I suspect the yield will depend on physiological parameters such as the platelet size and number, plasma vicosity, etc., as well as the centrifuge parameters. Blood services work on a "one size fits all" approach, assuming their "healthy" donors fall within the normal ranges for those physiological parameters and will optimise the centrifuge parameters to gain maximum yield from them [with continuous QC monitoring to ensure compliance].

When I used to work in a small Platelet Immunology [PI] lab I used 30mL universal tubes containing 2mL of 5% NA2EDTA and added 18mL blood. This was spun at 2400rpm for 5min [brake off] to get a PRP [don't recall the g, but it was about 5.5 inch from spindle to the interface]. This was transferred to a new tube and spun at 3400rpm [1000g] for 6min to get a very good sized pellet [brake on] from a person with a normal count. Later on, in a larger PI lab, we used 6mL K3EDTA tubes - 3 x 6mL would usually get enough platelets to test even from a thrombocytopenic patient [only one needed from a normal donor]. Neither were optimised to reduce activation.

When we quantitated platelet glycoproteins [GP] we found citrate being better than EDTA to prevent activation [as measured using an activation MoAb alongside the other GP MoAbs], and used citrate wash buffers [as in method below]. If activation was above a certain level we rejected the test. For general PI work EDTA was better to handle the platelets and we used EDTA/PBS with Bovine Serum Albumen added.

6.2 Prepare PRP by centrifugation of citrate samples at 1200 rpm for 10 minutes (brake off)

6.3 Transfer the PRP into a glass tube and prepare to count samples using the sysmex K1000 haematology analyser.

6.4 Resuspend PRP to a concentration of 5 x 109/L:

6.4.1 Perform count on neat PRP and divide the result by 10.

6.4.2 Take the reciprocal of the calculation, and multiply by 3000.

6.4.3 The value given is the volume of neat PRP in microlitres, to be

added to 3ml of GP estimation working solution in a clean universal container.

6.4.4 Check the platelet count of the diluted sample is approximately

10 x 109/L.

6.4.5 Add up to a further 3ml of working solution to the dilution in

order to reduce the count to 5 x 109/L.

6.4.6 Note the final platelet count on the worklist.

Important

Barrier pipette tips must be used when handling the stock monoclonal antibodies. Check each antibody batch is within the expiry date,and note batch numbers.

6.5 Add the correct volume of (saturating concentration) MoAb to the relevant facs tubes according to the worklist and using the table below.

l of 5 x 109 /L plateletsm6.6 Add 100 (prepared in 6.4) to each tube according to worklist. Check the dry incubator is C and incubate in the dark for 30 minutes.°set at 18-22

6.7 Add 2 mls of working solution to each tube and spin at 3000 rpm for 6 minutes, with the brake off.

6.8 After centrifugation discard the supernatant and gently resuspend the pellets using a flicking action.

Don't know if this helps any. There are other discussions on researchgate regarding similar issues. 

To prepare PRP from anticoagulated blood is very simple , but it depends upon the centrifuge you use. If you will use a benchtop  centrifuge you need to centrifuge anticoagulated blood at about 250 g per 15 minutes and then you will collect surnatant (PRP) but if you use other types of centrifuges (more potent) you have to transform 250 g in rpm (it depends upon the radios of your centrifuge) for example you may need to centrifuge at 800 rpm for 10 - 12 min (with this different kind of centrifuge). you can find a table (online) to see the change from g in rpm depending upon your centrifuge radios.

Otherwise it may happens that you cannot find platelets into the surnatant. The best is abut 7 ml of anticoagulated blood into 15 ml falcon at 250 x g by using a benchtop centrifuge!

Let me know!

I can agree with Carla. One must be aware that different rotors (radius) generate different g. It is important for who reason you need to obtain PRP. If you need PPR for optical aggregometry (LTA), I recommend you centrifugation at 150 g for 10 min with a slow brake, at room temperature. To use of a swing-out bucket rotor centrifuge is also recommended. In this condition you can obtain the most efficiency of a platelet count is the best.

It is always a compromise between leucocyte contamination and a platelet number. In such conditions (150g , 10 min) you will have a heterogeneous fraction of PRP with a quite high buffy coat layer. To avoid contamination with a buffy coat you must pipette plasma for 0.5 to 1.0 cm above the layer. It depends of the volume of the tube, for a 8.5-10.0 mL citrated tube I usually stopped pipetting 1.0 cm above. General recommendation is to pipette the top 2/3 of PRP.

Number of platelets depends on the initial number of platelets in a blood sample, mostly. In some patients you can have a low platelet count, so you should perform CBC test before. For LTA, use of 250 x109 L PRP is recommended, and in healthy donors you can usually have that count. The minimal platelet count you can use for optical aggregometry is 150 x 109 L, and the highest is 600 x 109 L.

I totally agree that the g-force and not the rpm is the important factor and that swing buckets are better. 

I have just found one published article ( http://www.ncbi.nlm.nih.gov/pubmed/25006472 - Relevant aspects of centrifugation step in the preparation of platelet-rich plasma) but this uses 2 centrifugation steps.

There are many claims about the efficacy of PRP in cosmetic/aesthetic work but very little hard fact! Uniformly the companies selling kits do not gave 2 centrifugation steps, and do not publish the expected platelet concentrations, so my potential research is to see what is the optimal g-force/time to get the most concentrated harvest on a single spin just above the buffy coat.

My plan as a pilot study is to centrifuge 10ml citrated blood at between 200g and 500g (measured at the rbc/plasma interface) for various times between 5 and 15  mins, take a series of 1 ml plasma samples serially from the top down (approx 5 samples per tube) and measure the platelet concentrations in the samplesDo you have observations on improving this protocol?

Separately

The link above should be

http://www.ncbi.nlm.nih.gov/pubmed/25006472

200 g is appropriate for all PRP preps. The only rider to this is the time for spinning which is related to the size of the specimen and the platelet count. For a normal count and a standard 3.5 ml container 15 min at 200g will be appropriate. For a smaller volume a shorter period eg 5 min for a 1ml sample and if the platelet count is low on a 3.5ml sample a 5 min spin again at 200g will be useful.