Besides specializing in the repair of HPLC vacuum degassers, I have been repairing and servicing ALL of the HP/Agilent HPLC and LC/MS modules since 1985 so would like to add several comments.

First, lets get some terminology addressed for others reading this regarding the 3 different types of older electronic vacuum degassing modules. The G1322A degasser (which is still being made and sold today) has the single modular, 4-channel vacuum chamber with 12 ml channels. The G1379A degasser is identical to the G1322A, but has four individual (in blocks of 2), 1 ml volume vacuum chambers. The G1379B (now known as the G4225A) has a completely different design inside (different parts), but uses the same type of 1 ml vacuum chamber channels found in the G1379A model it replaced. *Agilent's series numbers such as 1100, 1200 and 1260 mean nothing in this regard (marketing names given to them), look at the model # to compare units. Most likely you will compare the G1322A to the G1379A or B.

All of these degasser modules (this includes other brands too) last about 5-6 years before failing. This is normal and they require regular cleaning and servicing similar to other HPLC modules, but for some reason, clients ignore them until they break. Long before that red LED turned ON, the Yellow light stayed on all of the time indicating that the unit was not working (and not degassing properly). When the red light finally turns on, the unit is dead. The vacuum pump usually fails first, but the vacuum solenoid valve and tubing also fail from the stress of the failing system and age at the same time. If the vacuum chambers have been contaminated (and they often are), then these will need to be cleaned, replaced/serviced BEFORE you install any new parts or your new parts will be damaged once again. Correct diagnosis and servicing is critical. AGILENT does not service these units, but instead they offer refurbished (used) replacement units as a solution (this insures the client gets a working degasser quickly and no time is spent diagnosing and servicing the unit). It is cost effective (for the manufacturer).

If you are asking which of the above degasser models would be better for your application of flow rates of 0.500 to 1.000 ml/min with ACN/Buffers, then any of them would be suitable. While the G1322A's very large 12 ml chamber volumes do contribute to wasted solvent (you need to flush them at the start of each day and they waste ~50-100mls liquid vs 10-12mls), they have demonstrated one big advantage over the other degasser modules with either the 0.5 and 1.0 ml vacuum chambers. They take more abuse and run longer before failing. Failure is often caused by solvent vapors and buffer salts accumulating over time in the tubing/membranes. These contaminate the vacuum chambers, then damage the valve and vacuum pump leading to failure. The design of the enormous, empty portion of the chamber in the G1322A means that it takes more abuse before causing damage to the rest of the system whereas it is almost immediate with the G1379A, G1379B and G4225A units. The chamber volume size is the most significant difference between modules, but the G1379B degasser also uses a different internal design with a modern two-speed vacuum pump that runs continuously (vs on/off) to maintain a more stable baseline (in some circumstances). While the design of the G1379B is more "modern", we have also seen these modules fail far more often than any of the other versions. The small chambers and delicate by-pass valve used are easily contaminated and stressed requiring more frequent service. *The newer G4225A uses better vacuum chambers, but so far appears to share the reliability issues present with the G1379B.

Which ever system you select, be sure and have it serviced every 5 years and follow the manufacturer's operating guidelines. Install new vacuum tubing after 5 years, keep an eye on the LED color and take action at the first sign of trouble (continuous 'yellow' light or unusual pump noise). If possible, avoid highly volatile solvents such as n-hexanes as these will go through the membrane/tubing pores faster and attack the plastics in the tubing and valve/pump seals. BTW: THF will also destroy the model G1379A, G1379B and G4225A in record time (never use THF in those models). Always flush all buffers from the system when not using the unit (this includes overnight).

The price you were quoted of 3000 Euro (~ $3,350 USD) for a refurbished unit sounds very high, and this is one reason we repair them down to the component level. It is often far less expensive to repair them, than buying a used module from Agilent. We routinely professionally refurbish and repair these modules in the USA for an average price of 900 Euro (some for much less, some for more) and the most expensive G1322A degasser repair I can think of cost the client around 2,000 Euro ($2,250 USD) and that was for a complete replacement and upgrade of the entire internal degasser to a higher quality system. If you can find a way to inexpensively ship it to us in the USA for a diagnostic service, then we could provide you with a repair quote. A few countries do not levy VAT on instruments returned for repair so it might be worth looking into?

http://www.chiralizer.com/hplc-degasser-repair.html

http://www.hplctools.com/agilent-hplc-degasser-repair.pdf

Besides specializing in the repair of HPLC vacuum degassers, I have been repairing and servicing ALL of the HP/Agilent HPLC and LC/MS modules since 1985 so would like to add several comments.

First, lets get some terminology addressed for others reading this regarding the 3 different types of older electronic vacuum degassing modules. The G1322A degasser (which is still being made and sold today) has the single modular, 4-channel vacuum chamber with 12 ml channels. The G1379A degasser is identical to the G1322A, but has four individual (in blocks of 2), 1 ml volume vacuum chambers. The G1379B (now known as the G4225A) has a completely different design inside (different parts), but uses the same type of 1 ml vacuum chamber channels found in the G1379A model it replaced. *Agilent's series numbers such as 1100, 1200 and 1260 mean nothing in this regard (marketing names given to them), look at the model # to compare units. Most likely you will compare the G1322A to the G1379A or B.

All of these degasser modules (this includes other brands too) last about 5-6 years before failing. This is normal and they require regular cleaning and servicing similar to other HPLC modules, but for some reason, clients ignore them until they break. Long before that red LED turned ON, the Yellow light stayed on all of the time indicating that the unit was not working (and not degassing properly). When the red light finally turns on, the unit is dead. The vacuum pump usually fails first, but the vacuum solenoid valve and tubing also fail from the stress of the failing system and age at the same time. If the vacuum chambers have been contaminated (and they often are), then these will need to be cleaned, replaced/serviced BEFORE you install any new parts or your new parts will be damaged once again. Correct diagnosis and servicing is critical. AGILENT does not service these units, but instead they offer refurbished (used) replacement units as a solution (this insures the client gets a working degasser quickly and no time is spent diagnosing and servicing the unit). It is cost effective (for the manufacturer).

If you are asking which of the above degasser models would be better for your application of flow rates of 0.500 to 1.000 ml/min with ACN/Buffers, then any of them would be suitable. While the G1322A's very large 12 ml chamber volumes do contribute to wasted solvent (you need to flush them at the start of each day and they waste ~50-100mls liquid vs 10-12mls), they have demonstrated one big advantage over the other degasser modules with either the 0.5 and 1.0 ml vacuum chambers. They take more abuse and run longer before failing. Failure is often caused by solvent vapors and buffer salts accumulating over time in the tubing/membranes. These contaminate the vacuum chambers, then damage the valve and vacuum pump leading to failure. The design of the enormous, empty portion of the chamber in the G1322A means that it takes more abuse before causing damage to the rest of the system whereas it is almost immediate with the G1379A, G1379B and G4225A units. The chamber volume size is the most significant difference between modules, but the G1379B degasser also uses a different internal design with a modern two-speed vacuum pump that runs continuously (vs on/off) to maintain a more stable baseline (in some circumstances). While the design of the G1379B is more "modern", we have also seen these modules fail far more often than any of the other versions. The small chambers and delicate by-pass valve used are easily contaminated and stressed requiring more frequent service. *The newer G4225A uses better vacuum chambers, but so far appears to share the reliability issues present with the G1379B.

Which ever system you select, be sure and have it serviced every 5 years and follow the manufacturer's operating guidelines. Install new vacuum tubing after 5 years, keep an eye on the LED color and take action at the first sign of trouble (continuous 'yellow' light or unusual pump noise). If possible, avoid highly volatile solvents such as n-hexanes as these will go through the membrane/tubing pores faster and attack the plastics in the tubing and valve/pump seals. BTW: THF will also destroy the model G1379A, G1379B and G4225A in record time (never use THF in those models). Always flush all buffers from the system when not using the unit (this includes overnight).

The price you were quoted of 3000 Euro (~ $3,350 USD) for a refurbished unit sounds very high, and this is one reason we repair them down to the component level. It is often far less expensive to repair them, than buying a used module from Agilent. We routinely professionally refurbish and repair these modules in the USA for an average price of 900 Euro (some for much less, some for more) and the most expensive G1322A degasser repair I can think of cost the client around 2,000 Euro ($2,250 USD) and that was for a complete replacement and upgrade of the entire internal degasser to a higher quality system. If you can find a way to inexpensively ship it to us in the USA for a diagnostic service, then we could provide you with a repair quote. A few countries do not levy VAT on instruments returned for repair so it might be worth looking into?

http://www.chiralizer.com/hplc-degasser-repair.html

http://www.hplctools.com/agilent-hplc-degasser-repair.pdf

Hi Bill,

I was kind of already waiting for the possibly most valuable answer on this topic. You are right, the degasser unit was quiet "invisible" to our eyes in the recent years...

Thanks a lot, I'll discuss this with my supervisor. The option you gave me seems to be much more pleasurable.

Marcus

Marcus: Your are very welcome. We repair these units every week for clients (I have 3 in our shop right now being tested!). Helium sparging of mobile phases never caused these types of problems! Sometimes technological advances result in one step forward and two steps backward.

You could also buy a used unit for between $1,000 and $,2000 US from one of the vendors on Lab X see link. That probably would be the quickest way to fix your problem. I would recommend going that route rather than having to spend $3,000 for a repair from Agilent. You could also have the unit generically repaired for less; see 2nd link.

If you are handy you could probably repair the unit yourself getting the OEP parts from Systec (part of IDEX) see 3rd link. I have repaired many of these units myself; typically the vacuum pump fails which is immediately obvious when you remove the cover and power up the unit.

I recommend spending as little money as possible to keep and old system running and would not purchase a new degasser for the system. Save your money for the new system you will purchase at a later time or keep the money in reserve for when something else on your older HPLC system fails.

As far as the difference between the micro and normal units what are you getting by spending more money on the micro unit? It will still work the same as the cheaper standard unit for your purposes. Both systems expose the solvents to semipermeable membranes which share a common vacuum chamber. This causes mixing of the solvents to some degree (diffusion happens). Try running a propylene glycol analysis using RI detection on a Hamilton HC-75 column with acetonitrile in one of the degasser lines!

http://www.labx.com/V2/adsearch/search.cfm?sw=degasser&ca=408

http://www.lc-ms.com/G1379A%20Degasser%20Repair.htm

https://www.idex-hs.com/degassers.html

Unless you can buy a used one for a few hundred dollars, I would strongly discourage the purchase of a used degasser from an auction website such as LABX or ebay as 99.9% of those are all broken degassers with the same or worse problems than yours has. *Each week we receive those degassers in our shop from clients who were told they were buying a "working" degasser from a re-seller, but instead received a broken one requiring $1-2K+ USD in repairs (plus the initial $1-2K they spent on the purchase). Many of the used HP/Agilent/Waters degassers advertised for sale are broken units which were put aside by their original owners, then resold on the auction market to equipment recyclers and resellers who resell them. In most cases, it is more cost effective to fix the one you have and not inherit someone else's problems (and contamination) or get a refurbished one from Agilent.

BTW: If the vacuum degasser pump is worn out, then so are some of the other parts/tubing (esp after 5 years). Replacing just the vacuum pump in a "broken" degasser which has vacuum chamber damage will result in the vacuum pump being destroyed, again (We receive incorrectly repaired units in our shop every week). These are consumable parts (similar to HPLC columns) and they have a lifetime which is not infinite.

Hi all,

just want to inform you that the refubished degasser unit arrived this week. It is working very well, no red LED visible :)

The Agilent exchange program was satisfying, great service (although it was rather expensive). I just have one additional question: What to do in the future when the LED may turn yellow? Which parts do I need to exchange? I know that Bill's company offers maintenance kits for that purpose - this will be the right thing to go with?

Marcus

HI Marcus: Curious to hear which used Agilent degasser did you replace it with (the exact model #)?

You asked "Which" parts to exchange in the future? Impossible to say without thoroughly diagnosing which parts are worn or need replacement. Replacing one worn part and not addressing possible others usually results in early failure or contamination of any new parts added. *The internal vacuum tubing is probably the one item I would always exchange.

The general guidelines is to have the module professionally serviced: (1) any time the Yellow LED stays on; (2)  If the system has been compromised (i.e. left in buffer too long w/o flushing, running inappropriate mobile phase through system, etc); or (3) Every five years for a complete cleaning and replacement of any worn parts. This is the least costly method of maintaining the system.

Hints & Tips: HPLC Vacuum degasser modules are very delicate.

• Never push liquid through them, only draw liquid through (via syringe or pump). High pressure applied into the chambers can cause the membranes to leak or rupture!
• Always keep ALL vacuum channels filled with liquid, never air.
• Always consult the manufacturer's chemical compatibility table before using (different models have different exclusions). e.g. Many degassers are not compatible with Hexanes, DCM, THF and/or Sodium Azide. Special vacuum chambers are available from some manufacturers (not Agilent) to address these exceptions.
• Always flush buffer salts from each channel when not in use.
• Always turn OFF the vacuum degasser when it not being used.
• Always flush each channel at the start of each day, before use.
• The vacuum chambers are much more likely to be contaminated from the use of more volatile mobile phases. They pass through the degassing tubing/membranes and deposit themselves inside the vacuum tubing, then any valves and the pump causing damage.
• Be cautious when using highly aqueous mobile phases. Water vapor is known to diffuse through the degassing membrane (esp Teflon AF) and condense on the inside of the tubing and vacuum pump resulting in failure of the system.

Hi Bill,

thanks again for the very valuable tips! We currently take care of flushing any buffers out, which are than replaced by water /w 0.02% NaN3. We never work with hexanes, only aqueous solvents, which should not be a problem. The only solvent line which contains a high amount of organic solvents is 95% Acetonitrile/5% H2O with 0.1% HCOOH. Would you suggest to exchange this also by H2O if not in use for a longer time (> 2 days)?

What do you mean with "Every five years for a complete cleaning and replacement of any worn parts." Shipping it back to the Agilent maintenance service? Just replace the tubings and vacuum pump by myself as a precaution? I mean, I can not see if the tubing inside the vacuum chamber are damaged. The visible parts (after removing the top plate) are only a few.

Our replacement unit G1322A has the serial-# JP73017956

Marcus

The G1322A is a very rugged unit and takes a lot of abuse so you made a good choice. Just be sure and flush each channel down with about 30+ mls of solution each day before use (it does waste a lot of mobile phase).

95% ACN with Water and a pinch of acid is fine in the one line/chamber. *If the system is going to sit more than one week unused, then flush all channels out with MeOH/Water (80/20) or pure IPA.

Every five years: A professional should verify correct operation of the system (to insure it is not contaminated and meets full factory spec). The vacuum tubing should always be replaced at this time (it is inexpensive) as it fails from normal use and age. The only way to know if other parts are failing or worn is to test them. This could be done when the rest of the HPLC is receiving its semi-annual service.

* For clients in North America, Chiralizer Services offers a low cost diagnostic evaluation service for all brands of HPLC vacuum degasser modules. We can quickly find out what the condition of the degasser is and, if applicable, what types of repair services it may need to restore full operation. Repairs can be made for a fraction of the cost that the manufacturer charges.

http://www.chiralizer.com/hplc-degasser-repair.html