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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Juice

Classification: Vegetable -> sugar cane -> juice

Citations 5

"Determination Of Sucrose In Sugar-cane Juice And Molasses By Flow Injection Spectrophotometry"
Anal. Chim. Acta 1988 Volume 204, Issue 1-2 Pages 259-270
E. A. G. Zagatto, I. L. Mattos and A. O. Jacintho

Abstract: The diluted and filtered sugar cane juice or molasses is introduced into a flow injection analyzer. with two merging streams, producing two sample zones. One zone is fed directly to the confluence of the streams but the other first flows through a heated coil where partial and reproducible sucrose (I) inversion is achieved at controlled pH and temperature At the confluence point a buffered IO4- reagent is added to oxidize I. The consumption of IO4- is measured spectrophotometrically as a transient lowering of the iodine concentration, produced by reaction of IO4- with I-. The two zones are fed sequentially to a flow cell where two peaks are recorded. The I concentration. is proportional to the difference in peak heights. About 30 samples h-1 of sugar-cane juice can be analyzed. The coefficient of variation was 0.51% for a I concentration. of 13.66% in cane juice (n = 7). Similar precision was obtained with the modified system for molasses (20 samples h-1).
Sucrose Spectrophotometry Indirect Merging zones Optimization Heated reaction

"Spectrophotometric Flow Injection Determination Of Sucrose And Total Reducing Sugar In Sugar-cane Juice And Molasses"
Anal. Chim. Acta 1988 Volume 214, Issue 1-2 Pages 247-257
I. L. Mattos, E. A. G. Zagatto and A. O. Jacintho

Abstract: Samples of sugar-cane juice or molasses were injected into the carrier stream (H2O at 1 mL min-1) which was then mixed with 1 M HCl in a 250-cm PTFE coil for hydrolysis of sucrose. This solution then merged with 3 M NaOH - 1%K3Fe(CN)6 reagent solution in a 580-cm PTFE coil, the solution was debubbled and 0.1% 1,10-phenanthroline - 0.5 M acetic acid - 0.1 M citric acid - 30 mg L-1 of Fe(III) was added. The solution passed through a 200-cm polyethylene coil and the absorbance was measured at 512 nm. The sampling rate for determination of sucrose and total reducing sugar was 40 h-1. The sampling rate was almost doubled when only reducing sugar was determined and a simplified flow system (illustrated) could be used. The coefficient of variation for determination of sucrose and total reducing sugar in sugar-cane juice were 0.47 and 0.38, respectively; those for molasses were 0.54 and 0.44%. Results generally agreed well with those from classical methods.
Sucrose Sugars, reducing, total Carbohydrates Spectrophotometry Debubbler Merging zones Method comparison

"Application Of Square-wave Voltammetry For The Determination Of Ascorbic Acid In Soft Drinks And Fruit Juices Using A Flow Injection System"
Anal. Chim. Acta 1992 Volume 261, Issue 1-2 Pages 375-380
Ying-Sing Fung* and Song-Ying Mo

Abstract: A portion (100 µL) of test solution was injected into a stream of the supporting electrolyte (Britton - Robinson buffer) for transfer to a thin-layer electrochemical cell (volume 16 µL) equipped with vitreous-carbon working, stainless-steel counter and Ag - AgCl reference electrodes. The normal flow rate was 0.5 mL min-1, and the potential of the working electrode was scanned from +0.2 to +0.7 V in 1 s, with application of a computer-generated square waveform and measurement of the oxidation peak current at +0.46 V. The buffer pH was 2.87 to stabilize the ascorbic acid. The peak signal was rectilinearly related to ascorbic acid concentration. from 2 µM to 6 mM; food additives at normal concentration. levels did not interfere. Results obtained on blackcurrant juice, lemon tea, sugar-cane juice and apple juice were satisfactory. The application of square-wave voltammetry for detection in the flow injection determination of ascorbic acid in soft drinks and fruit juices was investigated. The pH of the solution was buffered at 2.87 to stabilize the ascorbic acid prior to anal. Parameters such as scan rate, square-wave amplitude, step height and flow-rate of electrolyte were found to have little effect on the potential, but a significant effect on the current. The anal. current is only slightly affected by the flow-rate of the electrolyte and a max. scan rate of 0.5 V/s can be used. As a compromise between sensitivity and selectivity, 40 mV was chosen as the amplitude of the square wave and 10 mV as the potential step height. Similarly, a flow-rate of 0.5 mL/min and an injection volume of 100 µL were chosen as a compromise between the sensitivity and resolution of the FIA method. With these procedures, the max. number of samples that could be analyzed was 120/h. The linear calibration range was from 2 x 10^-6 to 6 x 10^-3 M and the determination limit (10s) was 2 x 10^-7M. No significant interference was found from additives commonly found in juice and drink samples within their normal concentration. ranges. Four juice samples were analyzed using the developed method and the results were compared with those given by the established AOAC method. No significant difference was observed between the two methods used for the four samples studied.
Ascorbic acid Voltammetry Electrode Standard method Method comparison Interferences

"Multi-site Detection In Flow Analysis. 3. Periodate Tubular Electrode With Low Inner Volume As A Relocatable Detector"
Anal. Chim. Acta 1994 Volume 285, Issue 3 Pages 293-299
José A. Gomez Neto, Ana Rita A. Nogueira, H. Bergamin Filho and Elias A. G. Zagatto*, José L. F. Costa Lima and Conceição B. S. M. Montenegro

Abstract: The membrane sensor comprised 30% PVC, 63% o-nitrophenyl octyl ether and 7% tetra-octylammonium periodate, with an inner volume of 45 µL. Its position could be changed with use of an electronic commutator, to which were attached the working and Ag/AgCl reference electrodes. Two configurations are described. In one, used for the determination of glycerol, the sensor could be moved to either of two identical channels. Glycerol solution (30 µL) were injected into a reagent carrier of 3 mM NaIO4, 0.5 M Na2SO4, 0.1 M acetic acid and 0.1 M sodium acetate (0.5 ml/min). The carrier passed through a coiled reactor (1 m x 0.7 mm i.d.) to the sensor, where unconsumed periodate was measured. Calibration graphs were linear for 0.05-0.2% glycerol. The commutator was switched to the parallel channel a few s after the peak maximum was reached, thus the sampling rate of 100/h was not affected by the wash-out time. For sucrose, the sensor was moved to a position downstream in the same channel. Calibration graphs were linear for 0.1-0.5% sucrose. Glycerol was determined in soaps and detergents, and sucrose was determined in sugar cane juice and syrups.
Glycerol Sucrose Electrode Sensor Apparatus Detector

"Determination Of Glucose In Soft Drink And Sugar-cane Juice Employing A Multicommutation Approach In Flow System And Enzymatic Reaction"
Fresenius J. Anal. Chem. 1999 Volume 364, Issue 4 Pages 358-361
Eloísa A. M. Kronka, Ana Paula S. Paim, B. F. Reis, José L. F. Costa Lima, Rui A. Lapa

Abstract: A flow system based on a multicommutation approach was developed for the determination of glucose and sucrose employing enzymatic reactions. The determination was based on the reaction with D-glucose generating hydrogen peroxide catalyzed by glucose-oxidase (GOD). Subsequently, the H2O2 generated reacts with 4-aminefenazone plus phenol to form 4-(p-benzoquinone-mono-imine) fenazone detected at 510 nm. This reaction is catalyzed by the peroxidase enzyme (POD). The flow network comprised a set of three-way solenoid valves and was controlled by means of a microcomputer furnished with an electronic interface and running a software written in Quick BASIC 4.5. The flow network and control software were designed to implement the multicommutation approach providing facilities to handle sample and reagent solutions, so that, sample dilution could be easily performed on line. Accuracy was assessed by comparison with results obtained by known procedures and no significant difference at the 95% confidence level was observed. Other advantageous features were a linear response ranging from 0.05 to 0.20% (w/v) glucose without prior dilution, a reagent consumption of 336 µL per determination, an analytical throughput of 30 samples per hour.
Glucose Sucrose Spectrophotometry Multicommutation Immobilized enzyme Computer Method comparison