1 M NaOH Channel B: 1 M NaOAc in 0.1 M NaOH Channel C: Milli-Q water Eluent A and B are most labile for carbonate contamination and should be handled accordingly.the following is a description for generation of each eluent but should be performed alongside so that all three eluents are done approximately at the same time. All eluents are sensitive to atmospheric air. Therefore don t leave any of the newly prepared eluents standing without N 2 over pressure in the headspace for more than 15 minutes. Before any eluents are made, turn off the flow on the system and release the nitrogen pressure on the restriction valve positioned on the backside of the autosampler. Empty all eluent bottles and rinse them thoroughly in Milli-Q water. Special pressure stable eluent bottles are used since strong corrosive eluents are pressurized during running. Therefore, don t send the bottles off to washing, but rinse them properly before reuse. Eluent A: 0.1 M NaOH (2L) 1. Measure out 2 L of Milli-Q water in a measuring flask. Make sure to use clean glassware. 2. Poor the two liter of water into the eluent bottle named Eluent A (0.1 M NaOH). 3. Loosely place a lid on the bottle, but don t tighten it. 4. Place the eluent bottle in the sonication bath and adjust the water volume in the bath to the level indicated as working level. The sonication bath will fit two eluent bottles at a time. 5. Sonication for 20 min. DON T put your hands into the sonicator while it is operating and close the door to the room when you leave it. 6. When the sonication is done, close the lid securely and move the eluent bottle to the HPLC. 7. Connect channel A to the eluent bottle and start the nitrogen flow. Exchange the air in the head space by repeatedly opening and closing the lid on the bottle to relieve pressure. A total of three reliefs are sufficient. 8. Use a sterile plastic pipette with a total volume of 10 ml and a manual pipette bulb for pipetting a concentrated 50% NaOH solution (Fluka, L). The solution is stored in the exhausted waste cupboard underneath the HPLC and is extremely concentrated. ALWAYS wear

7 proper personal protection equipment (glasses, gloves and lab coat/acid rubber coat) when handling this solution. I am not kidding getting that stuff in your eyes will ruin your eyesight! 9. Check the level of NaOH solution in the bottle if the content is less than half of the original replace with new to prevent risk of carbonate contamination in the NaOH solution. Place the remainder of the solution in the toxic cupboard and mark it with COMMON USE for other purposes than HPLC. 10. Pipette 10.4 ml to the 2 L bottle of eluent. Be careful when pipetting, as the solution is very viscous. Don t dip the entire pipette into the solution only the tip underneath the surface. Close the lid to the NaOH solution immediately after use and only use the same pipette ONCE in the solution. Don t double dip take a new pipette. 11. Dispense the NaOH solution to the water in the eluent bottle underneath the water surface and be patient as the liquid will flow very slowly (viscous). Slowly rinse the inside of the pipette by gently pipetting up and down 3 times. 12. Close the lid to the eluent bottle and exchange the headspace air with nitrogen as done in step 7. Swirl the eluent bottle carefully DON T shake it, to distribute NaOH evenly. Eluent B: 1 M NaOAce in 0.1 M NaOH (1L) 1. Weigh g anhydrous sodium acetate (Sigma-Aldrich, KG,or Fluka). It is important that the correct quality of sodium acetate is used. 2. Poor this into a 1 L measuring flask (use clean glass ware) and add about 0.8L Milli-Q water. 3. Add a magnetic stir bar and place the solution on a magnetic stirrer till you have a complete dissolution. 4. Remove the magnetic stir bar (without dipping the magic stick into the solution!) and fill the remaining volume to 1 L (with freshly tapped Milli-Q water). 5. Mount a 0.22 µm sterile filter cup on top of the cleaned eluent bottle (f.ex µm stericup GP Millipore Express PLUS membrane, 250 ml funnel, 45 mm neck size). Apply vacuum to filter the eluent. 6. Loosely place a lid on top of the eluent bottle. Don t tighten it. 7. Place the eluent bottle in the sonication bath, make sure water surface in the bath is at the working level. 8. Sonicatefor 20 min. DON T put your hands into the sonicator while it is operating and close the door to the room when you leave it. 9. When the sonication is done, close the lid securely and move the eluent bottle to the HPLC. 10. Connect channel B to the eluent bottle and start the nitrogen flow. Exchange the air in the head space by repeatedly opening and closing the lid on the bottle to relieve pressure. A total of three reliefs are sufficient.

8 11. Follow the procedures for NaOH addition as described for Eluent A step EXCEPT! Only add 5.2 ml NaOH to the 1 L NaOAc-solution (ie. there should be the same NaOH concentration in both channel A and B). Eluent C: Milli-Q water 1. Fill the rinsed eluent bottle with Milli-Q water freshly tapped from the system. 2. Loosely place a lid on top of the eluent bottle. Don t tighten it. 3. Place the eluent bottle in the sonication bath and adjust the water volume in the bath to the level indicated as working level. 4. Sonicatefor 20 min. DON T put your hands into the sonicator while it is operating and close the door to the room when you leave it. 5. When the sonication is done, close the lid securely and move the eluent bottle to the HPLC. 6. Connect channel C to the eluent bottle and start the nitrogen flow. Exchange the air in the head space by repeatedly opening and closing the lid on the bottle to relieve pressure. A total of three reliefs are sufficient. End the preparation procedure by purging all three channels as described below and note in the logbook date of eluent change. Purging eluents When eluents are changed the pump needs to be purged to remove air bubble formation and old eluent from the tubes. The system is sensitive to air (as all HPLCs) and purging is therefore important. Purging the eluent channels is done be applying high flow through the specified channels and will create high back pressure on the system, if the purge valve has not been open (Open the purge valve (figure 4) by approx. half a turn). This will direct the flow path to a waste tube and relieve the pressure on the system (and the column in particular). Once the purge valve has been opened choose the appropriate channels and flow distribution to purge in CM and activate the purge/prime function (figure 5). It is possible to purge more than one channel at a time by setting the percentage distribution between the channels as desired (equal distribution, 50:50 when two channels, 33% when three and 25% when all four channels are to be purged). The software is preprogrammed to perform purging for 500 seconds at 5.7 ml/min. Repeat purging (if necessary) until air bubbles are no longer visible in the eluent channels from the bottles to the pump. IMPORTANT: Before purging the software will inform that this operation will generate a high flow through the system and that the purge valve should be open before executing. Press Execute despite warning, if the purge valve is open. If the system senses any pressure increase (even minor) during purging, the command will be terminated. Make sure that the valve has been sufficiently loosened and try again.

9 Retention time count Module connection Pump motor Flow settings Pressure indicator Prime/purge function Solvent distribution Figure 5: Pump tab. Relevant functions marked for purging, flow settings ect. Once the purging is done, close the purge valve again tightly to redirect the flow path to the column. If the valve is not tightened enough, the pressure during operation will not be sufficiently high meaning that the flow delivery to the column is insufficient. No warnings about low pressure will occur, unless pressure is completely lost (less than 200 psi) so please do observe that correct pressure is obtained during start up. Normal operating pressure for CarboPac PA1 incl. guard is at least psi (this includes a pressure restrictor coil at 1000 psi). Operating the autosampler Samples are placed in the autosampler prior to operation. The front door of the autosampler is opened (held in place by a relatively strong magnet pull it hard!) and the vials placed in the sample tray (figure 6). On the outside of the autosampler in the lowest left corner is the main power switch not a door opener! Only press this button if you really want to cut the power to the autosampler. Sample position in the tray is straight forward numbering from 1 to 100. Each position is marked on the tray. The tray may be removed from the autosampler when samples are being loaded (be careful ). The sample tray is placed in a cooled compartment and the autosampler will not operate if the front door is open. A sound alarm will occur if the door is left open (turns off again when the door is closed). Don t open the door if the robot arm is moving as this will immediately interrupt the movements. The front panel will inform

10 about the state of the autosampler: Idle means that the autosampler can be opened for vial handling (this is also the case for idle status during a sequence run). Otherwise, the front panel is used for manual handling and is not used during routine operation. All normal operational control is handled via CM. Figure 8 shows the routine operations of the autosampler from CM. The sampler has a fixed volume loop and if this needs to be changed, call a super user. Partial injection may be applied if necessary, but will result in increased standard deviations, but please consult super user or manual. NB: Be aware that the sampler consumes approx. 40 µl sample for a 2 µl injection. On top of the autosampler (towards the back) is the syringe tower (figure 6). This is where sample, buffer etc. is taken and measured before injection to the column. Make sure no air bubbles are trapped in the syringe by priming sampler before you start your analysis. The syringe is connected to a wash solution consisting of 20% methanol. The sample is introduced via the injection port, via the diverter valve (position 1 directs sample to system 1), via the loop (flow path is via the loop when the injection valve is in inject mode, meaning always except during an injection cycle) to the column. When the needle leaves the inject port (figure 7) the bed should be dry with no droplets/spillage. If not, something is obstructing the injection and poor/no signals will be observed in the following chromatogram. The needle is washed before each injection in the flush port (figure 7) next to the injection port. Here, wash solution will appear (and may spill) which is normal.

11 Diverter valve Figure 6: Autosampler with sample tray dismounted from the tray compartment Figure 7: Injection and flush port in autosampler

12 Autosampler status Sample loop size Temperature control in sample tray Prime syringe flush sample Diverter valve/inject valve Figure 8: Autosampler tab in CM. Operating the column compartment The column compartment is the module where the column is connected (figure 9). During operation the front cover of the column compartment should preferably be closed and especially if temperature control is applied (improved reproducibility is observed when temperature is set slightly above ambient). As mentioned above the flow is directed from the autosampler via the left injection valve (for pump 1) to the column. The loop is also mounted on the injection valve. Do not mess around with the tube connections here! The column is fitted in an appropriate holder in the back of the compartment.

13 Left injection valve for Pump Analytical column Note flow direction: Right to left! Analytical Column flow direction Guard column Note flow direction: Left to right! Figure 9: Internals of column and detector compartment. Blue arrow indicates flow direction on the column, which should fit with column flow directions. Upper thrid of the compartment is not present in this particular instrument set up. When a column is fitted and flow is applied please ensure that there are no leaks. Leaks at the column inlet will result in pressure decrease, whereas leaks at the column outlet may not affect the pressure but will affect the detector signal and potential flooding of compartment. If leaks are observed or registered by the system, further tighten the connections either by hand or by a wrench key (be careful, PEEK connections are weak). Column temperature is specified in CM (figure 10) and the desired temperature is written in the field for Set. Press Enter to execute the command. The field Actual will inform about the actual temperature in the column compartment (which initially is not necessarily the same as the column temperature).

14 Temperature control Figure 10: Column compartment tab for controlling column temperature. Operating the PAD detector The detector is placed as can be seen in figure 9 (item 2) and a close-up photo in figure 11. The detector consists of a gold working electrode and a ph reference electrode. The ph reference electrode (number 3 in figure 11) has very limited needs for maintenance during routine operations and should not be removed from its socket. The working electrode on the other hand is disposable and needs to be changed regularly. Routines for changing working electrode are described below. The detector can only be turned on when flow is on the system and a pump link exists where the cell voltage on the electrode is turned off, if the flow is stopped. However, cell voltage should only be turned on during sequence running and other diagnostic runs, since prolonged voltage will decrease the electrodes life time. When running, the electrode senses two signals, a total signal (a background signal that depends on the type of eluents and state of the electrode) and a baseline/real sample signal which can be autozero ed. The detector responds to any substances that are either oxidizable or reducible and the electrical output results from an electron flow caused by the chemical reaction that takes place at the surface of the electrodes. The eluents are highly charged and this can be observed as the background (Total) signal. Normal operating Total Signal should be between 15 and 35 nc. The reference electrode is capable of

15 adjusting/compensating changes in background signal when gradient elution profiles are run and in that sense maintain a stable baseline. If the reference electrode is not installed/out of order, the baseline will rise considerably when gradient profiles are used. PAD is a particularly strong detection principle for carbohydrates, because the highly alkaline eluents will charge the hydroxyl groups and therefore give rise to signals in the detector. Furthermore, this detection principle is highly sensitive and therefore makes it superior for carbohydrate analysis. From column Figure 11: PAD electrode To waste

16 Signal and Total Signal (background) Autozero (of Signal) Turning on/off cell voltage Figure 12: PAD tab in CM. Changing working electrode When the Total Signal becomes too high (above nc) or the signals during running behaves strange (extremely high signal or seemingly no signal at all/increased background signals), changing the working electrode may be needed (The electrode has a life time normally between 1 and 3 weeks continuous operation). If you suspect the electrode may be worn out, check last date of change in the logbook to verify. New users should consult a super user before changing the electrode the first time. Hereafter do as follows: 1. Turn off the flow and thereby the cell voltage. 2. Disconnect the inlet and outlet of the detector (by the incoming and out coming of the red tubing in figure 11). You may need a wrench key. 3. Unplug the blue and the yellow power plugs (figure 11). 4. Grab the electrode by two hands and pull it firmly towards you in one motion (yes, it will come off). 5. While performing the following steps, try to keep the entire electrode in an upright position. The ph reference electrode contains KCl which may leak if turned upside down. 6. Loosen the big knob (picture A, figure 13), press the two side-wings on the clips that holds the spacer block in place and take off the entire clips.

17 7. Remove the spacer block and now the individual parts of the electrode are visible (picture B, figure 13). The working electrode is the disposable one but take EXTRA care of the gasket. They are not supplied enough to be changed every time. Unless it is torn or otherwise damages it should be reused. 8. Inspect the working electrode on the gold -side. Salt precipitations or loss of connection between top and bottom is reason for loss of signal. Discard the electrode. 9. Inspect the cell body and carefully rinse it if visible salt precipitations are seen (picture B, figure 13). 10. Take a new working electrode from the package, but ONLY lift it in the snip of white tape that goes outside the actual electrode which says lift here. Use a pair of tweezers if necessary. 11. Place the working electrode and the gasket back on the cell body. Note that the two positioning holes in the gasket are different in shape, which compared to the spacer block indicates the positioning. The same goes for the working electrode. Furthermore, the electrode should be placed so that the golden parts face the cell body and so that the small circle fits over the slit in the gasket. Do not bend the working electrode in any way! Position it precisely over the two rods and slide it onto the cell body. See correct placement of the working electrode in picture C, figure Place the spacer block and the clips back on the electrode and turn the big knob until you hear a click. This is as tight as it gets. 13. Reposition the entire electrode in the detector compartment (it needs to say click), re-plug the electrical cords (yellow in yellow, blue in black!), reconnect column and waste tubings, restart flow on system (make sure there are no leaks!!) and set cell voltage on. 14. Monitor baseline for a while (approx min). The signal can be quite unstable in the beginning (and very high), but will eventually stabilize. Total signal should preferably stabilize between 15 and 30 nc. A B C Spacer block Spring- clips Working electrode Cell body Gasket Spacer block Figure 13: Changing disposable gold electrode

18 Waste collection From the detector the flow stream is passed to a waste container standing in the exhaust cabin underneath the system. This waste container needs to be checked regularly and emptied. The waste is almost exclusively consisting alkaline salts and can therefore be poured in the drain. For the same reason spillage of waste will generate vast amounts of salt precipitations and should therefore be avoided. Starting up for operation 1. Make sure that eluent level is good and check the last date for eluent preparation. If the eluents are more than 2 days old, consider if you should make new eluents before your run. If preparing new eluents, remember to purge all channels in use (A,B and C) after eluent preparation 2. Check that the correct column is on. 3. Check that flow is on and pressure correct (column flow: 0.25 ml/min, pressure: psi) 4. If column temperature control is applied make sure that the column compartment is closed (lower door). 5. Turn on the detector cell (apply cell voltage). 6. Start Baseline Monitoring (see figure 14) and watch the detector signal stabilize. 7. If the signal does not stabilize or if the total signal is very high (above 45 nc) it may be time to change the working electrode. Follow the procedure for doing so, if necessary. 8. Prime sampler, flush sample loop (make sure no air is entrapped in sample syringe) 9. Place the samples in the autosampler and prepare the sequence (see section below). If starting up after eluent change, the first sample should ALWAYS be a blank sample running the instrument method: Start after eluent change. This is to ensure regeneration of column after possible carbonate contaminations. Afterwards condition the column with 1-2 blank runs with the instrument method you intend to use before injection of the first real sample/standard. These conditioning blanks should always be run no matter if eluent has been changed or not. 10. Stop baseline monitoring. 11. Start the run either by starting the sequence directly or by queuing the sequence (add to queue in the Queue tab). Press Ready Check to get an estimate of eluent use during the entire queue.

19 Monitoring baseline. Monitor pump pressure Queue tab. For queuing several sequences Successful ready check Adding a sequence to the queue. Ready check. Testing if the system is ready for operation. Gives an estimate of eluent use. Figure 14: Queue tab. Here sequences can be queued for automatic start and general checking of system status (ready check) is performed. Setting up a sequence in CM The data structure in CM is shown in figure 15, which is initially divided between different instruments. The PAD detector is set up to system ED_1. Hereafter, a general data folder contains a folder for each user, specified by name. Maintain this order of data structure and save your sequence under your own name.

20 Switching between Instrument and Data panel Figure 15: Data structure in CM. Note the switch between Instrument and Data panel. When making a sequence, choose Create from the top menu and choose Sequence. Hereafter a wizard will start, that will guide you through setting up of a sequence: 1. Choose system: ED_1 2. Write a recognition name that it will be copied to for each sample (may be edited later), choose number of samples, number of injections pr. sample (most often 1), position of 1 st vial and injection volume (ul), normally the same as the sample loop size. 3. Choose Instrument Method (analytical run method) by accepting the lastly used method or by browsing through folders. Choose Processing Method if applicable. Can also be added later. Set default channel to ED_1. 4. Write a comment describing the particular samples (not obligatory). 5. Press finish and save the sequence to your folder under an appropriate name starting with the following date format: YYMMDD_ Figure 16 shows and example of a prepared, finished sequence. Most fields in the sequence can be edited before, during and after the run. This includes: Name, Type (blank, unknown, standard), Level (only relevant for quantification), Position (vial position in the autosampler), Volume (injection volume), Instrument Method (analytical run method, can only be edited before running) and

21 Processing Method (qualititaive/quantitative method). Some fields have scroll down menus, others are text fields. Always press Save after editing any fields. A shortcut called Fill Down is made for fast assigning sample position in the autosampler. Mark the Position field from the position of the first vial, press F9 and choose Renumber. Press enter. Alternatively, select the Fill Down menu (figure 17), choose Renumber and write the name of the first sample position. Press OK. Note that the fill down function may be used in all the other columns as well. IMPORTANT: Changing any of these fields mentioned above will not affect the results, but changing the field Status will erase data behind, if the samples have been run; Idle indicates a sample not yet analysed, Finished indicates a sample analysed and therefore a file containing data. Interrupted is a sample stopped during analysis due to some sort of error message, may also contain data, but sometimes not useful data. Figure 16: Prepared, finished sequence.

22 Fill Down menu Marked cell for 1 st vial position Figure 17: Fill down menu for fast sample position assignment. Press Fill Down or F9 to open window. Alarms and warming Pressure alarm If the pressure falls below or reaches the upper limits of the settings (which are mainly set to protect the column) a pressure sound alarm will be initiated. At the same time, all flow will be stopped. High pressure may occur if the samples contain insoluble particulate material, if the solvent concentration suddenly changes, temperature control fails or if the column is overloaded with sample due to many injections without regeneration. Loss of pressure may occur if the eluent bottles are empty, air is introduced in the system or if leaks happen on the upstream /pressure side of the column. If leakage is the cause, the system will detect the compartment where this is occurring via leak detectors and the audit trail will inform about this. Identify the source of the pressure violations, take proper action and restart the system. Leak/humidity alarm Identify the reason for leakage (which compartment) and correct if possible. Dry up any spillage in the compartments with soft tissue paper.

23 No pressure? Check that the purge valve is properly closed. Check that all fittings are securely tightened. If this is not enough purge the channels as air may have been trapped in the pump. No connection to modules? Check that the Instrument Controller is running (figure 2). When this is positivly running, reconnect the non-connected modules by pressing Connect in each module tab (see figure 5 or 8). If there is still no connection restart the computer and start the Instrument Controller again. Still no connection call security. Software error messages Close all active windows and restart CM. Still software errors, restart computer and start the Instrument Controller again. Still errors call security. No contact with Autosampler The autosampler needs a restart once in a while. If no contact can be achieved through the software, turn off the autosampler (power button lower left corner, front). Leave it off for 1-2 minutes and start again. It will now perform a few self tests (this takes a couple of minutes. When this is done, reconnect in CM. If there is still no connection, call security. Call security For more advanced guidance either contact Super users or consult the general equipment manuals found on the CD-rom: Reference Library provided by Dionex. Super users: Jane Wittrup Agger (jane.agger@umb.no; ) Bjørge Westereng (bjorge.westereng@umb.no; )