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16 Blocked column from proteins in the sample matrix can be recovered

It is of crucial importance to always filter your samples prior to introduction to an HPLC instrument. Most samples will contain particulates and other matrix components that can cause blockages in the…

17 Buffer concentration can affect ANP retention of acids.

If you are using ammonium acetate or formate in an ANP method, the concentration used may play a significant role in the retention of organic acid analytes. Although buffer concentration may affect a…

18 Calculating relative response factor (RRF) on different instruments/detectors

The RRF value you calculate should be the same, irrespective of the instrument or detector used, as long as linearity has been demonstrated on all the involved instruments/detectors. © Copyright MicroSolv…

19 Calculating Theoretical Plates N half height

The theoretical plate number N0.5 can be calculated from a chromatogram using the equation below: N 0.5 = 5.54 (t R /w 0.5 )2 Where tR is retention time and w0.5 is the peak width at half its height.…

20 Can ANP chromatography be used to retain steroids?

It always depends on the individual compounds but generally speaking ANP is best suited to compounds of a more polar nature. In contrast, steroids as a class of compounds are mostly too hydrophobic for…

21 Can Cogent TYPE-C HPLC columns be used in supercritical fluid chromatography (SFC)?

As far as compatibility in SFC is concerned, the answer is yes. These columns are fully compatible with the typical conditions used in an SFC application and the packing material and hardware will not…

22 Can concentration changes effect retention time in HPLC? Is this a difference between HILIC and ANP?

No, it can happen at any mode, so it is not a contrast between HILIC and ANP. Of course retention can change with concentration from two sources. All separation processes follow a "Langmuir model"; when…

23 Can concentration changes effect retention time in HPLC? Is this a difference between HILIC and ANP?

No, it can happen at any mode, so it is not a contrast between HILIC and ANP. Of course retention can change with concentration from two sources. All separation processes follow a "Langmuir model"; when…

24 Can I make the PTFE syringe filter more hydrophilic?

Yes, if you are wiling to introduce Methanol into your method. For a 25mm device, if you use 15-20mls of methanol as a blank filtrate, the membrane will give you less back pressure after that for aqueous…

25 Can I use acetone as a mobile phase solvent in ANP?

If you are using LCMS, the simple answer is yes but pH is also something to consider. Acetone has a high UV cutoff and therefore can be a problem for UV detection. However, this is not a problem when…

26 Can I use primary amines with acetone as the mobile phase component in LCMS?

Yes, you can. However, some labs react acetone with primary amines (+heat) to form acetone adducts (imines) in GC and GCMS. This reaction while using acetone as a mobile phase component in LCMS along…

27 Can I use the knitted reactor coils (KRC) of the post column photochemical reactor with my HPLC fluorescence detector?

The only restriction on whether or not you can use the knitted reactor coils of the post column photochemical reactor is the inlet tubing of your detector. The absolute minimum ID can be 0.008". It is…

28 Can I use trifluoroacetic acid (TFA) to improve the chromatographic performance in LC-MS analysis?

Trifluoroacetic acid (TFA) is very often used as an additive in HPLC, because of its excellent solvating and ion pairing characteristics. It is a highly volatile acid as well, which could make it an additive…

29 Can I use trimethylamine with Cogent™ columns such as the Diamond Hydride™?

Most of the Cogent HPLC columns have an upper pH use limit of 8. However short exposure and possible use depends on how concentrated the solution is, what the pH of the solution is, and how long the column…

30 Can sample concentration have an effect on peak shape when using an HPLC column?

Injecting a very high concentration can result in lower retention and distortion in peak shape for your analyte in Aqueous Normal Phase (ANP) or Reversed Phase (RP) HPLC. The following study examined…

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