Pressure-compensated temperature INDEX

Here functions Qnt X), Qj(X), and QP(X) can be determined experimentally using calibration samples. If these functions are linear independent then the parameters Ank, A, and Ap can be uniquely determined from the variation of P /1, , n2,. .. /( . /. / considered as a function of X. In particular, the side effects, i.e., the temperature and pressure dependences, can be eliminated from the transmission spectrum. The sensing method based on this simple idea was applied in Ref. 69 for determination of microfluidic refractive index changes in two microcapillaries coupled to a single MNF illustrated in Fig. 13.26c. The developed approach allowed to compensate the side temperature and pressure variation effects. 

A eonsequence of using a bulk property for detection is that this property of the solvent must be controlled very closely the refractive index of the eluant is sensitive to fluctuations in pressure, temperature and composition. Whilst the pressure and composition can be controlled using pulse dampners and reciprocating pumps, the limits of sensitivity and stability of the RI detector are determined by temperature. The temperature must be controlled to +0.0001 K for accepted noise levels. Fluctuations in the RI caused by temperature and noise changes are compensated for by use of a reference cell. 

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