How much bacteriostatic water do you need for a 2 mg vial of TB-500?

That depends on the concentration you are working to, so it is arithmetic rather than a fixed number. 2 mg of TB-500 in 0.5 mL of bacteriostatic water gives 4 mg/mL; in 1 mL it gives 2 mg/mL; in 2.5 mL it gives 0.8 mg/mL. Every volume on this page falls between 0.5 mL and 2.5 mL, so one 10 mL vial of bacteriostatic water covers this mix.

What concentration does 2 mg of TB-500 in 1 mL give?

2 mg/mL. 2 mg ÷ 1 mL = 2 mg/mL. On a 1 mL U-100 insulin syringe that is 0.02 mg in each unit mark and 0.2 mg in ten marks.

How do you work this out yourself?

Divide the amount of powder printed on the vial by the number of millilitres of water added. The answer is the concentration, in mg per millilitre. To turn that into syringe marks, divide again by 100, because 100 unit marks on a U-100 insulin syringe is exactly 1 mL.

Does this page say what amount to use?

No. This page is dilution arithmetic. It says what is in the vial once powder and water are mixed, and nothing at all about what to do with it afterwards. That belongs to the prescriber or the researcher responsible for the vial.

Bacteriostatic water for 2 mg TB-500

Mixing a 2 mg vial of TB-500 with 1 mL of bacteriostatic water gives a concentration of 2 mg/mL, which puts 0.2 mg in every 10 unit marks on a 1 mL U-100 insulin syringe.

Other water volumes give other concentrations. The full chart is below, with the arithmetic written out so you can check it against your own vial rather than taking this page at its word.

Bac water chart for 2 mg TB-500

Water volume, resulting concentration and syringe marks for a 2 mg vial of TB-500
Bacteriostatic water added	Resulting concentration	In 1 unit mark	In 10 unit marks	Whole vial, in unit marks
0.5 mL	4 mg/mL	0.04 mg	0.4 mg	50 units
1 mL	2 mg/mL	0.02 mg	0.2 mg	100 units
2 mL	1 mg/mL	0.01 mg	0.1 mg	200 units
2.5 mL	0.8 mg/mL	0.008 mg	0.08 mg	250 units

Unit marks are the numbered lines on a 1 mL U-100 insulin syringe: 100 marks = 1 mL, so one mark is 0.01 mL. A value written with a leading “~” has been rounded for display; amounts are shown in mg.

The arithmetic, shown

2 mg ÷ 1 mL = 2 mg/mL
2 mg/mL ÷ 100 unit marks per mL = 0.02 mg per unit mark

Concentration is the amount of powder divided by the volume of water. The volume of the powder itself is not counted, because at these amounts it is far smaller than the smallest line on the syringe - the same assumption every printed reconstitution chart makes.

What each mark holds at 2 mg/mL

At 2 mg/mL - that is 2 mg in 1 mL - a 1 mL U-100 insulin syringe reads like this. One unit mark is 0.01 mL, because 100 marks make 1 mL.

What each unit mark on a 1 mL U-100 insulin syringe holds at 2 mg/mL
Unit mark	Volume	Contains
2	0.02 mL	0.04 mg
4	0.04 mL	0.08 mg
5	0.05 mL	0.1 mg
10	0.1 mL	0.2 mg
15	0.15 mL	0.3 mg
20	0.2 mL	0.4 mg
25	0.25 mL	0.5 mg
30	0.3 mL	0.6 mg
40	0.4 mL	0.8 mg
50	0.5 mL	1 mg
60	0.6 mL	1.2 mg
80	0.8 mL	1.6 mg
100	1 mL	2 mg

How much bacteriostatic water do you need?

You need about 2.5 mL of bacteriostatic water to mix a 2 mg vial of TB-500.

Every water volume in these charts is between 0.5 mL and 2.5 mL, so a single 10 mL vial of bacteriostatic water covers the largest of them 4 times over. Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol as a preservative, which is what allows the same vial to be punctured more than once.

See the 10 mL vial

Storage and shelf life

Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol as a preservative. The preservative is the reason a vial can be entered more than once rather than being discarded after a single use. An unopened vial keeps until the expiry date printed on it; once the stopper has been punctured, the discard window printed in the manufacturer’s insert for that vial applies.

Store water and mixed vials as the labelling for each one directs, out of direct light. If the liquid changes colour, goes cloudy, or shows anything floating in it, it goes in the bin rather than in a syringe.

How long bacteriostatic water lasts, in detail

Common questions

How much bacteriostatic water do you need for a 2 mg vial of TB-500?: That depends on the concentration you are working to, so it is arithmetic rather than a fixed number. 2 mg of TB-500 in 0.5 mL of bacteriostatic water gives 4 mg/mL; in 1 mL it gives 2 mg/mL; in 2.5 mL it gives 0.8 mg/mL. Every volume on this page falls between 0.5 mL and 2.5 mL, so one 10 mL vial of bacteriostatic water covers this mix.
What concentration does 2 mg of TB-500 in 1 mL give?: 2 mg/mL. 2 mg ÷ 1 mL = 2 mg/mL. On a 1 mL U-100 insulin syringe that is 0.02 mg in each unit mark and 0.2 mg in ten marks.
How do you work this out yourself?: Divide the amount of powder printed on the vial by the number of millilitres of water added. The answer is the concentration, in mg per millilitre. To turn that into syringe marks, divide again by 100, because 100 unit marks on a U-100 insulin syringe is exactly 1 mL.
Does this page say what amount to use?: No. This page is dilution arithmetic. It says what is in the vial once powder and water are mixed, and nothing at all about what to do with it afterwards. That belongs to the prescriber or the researcher responsible for the vial.

TB-500 is a synthetic peptide fragment supplied as a freeze-dried powder and sold for laboratory research use only. It is sold for laboratory research use only and is not approved for human use. This site sells bacteriostatic water. It does not sell TB-500.