Handbook of best practices

An example of calculations for the optode 3830 has been detailed here:
DOXY [µmol/kg] = C 0 + C 1 DPHASE + C 2 DPHASE 2 + C 3 DPHASE 3 + C 4 DPHASE 4
with C i = C i0 + C i1 T + C i2 T 2 + C i3 T 3
and DPHASE = BPHASE (blue light) considering RPHASE = 0 (red light)
This equation needs 20 sensor-dependant coefficients and calibration at this time was
performed with two points calibrations (0 and 100% saturation).
The more recent optode 4330 (faster time response) offers more accurate oxygen
concentrations but with more complex equations:
Δp = C 0 x T m0 x CalPhase n0 + C 1 x T m1 x CalPhase n1 + ... + C 27 x T m27 x CalPhase n27
Air Saturation(%) = Δp x 100 / [(Nom Air Press – p vapour (T)) x Nom Air Mix]
DOXY [µmol/L] = [C* x 44.614 x Air Saturation] / 100
with CalPhase = f(Tphase) and TPhase = C 1 Phase – C 2 Phase (blue-red light)
This equation used 27 calibration coefficients and was reduced to 7 coefficients from Stern-
Volmer equation taking into account the pressure and salinity compensation (Uchida et al.
2008, Bittig et al. 2012, Asaro& McNeil, 2013):
DOXY [µmol/L] = [(C 4 +C 5 x T)/(C 6 +C 7 x TPhase) - 1] / [C 1 +C 2 xT+C 3 xT 2 ]
Since 2012, Aanderaa (XYLEM) performs a multipoint calibration method for the new optode
in order to improve accuracy of Ci and DOXY precision (40 calibration points). However,
after some tests, an offset of oxygen is still observed.
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