DPBS Powder: Reconstitution, pH and Osmolality Checks, and How a Pack Converts to Litres

The pack is dry salts, so the buffer is only as clean as the water and the filter your team uses. Buyers often read "10 L" as ten litres of finished sterile buffer; it is the volume the powder makes once someone dissolves, checks and filters it.

Prices are site list prices and exclude shipping; bulk pricing is quoted on request.

• Cost. Per litre of working buffer the powder is the cheapest of the three formats by a wide margin, the 10x concentrate sits in the middle, and the ready bottle costs the most. One 10 L powder pack replaces twenty ready 500 mL bottles; the current list prices are in the table above and on each product page.
• Storage. All four formats are listed for 2 to 30 °C storage protected from light, so none of them needs fridge or freezer space. The difference is shelf volume: twenty 500 mL bottles against one pack of powder for the same 10 L.
• Shelf life. Powder, concentrate and ready bottles all carry 48 months as supplied, so stocking a quarter or a year ahead carries little expiry risk.
• Shipping class. Every format ships at room temperature, with no cold chain to pay for. What changes is weight: the powder travels dry, while the bottles are mostly water.
• Labour. The saving is real only if someone has time, purified water, a pH meter and a sterilising filter. A lab without those is better served by the ready 500 mL bottle.

The powder and the 10x concentrate are both listed without calcium and magnesium; the version with both ions is a ready-to-use 500 mL liquid. Our PBS and DPBS composition reference explains why: calcium and magnesium phosphates can precipitate in concentrates and under heat, so those versions are supplied as filtered liquids. For the order, the rule is short: the ion-free buffer is the rinse before a dissociation step, and the version with ions is for washes where cells must stay attached.

The neighbouring buffers a buyer may be asked to quote in the same order:

The Hank's buffers carry 24 months, half the shelf life of the DPBS lines, so do not stock them as deep. The PBS-EDTA and EDTA bottles are listed with EDTA and without calcium and magnesium, and the EDTA solution is classed as a dissociation reagent, so neither is a plain rinse. Choose a Hank's or Earle's buffer instead of DPBS when the protocol calls for glucose or bicarbonate in the salt solution; both list 1.0 g/L glucose, which DPBS does not carry.

1. Water first. Use cell culture quality purified water and a clean vessel large enough to mix the full batch.
2. Dissolve the whole pack. The pack is blended for 10 L; make the full volume instead of splitting the powder by weight.
3. Measure and record pH. The powder is listed at pH 7.2 to 7.7, a wider and higher window than the 7.0 to 7.4 of the ready liquid, so do not assume a fixed value: read it, write it down, and adjust only if your protocol sets a tighter target.
4. Check osmolality. The acceptance range is 270 to 300 mOsmol/kg, the same range listed for the ready-to-use DPBS liquids. A reading outside it usually means the wrong water volume.
5. Sterilise by filtration. Filtration is the listed method for this pack. Pass the buffer through a sterilising-grade membrane into sterile bottles.
6. Label and date. The 48 months applies to the pack as supplied, not to the buffer you made. Set an in-house expiry for reconstituted buffer and write it on every bottle.
7. Keep the batch record. Pack lot, date, pH and osmolality on one line are enough to trace a later culture problem back to a buffer batch.

A buyer who moves a lab from bottles to powder will hear two questions.

• Does it need autoclaving? No. Filtration is the listed method for this pack: pass the made-up buffer through a sterilising-grade membrane.
• When does the made-up buffer expire? The 48 months applies to the pack as supplied. Set an in-house expiry for reconstituted buffer and write it on every bottle.

• Treating the powder as sterile buffer. It becomes usable buffer only after dissolving, checking and filtering.
• Autoclaving out of habit. The listed method is filtration, and the autoclave question is the most common one posted.
• Expecting pH 7.4 without measuring. The powder window is 7.2 to 7.7 and the ready DPBS liquid is 7.0 to 7.4; a lab that needs a narrow 7.3 to 7.5 should look at the PBS pH 7.4 bottle or adjust and record.
• Using the wrong buffer as a rinse. PBS-EDTA carries 1 mM EDTA and is not a neutral wash.
• Ordering the version with calcium and magnesium for the pre-dissociation rinse. That rinse is the job of the ion-free buffer.
• Copying salt weights from a video. Every weighing is a chance for an error; a pre-blended pack removes it: one pack, one volume of water.
• Buying powder with nobody to make it. If no one will keep the batch record, the ready bottle is the safer purchase.

Email [email protected] to request a wholesale quote or bulk pricing for DPBS powder or the spec sheet, or to ask about a trial quantity. Tell us:

• packs per quarter, or litres of wash buffer per month;
• with or without calcium and magnesium;
• the delivery country;
• whether you buy for resale, private label or your own use.

If you work to pH and osmolality limits, send them with the enquiry: ask us for the lot data and we tell you what is available for that lot.