• Bill Letter posted a new activity comment 4 months ago

    In reply to: Tao Wang posted an update in the group Analytical Laboratory Instrumentation
    #Discussion Hello, I am trying to develop a GC-FID method for analyzing glycol that comes from glycol dehydration plant […]
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    It sounds like you may need to address the instrument issues first. Has maintenance been done?

  • Bill Letter posted a new activity comment 4 months ago

    In reply to: Tao Wang posted an update in the group Analytical Laboratory Instrumentation
    #Discussion Hello, I am trying to develop a GC-FID method for analyzing glycol that comes from glycol dehydration plant […]
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    “Error” and large variation in results have many causes. Please explain how you measured this error? How many replicates did you use? Investigation of any problem requires that we first understand what method you are using. Please provide the detailed GC method used. Please include any sample prep procedures too, as these are just as important as the analysis. Can you tell us if this same method has ever worked for you in the past, and provided much better results (~ 1-2% RSD)? This woudl help put your question into context and allow us to have a discussion about which areas may need to be addressed.

  • Bill Letter posted a new activity comment 4 months, 3 weeks ago

    In reply to: Neha Sharma posted an update in the group Analytical Laboratory Instrumentation
    Trying to develop an LCMS/MS method for oligonucleotides (dATP, dCTP, dGTP and dTTP) on HILIC (kinetex; 150×2.1mm, 2.6um) […]
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    And the flow rate is … ?

  • Bill Letter posted a new activity comment 5 months, 3 weeks ago

    In reply to: Steven Miles posted an update in the group Analytical Laboratory Instrumentation
    When developing an HPLC method, are you open to exploring buffers beyond the established norm?
    […]
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    More Info can be found at this link: “Popular LC/MS and HPLC Volatile Mobile Phase Buffers”; https://hplctips.blogspot.com/2014/06/popular-hplc-volatile-mobile-phase.html

  • Bill Letter posted a new activity comment 6 months, 3 weeks ago

    In reply to: Justin Williams posted an update in the group Analytical Laboratory Instrumentation
    Anyone familiar with Daniel Model 500 (I think) GCs? I’d like to secure a few 6-port valve rebuild kits and/or spare […]
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    Sounds like you are referring to “The Danalyzer”. This is a “specialty” product and very different from the typical HP/Agilent GC system. Emerson is a distributor and has probably given them a fair quote for parts. Contact the GC manufacturer (Daniel) for more information (In TX). They provide very good documentation on their products which is easy to obtain. Valves wear out and get contaminated over time. Regular maintenance should always be budgeted into ownership. Optionally, visit the client’s site and look at the systems to determine which valves are used and what parts may be needed.

  • Bill Letter posted a new activity comment 6 months, 3 weeks ago

    In reply to: Justin Williams posted an update in the group Analytical Laboratory Instrumentation
    Anyone familiar with Daniel Model 500 (I think) GCs? I’d like to secure a few 6-port valve rebuild kits and/or spare […]
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    Often, our job is to also help educate the client regarding what is ‘normal’ and what should be planned for.