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Acetylcholine
Applies to Electrochemical detector, application note 213_014 Summary The analysis of Acetylcholine (ACh) is done using reversed phase HPLC separation followed by enzymatic conversion of ACh into H2O2 (hydrogen peroxide). The peroxide is detected using an electrochemical flow cell with platinum w...


After installing a (new) column the sensitivity is lost
Applies to Electrochemical detector Summary Immediately after installation of a (new) column a relatively high cell current is observed, the baseline drifts continuously and is noisy. Cause Installation of a new or used column Diagnosis The problems started with exchanging the column. Reme...


ALEXYS system with poor reproducibility
Applies to ALEXYS system, AS 100 autosampler Summary Poor reproducibility in peak height and peak area. Typically %RSD improves with concentration, however sometimes the %RSD is much worse than expected. Cause Possible causes: Autosampler most often: air in sampling tubing or syringe ...


Can I hook up an Antec flow cell to any EC controller?
Applies to Electrochemical flow cell Summary Technically, Antec flow cells can be connected to any controller that supports a 3-electrode flow cell. Never connect metal tubing directly to the cell, use at least 5 cm of PEEK or Teflon tubing in direct contact with the cell.  Disclaimer: ...


Can I use an ISAAC reference electrode?
Applies to Sencelll, Flexcell, VT03 and other Antec flowcells. Summary Antec flowcells are available with different reference electrodes. The ISAAC (in situ Ag/AgCl) reference is user friendly and easy maintenance. To use such reference electrode, the mobile phase must contain 2 mmol/L KCl. The c...


Can I use my detector in strongly alkaline or acid media?
Applies to Electrochemical detection Summary Yes, the electrochemical flow cell is the wetted part in electrochemical detection and it can be used between pH 1 and 14. Metal working electrodes may have a short lifetime in strongly acidic environment. At high pH the background current will b...


Can I use Teflon for low pressure tubing?
Applies to Electrochemical detection Summary Teflon tubing is not recommended in combination with ECD for 2 reasons. Firstly it is permeable for oxygen, which makes it unsuitable for use in reductive ECD. Secondly, Teflon tubing is indented when using it in combination with finger tights. T...


Cell current goes from a high positive value to a high negative value
Applies to Electrochemical detection Summary A large drift in baseline is noticed. Cause Malfunctioning reference electrode, for example because of air in the REF compartment of the salt bridge or poor connection in the cell cable. Also a sudden contamination could cause this. Remedy Perfo...


Characteristics for a silver working electrode
Applies to Characteristics for analysis of iodide (212_003) using a flow cell with silver working electrode. Summary A summary is given of some practical issues when working with a silver working electrode. These are: Silver always reacts with iodide between -100 and +100 mV working pote...


DECADE II displays an error code
Applies to DECADE II Summary The following error messages can be displayed in the DECADE II LCD display:01  Incompatible boot version02  Control board error03  Sensor board x error (x = board number)04  Firmware program error05  Record error06  Incompatible FW versio...


DECADE II firmware upgrade advise
Applies to DECADE II only (not for SDC) Summary When upgrading firmware on a DECADE II, we recommend to upgrade to FW 3.50 with temperature control using the new LM35 sensor with analogue control . Although this is not absolutely required for single cell configurations (SCC) we recommend this bec...


Decrease in detector response
Applies to Electrochemical detector Summary For the same standard solution at the same detector and LC settings, a decrease in detector response is noticed over a period of hours or days. Cause Decrease in detector response can be caused by:  Contamination of the working electrode. Th...


Dummy cell test
Applies to   Electrochemical detector Summary The dummy cell test can be used to check the detector electronic circuit and stability performance of the baseline (and oven temperature). The dummy cell consists of a resistor and a capacitor, simulating the function of a real flow cell, but wi...


Dummy test is not according to specifications
Applies to Electrochemical detector, dummy cell test Summary Dummy test is not successful. Noise or I-cell out of spec. Cause Noise too high: problem in electronics, data acquisition or connecting cables. Too much drift: electronic or heater problem, too short equilibration time Current (Ic...


Flow cell contact test
Applies to Electrochemical flow cell Summary Test for contact between the working electrode (WE) and auxiliary electrode (AUX). In case of contact the cell will have noise, high background current, poor signal to noise ratio. Cause Several causes: wear and tear heating of the cell ultr...


Gas bubbles in flow cell
Applies to Electrochemical detector Summary Proper and continuous degassing is necessary in LC-EC, one time degassing using ultrasonic treatment is usually not enough. Cause Gas bubbles in the flow cell are caused by: Under-pressure in the cell because the outlet is below the flow cell level...


High background current
Applies to Electrochemical detector Summary The background current is related to the working potential, working electrode diameter and material and the mobile phase composition. Therefore, to recognize an abnormally high background current, its normal value should be considered. If an increase fr...


How can I check the performance of my flow cell?
Applies to Electrochemical flow cells Summary Performance of electrochemical flow cell with glassy carbon electrodes can be checked with an Operational Qualification procedure. Typically, such a procedure describes the analysis of a standard solution. The minimum required peak height and noise le...


How much volume can I inject on my LC EC system?
Applies to Electrochemical detection Summary Injection volume, or loadability in HPLC depends on several parameters. Most important: flow rate (column diameter) plate number retention time sample buffer composition Loadability increases with the flow rate which  increases with the s...


How often must I clean my flow cell electrodes?
Applies to Electrochemical detection Summary Frequency of maintenance of the working electrode depends on the sample and type of analysis. Typically, with relatively clean samples in catechol amine analysis once or twice a year is enough. This is in strong contrast to other analyses such as nitro...


How strongly must I tighten the flow cell bolts?
Applies to Flow cells Summary Cell bolts are tightened using the factory supplied hex key. Over-tightening may cause an increased noise level. The bolts are tightened 'a bit more than finger tight'. For cleaning, maintenance and installation of flow cells see flow cell manual.   Article ID...


How to apply grounding in the flow path
Applies to HPLC with ECD Summary An increased oscillation or random noise on the baseline can come from electric sources of surrounding equipment. Such noise is usually effectively terminated by using a properly configured ALEXYS system. However, there are exceptional circumstances where addition...


How to improve my detection limit
Applies to LC-EC system Summary The detection limit is the peak height that gives a significantly (at least 3 times) higher signal than the baseline noise. It is improved if the signal increases and/or the noise decreases. Signal and noise are not only determined by the detector but in fact by th...


How to install a new column?
Applies to Chromatography, HPLC, reversed phase columns Summary When installing a new column a few things have to be kept in mind. New (untreated) columns are usually not suitable to be used with electrochemical detection. The background current may be unacceptably high and substantial cont...


I do not get much reaction products
Applies to ROXY, ReactorCell, µ-PrepCell, SynthesisCell Summary The yield of reaction products is very low, or nothing is found in the MS spectra. Cause Possible causes can be related to equipment or measurement conditions. Equipment related: Cell cable with capacitor ...


I have too much noise on my baseline
Applies to Electrochemical detector Summary The noise level is much higher than expected. Cause Studying the noise trace can be helpful to find the source of noise.     Fig. 1. Examples of noise. A: ‘normal’ random noise (shown for comparison, not problematic) B: ...


Is it sufficient to thermostat my flow cell, not the column?
Applies to Electrochemical detection Summary The residence time of the mobile phase in the cell is less than a second. Therefore, it is definitely not enough to thermostat the cell only. For best temperature stabilisation, the column should also be in the temperature controlled oven cabinet. ...


ISAAC shows light coloured spots
Applies to Sencell, ISAAC Summary After a period of use the ISAAC reference electrode changed colour. Light spot(s) are visible. Cause Due to the higher linear flow rate in the Sencell there is a chance that the Ag/AgCl coating disappears after prolonged use. It is considered normal wear and ...


Migration of Clarity to a new PC
Applies to Clarity software 3 and higher. Summary Procedure to transfer an excisting Clarity environment to a new PC. Software revision stays the same. In case the software is upgraded, it might be necessary to recreate the configuration files. Check this with Antec support. Steps These are the...


My peaks are (much) wider than to be expected
Applies to HPLC, chromatography. Summary Peak width is much larger than expected. Cause Abnormal peak broadening, or loss of plate number can have several causes. By systematically eliminating all possible sources the problem can be found. Look back in your data when the problem first started, ...


Netilmicin
Applies to Netilmicin analysis according to EP 9.2, Au electrode, application note 217_031, aminoglycoside antibiotics Summary Shift in retention times, high noise and bad peak shape in Netilmicin Sulphate analysis according to EP 9.2 method Cause and remedy Retention time. The method for ana...


No signal
Applies to Electrochemical detector Summary After injection of the electrochemically active standard no signal is obtained. Cause Lack of detector response usually points at: Incorrect detector settings. For example the cell is off, cables are not connected, an insensitive range setting ...


OQ or PQ is 'failed'
Applies to ALEXYS system, electrochemical detector Summary OQ or PQ is 'failed'. Cause Several possible causes for 'failed' result: electronic malfunction problem with chromatography, equipment, flow cell, cable connections or data acquisition problem with a test tool, column or standar...


Pressure increase in HPLC
Applies to ALEXYS, HPLC, UHPLC Summary Over time a gradual pressure increase in HPLC is noticed. Cause Increase in pressure points at an obstruction in the HPLC flow path. This obstruction can be at the column, tubing, connections, inline filters, or any other part in the flow path. Diagnosi...


Stop flow test
Applies to Electrochemical detector Summary In case there is a problem with noise or background current, the stop-flow test can be helpful to check if the problem originates from the flow cell or from another part of the system (flow cell only being the messenger of the problem). For the test, th...


Thiols, disulfides, bad peak shape, loss of signal on BDD diamond electrodes
Applies to FlexCell with BDD working electrode, 211_005_02 - Aminothiols, Glutathione and Disulfides. Summary Bad peak shape, or loss of signal in Thiols analysis on a BDD electrode. The responsiveness of this electrode shows an optimum at a background current around 1 µA (at 1.8 V vs saltb...


What are normal detection limits?
Applies to Electrochemical detection Summary Detection limit is usually defined as the peak height that gives a significantly (at least 3 times) higher signal than the baseline noise. Detection limits in LC-EC highly depend on the system configuration (injection volume, column efficiency and...


What does the 5 year warranty on the flow cell mean?
Applies to Warranty Summary All instruments manufactured by Antec Leyden are warranted to meet the specifications indicated in the corresponding manual and to be free from defects in materials and workmanship for the periods specified and in accordance with terms agreed upon in writing between An...


What is the best position of my flow cell?
Applies to Electrochemical flow cells Summary Flow cells are placed with outlet on top. This reduces the possibility of bubbles trapped in the cell. For cleaning, maintenance and installation of flow cells see flow cell manual. Article ID: 01043 Last reviewed: 13 Oct 2008...


What is the best pump for LC EC?
Applies to Electrochemical detection Summary A limiting factor in getting better detection limits is the factor that predominates the system noise. Any properly functioning HPLC pump that is not predominating the system noise is in principle suitable for LCEC. The mobile phase is in direct contac...


What is the maintenance on my REF and cell?
Applies to Electrochemical flow cell Summary For cleaning, maintenance and installation see flow cell manuals.   Article ID: 01041 Last reviewed: 13 Oct 2008...


What precautions should I take when measuring in the reductive mode?
Applies to Electrochemical detection Summary Reduction of oxygen causes an unacceptable high background current in reductive amperometric detection. Therefore the mobile phase and the sample must be virtually oxygen free. This is done by: Degassing of mobile phase using helium of highest purit...


Where do I put the yellow crocodile clip?
Applies to DECADE, INTRO with yellow wire/clip on cell cable. Summary The yellow crocodile clip is applied when a manual valve is used in the DECADE or Intro. This manual valve is usually not grounded by itself and therefore interferes with the Faraday shield. If properly grounded by means of the...


Which reference electrode do you recommend?
Applies to Electrochemical flow cells Summary Three reference electrodes are available:  standard salt bridge Ag/AgCl  in situ Ag/AgCl (ISAAC) HyREF reference electrode For different application areas see flow cell manuals and Application notes. Article ID: 01030 Last revie...


Why do I need a Faraday shielded oven?
Applies to Electrochemical detection Summary Electrochemical detection is characterised by its extremely low limits of detection that can be obtained. In order to get the best possible performance all sources of noise should be minimised. Such a source of noise is electrical interference fr...


Why is my electrode broken?
  Applies to u-Prepcell Summary The large working electrodes of the micro Prepcell are fragile and might break under certain conditions (GC and BDD type). The electrodes are consumables, they are easily exchangeable and replaceable.  Cause BDD and GC electrodes are ...