hi all
i’m using 5x5 centemeter square plates(ss plate) for cleaning analytical method validation recovery purpouse.my doubt is howto fix area for swabbing(5x5).
hi all
i’m using 5x5 centemeter square plates(ss plate) for cleaning analytical method validation recovery purpouse.my doubt is howto fix area for swabbing(5x5).
I am not getting your question, Are you talking about the taking 5 X 5 cm area or taking the swab for actual sampling.
anil
the swabbing area is not fixed and it can be varied. Anyway this method of swabbing of 5 x 5 cm2 can be followed. only thing which is important is the recovery studies should be done on the same surface area and recovery of 80% is generally preferable.
[quote=prince]hi all
my doubt is howto fix area for swabbing(5x5).[/quote]
Get a template square made up with a centre cut out which equals 5x5.
On a related topic, in recoverability trials i have technicians who are continuously failing there recoverabilities (~40%). The active is hard to clean. I am therefore considering changing the swabbing action, repeating the swab over the same area twice with the other side of the swab.
Currently we swab over the 25cm2 area once, my concern is we are leaving much of the residue on the area as opposed to ‘recovering’ it. Therefore i am proposing to trial different method. Any comments/thoughts?
ALITOAST
[quote=Alitoast]Get a template square made up with a centre cut out which equals 5x5.
On a related topic, in recoverability trials i have technicians who are continuously failing there recoverabilities (~40%). The active is hard to clean. I am therefore considering changing the swabbing action, repeating the swab over the same area twice with the other side of the swab.
Currently we swab over the 25cm2 area once, my concern is we are leaving much of the residue on the area as opposed to ‘recovering’ it. Therefore i am proposing to trial different method. Any comments/thoughts?
ALITOAST[/quote]
ALITOAST,
assuming the problem appears consistently with all the trained technicians (if not, it may be a training and not a procedural issue), my first approach would be to pass the same swab again over the surface (in fact, our SOP states to swab the same surface three times: horizontally, vertically and diagonally, with both swab sides, and we get recoveries of more than 90%). You can even consider to use more than one swab. Second approach would be to increase the swabbing area, because when lifted off at the borders of the swabbed area, wet swabs leave some liquid with dissolved active, with higher impact the higher the relationship between border length and swabbed area is. Third, get sure the swabbing solvent is adequate (sometimes highly volatile solvents cool the swab below the dewpoint, and water insoluble actives are precipitated again on the surface).
Best regards
Alfred
hi alfred you are ginen good information for me.
Alfred,
thanks for your comments,
Alitoast
Can any body pl tell me how to calculate recovery factor
calculation wise pl.
[quote=santoshp_2009]Can any body pl tell me how to calculate recovery factor
calculation wise pl.[/quote]
Dear santoshp_2009,
it is very simple: You spike the plate with a known amount of analyte (i.e. 10 µg dissolved in 5 ml solvent, spread over 100 cm² on the plate and let dry). Then swab the plate per your procedure, extract the swab and determine analytically the amount of analyte in the swab. The quantity of analyte found in the swab (and thus recovered) divided by the spiked amount gives you the recovery factor. (in the example, if you recovered 7,8 µg, your recovery factor is 0,78 or 78%).
Best regards
Alfred