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What is a Standard Curve?
Why do I need to have one?
In order to convert Periotron and Sialo readings to microliters (ml)
and micrometers (mm)
respectively, standard curves need to be prepared. This is done by
delivering fixed volumes of serum or saliva onto strips using a Hamilton
syringe, recording the Periotron readings, and plotting readings as a
function of volume. In setting up the standard curve, each volume should be
tested at least 3 times and the readings averaged for that volume. Periotron
Professional 3.0 provided with the Periotron Model 8000, allows entry of the
data into the computer for automatic fitting of a 4th order polynomial to
the data points. Automatic conversion of Periotron readings to microliter
volumes is facilitated by this program.
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Once you have set-up your
calibration curve, it should remain relatively unchanged for months. Each
Periotron 8000 is set at the factory to read about 100 with 0.5
ml of fluid on the
PerioPaper scale and about 100 with 1 ml
of fluid on the SialoPaper scale. You can check the working of your
Periotron instrument by setting the zero with a dry strip and see if you
get, for example, a reading of about 100 for 0.5
ml if on the PerioPaper
scale. You can use saliva as well as serum (bovine is fine) for this
purpose. Distilled water can also be used but it is less accurate at the
high end of the scale. Saliva can be collected by chewing wax paper made
into a wad and spitting into a test-tube or small beaker. |
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