Buyer guide

MEM Amino Acid Solutions: 50x Essential and 100x Non-Essential - Dilution, Which Media Already Contain Them, Storage

Two small bottles cause a steady share of media-prep errors: one is added at the wrong volume, the other is added to a medium that already contains it, and the wrong medium is only found when the cells slow down. The MEM non-essential amino acids solution is a 100X concentrate in a 100 mL bottle, and the MEM essential amino acids solution is a 50X concentrate in a 100 mL bottle. This page is for distributors, resellers and procurement buyers: how far a bottle goes, which of our media already carry the supplement, what ships cold and what ships frozen, and what to send us for a wholesale quote.

Buying for resale, private label or bulk supply? Email [email protected] or use the quote form to request a wholesale quote — our team replies within one business day with pack options and wholesale pricing.

The two bottles

	Non-essential amino acids (NEAA)	Essential amino acids (EAA)
Strength	100X	50X
Pack	100 mL	100 mL
Form	Liquid, filter-sterilised	Liquid, sterile-filtered
Raw materials	Animal origin-free	Animal origin-free
Storage	2 to 8 °C, protected from light	2 to 8 °C, protected from light
Shipping class	Blue ice	Blue ice
Shelf life	24 months	24 months

Both bottles are the same size, sit in the same fridge and arrive in the same blue ice box, which is exactly why they get mixed up. The strength on the label is the only difference a busy bench sees.

How far a bottle goes

Bottle	Strength	Add to make working-strength medium	One 100 mL bottle supplements
NEAA	100X	One part in a hundred: ten millilitres per litre, five per 500 mL bottle of medium	Ten litres, or twenty 500 mL bottles
EAA	50X	One part in fifty: twenty millilitres per litre, ten per 500 mL bottle of medium	Five litres, or ten 500 mL bottles

The business case is in the last column. The 100X bottle covers twice the medium volume of the 50X bottle, so at the list prices in the table above (the same for both bottles) the essential amino acids supplement costs about twice as much per litre of finished medium. A lab that uses both should order two EAA bottles for each NEAA bottle to cover the same volume. With 24 months of shelf life at 2 to 8 °C, a year of supply can be bought in one order without expiry risk.

Check the medium first: which of ours already contain NEAA

The costliest error is paying for a supplement and then adding it to a medium that already has it. Media with near-identical names differ on this one line, so read the additions list before the bottle goes on the order.

Medium	Pack	NEAA in the formula	Other listed additions	Order the NEAA bottle?
MEM with Earle's salts, glutamine and NEAA	500 mL liquid	Yes	1.0 g/L glucose, 2 mM glutamine	No
MEM alpha modification	500 mL liquid	Yes	1.0 g/L glucose, 2 mM glutamine, 0.11 g/L sodium pyruvate	No
MEM powder with Earle's salts	100 L powder	Yes	1.0 g/L glucose, 2 mM glutamine	No
Reduced-serum high-glucose DMEM	500 mL liquid	Yes	4.5 g/L glucose, 0.11 g/L sodium pyruvate	No
MEM with Earle's salts and glutamine	500 mL liquid	No, listed as without	1.0 g/L glucose, 2 mM glutamine	Only if the protocol calls for it
High-glucose DMEM	500 mL liquid	Not listed	4.5 g/L glucose, 4 mM glutamine, 0.11 g/L sodium pyruvate	Only if the protocol calls for it

Two of the MEM liquids are both sold as 500 mL bottles with phenol red, glutamine and Earle's salts; one lists the non-essential amino acids and the other is listed without them. A buyer who swaps one for the other because it was available changes the formulation for every culture that uses it. The same check applies to pyruvate and glutamine: the high-glucose DMEM already lists 4 mM glutamine and 0.11 g/L sodium pyruvate. For what the amino acids do and which are in each concentrate, see our amino acid supplement reference page; this page stays with ordering and handling.

What ships cold and what ships frozen

Amino acid bottles are rarely ordered alone, and the supplements on the same order do not share one storage class.

Supplement	Pack	Storage	Shipping	Shelf life
MEM NEAA solution 100X	100 mL	2 to 8 °C	Blue ice	24 months
MEM EAA solution 50X	100 mL	2 to 8 °C	Blue ice	24 months
MEM vitamin solution 100X	100 mL	-30 to -5 °C	Dry ice	24 months
L-glutamine 200 mM	100 mL	-30 to -5 °C	Dry ice	24 months
L-alanyl-L-glutamine 200 mM	100 mL	2 to 8 °C	Blue ice	Not listed; ask us
Sodium pyruvate 100 mM	100 mL	2 to 8 °C	Blue ice	24 months
L-glutamine powder	1 kg	2 to 30 °C	Blue ice	24 months

What this means for the order:

Two temperature classes. The amino acid bottles, the pyruvate and the alanyl-glutamine travel on blue ice; the vitamin solution and the liquid glutamine travel on dry ice. A mixed order ships as two boxes, and freight is quoted per order.
Freezer or fridge. The vitamin solution and liquid glutamine are stored at -30 to -5 °C; putting them in the fridge with the amino acid bottles is a storage error.
Glutamine is a separate purchase. The amino acid concentrates do not replace it; glutamine is its own bottle at 200 mM. A lab without freezer space can ask for the alanyl-glutamine form, which is listed for 2 to 8 °C storage at a higher list price.
Scale. A facility that makes medium by the hundred litres can take glutamine as a 1 kg powder stored at 2 to 30 °C, and MEM itself as a 100 L powder pack that already includes the non-essential amino acids.

Adding the supplements: order of work

Read the medium's additions list. If NEAA is already listed, stop.
Confirm the strength on the label. 100X and 50X bottles look alike and need different volumes.
Add supplements to the basal medium, then filter the complete medium once. A media preparation video from a major supplier treats serum, amino acids and antibiotics as one group of supplements and teaches when to sterile filter the complete medium.
Do not use supplements to steer pH. Under a DMEM preparation video a viewer asks how to keep the medium at a lower pH; that is a buffer and gas question, not a job for the amino acid bottles.
Write the additions on the bottle. Date, lot of each supplement and volume added.
Return the concentrates to 2 to 8 °C, away from light.

Mistakes that cost money

Supplementing a medium that already contains NEAA. Four of our media list it in the formula.
Using the wrong volume. The 50X bottle needs twice the volume of the 100X bottle for the same medium.
Ordering equal numbers of both bottles. The 100X bottle covers twice the volume, so equal numbers leave NEAA on the shelf.
Skipping glutamine because amino acids were added. It is a separate 200 mM bottle.
Storing everything in the fridge. Vitamins and liquid glutamine are frozen items.
Receiving a dry ice box with no one at the freezer. Plan the delivery day for the frozen supplements.
Swapping look-alike MEM bottles. One lists NEAA and one is listed without.

Request a wholesale quote, the spec sheet or lot data

Email [email protected] to request a wholesale quote or the spec sheet for the 100X and 50X amino acid solutions, or bulk pricing for larger packs. We do not print pH or osmolality for the two concentrates here; ask us for the lot data and we tell you what is available for that lot. Tell us:

the basal medium and cell line;
the serum level and litres of medium per month;
the delivery country;
whether you buy for resale, private label or your own use.

We reply with which bottles you need, how many, and wholesale pricing.

Reference pages on this topic

Essential vs Non-Essential Amino Acids in Cell CultureIn cell culture, an amino acid is called essential if cultured mammalian cells cannot make enough of it and it must be supplied in the medium - thirteen of them, the set Harry Eagle defined, including arginine, cystine, tyrosine and glutamine that are not classed as dietary essentials. The seven non-essential amino acids - glycine, alanine, asparagine, aspartic acid, glutamic acid, proline and serine - can be synthesised by most cells, and are supplied anyway because making them consumes carbon, ATP and reducing equivalents that would otherwise go into growth. A MEM NEAA 100X supplement contains all seven at 10 mM, giving 0.1 mM of each at working strength; add it to MEM or DMEM, which contain few or none, and leave it out of Ham's F-12, IMDM and DMEM/F-12, which already carry all seven.
MEM Alpha (α-MEM) and Minimum Essential MediumMEM alpha (α-MEM) is Eagle's Minimum Essential Medium enriched with all the non-essential amino acids, sodium pyruvate, lipoic acid, ascorbic acid, biotin and vitamin B12, and is supplied either with or without ribonucleosides and deoxyribonucleosides. It uses the same salt base as MEM — 2,200 mg/L sodium bicarbonate matched to a 5% CO2 atmosphere, 1,000 mg/L glucose and 1.8 mM calcium — and is the standard medium for mesenchymal stromal cells, bone marrow cultures, osteoblasts, CHO-DXB11 and CHO-DG44 selection, and many primary cell types. The nucleoside-free version is required for HAT and methotrexate-based selection systems.
EMEM vs DMEM: What the Modification Actually ChangedEMEM (Eagle's Minimum Essential Medium, also sold as MEM) and DMEM (Dulbecco's Modified Eagle Medium) are the same medium one generation apart: DMEM is Eagle's formulation enriched, with roughly four times the vitamins, about twice most amino acids, twice the glutamine, added glycine and serine, ferric nitrate, and 3.7 g/L sodium bicarbonate against EMEM's 1.5-2.2 g/L. The practical consequence is that DMEM supports fast-growing, metabolically demanding lines such as HEK293 and NIH/3T3, while EMEM suits slower, less demanding adherent cells and primary lines - and because DMEM's higher bicarbonate is formulated for 10% CO2 while EMEM's suits 5%, the two are not interchangeable without checking your incubator.
DMEM (Dulbecco's Modified Eagle Medium)DMEM (Dulbecco's Modified Eagle Medium) is a basal cell culture medium derived from Eagle's Minimal Essential Medium by raising the amino acid and vitamin concentrations roughly fourfold. It is supplied in high-glucose (4,500 mg/L, 25 mM) and low-glucose (1,000 mg/L, 5.6 mM) forms, buffered with 3,700 mg/L sodium bicarbonate, and requires serum or a defined supplement plus a CO2 atmosphere to hold physiological pH. DMEM is the default medium for adherent lines such as HEK293, HeLa, NIH/3T3, Vero and CHO-derived adherent cultures, and for most primary fibroblasts.
HEPES buffer in cell cultureHEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic organic buffer used in cell culture to hold medium at physiological pH without depending on incubator CO2. Its pKa is about 7.5 at 20-25 degrees C and about 7.3 at 37 degrees C, giving useful buffering across roughly pH 6.8-8.2, and it is normally added to medium at 10-25 mM from a sterile 1 M stock. Because HEPES buffering does not rely on the carbonic acid/bicarbonate equilibrium, HEPES-supplemented medium resists the fast alkaline drift that occurs when a flask leaves a 5% CO2 incubator.
Counting Cells with a HemocytometerA hemocytometer is a thick glass slide bearing a precisely etched grid over which a coverslip creates a chamber exactly 0.1 mm deep, so that a known volume of cell suspension can be counted under a microscope and converted to a concentration. For mammalian cells you count the four 1 mm2 corner squares, take the mean, multiply by the dilution factor, and multiply by 10^4 to obtain cells per mL, because each corner square encloses exactly 10^-4 mL. Mixing the sample 1:1 with 0.4% trypan blue before loading gives a viability percentage from the same count, since only dead cells with compromised membranes take up the dye.

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