University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Agricultural -> dairy -> egg

Citations 3

"Flow Injection Determination Of Proteins Based On The Lowry Spectrophotometric Method"
Anal. Chim. Acta 1989 Volume 217, Issue 2 Pages 359-362
Hans Lüdi and Anita Bärtschi

Abstract: The flow injection system was based on the use of Folin - Ciocalteu reagent, with 1,4-dithio-DL-threitol to accelerate the formation of the colored complex, which was detected at 700 nm. The calibration graph for bovine serum albumin was rectilinear between 0.01 and 0.1 mg mL-1. The detection limit was 5 µg mL-1 and up to 0.5 mg mL-1 could be determined. The injection frequency was 20 h-1. Results obtained by the flow injection method and by the manual Lowry procedure correlated well. Egg lysozyme, alkaline phosphatase and β-lactoglobulin were also determined.
Albumin Lysozyme Enzyme, alkaline phosphatase β-Lactoglobulin Spectrophotometry Complexation Method comparison

"Simultaneous Spectrofluorimetric Determination Of Selenium(IV) And (VI) By Flow Injection Analysis"
Analyst 1997 Volume 122, Issue 3 Pages 221-226
M. J. Ahmed, C. D. Stalikas, P. G. Veltsistas, S. M. Tzouwara-Karayanni and M. I. Karayannis

Abstract: A sample (100 µL) was injected into a carrier stream of 2 M H2SO4 at a flow rate of 0.1 ml/min and mixed with a reagent stream of 0.2 mM 2-(α-pyridyl)thioquinaldinamide in propan-2-ol at a flow rate of 0.3 ml/min. The fluorescence intensity due to Se(IV) was measured at 500 nm (excitation at 350 nm). A second portion (100 µL) was then injected into the carrier stream and passed through a coil (40 cm x 0.8 mm i.d.) where it was irradiated at 254 nm. The irradiated sample stream was then mixed with the reagent stream and the fluorescence intensity due to total Se was measured. Se(VI) was determined from the difference in the two fluorescence intensity values. The calibration graphs were linear from 0.01-2.2 and 0.1-2.4 µg/ml Se(IV) and Se(VI), respectively; corresponding detection limits were 1 and 10 ng/ml. RSD were 0.1-2% (n=5). The throughput was 25 samples/h. The method was applied to the analysis of alloys, hair, tap and lake water, sediments, soil, tea, flour and eggs. A simple, sensitive, highly selective, automatic spectrofluorimetric method for the simultaneous determination of selenium (IV) and (VI) as selenite-selenate by flow injection analysis (FIA) has been developed. The method is based on the selective oxidation of the non-fluorescent reagent 2-(α-pyridyl)thioquinaldinamide (PTQA) in acidic solution (1.5-3.0 M H2SO4) by Se(IV) to give an intensely fluorescent oxidation product (lambda ex =350 nm; lambda em = 500 nm). Selenium (VI) is reduced online to Se(IV), in a reduction coil installed in a photo- reactor, which is then treated with PTQA and the fluorescene due to the sum of Se(IV) and Se(VI) is measured; Se(Vi) is determined from the difference in fluorescence values. Various analytical parameters, such as effect of acidity, flow rate, sample size, dispersion coefficient, temperature, reagent concentration and interfering species were studied. The photo-reduction conditions were optimized, with an FIA procedure, for Se(VI) on the basis of its reduction efficiency. The calibration graphs were rectilinear for 0.1-2.4 µg mL-1 of Se(VI) and 10 ng mL-1 - 2.2 µg mL-1 of Se(IV), respectively. The method was applied to the determination of Se in several Standard Reference Materials (alloy, sediments and tea), as well as in some environmental waters (tap and surface water), food samples (flour and egg), a biological sample (human hair), soil sample and in synthetic mixtures. Up to 25 samples per hour can be analyzed with an RSD approximately 0.1-2%.
Selenium(IV) Selenium(VI) Fluorescence Speciation Photochemistry Selectivity Reference material Interferences

"Microdetermination Of Proteins With The 1,10-phenanthroline-H2O2-cetyltrimethylammonium Bromide-Cu(II) Chemiluminescence System"
Microchem. J. 1998 Volume 60, Issue 3 Pages 217-223
Li Zheng Ping, Li Ke An and Tong Shen Yang

Abstract: Proteins can enhance the chemiluminescence (CL) intensity of the 1,10-phenanthroline-H2O2- cetyltrimethylammonium bromide (CTMAB)-Cu(II) system because unsaturated complexes of Cu(II) with protein have a much stronger catalytic effect on the CL reaction than does Cu(II). On this basis, a new flow injection analysis method for detection of some proteins was established. The method gives Linear responses over two orders of magnitude and detection limits at the 0.02-0.05 µg mL-1 level for bovine serum albumin, human serum albumin, γ-globulin, and egg albumin. The method was used for determination of proteins in human serum with satisfactory results.
Proteins Albumin Chemiluminescence