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
Email: schalk@unf.edu
Website: @unf

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Dual injector

Classification: Manifold component -> Dual injector

Citations 4

"Sequential Flow Injection Spectrofluorimetric Determination Of Coumarins Using A Double-injection Single-line System"
Anal. Chim. Acta 1995 Volume 308, Issue 1-3 Pages 293-298
P. Solich*, M. Poláek and R. Karlíek

Abstract: A flow injection technique with fluorimetric detection was described for the sequential determination of 6-methoxy-7-hydroxycoumarin (scopoletine) and 7-hydroxycoumarin (umbelliferone) without prior separation. A single-line flow injection system equipped with a double-injection valve was employed to allow the simultaneous injection of sample (40 µL) and phosphate buffer (100 µL) into an aqueous 50% ethanol carrier stream (1 ml/min). The buffer-sample-buffer plug was propelled through the mixing coil (0.5 m x 0.5 mm i.d.) to the detector where the fluorescence at 418 nm was measured (excitation at 350 nm). Buffer solutions of pH 6 and 11 were injected sequentially. A calculation method based on differential fluorimetry was used to determine 1 µM-scopoletine in the presence of a 9-fold excess of umbelliferone or 1 µM-umbelliferone in the presence of a 23-fold excess of scopoletine. The analysis of synthetic binary mixtures containing 24 µM-coumarins yielded recoveries of 96-115%. The technique can be applied to the analysis of binary mixtures of other fluorescent compounds which exhibit pH-dependent excitation spectra.
Coumarin, 6-methoxy-7-hydroxy 7-Hydroxycoumarin Fluorescence

"Multifunction Valve For Flow Injection Analysis"
Anal. Lett. 1987 Volume 20, Issue 12 Pages 1951-1976
Jun'Ichi Toei

Abstract: A multi-function valve with six injection modes is described and illustrated. It is partly constructed from stainless steel and can be used in high-pressure analysis. The valve has the capability for simultaneous injection of sample and reagents, thus increasing utilization efficiency of materials and time. It is applied in the determination of Ca with o-cresolphthalein at 254 nm with water as carrier. The precisions obtained in various injection modes are tabulated. Generally, the coefficient of variation are <2.5% (n = 5 to 7). The valve is also suitable for use in HPLC.
Calcium o-Cresolphthalein Spectrophotometry

"Automatic Continuous Online Monitoring Of Salicylic Acid And Acetylsalicylic Acid [aspirin] In Pharmaceuticals"
J. Autom. Methods Manag. Chem. 1990 Volume 12, Issue 6 Pages 263-266
J. M. L&Oacute;PEZ FERN&Aacute;NDEZ, M. D. LUQUE DE CASTRO, and M. VALC&Aacute;RCEL

Abstract: An asymmetrical flow injection analysis (FIA) merging-zones manifold has been developed for the simultaneous determination of salicylic acid (I) and aspirin at a sampling frequency of 30 h-1. The manifold is based on dual injection of two sample micro-volume into two sample plugs, one of which is prehydrolyzed on injection into an NaOH stream and is circulated through a longer channel than the other plug, so yielding two FIA peaks corresponding to salicylic acid and the overall content, respectively. Complexation between the Fe(III) reagent continuously introduced into the system and salicylic acid is monitored photometrically at 520 nm. Calibration graphs are rectilinear for 100 to 600 mg L-1 of I and 300 to 1800 mg L-1 of aspirin, with coefficient of variation of 0.4 and 0.5%, respectively. The manifold was successfully applied to the dissolution testing of aspirin tablets.
Acetylsalicylic acid Salicylic acid Pharmaceutical

"FAAS Determination Of Calcium And Magnesium In Gelatin Using The FIA Online Automatic Dilution Technique"
Lihua Jianyan, Huaxue Fence 1996 Volume 32, Issue 2 Pages 82-91
Zhang Min, Chen Shuyu, Lin Shuqin and Cheng Lin

Abstract: Sample (1.2 g) was soaked in 15 mL water for 15 min and digested with 1 mL concentrated HCl, 1 mL concentrated HNO3 and 4 mL H2O2. The digest was diluted with to 25 mL with water for FIA with flame AAS detection of Ca and Mg. Test solution was injected and carried to two sampling loops with a stream of water for alternating feeding, primary and secondary injection volumes being 21 and 70 µL, respectively. The solution was allowed to mix with a stream of 0.3% La solution prior to splitting into two streams by passing through two dilution tubes of 50 and 150 cm in length, respectively, with dilution of 87 to 233-fold, and detection. The peak B of the sets of signals was employed for measurement of Ca whereas the trough E for Mg. Determination was at µg/g level. RSD were 1.3-2.1%. The method was applied to the analysis of wheat, shrimp, pig liver and shrub leaves. Interference from phosphate was overcome. Sampling frequency was 96 runs/h.
Calcium Magnesium Organic compound Wheat Shrimp Liver Leaves Sample preparation Spectrophotometry