2 - Isoproterenol Flashcards
What is isoproterenol?
Bronchodilator that relaxes lung smooth muscle and improves breathing in asthma, bronchitis, and emphysema
How is isoproterenol available?
Injection
What is the point of calibration?
- Compare to a defined standard or reference
- Essential for understanding and interpreting data to establish a relationship between quantities
Difference between relative and absolute calibration?
- Relative = evaluated by comparison to standards; used in pharmaceutical analysis for quantitative measurements
- Absolute = relies of physical/chemical constants; used in instrumentation calibration
Difference between one-point calibration and multiple-point calibration? Which was used for this experiment?
- One-point = uses one standard as a comparison that is reliable and reproducible; zero measurement produces zero response; linear and can’t extrapolate
- Multiple-point = uses > 3 different standards (other than zero); more accurate/reliable and extrapolation can be done; linear (y = mx + b where y = absorbance and x = concentration); *used for this lab
Which wavelengths are UV and which are visible?
- UV = 200-380 nm
- Visible = 380-800 nm
Advantage of UV/Vis spectrophotometry?
- Easy, inexpensive, and robust approach for quantitative measurement of drugs
- Routine method for physical and chemical characterization
UV/Vis spectrophotometry is routine for ____
Characterization of drugs
What is the basis of spectrophotometry?
The relationship between concentration of an analyte and the intensity of its light absorption
Disadvantages to UV/Vis spectrophotometry?
- Assay selectivity is low b/c depends on the chromophore (extended systems of double bonds)
- Analysis of mixtures is difficult because 2 compounds may have maximum absorbance at the same wavelength
What 2 factors govern absorption of radiation by a molecule?
- Structure of the chemical molecule
- Wavelength of radiation
Why does spectrophotometry use longer wavelengths (> 200 nm)?
- Short wavelength UV radiation (< 150 nm) can cause the strongest bonds in organic molecules to break and thus is very damaging to living organisms
- Longer wavelengths allow weaker bonds to be excited
When will absorption take place for molecules w/ more double bonds?
Longer wavelengths and w/ greater intensity
Formula for Beer-Lambert law and what each parameter means
A = A(1%, 1 cm) bc
- A = absorbance
- A(1%, 1 cm) = absorbance of a 1% (1 g/100 mL) solution in a 1 cm cell
- b = pathlength of the cell in cm
- c = concentration of the analyte (mol/liter)
3 basic components of a UV/Vis spectrophotometer
1) Light sources - deuterium lamp for UV (190-350 nm) and quartz halogen or tungsten lamp for visible (350-900 nm)
2) Monochromator - disperses light into wavelengths; can also rotate wavelengths so they can pass through the sample
3) Optics - splits the light beam to pass through 2 sample compartments; use a blank to correct the reading (blank is usually the solvent in which the sample is dissolved)
