Advice

Ethanol (more commonly known as ethyl alcohol, spirits, or simply alcohol) is an incredibly useful chemical compound. Generally made through the fermentation of sugars by yeast, once distilled, it has a wide range of uses: as a solvent, an antiseptic sanitizer, a component in fuels, and probably most widely as a recreational drink. 

Because ethanol is so popular as a component of alcoholic beverages, the sale of ethanol in Australia is restricted under the ATO’s Concessional Spirits Scheme. This means, if you’re looking to purchase ethanol in Australia for any purpose, you need a Concessional Spirit Permit or be subject to excise duty; the commodity-based tax on alcohol, tobacco, and fuel and petroleum products manufactured or produced in Australia.

Let’s take a quick look into the different types of ethanol available, who is eligible to purchase them, and how to apply for your permit. 

Denatured vs Undenatured Alcohol

There are two types of alcohol available for purchase: Undenatured and Denatured.

• ‘Undenatured’ alcohol is restricted for purchase in Australia. It is more commonly known as simply ethanol or alcohol. This is the pure version of the chemical compound. If you’re looking for ‘food grade alcohol’ or ‘pure ethanol’ this is what you’re after. 
• ‘Denatured’ alcohol is unrestricted for purchase in Australia, as it has been made unfit for human consumption and is no longer any fun. It contains additives to make the alcohol poisonous and taste and smell nauseating. The most common example is Methylated Spirits, which contains roughly 10% methanol, as well as other additives such as denatonium benzoate to make it unpalatable. Because ethanol is dangerous and taxed so highly by governments, it must be made unfit for drinking before sale to the general public. 

Denatured ethanol is widely available and cheap to purchase. It is often used as a household cleaner, fuel for camping stoves, paint thinner and more. However, due to its toxicity, it cannot be used, for example, in the production of hand sanitizer due to the toxic effects of methanol when absorbed through the skin. There are still a great many uses where only undenatured alcohol will do, and getting your hands on some takes work – though it is not impossible. 

Who is Eligible to Purchase Undenatured Alcohol in Australia?

If you work as a health care practitioner, a veterinary practitioner or for a medical, government and educational institution, we have good news: you are already eligible to purchase and use ethanol (for approved purposes only) under the tax-free 3.6 tariff without needing a Concessional Spirit Permit.  

If you do not work for one of these institutions or practices, don’t worry. If you plan on using the ethanol for an approved industrial, manufacturing, scientific, medical, veterinary or educational purpose, it shouldn’t be too difficult to get approval for purchase. 

Regulations around the use of ethanol are governed by relevant local, state, territory and federal bodies, so it is difficult to provide a comprehensive list. However, approved uses include, but are not limited to:

• Fortifying Australian wine or grape must
• Manufacturing
  • medicines, including vaccines
  • essences and flavours
  • mouthwashes
  • printing inks
  • foodstuffs
• Sterilising equipment
• Preserving specimens
  

If you aren’t sure if your planned use of ethanol is allowed, please contact the ATO. For a full list of excise duty rates for alcohol and alcoholic beverages, click here. 

Applying for a Permit to Purchase Ethanol

If you believe your planned use of ethanol will be approved, and all you need to do now is submit an Application For Approval to Use Spirits. This is a simple process. Download the form from the ATO here and follow the steps provided. 

Depending on your use case, permits are generally valid for the following periods:

• Permit for one-off specified quantity: six weeks
• Initial ongoing permit: one year
• Renewals of ongoing permit: five years.

You will only be allowed to purchase the allowed quantity of ethanol during this period. During your permit period, you will also need to keep clear records to show how you are using it. This means:  

• The amount you hold
• The amount you obtained
• The date you obtained it
• The name of your supplier
• The purposes for which you used it

These records must be kept for at least five years. 

Purchasing Ethanol 

Congratulations! If you have an approved permit, we can supply you with Ethanol! 

Don’t hesitate to get in touch if you have any questions, or would like to place an order.

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This article was originally published by Sequoia Scientific. It details the advantages of their new ‘Super Turbidity’ sensor; the LISST-AOBS. 

The short explanation

Briefly, the difference between turbidity and Super-Turbidity (Patent Pending) can be summarized as follows:

Turbidity (NTU) = Optical Backscatter; Needs Calibration for SSC; less accurate
Super-Turbidity (mg/l) = Optical & Acoustic Backscatter; No Calibration for SSC; more accurate

• NTU: Nephelometric Turbidity Unit
• SSC: Suspended Sediment Concentration

The slightly longer explanation

Traditional turbidity sensors deliver a reading in NTU, which must be calibrated to SSC with samples. Turbidity sensors are highly sensitive to fine particles, and insensitive to large particles. In contrast, the LISST-ABS delivers a DIRECT reading of SSC in mg/l and has a nearly constant sensitivity for particles larger than about 30 µm, out to about 500 µm. But, below this range, the response is also size dependent.

LISST-AOBS Super-Turbidity – the combination of a turbidity sensor and a LISST-ABS – delivers a direct reading of SSC in mg/l. This SSC reading is far more accurate for both fine and coarse particles than either sensor on its own.

LISST-AOBS Super-Turbidity compared to turbidity and LISST-ABS

The figure below shows a real-time plot of Super-Turbidity compared to the optical and acoustic backscatter sensors individually.

On the top plot we see time history of turbidity sensor output in V (orange) and LISST-ABS concentration in mg/l (blue). Each sample is at 1 s interval. The two sensors were installed together in a beaker with equal amounts of 5-10 and 75-90 µm particles. The particles were kept in suspension and well-mixed with a magnetic stir-bar. Around sample number 30 the stir-bar was turned off. A few seconds later the 75-90 µm particles have fallen out of suspension. We see the LISST-ABS concentration dropping almost 1,000 mg/l, but the fine 5-10 µm particles stay in suspension. Crucially, there is almost no response from the turbidity sensor; it does not see the coarse particles disappearing, only the 5-10 µm particles in suspension.

The bottom plot shows the COMBINED LISST-AOBS Super-Turbidity response from the two sensors, paired according to Sequoia’s patent pending method. The output is directly in mg/l. It is evident that the COMBINED output shows the concentration decrease from the large particles settling AND the concentration of the remaining finer particles.

The longer explanation

The figure below shows the response of the LISST-ABS and an optical turbidity sensor for a range of standard particles with varying grain-sizes. Each curve shows the response of the LISST-ABS (circles) or turbidity sensor (plusses) for a given grain-size as a function of concentration. Note that the concentration varies three orders of magnitude from ~5 mg/l to a few 1000 mg/l.

Let us look at the four LISST-ABS curves at the top of the plot. These are for particles from 40-80, 63-75, 75-90 and 125-150 µm in size. We can see that they are all very close together. We can also see that these four curves are on or very close to the 1:1 line (line not shown). This shows that the LISST-ABS measures the correct concentration, regardless of grain-size, as long as the particles are coarse. Note that the LISST-ABS output is directly in mg/l from the factory, without the need for any further calibration.

Let us now look at the two red, two green and one blue line from the OBS that plots together. These are for particles from 4-8, 5-10, and 10-20 µm in size. They all plot close together. This shows that the OBS output is constant for a given concentration, as long as the particles are fine. If desired, the OBS output for these fine particles can be calibrated to concentration with a high degree of accuracy.

Now, let us look at the second figure below.

This figure shows ALL data points from the previous plot. The data has been converted to LISST-AOBS Super-Turbidity using Sequoia’s patent pending methodology. It involves combining the data from the turbidity sensor and the LISST-ABS using a weight factor for the turbidity sensor output.

The units for the turbidity sensor output are completely irrelevant for the sensor pairing. It doesn’t matter if the turbidity sensor output is V, mV, FNU or NTU or any other unit. When pairing two sensors using Sequoia’s patent pending method, their COMBINED output will be in units of mg/l – as shown on the plot – regardless of the turbidity sensor unit.

Also shown on the plot is the 1:1 line. We can see that all data plot within a factor of two from the 1:1 line, regardless of changes in grain-size and concentration. This means that the combined output from the two sensors is far superior than each sensor on its own.

‘Super-Turbidity’ is a Sequoia-developed patent pending methodology.

CHECK OUT THE NEW SUPER TURBIDITY SENSOR

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When we talk about pure water, we usually think ‘clean’ and ‘fresh’. This is great for drinking, and the principle marketing tactic of the vast majority of bottled water companies. However, in order to guarantee the accuracy of our results in laboratory experiments and ensure the high-quality production of various materials (such as semiconductors, pharmaceuticals and photovoltaic cells) we need to stick to some much stricter specifications for purity than ‘clean’ and ‘fresh’.

Elements and compounds such as sodium, calcium, or copper – even present in the parts per billion range – could interact with samples, active media or system components.

This means, unfortunately, if you’re running a lab, even Mount Franklin or Voss isn’t going to cut the mustard. You can’t use ‘pure’ water. You’re going to need ultrapure water.

The Universal Solvent

Water dissolves more substances than any other liquid around. Hence, it’s known as the ‘universal solvent’.

The chemical composition of water is what gives it this unique attribute. The Oxygen atoms that make up H2O are positively charged, whereas the Hydrogen atoms are negative. The structure of their arrangement means that they line up end-to-end in a polar fashion. This allows water to attract many different types of molecules, and rip them apart by disrupting the attractive forces that keep them together. Ergo; dissolving them.

Just take a look at our oceans. Salt (Sodium Chloride), is dissolved readily in water. H2O molecules separate the bonds between the Sodium and Chlorine atoms, creating a solution of salt and water. As salt is quite a common molecule, and water is such a fantastic solvent, the salinity of our oceans is now, on average, 35 parts per thousand. That means for every liter of water, there’s approximately 35 grams of salt. Even more surprisingly, water could happily dissolve 9 times more salt (if it was available) before it became saturated. That’s about a third of its own weight.

Grading water purity

Now we know how readily water will take up impurities, let’s take a look at how we define ‘purity’.

For laboratory uses, water purity can be assessed using a range of techniques – depending on what the water will be used for. However, most commonly, purity is measured through resistance or conductivity.

Contrary to popular belief, water isn’t actually conductive. It needs suspended metals and ions to help it pass a charge. The more impurities in the water, the greater charge it can conduct. I.e: the lower the conductivity the more pure the water is. Thus, most water purity standards are measured by their resistance, usually measured in milliohms per centimeter (MΩ.cm).

There’s a few different grades of water purity. This is how the American Society for Testing and Materials (ATSM) defines them:

Type III – Primary Grade Water – less than 1 MΩ.cm at 25°C

Type III is clean – but it’s not technically ‘purified’. This grade of water is generally used for non-critical applications like rinsing glassware, filling water baths, and feeding autoclaves and other sterilisers.

Type II – Purified water – 10-15 MΩ.cm at 25°C

Type II water doesn’t quite reach the standards of ‘ultrapure’, but it’s still pure enough for general lab use. This is generally what is used to prepare medias or buffers.

Type I – Ultrapure water – 18.2 MΩ.cm at 25°C

Ultrapure water, by definition, only contains H20 and H+ (Hydrogen) and OH- (Hydroxide) ions. Everything else has been completely stripped away.

Type I water is used in manufacturing, as well as laboratory applications such as spectroscopy, spectrometry, histology, and more.

Producing your own ultrapure and deionised water

If you want ultrapure water – just water; nothing else – you’re going to need to put it through some pretty serious treatment to remove any unwanted ions or impurities. That means following one, or a few, of these methods.

Reverse osmosis

‘Osmosis’ describes the tendency of solvents to move through semipermeable membranes from solutes with a higher concentration into solutes of a lower concentration.

For example, water molecules inside a cell will travel through the cell wall when it’s submerged in saltwater. And if a cell is submerged in freshwater, water molecules move into the cell if the water inside is saltier.

Through this naturally occurring mechanism plant roots take up water from the soil, our intestines absorb water from a can of coke, and slugs shrivel up if you pour salt on them.

However, it is also possible to reverse osmosis with a technique called… well, ‘reverse osmosis’ (or ‘RO’).

Using a lot of mechanical force to push a solvent with a high solute content (i.e; saltwater) through a filter can help to remove any particles too big to fit through the gaps. It’s much the same process as removing rocks from sand with a sieve – but on a much smaller scale.

With some pressure and a semipermeable membrane with just enough room for water molecules to squeeze through, you can essentially filter out the sodium and chloride ions in salt water. You’re left with pure water and a waste brine solution.

Ion exchange

Another method of purifying water is by passing water through an ‘ion exchange resin’.

The resin is used normally in the form of small, porous beads. This gives the resin a high surface area, and helps water pass through easily.

Different resins will be coated in negatively or positively charged desirable ions (anions and cations, respectively). As the water passes through the resin, unwanted ions are ‘swapped out’ for more desirable ions, such as Sodium or Chloride. The resulting water can then be passed through reverse osmosis to easily remove the remaining impurities, giving you much more pure water than reverse osmosis alone could have achieved.

However, because of the nature of the process, the resin materials will become depleted over time. When the resins are ‘full’, they become unable to exchange ions any longer, and will need to be ‘cleaned’, ‘recharged’ or simply replaced.

Electrodeionization

The last, and perhaps most effective method of purifying water is through Electrodeionization (EDI). Most commonly, this is done through Merck-Millipore Elix® Water Purification Systems.

Rather than resin beads, electrodeionization uses an electric field to remove ions from your water. No beads means no need to change them regularly, which gives EDI a significant advantage over ion exchange systems.

EDI is often used, (as with ion exchange), in conjunction with reverse osmosis to ensure maximum purity. The water is first filtered to remove any large particulates, then treated with RO, and finally, through an electrodeionization field. Merck-Millipore guarantees water quality of >5 MΩ.cm at 25°C for most of their systems, however, they generally produce water at type II’s 10-15MΩ.cm range.

Storing ultra-pure water

Now that you have your ultrapure water, there’s a few things to consider.

Firstly, water doesn’t like being pure. Like an (ironically) dry sponge, it’s going to want to soak up anything it can. You’re going to need it kept in some very specific conditions to ensure it doesn’t pick up any harmful impurities such as organic or inorganic compounds, dissolved gases, or microorganisms.

This means your ultrapure water can’t be exposed to open air. This can be a rich source of contaminants such as carbon dioxide, volatile organics (if your laboratory uses solvents), acid fumes (if your laboratory uses strong acids), and of course, microorganisms.

Secondly, the material of the storage vessel should be carefully considered. Depending on the purity of your water, certain materials may leach contaminants. Glass, for instance, can release silica and sodium. Polymers can release plasticizers. Metal tanks can release metal ions.

Depending on the application you require your ultrapure water for, we would recommend selecting a storage option that releases the least harmful contaminants. Secondly, ensure that the inside of the tank is as smooth as possible. The reduced surface area will help lessen the amount of contaminants that can leach out of the container, and also make it harder for algae or bacteria to grow.

The best containers we have come across are often sold to be used in conjunction with Merck-Millipore Elix® systems. Depending on your requirements, these come with a range of features (such as UV lighting to keep algae and microorganisms from growing, etc) to prevent re-contamination. However, in order to guarantee purity and accurate test results, it is still not advisable to use them to store ultrapure water for extended periods.

The reality is; ultrapure water will eventually be recontaminated. It’s inevitable – there are simply too many ways that it can lose its purity over time.

If you need a steady source of ultrapure water for your laboratory, you’re going to need to create it on demand with a water purification system of your own. It’s simply not feasible to buy in bulk, and use as you need it.

Getting started with ultrapure water for your lab

If you’re looking for ultrapure water, storage, or a water purification system for your lab, we’d love to help you find the perfect solution.

Give us a call on (03) 6216 1500, or get in touch with the team!

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