Use of isosbestic point as a base line in differential spectrophotometry

Abstract

trol amplifier with the high current booster switched in, the working electrode potential was measured, with the control amplifier damping set at 0.01 pf. The electrode potential follows the imposed square wave well, but the same system with the control amplifier damping at 0.00033 pf and an imposed 20 cps square wave yields a wave whose shape is distorted by ringing. Fast scan work is possible, but requires careful adjustment of the damping capacitance.The circuit diagram in Figure 1 is not necessarily the ultimate design, but it illustrates an approach that provides a useful and convenient instrument with considerable versatility. A number of alternatives in terms of construction are possible. For example, the cost of the instrument, which for parts is about $1800, can be reduced by the use of utility grade operational amplifiers; this will not impair the performance noticeably at ambient temperatures. Also, if the performance of the integrator-sweep generator is not crucial, a Philbrick P-75AU amplifier can be employed in place of the P-25A. On the other hand, if the performance of the integrator-sweep generator holds top priority, a Philbrick P-2A operational amplifier should be used for this component.

Small‐Volume pH Sensing with a Capillary Optode Utilizing Dye‐Loaded Porous Nanocapsules in a Hydrogel Matrix

“…The shape of the spectra is the result of our measurement protocol in which the spectrum of the sensing gel in its deprotonated form is used as a reference (see Figure S1 in the Supporting Information). In this representation the isobestic point (574 nm) emerges at zero absorbance 49. The zero absorbance at the isobestic point is an indication that the uncertainties related to the light scattering were adequately removed from the spectra (Supporting Information, Figure S2).…”

Preparation and characterisation of gels based on sucrose modified with glycidyl methacrylate

“…At this pH, the salycilic acid is converted into sodium salycilate (SSA) (Shane and Routh, 1967). After blotting, the gels were immersed in 50 ml of distilled water at 37ЊC with magnetic stirring (150 rpm).…”

Importance of isosbestic point in spectroscopy: a review

“…Use of isosbestic point as a base line in differential spectrophotometry. [94] In addition, to estimate quantum efficiency in transient absorption spectroscopy. [95] Employed of isosbestic point wavelength shifts to estimate the fraction of a precursor that is converted to a given product can be used to calculate the fraction of the precursor that is converted to products from the relationship, f = (Precursor)(M)/(Product)(M).…”