Sterlitech Blog

Marine biology and Oceanography organizations have long used a variety of filter media to assist with their research. While the ways in which filtration supplies can be used are as diverse as the life forms that live under the waves, here we highlight a couple of these applications that have previously been mentioned in published papers to give you an idea about some ways filters can be purposed in marine research.

In a study on mercury content of the ocean area between Antarctica and Tasmania, researchers from the Ifremer Institute used the 0.2 Micron, 47 mm polycarbonate membrane filters to filter samples of seawater and brine prior to determining their mercury content through atomic fluorescence spectroscopy. The PCTE membranes were used in conjunction with Sartorius filtration devices and a Nalgene vacuum pump to attain filtered water in volumes between 100 and 1000 mL. By applying this filtration setup the researchers were able to find patterns in how mercury travels the ocean.

Another oceanographic use for filtration materials comes from the study of zooplankton that live deep in the Pacific Ocean. 1.2 Micron silver membrane filters were used to pre-filter samples of plankton waste prior to nitrogen content analysis via a high temperature combustion technique.

Also using silver membrane filters (1.2 Micron, 25 mm) was an experiment by the Woods Hole Oceanographic Institution which used them as part of a study to see if the growth of marine phytoplankton in certain areas leads to organic carbon being exported. Here the membranes were used to collect and prepare particles from deep water samples for further analysis.

Remember, these are just a few examples of how filters can be used in the marine sciences. If you’ve been doing your own tests with filter media, let us know in the comments!

An especially pungent use for glass fiber filters is described in the latest issue of the Soil Science Society of America Journal. In the paper, “Influence of Dissolved Carbon and Nitrogen on Mineralization of Dilute Liquid Dairy Manure” two scientists from the University of California examined the wastewater used to flush dairy cow waste for the presence of these elements.

On dairy farms in which the milk cows are confined, water is used to flush away the manure and is then stored in lagoons to be treated for coarse solids before being re-applied to crop fields through irrigation. Refuse reuse if you will. One problem with this procedure is that if there is too much dissolved Carbon or Nitrogen in the wastewater it can create groundwater contamination.

For this study, the researchers collected wastewater samples from seven lagoons and analyzed them in order to investigate the relationship between the starting levels of Nitrogen and Carbon and the wastewater’s mineralization behavior. Their methodology included determinations of Totals Solids (TS) and Total Suspended Solids (TSS) by filtering the manure through a series of glass fiber filters, including the Advantec GF75 (0.3 micron) at several points. The GF75 was also used to filter wastewater samples prior to gravimetric analysis.

In this case, the authors found that the amount of Nitrogen that will be mineralized for crop consumption is very likely due to how much dissolved Carbon and Nitrogen is present on denitrification. Further investigation will be needed before scientists can accurately predict how much Nitrogen the crops treated with this water are actually exposed to.

The full paper is available here for American Society of Agronomy subscribers.

In a case of good news/bad news for industrial workers, OSHA (the Occupational Safety and Health Administration) is getting a budget increase for 2012, but the money comes with a delay on a proposal that would further limit workers’ exposure to carcinogenic silica dust.

The backstory: Last February OSHA sent a proposal to the White House Office of Management and Budget that called for a reduction in the silica PEL¹ (Permissible Exposure Limit), which would be the first change to this regulation since the 1960’s². The plan was to get the approval of the OMB and then open up the proposal to public debate after 90 days, but one year later and OSHA is still waiting.

The reason for the snag is most likely because of concerns raised by the industries that would be financially affected by stricter controls. Some opponents of the new OSHA proposal argue that the government needs to do a better job of enforcing the current rules before making any changes to the exposure level. Congress seems to agree with this priority, as the largest line item increase in the new budget is $5 million for additional enforcement OSHA’s sister organization, MSHA (Mine Safety and Health Administration). Representatives for the impacted industries, such as construction and mining, also point out that they subject themselves to voluntary monitoring and medical treatment for certain silica levels and these measures have been effective at eliminating the health risks to workers.

Unfortunately for those who disagree with that assessment, a stricter regulation is unlikely to happen in the immediate future since with the upcoming elections lawmakers aren’t in a hurry to pass a regulation that could paint them as “anti-business.” So at least for now OSHA is going to have to use their bigger budget to make the current regulations work.

For more information on the new OSHA budget we recommend this piece by NPR and this writeup from Patton Boggs LLP.

1)  The PEL for silica is a little tricky to explain – there are several variables and conditions that prevent it from being expressed as a simple number. You can read this blog post from The Safety Director’s Cut for a detailed explanation.

2) While the acceptable levels may change, there aren’t any expected changes to the recommended procedure for evaluating crystalline silica – which involves filtering samples on silver membrane filters and X-Ray Diffraction analysis. You can find the full procedure from the CDC here.

Last week we announced in our newsletter that we would be including free Sterlitech water bottles or coffee mugs in with online orders until Feb. 15th or while supplies last, and sadly for some we’ve reached the end of our supply today. Don’t fret if you missed out this time around, chances are good that we’ll be doing some more giveaways this year. Be on the lookout for upcoming promotions in our newsletter and online so you don’t miss out on the next one. In the meantime, stay thirsty my friends!

Got an idea about what our next promo item should be? Shirts? Golf balls? Let us know in the comments and we’ll try to make it happen.

There is a good article in “The Scientist” this month that covers how various labs have improved the throughput for their flow cytometry applications. The piece covers some of the problems users experience with flow cytometry, namely its time-consuming nature, as well as the steps that actual users have taken to improve the process for themselves.

Flow cytometry is a commonly used technique for performing cell counts and diagnosing diseases including leukemia. The use of flow cytometry to analyze cells in the fields of immunology research and drug discovery is growing thanks to new equipment that streamlines the process. A few of these solutions can cost tens or hundreds of thousands of dollars, so some of this equipment probably won’t be a feasible option for everyone. A less intensive-option that can improve processing speed is to outfit instruments with a well-plate sipper that can accept microtiter plates, such as the Empore 96-Well Solid Phase Extraction plates. The best solution will likely depend on the number of samples being processed by flow cytometry. As Steve McCellan, Senior Biological Scientist at the University of Florida, points out in the article, “Your arm would be paralyzed” if you had to test 20,000 samples with a normal flow cytometer.

You can read the full article online here to find out what else the pros have to say about flow cytometry.

Our apologies if you were affected by our sudden office closure yesterday due to a snowstorm here in Seattle. We’re back in business today and road conditions are improving, so we don’t expect to have any other forced holidays in the near future.

While there are many things Seattleites do well (software design, passive-aggressiveness), getting around in the snow is decidedly not one of them, as you can see in this YouTube video. Although in our meager defense, very little of the Seattle area sits on flat land and we do have the best soccer fanbase in the country. But until we can master the art of not braking through an ice patch, I get the feeling we will continue to be the object of ridicule from the Midwest, Northeast, and everywhere else that gets below-freezing temperatures from time to time.

Stay warm out there, wherever you are!

A recently completed test in Poland found that enhancing ultrafiltration (UF) flat sheet membranes with an anionic polymer increased the membrane’s ability to purify samples of galvanized wastewater. For this experiment, the researchers tested multiple concentrations of wastewater infused with zinc, nickel, and copper ions against EW and MW designation flat sheet membranes that were infused with a polyelectrolyte, in this case polysodium 4-styrenesulfonate (PSSS) with cation-exchange properties. The result was a more-efficient metal binding agent, enabling 97-99% retention of the target metals.

The EW membrane is made with Polysulfone while the MW is a modified Polyacrylonitrile known as Ultrafilic. Both designations ably treated the galvanized wastewater, but the MW membrane did have 2-3 times higher permeate flux values due to the membrane’s higher permeability.

In addition to membrane separation, common treatment options for galvanized wastewater include chemical processing and the ion exchange method. Unlike these other methods however, an effective membrane separation methodology has the potential to remove higher concentrations of effluent in a continuous process so these findings could impact how galvanic wastewater is processed in the future.

You can read the published paper here.

We’re sorry to say that we have just been informed that one of our ultrafiltration (UF) range flat sheet membrane designations, SelRO MPF-U20-S, has been discontinued. This means that we will no longer be able to offer our catalog numbers YMMPFU20S1818, YMMPFU20S195, YMMPFU20S475, or YMMPFU20S425. The SelRO MPF-U20-S designation was made from a proprietary Koch Membrane Systems polymer and used for a variety of research and industrial applications.

While this particular designation will be missed, we still have several other UF designations for sale that can meet your separation needs. To determine which designation is best for you, check out the Sterlitech UF specifications table.

Also, we have a very limited stock of these items still available so get in touch with us immediately if you are interested in your last chance to secure this membrane!

In the spirit of reflection we wanted to take a look at some of our favorite posts from 2011 that you may have missed, or may want to revisit for the sake of nostalgia. It’s been an amazing year for us, and we hope everyone out there has made the most of it as well! Here’s wishing you all a Happy New Year!

• Performance Improvement of Cross-flow Filtration for High Level Waste Treatment (Feb. 2011) - Tips on improving your filtration setup from the Department of Energy and Savannah River National Laboratory.
• Bean to Bar at Theo Chocolates (Mar. 2011) - Our own Kristina Shahbazian went on a tour of the only bean-to-bar, organic, fair trade chocolate factory in the USA, located right here in Seattle.
• Legionella Sampling Just Got a Whole Lot Sexier (Apr. 2011) - How the Centers for Disease Control utilized filtration sampling and social media Epidemiology to track an outbreak of legionella bacterium at Playboy mansion's infamous grotto.
• Deadliest Carch: Man-Made Pollution (Jun. 2011) - A collective of Scandinavian marine researchers created some new sampling techniques in order to perform analysis while out at sea.
• Silver Membrane Filters Play a Part in Antimatter Trapping (Jun. 2011) - A look at one of the more cutting-edge applications for our silver membrane filters - collecting antimatter in Physics research!
• Super Sand (Jul 2011) - Researchers are combining sand with a graphite oxide to create a super-efficient water filter.
• Wastewater Mistreatment (Aug. 2011) - The story of how one Canadian company's environmental mishaps led to fines and imprisonment.
• The T-SAR Approach to Study Nanofiltration Membranes (Sep. 2011) - German scientists are applying the T-SAR methodology to predict NF membrane performance.
• EPA to Create Standards for Natural Gas Wastewater (Oct. 2011) - Detailing new EPA standards being imposed on the water used in and resulting from hydraulic fracturing, or "fracking."
• NIH Issues $10,000 Challenge to Biomedical Engineering Students (Nov. 2011) - The National Institutes of Health created the DEBUT challenge to encourage students to develop new medical devices and technology.
• Crystalline Silica Exposure in Wisconsin (Dec. 2011) - The state of Wisconsin is considering tougher standards on the amount of carcinogenic dust it will subject its miners and industrial workers to.

In order to catch up with the massive backlog of chemical compounds that need toxicity assessments, the NIH, EPA, and FDA are expanding their Tox21 robot screening program to start testing a compound library of 10,000 samples. The Tox21 screening program was first conceived in 2005 and is a joint development between these three agencies. The Tox21 robot, located in Rockville, MD, was introduced earlier this year as the heart of the program and has already studied about 500 chemicals. To give you an idea of what an improvement this is, the EPA has only tested 200 chemicals since 1976. By speeding up chemical toxicity analysis the government will also accelerate the drug development process, as drug toxicity is one of the primary reasons new drugs fail.

The six-ton Tox21 robot system can test thousands of chemicals simultaneously using its vast network of tiny wells to perform high-throughput, cell-based assays at 15 different concentrations. The robot system is able to identify which chemicals have a potentially harmful reaction and then isolate them for further analysis by researchers. The economies of scale provided by Tox21 allow the program to keep the cost of testing each chemical to only a few hundred dollars.

The types of chemical compounds being tested by Tox21 are the same ones that go into food additives, medication, and industrial solvents, so the stakes for this project are high. To this end, the Tox21 team has opted for full disclosure of its results. From the Tox21 website you can see the full results of the chemicals that have already been tested, as well as the list of the 10,000 chemicals scheduled for analysis.

An added benefit of this project is that one of its mandates is to look for new chemical testing strategies that will minimize the number of laboratory animals used.

Learn more about Tox21 here.
Read the press release from NIH here.