Tips to Better Separation of Two Peaks for Reversed Phase (RP) HPLC.

There are a number of strategies to consider: 1. Change Solvent Percentages. In Reversed Phase HPLC, you have an Aqueous Component and an Organic Component (usually Acetonitrile). Here, Acetonitrile is the strong Solvent, and higher percentages of it will result in lower Retention. If you want to get better Resolution of two Peaks, they can be […]

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Troubleshooting: Fused Insert Vials Break During Injection.

When injecting Samples using Fused Insert Glass Vials, sometimes the Needle hits the Insert Wall, causing it to break. Is this due to the Inserts not being Properly Aligned, vertically? This problem is more likely due to the Needle not being Properly Aligned vertically; this can occur for a number of reasons, which may include: […]

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Using Methanol Instead of Acetonitrile in an HPLC Method. Caution.

Methanol is a very common choice for the HPLC mobile phase organic solvent component in Reversed Phase HPLC even though Acetonitrile is often superior in several aspects. On the other hand, Methanol is often less expensive and less toxic than Acetonitrile, so it has advantages as well. If you wish to simply substitute Methanol in […]

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What do You Suggest for an Internal Standard in Glucosamine LC-MS Analysis? FAQ

  If you are using a 13C-glucosamine internal standard though, you may encounter problems with detection reproducibility. Matching the concentration reasonably well with the amount in the sample should give you no more than about 1% error, which should be tolerable unless you need extreme precision in the quantitation. Alternatively, try using deuterated Glucosamine as an internal standard instead. In the EICs, you can readily […]

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What is Peak Inhibition, in LCMS? – FAQ

Peak inhibition is when the Signal-to-Noise Ratio (SNR) of an Analyte Peak is attenuated due to some Factor. A number of causes may be possible depending on the particular situation. One cause can be an increase in the background noise from the mobile phase. If the mobile phase has UV-absorbing impurities, for example, this can […]

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When to use Teflon Bottles for Your Mobile Phase Reservoirs.

For most HPLC applications, Mobile Phase Reservoirs made of standard Borosilicate Glass are suitable. There are certain circumstances in which Teflon© Bottles may be required instead and that is LCMS or LCMS/MS. Borosilicate Glass is made with Boron, Sodium, and other elements to make it malleable enough to form a bottle. During the glass forming […]

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Why am I Seeing Multiple Peaks in HPLC for Fructose?

I am running an HPLC method for Fructose but I see two or more peaks. What could be the cause? Suggestion: The peaks are likely due to the α and ß anomers as well as pyranose and furanose forms. In the open chain form, either a five-member or six-member ring can form. From there, the […]

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Why do I have Higher Pressure at a Lower Flow Rate in my Results?

All other factors being equal, the Pressure should not increase when the Flow Rate is lower. Therefore there must be something else causing the increased Pressure. Without more detail on the situation, it is difficult to determine with certainty. Some Possible Explanations are: • Blockages in the frits. If this is the case, use a disposable […]

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