pH Indicators for Spectroscopy

Benefits of Spectroscopy

• Flexibility regarding excitation and wavelengths as well as sample preparation
• Relative low cost of instrumentation & outstanding selectivity and sensitivity
• Identification of biomolecules using multiple parameters
• Direct detection of ions and determination of pH-values

Steady-State Spectroscopy Most of the applications are based on constant excitation
Conventional Fluorometry - Measurements of emission light intensities at defined wavelengths suggested as excitation certain emission maxima of a fluorophore.
Total Fluorometry - Collection of data for a continuum of absorption as well as emission wavelengths.
Fluorescence Polarization - Polarized light used for excitation. Binding of fluorochrome-labeled antigens to specific antibodies affects polarization extent.
Line Narrowing Spectroscopy - Low-temperature spectroscopy that derives its selectivity from narrow-line emission spectra.

Time-Dependent Fluorescence Spectroscopy Time-resolved measurements contain more information than steady-state measurements, since the steady-state values represent the time average of time-resolved determinations
Single Photon Timing Technique - The time between an excitation light pulse and the first photon emitted by the sample is measured.

Frequency-Domain Fluorescence Spectroscopy The time decay of fluorescence is typically measured using a light source with an intensity modulated sinusoidally at a given frequency, by determining the phase delay and the relative modulation of the fluorescence signal with respect to the exciting light