what effect would use of cuvet that has fingerprint on it have on the absorbance reading in spectrophotometric
337796
A fingerprint would increase the absorbance of the compound as detected by the instrument. This is because the grease from the print will reflect additional light, such that it does not reach the detector, thereby increasing absorbance.
196883
2 different kinds:\nhttp://home1.gte.net/vze72n8v/id18.html\n\nhttp://www.fingertipproductions.com/documents/Fingertip%20Contract.pdf#search='sample%20Performance%20contract'\n\nOr\n\nhttp://www.idwr.state.id.us/energy/epc/ESCO%20RFP.pdf#search='sample%20Performance%20contract'
744953
Yes. These are usually refered to as latent prints.\nPaper acts as a blotter, absorbing skin secretions when touched.\nWhen the paper is exposed to chemicals that react with the skin secretions they cause the print to become visible.
740646
Phase-only optical filter for use in an optical correlation system - Patent 4588260  \n... with zero phase does not reconstruct the correct structure, where as ... would be to construct such a filter by means of a computer generated hologram. ...www.freepatentsonline.com/4588260.html \nHolographic fingerprint device - Patent 6061463  \n... hologram, also affixed to the substrate but at a position along the ... slightly different angle than the one used to construct the hologram (and thus ...www.freepatentsonline.com/6061463.html
670951
Unevenly reflected, I guess.\n\nIf it is absorbed, it would be completely black. If it was evenly reflected, it would be completely white. If it was trasmitted, it would be clear like glass. Uneven reflections let you see colours and texture.
899107
Quantitative = amount \nSpectrophotometric = wavelength specific measurement\nAnalysis = determination\n\nCombining these terms gives you "the determination of the amount of material present by the use of specific wavelengths of light".\n\nMany compounds have chromophores, or specific portions of the molecule, that absorb energy of a specific wavelength.  Therefore, using a spectrometer, you can determine that a light source produces a given amount of energy at some predetermined wavelength.  When the analyte of interest is inserted into the light path, some of the energy will be absorbed, which will be proportionate to the amount of material present.  (Increasing the amount of material will absorb more energy, decreasing the amount of material will absorb less energy.)\n\nBy comparing the unknown material to a series of samples prepared in known concentrations, you can determine the concentration (amount) of the unknow sample.  The actual formula for this process is known as the Beer-Lambert Law.
840473
Need more specifics as to your problem.\n\nHowever, I assume you are trying to do a quantitation on a UV or vis absorbing substance.\n\nMake up  a set of standards of known concentration of your analyte in the solvent you will be analyzing in.  Then do some scans over the whole wavelength range. \n\nUsually pick the wavelength at the top of the largest absorbance peak, unless that is a wavelength which will have interferences from other substances present.  If so, then pick a wavelength with good absorbance that is not subject to such interference.
677394
Here are some of the more common applications of these techniques:\n\nGas Chromatography - Flame Ionization Detector, also called GC-FID.  This method is used to analyze mixtures of substances which have an appreciable vapor pressure and are capable of burning.  GC-FID is often used to periodically check a reaction mixture to see how far a particular reaction has gone.  It is also used to check for purity of the final product and to check for undesirable impurities.  \n\nHPLC can also be used in a similar way to GC-FID except that it is better at analysis of non-volatile compounds.  HPLC is often used to analyze the final purity of a product, or to analyze the concentration of a pharaceutical product in a physiological sample (blood, plasma, urine, etc).  \n\nUV-vis is good at measuring the concentration of a UV-absorbing compound in a matrix which contains no other UV-absorbers.  Sometimes you can take your final product and dissolve in non-uv absorbing solvent and measure the UV-vis absorbance to determine concentration or assay.\n\nThe above are just some of the more common uses.  There are many more uses for these techniques in the Pharma industry.
142624
Spectrophotometer is a photometer (a device for measuring light intensity) that can measure intensity as a function of the color, or more specifically, the wavelength of light. There are many kinds of spectrophotometers. Among the most important distinctions used to classify them are the wavelengths they work with, the measurement techniques they use, how they acquire a spectrum, and the sources of intensity variation they are designed to measure. Other important features of spectrophotometers include the spectral bandwidth and linear range.\n\nFollow the link for more information.\n\nhttp://en.wikipedia.org/wiki/Spectrophotometer
306417
Circular dichroism (CD), is the differential absorption of left- and right-handed circularly polarized light. It is a form of spectroscopy used to determine the optical isomerism and secondary structure of molecules.\n\nAt a given wavelength,\n\nΔA = (AL − AR) \nwhere ΔA is the difference between absorbance of left circularly polarized (LCP) and right circularly polarized (RCP) light (this is what is usually measured). It can also be expressed as:\n\nΔA = (εL − εR) C l \nwhere εL and εR are the molar extinction coefficients for RCP and LCP light, where C is the molar concentration and l is path length.\n\nThen\n\nΔε = (εL − εR) \nis the molar circular dichroism. This is what is usually meant by the circular dichroism of the substance.\n\nAlthough ΔA is usually measured, for historical reasons most measurements are reported in degrees of ellipticity.\n\nThe molar ellipticity is:\n\n[θ] = 3298Δε. \nIn general, this phenomenon will be exhibited in absorption bands of any optically active molecule. As a consequence, circular dichroism is exhibited by biological molecules, because of the dextrorotary (e.g. some sugars) and levorotary (e.g. some amino acids) molecules they contain. Noteworthy as well is that secondary structure will also impart a distinct CD to their respective molecules. Therefore, the alpha helix of proteins and the double helix of nucleic acids have CD spectral signatures representative of their structures.\n\nCD is closely related to the optical rotary dispersion (ORD) technique, and is generally considered to be more advanced. CD is measured in or near the absorption bands of the molecule of interest, while ORD can be measured far from these bands. In principle these two spectral measurements can be interconverted through an integral transform, if all the absorptions are included in the measurements.\n\nThe ultraviolet CD spectrum of proteins can predict important characteristics of their secondary structure. CD spectra can be readily used to estimate the fraction of a molecule that is in the alpha-helix conformation, the beta-sheet conformation, the beta-turn conformation, or some other (random) conformation. These fractional assignments place important constraints on the possible secondary conformations that the protein can be in. CD cannot, in general, say where the alpha helices that are detected are located within the molecule or even completely predict how many there are. Despite this, CD is a valuable tool, especially for showing changes in conformation. It can, for instance, be used to study how the secondary structure of a molecule changes as a function of temperature or of the concentration of denaturing agents. In this way it can reveal important thermodynamic information about the molecule that cannot otherwise be easily obtained. Anyone attempting to study a protein will find CD a valuable tool for verifying that the protein is in its native conformation before undertaking extensive and/or expensive experiments with it. Also, there are a number of other uses for CD spectroscopy in protein chemistry not related to alpha-helix fraction estimation. s\n\nCD spectroscopy is usually used to study proteins in solution, and thus it complements methods that study the solid state. This is also a limitation, in that many proteins are embedded in membranes in their native state, and solutions containing membrane structures are often strongly scattering. CD is sometimes measured in thin films.\nCD has also been studied in carbohydrates, but with limited success due to the experimental difficulties associated with measurement of CD spectra in the vacuum ultraviolet (VUV) region of the spectrum (100-200 nm), where the corresponding CD bands of unsubstituted carbohydrates lie. Substituted carbohydrates with bands above the VUV region have been successfully measured.\n\nMeasurement of CD is also complicated by the fact that typical aqueous buffer systems often absorb in the range where structur
462356
It probably requires a mass spec technique.  Infrared might work.  Your detection level will be the problem.
608906
may be with internal reflection
920352
Did you measure the absorbance of a standard in addition to the unknown sample?\n\nIf so, you could plug the values into (As / Au) = (Cs / Cu)\nWhere\nAs = Absorbance of the Standard\nAu = Absorbance of the Unknown\nCs = Concentration of the Standard\nCu = Concentration of the Unknown?\n\nAlternatively, did you get a value for the molar absorptivity of PNP at the wavelength you used? \nIf so, you could plug it into\n\nA = (epsilon)(b)(c)\n\nWhere\nepsilon is the molar absorptivity,\nb is the length of the path through which the light passed,\nc is the concentration of the chromogenic substance.\n\nAnd you could rearrange that to solve for c.\n\nHope it helps
614877
I think what you mean is FACS (Four Colour Cell Analyser) Calibur?\n\nIt uses flourescence as its detection method I think. Used in flow cytometry experiments. This website will probably explain it better than I could...\n\nhttp://www.pathology.wustl.edu/html/facilitiesfacsfaq.html
221791
Absorbance measures the fraction of light that does not pass through the sample.  If a solution is completely transparent (to the measured wavelengths) it will have no absorbance.  If a solution is opaque, it will have 100% absorbance.\n\nPrecipitation adds solids to the solution which will probably be opaque, increasing the measured absorbance.
590116
When light falls onto an object a part of the spectrum is reflected and another part is absorbed. Depending on the (micro)texture of the object, different parts of the spectrum are reflected and we sense another color. Since there is a differennce in microtexture between wet and dry clothes, we experience a slightly different color.
557970
Yes. Filters are best characterised using optical spectroscopy. An optical spectrometer contains a light source, a diffraction grating and a detector. The results obtained from it show how the transmission (and in some spectroscopes reflection as well) of the filter varies with wavelength.\nAnother instrument is the Fourier Transform spectrometer. It uses a michelson interferometer and fourier processing to characterise the spectrum of the filter.