Making your own saline, of any concentration, is very easy. Here I'll tell you how to make normal (i.e. isotonic, 0.9% NaCl) saline. Other strengths are straightforward to make.
What you'll need:
Okay, now to actual procedure. I apologize for the long-windedness; I wanted to include all the tips and tricks I've worked out.
Making Brine
Take a generous amount of salt and put it into a glass. Add some distilled water and swirl it around until the salt stops dissolving. Let the salt settle and pour off the milky solution. Repeat a few times to get most of the cloudy crap out. This will reduce filter clogging later on.
Add some more distilled water and swirl for a few minutes to get a saturated salt solution (brine).
Filtering
Fold your filter paper up and put it in your funnel / on the lip of your container of choice. There are two ways of folding it: the standard way and fluting. The standard way is to fold it in half twice and pull one layer out to get a cone. The easiest way of fluting is to fold the paper in half as many times as you can, alternating which direction you fold it in each time, then pulling it open to get a cone with ridges. (I recommend fluting, since it will cut down the filtering time.)
Carefully pour the brine into the paper, making sure not to overfill it. It should drip through at around a drop / 3 seconds with 11 cm paper. Add more brine to the filter as needed. Filter in small batches and make sure each one is perfectly clear by shining a light through it. If it's not, you'll have to clean out your funnel / whatever with distilled water and re-filter the brine with a new paper.
Making Saline
Now, for the magic formula. For isotonic (0.9%) saline, you'll need 28.4 mL of brine per liter of saline, the rest being distilled water. Measure out the brine into your saline bottle, fill 'er up the rest of the way with distilled water, and shake.
That's it. Now enjoy your pure, additive-free saline. Shoot some up your nose and enjoy the smooth lack of burning that the overpriced drug store crap always causes.
For other concentrations, adjust the amount of brine accordingly. For example, for 0.45% saline, use 14.2 mL of brine / liter of saline.
Side-note: the ratio of brine to water is almost totally independent of temperature since NaCl has an essentially flat solubility curve in water over anything that can be called room temperature.
What you'll need:
- Fine (small pore size) filter paper. I use 11 cm Whatman 50 paper, which is listed as having “fine crystalline” retention, the finest they make. (A coffee filter won't come close to cutting it, so forget about that.)
- Something to hold the paper. A funnel is ideal, although a shot glass, clean prescription bottle, etc. will do just as well, depending on the size of your paper.
- A container to hold the filtrate. It should be clear so you can verify that the filtrate is clear.
- A clean bottle of known capacity for making / storing the saline.
- A liquid measuring device. I use a syringe.
- Distilled water. Go to your local supermarket.
- Ordinary salt. Don't use the reduced / no-sodium stuff. It doesn't matter if it's iodized.
Okay, now to actual procedure. I apologize for the long-windedness; I wanted to include all the tips and tricks I've worked out.
Making Brine
Take a generous amount of salt and put it into a glass. Add some distilled water and swirl it around until the salt stops dissolving. Let the salt settle and pour off the milky solution. Repeat a few times to get most of the cloudy crap out. This will reduce filter clogging later on.
Add some more distilled water and swirl for a few minutes to get a saturated salt solution (brine).
Filtering
Fold your filter paper up and put it in your funnel / on the lip of your container of choice. There are two ways of folding it: the standard way and fluting. The standard way is to fold it in half twice and pull one layer out to get a cone. The easiest way of fluting is to fold the paper in half as many times as you can, alternating which direction you fold it in each time, then pulling it open to get a cone with ridges. (I recommend fluting, since it will cut down the filtering time.)
Carefully pour the brine into the paper, making sure not to overfill it. It should drip through at around a drop / 3 seconds with 11 cm paper. Add more brine to the filter as needed. Filter in small batches and make sure each one is perfectly clear by shining a light through it. If it's not, you'll have to clean out your funnel / whatever with distilled water and re-filter the brine with a new paper.
Making Saline
Now, for the magic formula. For isotonic (0.9%) saline, you'll need 28.4 mL of brine per liter of saline, the rest being distilled water. Measure out the brine into your saline bottle, fill 'er up the rest of the way with distilled water, and shake.
That's it. Now enjoy your pure, additive-free saline. Shoot some up your nose and enjoy the smooth lack of burning that the overpriced drug store crap always causes.
For other concentrations, adjust the amount of brine accordingly. For example, for 0.45% saline, use 14.2 mL of brine / liter of saline.
Side-note: the ratio of brine to water is almost totally independent of temperature since NaCl has an essentially flat solubility curve in water over anything that can be called room temperature.
