Hydrocarbon analysis for benzene - trust but verify

Hash and Stuff Extraction
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While most users receive analyses and paperwork from their suppliers that show no benzene in the hydrocarbon solvents they receive, benzene contamination continues to be a problem for the extraction industry. Making matters worse is that only processed output is formally tested for benzene content, making extractors the only party losing hard dollars because of the problem.

Ideally, extractors would test their hydrocarbon solvents for benzene contamination before the solvents are used. Rules and regulations for shipping hazmat are unknown by most extractors, making end-user pre-testing difficult if not impossible. To date, extractors have had no good way to verify the quality of the hydrocarbons they receive.

We are involved in the industry as a hydrocarbon fill plant and recognize that our analytics might be seen as biased. Regardless, we’ve developed a sampling kit that allows end-users to pull liquid samples directly from hydrocarbon solvent tanks and have those samples tested for benzene. Once the sample is taken it can either be returned to our lab for testing OR sent to a lab of your choice for testing. Regardless of where the sample is sent, we will arrange proper shipping to make the process as smooth as possible for the end-user.

We will not ask which company supplied the product being sampled. Our efforts are only to allow the extractor to confirm the analyses of the hydrocarbon solvents they receive. Our testing will only serve to inexpensively identify a problem that an end user may choose to act on. Hopefully the testing results will not detect benzene contamination in the solvent and no problem will to be addressed.

Our lab tests hydrocarbon samples against a known standard of benzene in n-butane. The sample will PASS if benzene is NOT DETECTED and will FAIL if any level of benzene is DETECTED. After testing, an analytical report along with a gas chromatogram of the analysis will be sent to the customer by email. In the event of a FAIL, and depending on how the customer wants to proceed, our lab is willing to assist with shipping the customer’s solvent cylinder to an accredited 3rd party lab for more complete testing / independent verification of the benzene contamination. Our goal is to help everyone in the industry get a handle on the source(s) of the issue.

Our lab is not your only option for analysis, but we are reasonably priced. If our lab does the analysis the total cost for shipping and analysis is $200, which must be paid prior to our shipping the kit. If the sample is sent to another lab for testing, the cost for the kit and all shipping by ground is $150, likewise prepaid. In this case, the customer will have to arrange for the 3rd party analysis and cover the costs associated with the analysis. Expedited shipping by FedEx is available for either or both legs of transport at additional cost. *** 3rd party labs have quoted us between $350 and $600 for analysis for benzene contamination ***.

If interested in such analysis, email lab@qualityextractions.com for information and instructions on how to proceed.

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what kind of set up are you all using for your benzene testing? FID or MS?

what is your LOQ/LOD on benzene in n-butane?

any difference in LOQ/LO Dfor propane or iso-butane matrix?

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Forgive me for this lengthy reply. Once I started typing, I just kept right on going.

We use FID analysis. Standard used for comparison is 2.32 ppm benzene in n-butane with a reliable LOD of at 0.20 ppm. We report a FAIL for any sample with benzene detected.

Attached is most recent in-house analysis of bulk delivery of n-butane along with analysis of our 2.32 ppm standard. Retention time of the benzene in standard is 7.99 minutes with area count of 13.7 units. The analysis of the bulk delivery showed no peak at anywhere near 8 minutes. Manufacturer’s analysis showed benzene at < 0.0 ppm with LOD at 0.1 ppm. Our testing showed benzene at < 0.20 ppm. While we cannot get to 0.0 ppm, this bulk delivery was a PASS with benzene undetected by our system.

Butane Bulk Analysis 9.26.24.pdf (649.2 KB)

We use the same benzene in n-butane standard for high-temperature analysis of all hydrocarbon samples, pure propane, pure butane, pure isobutane and blends of all 3. Regardless of the major hydrocarbon component(s) in the sample, the elution time for benzene contamination is fairly consistent and far outside the elution times of expected contaminates.

For the heck of it, we analyzed some of the little cans of butane offered on line and at hydroponic stores. We analyzed at three temps: 65C for good separation of C1-C4s; 100C for good separation of C4-C6 and high temp of 165C to get C6-C7 into vapor phase. One of these little cans claimed to be 99.9998% pure n-butane with the sole contaminate being 0.0002% isobutane. It tested to be disgusting at 60ish% n-butane and at 165C benzene appeared at 7.34 minutes at or about 14 ppm. I don’t even know what some of the peaks might be.

The last time we had a 3rd party check the butane in the larger cylinders they offer to the extraction industry, the n-butane showed higher purity at 96%, with undetected benzene, BUT, the 96% is far lower than every state’s minimum purity requirements. We’re not naming names, but I’m hoping that our down-and-dirty analyses will encourage resellers and end-users to get additional 3rd party analyses, which should cause them to avoid using such materials in the future.

Awful n-butane.pdf (692.5 KB)

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One of these little cans claimed to be 99.9998% pure n-butane with the sole contaminate being 0.0002% isobutane. It tested to be disgusting at 60ish% n-butane and at 165C benzene appeared at 7.34 minutes at or about 14 ppm. I don’t even know what some of the peaks might be.

The invisible hand of the market at work… Regulation is unamerican :face_exhaling::saluting_face:

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Whether in little cans sold to open blasters or in large cylinders sold to commercial extractors, I have nothing but disgust for companies that take advantage of customers who lack the ability to verify the quality of their products.

Most buyers of these little cans of butane are hobbyist extractors. I can’t speak to the accuracy of contents being “_____ times filtered” (fill in the blank) and I realize that cross contamination of n-butane with propane and isobutane won’t kill anyone, still, claims of offering 99.99+% pure butane are 100% bullshit if the contents are actually < 65% pure. There is no such thing as 99.999+% butane.

I admit and we didn’t test the purity of the n-butane offered by every manufacturer of little cans of n-butane, but the 4 we did test analyzed to be mostly n-butane with significant percentages of propane and isobutane. Of those we tested, only one manufacturer accurately represents the contents of their cans. They label their little cans as a "tri-blend’ of 54% n-butane, 22% propane, and 24% Iso-butane.

Commercial extraction facilities have their end-products tested for all kinds of contamination and would be well-advised to at least occasionally test incoming solvents to ensure a) compliance with legal requirements for minimum solvent purity and b) the presence of benzene which has the potential to cost them tens of thousands of dollars.

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