Over time I consistently observe that usually problems with Alpkem/OI Analytical Autoanalyzers whether Segmented Flow (SFA) or Flow Injection Analysis (FIA) are related to that which falls under the direct control of the operator such as water, reagents, standards, or basic instrument configurations such as pump tubes or luer connections.  When troubleshooting we should always go from the most likely and simple aspects of the system to the more complex hardwired components.  In my experience once an Autoanalyzer instrument is working it tends to work until something is done to make it not work; an ongoing preventative maintenance program especially helps to make this true but that is another discussion.

For some reason, once a problem occurs most operators tend to initially focus on the most complex aspect of an instrument, instead of looking at the simple things which are usually the cause of problems on a daily basis. The latest lab I was just involved with had experienced such a significant loss in peak signal height that they could no longer resolve the low level (10ppb) peaks from the baseline.  The operator had focused on the connections of the circuit board, the lamp, the valve and the photodiode, after these issues did not turn out to be the culprit they contacted us.  With Alpkem/OI Analytical Autoanalyzers I ALWAYS first look at the serial communication window which shows immediately if the lamps are working, the photodiode is giving proper signal, and the flowcell is not clogged or dirty.  This is a very fast and noninvasive action that simply requires monitoring the baseline and opening the serial communication window screen.  Once that aspect has been shown to be correct, at that point I usually assume it is one of the few simple things such as water, reagents, or standards.  But this lab’s troubleshooting process focused initially on the more complicated aspects of the system, in this case the circuit board as the culprit, even though the greater probability for the cause are reagents which are made every day, standards that can go bad over time or can be made wrong, and of course the fact that pump tubes wear out over time as they are being used.  To get to the point, it turns out that the standard was bad.  Yes, in my experience how many times have the standards been the problem; I cannot possibly count?  But for some reason operators are reluctant to focus on these simple things first.  I believe it is because they do not trust their instrument, they do not do timely preventative maintenance, and they do not follow simple troubleshooting procedures.

If you turn on the power and the autosampler does not come on then there is a problem with it, if the pump does not turn then there is a problem with it, if the lamp is dark then there is a problem with it but statistically rarely do problems come from mechanical issues or produce a difficult troubleshooting event since the smoke coming from the back of the unit usually details the problem.  In other words the big problems are usually very obvious.  On a day to day basis problems are usually simple almost always come from that which the operator controls and the solution is usually found in the path that starts from the simplest and evolves to the more complex.  If the operator does not thoroughly understand or trust the instrument and does not do timely maintenance then when a problem does arise they have no foundation to find the issue and invariably they head off in the wrong direction.  It is simple to remake a reagent, change the water, or make a new standard but for some reason operators want the problem to be a circuit board, flowcell, lamp or a photodiode.  I am not sure why, it could be that autoanalyzers can be difficult and frustrating, it could be that the operator is over tasked and behind schedule, or it could be that the operator really doesn’t understand the instrument.  I hope to help operators understand their instrument so that when issues do occur they initially will look at the simple things, remake a standard, insure the reagent is properly made and not outdated, make sure the reagents are actually flowing into the cartridge or that the surfactant is correct, for instance.  These are all simple things that will catch a problem 95% of the time in a timely organized fashion not the haphazard complex approach that so many operators tend to utilize when an issue occurs.

1.    Proceed slowly, thoughtfully and carefully.
a.    Being in a hurry usually ends up costing more time, in other words it is faster to go slowly and methodically.

2.    If a problem occurs stop and thoroughly observe the problem and come to a clear idea of what the issue is and insure the condition of the overall system is correct.
a.    For instance if there is surging at the debubbler is the problem because of the debubbler or is that only where the problem is evident but the cause is actually somewhere else?  Don’t just rashly replace the debubbler find the root issue…
b.    If there is leaking is it caused by an issue somewhere else such as a clog that is creating back pressure thus blowing a fitting off.  Don’t just over tighten the fitting to stop the leak, fix the clog because the system does not normally leak so if it does leak there is a problem somewhere.
c.    Surging at the cartridge caused by pump platen not being secured properly.  Don’t just quickly and rashly add more surfactant secure the platen properly and see if that solves the problem since with the proper amount of surfactant the system will flow perfectly every time.

3.    It is critically important to observe all aspect of a flow analyzer working perfectly on water before running chemicals and ultimately standards and samples.  In this startup mode insure that all wash bottles are filled, have proper amounts of surfactant, and luer connections are working properly also insure that all tubing are connected properly and flowing; including autosampler tubing, pump platens, cartridge to detector tubing, waste and debubbler lines.  If the primary setup is correct on a Flow Analyzer it is rare for there to be any other issues than chemical which is why it is so important to insure that the startup configuration is correct and the water is flowing perfectly.  Then once chemicals are added any problems that may occur usually relate to reagent or standard preparation.  You should observe on water:
a.    Quiet and flat baseline.
b.    Consistent bubble pattern.  They do not have to be perfect just consistent.  Each type of cartridge usually has a basic type of flow pattern based on the pump tube configuration for that analysis.  It is best to become familiar with it so that if something is wrong it is obvious.  In other words if one of the pump tube lines is pumping air instead of liquid it will change the pattern and this will save headaches later by finding the error before analysis starts.  Or not enough surfactant, or a clog etc.
c.    Serial communication values.  It is important to know the serial communication values of each chemistry and to visually insure they are within that historical range.  Otherwise there may be a problem with the flowcell, lamp, photodiode, or even detector and time may be wasted on changing other items that have nothing to do with the problem.
d.    Heater turned on and heating properly.
e.    Check for spills, leaks, or improperly connected fittings.  It is much easier to correct these issues before putting reagents into the system. It only takes a second to scan the entire system for these issues.

4.    If chemicals are flowing it is usually best to go back to water, unless the problem can be fixed instantly since stopping the pump while reagent/chemicals are in the system can damage heater tubing, mixing coils, and flowcells shortening their life and ultimately costing more down time from analysis.
a.    Erratic or Noisy Baseline
-Surfactant: If the system becomes noisy once the reagents are added then it is easier to associate with reagent preparation.  If the baseline was consistent and quiet on water and becomes noisy on reagents then check if there was enough surfactant in the buffer line (or the reagent that requires surfactant).
-Filtering: Some buffers like ammonia chloride need to be filtered because of the large amounts of chemicals added.
-Contamination:  If there is a contamination of the target analytes quite a bit of noise can occur and will usually be associated with a strong coloration most obvious at the debubbler.  General start with the most recently replaced solution or the easiest to replace like sampler wash.  But ultimately go through the reagents and the containers one at a time until the color goes away.
-Insure certain chemicals that can cause problems are correct or not bad like bleach for NH3, Ascorbic Acid for PO4, or the pH of NOx buffer.
b.    When no peaks occurs - This is not the time to start changing flowcells, lamps, pump tubes etc all those issues should have been resolved during startup.
-It is very important to first carefully insure the system is flowing properly and all pump tubes are flowing correctly, especially the sampler line.
-Pump tubes are connected to proper reagent bottles.
-Insure that the heater is working properly.
-Insure that the cadmium coils is installed.
-Insure that the valve is actuating.
-Insure reagents are correctly prepared and not expired.
-Insure that the software is properly configured to collect data on the active detector.

I hope this is helpful as an introductory discussion on troubleshooting basics.  This is the beginning of a series on troubleshooting, operation and preventative maintenance that we plan to release over time.  We have troubleshooting guides for different chemistries and platforms.  Please feel free to contact us for more details on this subject or more complicated issues if they do arise.  Thank you for taking to time to read through this I hope it is helpful.

Ken Earle
Ken.Earle skype