2021-02-26 20:42
By now, you’ve likely heard of Roundup. Roundup is the trade name for the broad spectrum herbicide developed by Monsanto in 1974 and it’s one of the world’s most widely use… Read More
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Chromablography: Restek's Chromatography Blog
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Topical and timely insights from top chromatographers. Covers gas and liquid techniques, with practical tips and thought-provoking observations.
2021-02-18 19:14
Calibration curves are an essential part to potency testing. A question often brought up by customers is “how many calibration points are needed for a calibration curve?” The ans… Read More
2021-02-15 18:17
Screening for volatile inhalants of abuse, as well as analyzing for blood alcohol content, is commonly performed in forensic toxicology laboratories using headspace gas chromatography with f… Read More
2021-02-15 14:43
In previous blogs (https://blog.restek.com/cyrogenic-cooling-for-air-analysis-interferences-from-n2-co2-and-o2/ and https://blog.restek.com/cyrogenic-cooling-for-air-analysis-part-2-combinin… Read More
2021-02-11 18:06
As we learn more about the chemical constituents of cannabis, more cannabinoids are being discovered and with it more THC isomers. You are probably very familiar with the two most commonly t… Read More
2021-02-05 20:18
We have had several blog posts and articles that discuss high backpressure observed in LC systems. Much of this discussion involves how to determine if the problem is in the column and what… Read More
2021-02-04 17:56
One of the tools we can’t live without when modifying/developing a GC method is the EZGC method translator. Changes made to GC method parameters like; inlet/outlet pressure, flow/carri… Read More
2021-01-19 12:09
Several years ago, my colleague, Alan Sensue wrote Chemical Reference Standards; don’t just snap and pour. In it, he described a personal experience where he mixed several expensive re… Read More
2021-01-14 20:50
Every once in a while, I meet a customer who is interested in analyzing cannabinoids by GC. Before Pro EZGC, these requests were difficult since we could only guess on the resolution and con… Read More
2021-01-06 21:10
Every GC analyst experiences baseline issues at some point in their career, whether the baseline is higher than normal, or it contains additional peaks/spikes, or becomes erratic and drifts… Read More
2021-01-05 00:26
The Farm Bill of 2018 has opened a lot of doors in the cannabis industry. The effects are prominent in selection of cannabinoid containing products offered on the market. One such product th… Read More
2020-12-31 21:28
Did you know that many forms of documentation, such as column and standard CofAs, are available one click away from our homepage? From here, pdfs of safety data sheets (SDSs), certific… Read More
2020-12-31 20:49
Like most folks who work in the lab, you likely have had some downtime in the lab due to various reasons, which could include a column, instrument, sample prep, standards, and even applicati… Read More
2020-12-29 19:50
Often times in technical service there will be a request for a column that can provide a certain separation on a lone pair of analytes. Take for example, the separation of CO from CH4… Read More
2020-12-22 23:14
This is the final part of the blog series “Tips on the analysis of pesticides and mycotoxins in cannabis products: Matrix matters!” In Part I (here) and II (here), we covered var… Read More
2020-12-14 21:39
Our most popular and successful LC column for the broadest range of pesticides is the Raptor ARC-18 column. We are able to retain, provide good separation and peak shape even for many of t… Read More
2020-12-10 10:48
In a previous post, we made the case that the foundation for analytical separations is sample preparation. In this post, we would like to talk about how it works the other way around… Read More
2020-12-08 21:51
In previous blog posts for this series on QuEChERS, we discussed QuECHERS dSPE Selection, Modifying QuECHERS..-Dry Samples, Modifying QuEChERS..-High Fat Samples, and Modifying QuEChERS..-Hi… Read More
2020-11-23 19:45
Our last several blogs covered the numerous ways to help clean up lab air to meet the new TO-15A guidelines for canister blanks. Absent from the previous blogs was how we were getting quanti… Read More
2020-11-02 15:08
The most labor-intensive part of determining the potency of samples containing cannabinoids is extraction. Due to a plethora of matrices, from candy, baked goods, lotions, and so on, selecti… Read More
2020-10-27 18:28
The Food and Drug Administration (FDA) has expanded their recall of hand sanitizers and found more chemical contaminants to include 1-propanol (n-propanol cas# 71-23-8). 2-propanol (isopropa… Read More
2020-10-19 20:29
Matrix-matched calibrations are a popular option for complex matrices, such as food commodities. When it is employed, one can assume that the majority of matrix effects will be accounted for… Read More
2020-10-14 20:12
Determining the length of your GC capillary column is essential for accurate control of carrier gas flow rate. Just because you purchased a 30 m column, does not mean that your column… Read More
2020-10-08 17:00
Anyone who has tried to analyze free fatty acids by GC realizes they have to derivatize these compounds. The inherently low volatility of free fatty acids and the carboxylic acid (-COOH) int… Read More
2020-09-24 15:58
I’ve been working on a detailed PCB congener analysis using the TSQ-9000 with the AEI. Typically this analysis is done by EPA Method 1668C, which uses high resolution MS. We get some s… Read More
2020-09-09 13:19
Restek is known as a leader in the field of chromatographic column technology. The idea is built into our very identity – resolution technology is at the heart of Restek. W… Read More
2020-09-08 19:52
Welcome Back! You and your lab have been through a lot these last few months and now it’s time to get your LC back up and running. After it has been down for a few months… Read More
2020-08-31 18:00
In my last blog, I presented a new technique called low pressure gas chromatography (LPGC, Figure 1). Just to recap, the LPGC system consists of a relatively short analytical column (10 &nda&hell…Read More
2020-08-21 15:04
In the previous blog (https://blog.restek.com/the-new-u-s-epa-method-to-15a-blog-series-part4-clean-lines-for-clean-air/) I left off with our system at or under the 20pptv limit required by… Read More
2020-08-20 18:28
In previous blog posts for this series on QuEChERS, we discussed QuECHERS dSPE Selection, Modifying QuECHERS..-Dry Samples and Modifying QuEChERS..-High Fat Samples
Once again, I suggest to… Read More
2020-07-28 19:11
The U.S. Food and Drug Administration has placed methanol containing hand sanitizers on an import alert (1). These products do not list this ingredient and some are incorrectly labeled &ldqu&hell…Read More
2020-07-24 08:00
Throughput is one of the most important parameters in the lab. The more samples we can analyze in a day, the sooner we can get home. Enter Low Pressure GC (LPGC) – this is an invention… Read More
2020-07-23 20:44
Often the gas samples contain some water vapor. Although we are usually not interested in the amount of moisture present in the sample, if we don’t dry it, the water will be injected o… Read More
2020-07-22 17:48
Several years ago, my colleague Scott Grossman wrote an excellent article entitled “It’s a Matter of Degrees, but Do Degrees Really Matter?” He measured the temperatu… Read More
2020-07-20 14:35
GC column bleed sounds like one of those old problems people used to have. The XLB was developed to lower detection limits by minimizing bleed. Now, virtually all polysiloxane GC columns are… Read More
2020-07-17 14:45
In previous blogs (Part 1, Part 2, Part 3) we’ve covered the need to use air instead of nitrogen as a fill gas, the new lower blank requirements, and how these increase the importance… Read More
2020-07-16 21:36
Recently I have been asked by several customers how to clean an injection port. My initial answer is always the same, you should clean the injection port according to the manufacturer… Read More
2020-07-09 18:08
From the start of this blog series, I have been teasing you with how to take your canister blanks from the following red trace down to the blue trace:
In this post, I shall finally stop dra… Read More
2020-07-06 12:06
Modern GC’s are equipped with advanced pneumatics controls, which allow for accurate control of flow rates and pressures. In order to accurately control or calculate flow rates… Read More
2020-07-01 19:42
Sometimes customers need to analyze natural gas and petroleum products, whether it is to confirm the purity of the product by looking for the impurities which may be present, or for an envir… Read More
2020-07-01 15:05
This post is part of a series on QuEChERS. Here are links to the previous two posts, in case you may wish to catch up before reading this one:
QuEChERS dSPE selection-which one is best?
Modi… Read More
2020-06-22 19:18
Beyond optimizing the inlet parameters of temperature and splitless valve time, initial oven temperature also plays an important role for splitless injections. When a liquid sample is inject… Read More
2020-06-15 14:00
Last month, Nancy published a blog summarizing how to approach samples with less than 80% water. Today, I want to go into more detail on how to deal with different commodities with less than… Read More
2020-06-12 16:33
I am back here to complete my Amphetamines blog series. In my previous posts, I have discussed the importance of separating the chiral d- and -l isomers to accurately identify the illicit is… Read More
2020-06-08 20:40
In my previous blog, I discussed optimizing inlet temperature for splitless injections. Today I would like to discuss another critical parameter for splitless injections: splitless pur… Read More
2020-06-01 13:43
Last time, we left you with a teaser, how to take your canister blanks from the following red trace down to the blue trace:
Before we get to that, let us back up to 2015, where both Wayne W… Read More
2020-05-26 22:20
Before getting in to this discussion, I recommend reading my previous blog post first regarding classical applications for methods based on Quechers. https://blog.restek.com/quechers-dspe-se… Read More
2020-05-22 08:00
We are back at it with another blog about terpene analysis! If you did not catch my previous post, be sure check it out here before moving on. Last time, I finished up by discussing how we w… Read More
2020-05-21 16:59
When you log into the ProEZGC Chromatogram Modeler software, you will see the screen below, which is what I refer to as the Welcome Screen. This is the starting point for all, and unfortunat… Read More
2020-05-18 15:41
In part I of this blog series, we learned about matrix effects, how to assess them, and how to address them (you can check the blog here). One of the main conclusions of part I was the impor… Read More
2020-05-14 16:01
One of the key parameters that requires optimization for splitless injections is inlet temperature. With liquid injections, the analyst is relying on the volatilization of the sample u… Read More
2020-05-11 14:53
They say when life hands you lemons, make lemonade. In this case, the COVID-19 pandemic has handed us all more downtime, so let’s talk about one aspect of a testing lab that tends to g… Read More
2020-05-07 14:35
Spring has sprung and now is a good time to give your GC system a thorough going over. There is routine maintenance that we should perform all the time to keep the GC in tip-top condit… Read More
2020-05-06 20:06
Predicting selectivity characteristics of adsorbent columns is often a wild guess. Yes, we know argon will have less retention than krypton, but how well do adsorbent columns separate noble… Read More
2020-05-02 18:00
Last year my colleague Landon publish his blog about pesticide multiresidue LC mix stability in a celery matrix and in a solvent. Today, I’d like to show you what happens when you do t… Read More
2020-05-01 12:37
In my previous blog on cryogenic cooling (https://blog.restek.com/cyrogenic-cooling-for-air-analysis-interferences-from-n2-co2-and-o2/) I touched briefly on ethylene oxide (EtO) and why it m… Read More
2020-04-30 15:55
Jason Herrington recently wrote a post titled SPME Arrow Configurations. The last paragraph in this post stated:
“One last talking point: We told you there is no free lunch when… Read More
2020-04-30 11:24
Split and splitless are the two most common modes of injection for GC. Each has its own set of pros and cons, with the required method sensitivity vs the sample concentration ultimatel… Read More
2020-04-24 16:29
To continue my blog parts 1 & 2 (Part 1:https://blog.restek.com/ p=67087,https://blog.restek.com/chiral-separation-on-a-c18-column-separation-of-d-and-l-amphetamines-part-ii/) , where I… Read More
2020-04-21 14:23
Method development for Quechers sample cleanup can be a complicated task. Not only does the analyst need to make sure their analytes of interest can be recovered, but the matrix interference… Read More
2020-04-20 16:57
The growing variety of cannabis products that are currently available in the market speaks volumes about the creativity of entrepreneurs within the industry. Vapes, lotions, balms, cookies… Read More
2020-04-17 17:27
Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in our society and can be found in a wide range of consumer products; hence they are widely present in the environment, people and a… Read More
2020-04-17 15:46
In Part I of this series, I posed the question of the impact of the amount of wool on liner performance. As a reminder, this study specifically examines Topaz liners that are prepacked… Read More
2020-04-15 20:07
Sometimes we get asked by customers for clarification when installing/connecting a new or replacement weldment from their purge & trap autosampler to their Agilent GC’s split/split… Read More
2020-04-09 15:44
The other day, I and some of my colleagues started a discussion about how chromatographers are handling the current Covid-19 situation. Some are working from home, and some are experiencing… Read More
2020-04-09 15:30
I know I am beginning to sound like a stuck record on this topic, but checking for leaks in your GC system on a daily basis, using an electronic leak detector, is a vital part of your routin… Read More
2020-04-09 15:10
It certainly does not only pertain to a quarantine period, but certainly more likely during the current Covid-19 crisis. Some of you might be needing to shut down your projects for a while… Read More
2020-04-09 15:02
March 2016, the U.S. EPA announced it would start updating the long overdue (i.e., not updated since 1999) Compendium of Methods for the Determination of Toxic Organic Compounds in Ambient A… Read More
2020-04-09 15:01
If you’ve followed my previous blogs on GC liner selection, you will know that the wool in inlet liners plays an important role for both split and splitless injections (GC Inlet Liner… Read More
2020-04-08 15:27
In this current economy with stay-at-home recommendations/requirements due to the coronavirus, it has been unfortunate that many laboratories have been or will be forced to temporarily close… Read More
2020-04-06 17:24
Spring is already here and summer is just around the corner and soon we’ll be trying to stay cool. For those of us doing ambient air analysis though, keeping cool can sometimes m… Read More
2020-03-31 17:30
In the past few months, we have collected a variety of chromatograms using two different column phases, and three different column dimension formats. The peak identifications were performed… Read More
2020-03-30 15:15
It’s time to dive back into analyzing terpenes! Previously, we looked at two types of sample preparation for analyzing terpenes via HS-Syringe and HS-SPME. If you missed those blogs, b… Read More
2020-03-27 18:39
If you have experienced retention time shifts with LC, you know it can be complicated and can cause problems with quantitation if not resolved. Hopefully this post will help you navigate thr… Read More
2020-03-24 13:48
If you have been looking at SPME Arrows, because we convinced you of the Arrows’ mechanical robustness, sensitivity, speed, etc., you could find yourself in a decision dilemma. Beyond… Read More
2020-03-17 14:22
If you use the correct fittings and seals in the gas chromatography system, and follow some simple steps, there is absolutely no need to over tighten any fitting to achieve a leak free seal… Read More
2020-03-10 12:38
We have been warning about the consequences of using liquid leak detection products for years (see Blog). These products, like Snoop, contain a whole host of compounds that can easily… Read More
2020-03-06 23:44
I completed my winter internship at Restek and my main task was to expand the Pro-EZGC libraries.
So I created a library for Nitrosamines on the Rxi-1301Sil MS and while acquiring data we no… Read More
2020-03-03 22:41
We’re taking you to Austin, Texas to meet the amazing team at Santé Laboratories for this investigation! This project, led by the analytical team at Sante Laboratories, put the… Read More
2020-03-03 20:41
My colleagues have written plenty of articles over the years with how to cut columns and get the perfect press-tight connection:
Jaap – How to make a good fused silica seal using a Pre… Read More
2020-02-28 23:24
Avocados are a popular produce item. In fact, the consumption of avocados rose by 450% since 2000! The good news – avocados are ranked number 1 on the clean 15 list, meaning they have… Read More
2020-02-15 17:30
My last blog examined the analysis of essential oils using GC columns with wax phases. While these columns are commonly used for natural oils, they are not the only option. Another choice th… Read More
2020-02-05 21:56
While attending Dioxin 2018 in Krakow, I noticed that several academic researchers were studying the toxicity of specific PBDE congeners not on the standard target compound list for EP… Read More
2020-02-05 15:16
Azo dyes are commonly used in many products, including food, textiles, and paints. In some azo dyes the azo functional group (R-N=N-R’) can be broken in reductive conditions to form ca… Read More
2020-02-03 22:20
We’re providing a creative trick for extending guard cartridges and column lifetimes. This preventative maintenance consumable also acts as a handy troubleshooting tool for probl… Read More
2020-01-31 20:01
In parts I and II of this blog series I discussed the various liner configurations available for both split and splitless analyses. One thing I did not mention was liner volume and inn… Read More
2020-01-21 13:28
The other day a customer contacted me to share the following discrepancy she has observed on several occasions: “when I collect ambient air samples with Restek 3 L canisters and colloc… Read More
2020-01-15 18:00
The most common way to analyze essential oils is to use GC with either a FID or MS. The wax-based columns are the number one choice for many users and following up on an excellent blog post… Read More
2020-01-09 12:15
Please join one of our courses presented next Pittcon in Chicago:
“Injection Techniques in GC”: Monday, March 2, 08:30-12:00, Session: SC1230.
“Practical… Read More
2020-01-07 22:38
To continue my blog part 1, where I have briefly discussed the importance of separating the d and l isomers to accurately identify the illicit isomer using an achiral method on a Raptor C18… Read More
2019-12-31 21:14
An early lesson most of us learn in liquid chromatography is this: Always match your diluent to your mobile phase. Once the exams are done, if you learned this in a college course, or… Read More
2019-12-30 14:40
As we approach the end of the year we are indulging in a bit of nostalgia and most experts agree that reminiscing about the past is a good thing1. It makes us more optimistic and generous. R… Read More
2019-12-20 21:28
In a recently published blog. We introduced the advantages of cleaning EPA Method 8081 extracts using CarboPrep Plus (CPP) as a replacement. The sample preparation for PCBs by EPA Meth… Read More
2019-12-19 19:59
LC-MS/MS using electrospray ionization (ESI) is a widely used platform for routine target analysis and quantitation. However, one big challenge faced through the use of ESI is the presence o… Read More
2019-12-18 19:30
The inlet liner is the first surface analytes will interact with after introduction into a GC. It is critical that liners are deactivated, as a number of adverse interactions can occur… Read More
2019-12-13 15:23
Welcome back my fragrance fanatics! Today, we continue exploring approaches for analyzing terpenes. If you missed part one, you can get caught up here! Last time, we discussed two HS approac… Read More
2019-12-06 20:51
Amines can be difficult to analyze by GC, since they are active and adsorb to surfaces within the chromatographic system, including the inlet liner and the column. This leads to loss o… Read More
2019-12-05 22:57
Did you know that chiral chemistry was discovered by Louis Pasteur, a French chemist and biologist in 1848? However, it took about a century to find that chirality plays a key role not only… Read More
2019-11-28 19:42
We recently took a look at combining Vitamin E Acetate and cannabinoids into one method https://blog.restek.com/?p=65679. This route allows labs to diversify their testing services wit… Read More
2019-11-22 16:56
Tetrachlorobenzenes are manufactured as intermediates for the production of fungicides, herbicides, defoliants, insecticides as well as dielectric fluids for transformers (1). There are thre… Read More
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