Tekmar Talk Blog

This is the second in our Troubleshooting series for VOC Analysis. 

Part one is linked here, VOC Analysis Troubleshooting Part 1: How to Begin Troubleshooting

Part 2 will discuss No, or Low, Analyte Response and Carryover.

Troubleshooting your instruments can be a frustrating process, but I hope this series eases some of that pain and helps you through it. If you’re dealing with no or low response from your analytes, you first need to know if the analytes are even getting to the Gas Chromatograph and Mass Spectrometer (GC-MS). Following the advice in part one of this series, start with a direct injection into the GC of the same standards you use on your Purge and Trap (P&T), to confirm normal operation of the GC-MS. If you see poor chromatography and resolution or reduced response, you should change your inlet liner and clip the column.

A carefully designed and faithfully executed preventative maintenance program is the best method for maintaining your scientific instruments. Keeping up with daily, weekly, monthly, and even quarterly maintenance tasks will help maintain the performance of the unit and decrease downtime. Maintenance checklists can be found in the manual to your Teledyne Tekmar instrument. The manual can also be an immense help with troubleshooting, because it has tips and instrument flow diagrams.

Water vapor entering the gas chromatograph (GC) inlet, column, and, ultimately, the mass spectrometer (MS) can minimize the sensitivity of our early eluting compounds, including our gases. It can also cause poor peak shape, compounds to co-elude, and shift in retention time, even in compounds outside of the water peak. So, once the water is introduced into our system, it starts to wreak havoc on all our compounds. Some say water doesn’t affect column phase or lifespan, but some have seen an effect, especially if you’re running a lot of samples; water can shorten the column life of your GC column and can cause vacuum issues if you’re using a MS system, which could lead to shorter filament lifetime and having to clean the source more often.

Throughout this blog series, we’ve discussed ways to minimize the amount of water vapor introduced to the GC-MS, using Teledyne Tekmar’s moisture control fitting and application control. We can continue to control moisture not only through this hardware designed for the Purge and Trap, but also through method parameters we can adjust and using smart method parameters on the GC.

The last two Purge and Trap (P&T) settings we will discuss in this blog series might be the most important for moisture control in this volatile organic compound (VOC) analysis: desorb and bake settings.

We can adjust our desorb time to help reduce the amount of moisture we put onto the gas chromatograph (GC) and mass spectrometer (MS). A longer desorb time will remove more of compounds from the analytical trap and send them to the GC, but this includes water, leading to a longer water peak in the total ion chromatogram. If the desorb time is shortened, less of that analyte material is transferred to the GC, but we will have a much shorter water peak, giving the compound peaks better shape and resolution. This gives us an opportunity for method optimization with the desorb settings both in time and temperature.

Well, the season is changing here in the Midwest and sample collection time will soon be upon us. In the laboratory, much like at home, a good spring cleaning goes a long way.

For Volatile Organic Compound (VOC) analysis, multiple cleaning procedures or preventative maintenance techniques should be employed.

In part one of this series, we learned why water vapor is bad for volatile organic compound (VOC) analysis. In part two, we will explore ways we can optimize moisture control in the Purge and Trap (P&T) system.

Analyzing volatile organic compounds (VOCs) is an essential part of environmental monitoring, flavor and fragrance analysis, and analysis in the pharmaceutical and petrochemical industries. Gas Chromatograph (GC) columns and detectors, namely Mass Spectrometers (MS), do not perform well in the presence of water. Before the sample is introduced to the GC, it must become a vapor.

For this reason, there are many samples, such as

In June 2016, the Toxic Substances Control Act, the law that governs chemicals in household and industrial products, was updated for the first time in nearly 40 years. In the past, before the agency could request safety data from the industry for new chemicals, the agency had to first show that a chemical may pose a risk. The passing of the revised TSCA allows the Environmental Protection Agency to request safety data and assess the safety of chemicals that are currently being used in a variety of products. In November, the agency selected the first 10 chemicals to evaluate under the new guidelines. The chemicals included:

• 1,4-Dioxane (solvent, stabilizer)
• 1-Bromopropane (solvent)
• Asbestos (wide variety of uses, e.g. building materials)

If you have wondered what was really making your clothes smell before you threw them into the wash, and even after they were supposedly cleaned, you are not alone. Scientists from Northrumbia University recently published a study in the Journal of Chromatography that revealed the molecules that make your socks stink. Beyond the dirt and sweat, believe it or not there are six volatile organic compounds (VOCs) that simply can’t be washed out in traditional eco-friendly cycles (68 degrees Fahrenheit). In other words, the stinky VOCs survive the wash.

There is no doubt that more people are paying more attention to the environmental footprint of their day-to-day activities. Washing clothes without hot water or using detergents that are less environmental friendly have become more viewed as ways to be more friendly to the environment. Scientists argue that because of this increasing awareness of the ecological impacts of washing clothes, it’s “important to understand why dirty clothes smell, in order to find the best way to clean them.” The VOCs “could be used to test the effectiveness of washing at different temperatures.”

Now that the Holidays are passed, it’s time to box the lights and put away the decorations. But before you store the fake Christmas tree for the next 11 months, consider whether the tree is making you sick. Men’s Health recently questioned whether fake trees are harming our health because most of them are made from a synthetic plastic called polyvinyl chloride (PVC). Depending on whom you ask, PVC could be safe or dangerous.

Dr. Glenn Harnett, the Chief Medical Officer of American Family Care, the nation’s leading urgent care provider told Men’s Health that PVC is harmful “in part because PVC is a fire-resistant compound that can use metals like lead, tin or barium as stabilizers,” adding “PVC also releases gases known as volatile organic compounds, which are gases that can irritate the eyes, nose, and lungs.”