Determination of lactate dehydrogenase (LDH) activity in the SMAC (Technicon) is based on the change in NADH absorbance between two flow cells. We noted that results for patients' specimens and controls changed when the fiber optic terminations for the two LDH channel flow cells were adjusted or "peaked" at the colorimeter chopper assembly. The energy (intensity) of light reaching the flow cell...

The distribution of aromatic constituents, including lignin , in the leaf cell walls of "Coastal" hermudagrass (Cynodon dacrylon (L.) Pers.) was investigated using scanning ultraviolet (UV) microspectrophotometry. Leaf blade sections and individual ti ssue types were scanned at three wavelengths representing the absorbance maxima (318 , 287 and 250 nm) o f aromatic constituents present in bermu...

Curcumin metabolites namely curcumin monoglucuronide and curcumin diglucuronide were synthesized using an alternative synthetic approach. The anti-oxidant potential of these curcumin glucuronides was compared with that of curcumin using DPPH scavenging method and Oxygen Radical Absorbance Capacity (ORAC) assay. The results show that curcumin monoglucuronide exhibits 10 fold less anti-oxidant ac...

*Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, U.S.A., ‡Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08901, U.S.A., §Skidmore College, Environmental Studies Program, Harder Hall 192, Saratoga Springs, NY 12866, U.S.A., {The Pennsylvania State University, School of Forest Resources, 02C Ferguson Bu...

This paper demonstrates that, for applications in resource-limited environments, expensive microplate spectrophotometers that are used in many central laboratories for parallel measurement of absorbance of samples can be replaced by photometers based on inexpensive and ubiquitous, consumer electronic devices (e.g., scanners and cell-phone cameras). Two devices, (i) a flatbed scanner operating i...

A new approach to the use of spectroscopic absorbance measurements for anisotropic crystals allows results to be extracted using unpolarized light incident on random crystal orientations. The theory of light propagation in anisotropic absorbing crystals is developed from Maxwell’s equations to devise an expression for the transmittance of linearly polarized light traveling in an arbitrary direc...

Objective: Two simple, accurate and reproducible spectrophotometric methods have been developed and validated for simultaneous estimation of pyrimethamine and sulphadoxine in combined dosage form. Methods: Pyrimethamine shows maximum absorbance at 285.6 nm and sulphadoxine shows maximum absorbance at 273.4 nm. In dual wavelength method, two wavelengths were selected for each drug in a way so th...

Label-free, non-invasive, rapid absorbance spectral imaging A(x,y,λ) microscopy of single live cells at 1.2 μm × 1.2 μm resolution with an NA = 0.85 objective was developed and applied to unicellular green algae Chlamydomonas reinhardtii. By introducing the fiber assembly to rearrange a two-dimensional image to the one-dimensional array to fit the slit of an imaging spectrograph equipped with a...

A rapid method based on UV spectrophotometry is described for simultaneous determination of salicylates and barbiturates in serum. While barbiturates have no absorbance above 280 m and extracted normal serum has insignificant absorbance, salicylate has a maximal absorbance peak at 296 mjh, which is proportional to concentration. The barbiturate concentration can be calculated from absorbance di...

Maximum specific growth rate (mu(max)) and lag time (lambda) were estimated from viable count and absorbance data and compared for different microorganisms, incubation systems and growth conditions. Data from 176 growth curves and 120 absorbance detection times of serially diluted cultures were evaluated using different mathematical growth models. Accurate estimates of mu(max) and lambda were o...