Liquid Chromatography

In HPLC Solutions #110 we looked at a problem of baseline noise created by a pump malfunction. In this instalment, we’ll look at what can be done about electronic noise in the chromatogram.

In the last HPLC Solutions #111, we looked at the influence of signal averaging on baseline noise for a simulated chromatogram. Let’s look now at how the detector time constant can be used to reduce baseline noise. The detector time constant (also...

In the last instalment of HPLC Solutions #112, we looked at one of the two most common ways to filter the detector signal to reduce baseline noise – the detector time constant. The second technique is to adjust the data system data rate. The data...

For the last few instalments of HPLC Solutions , we’ve been looking at ways to reduce baseline noise. We’ve been particularly focused on noise from electrical sources which tend to reflect the frequency of the power delivered to the laboratory. This...

A question that commonly arises in my Master Classes is the proper technique to integrate chromatograms where the peaks are not fully baseline resolved. For this, I most commonly draw on what I call the 10% Rule. This applies when a minor peak is...

Q: I have just developed a gradient HPLC method and need to set the acceptance criteria for system suitability. The column efficiency is one of the measurements we usually include in system suitability, but I don’t know which peak I should use to...

Most of us take advantage of the autozero function on our HPLC data systems to make the chromatogram look more pleasing to the eye. The autozero function is quite simple – it just takes whatever signal the data system is receiving and sets it at the...

Q: I’m wondering why most of scientists prefer to use a manual injector?! I know that autosamplers are used more to improve the productivity and it is standard with many HPLC systems. I was working with both and the autosampler produced better...

This discussion follows on the last HPLC Solutions instalment (HPLC Solutions #118), where we discussed the relative merits of manual injectors and autosamplers. A little better understanding of the loop filling characteristics will help us realize...

As a follow-up on the last two HPLC Solutions discussions (HPLC Solutions #118, #119) regarding sample injection, I’d like to take the opportunity to describe the two most popular types of autosamplers in use today. These are what I call the...

In the last instalment of (HPLC Solutions #120) we looked at one popular autosampler design, the push-to-fill autosampler. Now we’ll turn our attention to the other most popular design, which I call needle-in-loop.

This installment of HPLC Solutions begins a series on different measurements that we make on chromatograms. Measuring the baseline noise generated by an HPLC system may seem like a singularly boring subject. But if you think about it, noise can be a...

In HPLC Solutions #122, we looked at how to measure baseline noise from a liquid chromatogram. One practical application of such measurements is to determine the noise and drift of the detector, which we’ll consider now.

In HPLC Solutions #122, we looked at how to measure baseline noise from a liquid chromatogram. One practical application of such measurements is to determine the signal-to-noise ratio (S/N), which we’ll consider here.

In this issue of HPLC Solutions we’ll look at the first two methods, and then consider the third in #126. For additional references, you might want to look at #122 for the determination of noise and #124 for calculation of the signal-to-noise ratio...