Dani Xing
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Activity overview
Latest activity by Dani Xing-
Dani Xing created an article,
What typical pressures do you see for bioZen?
Pressures will vary depending on the particle size, length, internal diameter as well as the solvents/temperature used. Here are some of the typical pressures we observe for columns found in the b...
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Dani Xing created an article,
How do I store my bioZen SEC-2, SEC-3 columns?
You can store your bioZen SEC column in 0.05% Sodium Azide in water or with 10-20% methanol. However, if you do store in organic, you have to be mindful of reconditioning the column: use low flow a...
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Dani Xing created an article,
Are the guard columns for bioZen also biocompatible?
Yes, the guard columns for bioZen are biocompatible. Though the holder is not titanium, the analyte flow path is biocompatible.
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Dani Xing created an article,
What are some of the main differences between APCI and ESI MS ionization modes, and how will this affect LC/MS method development?
There are a few major differences between APCI and ESI modes of ionization that are especially important in LC-MS method development: With APCI-MS compounds are ionized in the gaseous state, s...
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Dani Xing created an article,
Consecutive injections are causing ghost peaks in my GC chromatogram, how can I avoid this?
There are two common causes for this phenomenon. The first is that the sample is being contaminated with every injection. This is common when a needle pierces the septum of the vial and deposi...
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Dani Xing created an article,
Acidic or basic peaks are tailing in my LC method, what can I do?
Ensure that you are using an adequate buffer. Some methods require 50-100 mM buffer. Also, ensure that the pH of mobile phase is appropriate for the buffer being used.
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Dani Xing created an article,
When doing headspace injection, what can I do to avoid peak splitting of some analytes? A direct injection on same system is giving the same split peaks.
Headspace injections may initially have poor peak shapes if there is mixing or diffusion occurring in the system. This typically occurs in the inlet. Use a 2.0 mm ID (or smaller) liner to keep the ...
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Dani Xing created an article,
Which is the best acidic buffer to use for my reversed phase analysis?
Most common acid modifiers to the mobile phase in reversed phase separations are as follows: phosphoric acid trifluoroacetic acid (TFA) formic acid acetic acid Phosphate salts can be ...
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Dani Xing created an article,
What solvents do I have to analyze using USP Chapter 467, Residual Solvents/Organic Volatile Impurities?
The latest revision of 467 allows testing for solvents that one expects could be present in the sample. If a solvent is never used anywhere in the manufacturing process one doesn’t need to test f...
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Dani Xing created an article,
What are the reasons for noisy baseline with ELSD ( Evaporative Light Scattering Detectors )?
The reasons for noisy baseline with ELSD detectors are: Evaporation temperature too low - the solvent is not completely evaporated. Evaporation temperature too high - the solvent is boiling ...