scholarly journals Novel Integrated Flow-Based Steam Distillation and Titration System for Determination of Volatile Acidity in Wines

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7673
Author(s):  
Justyna Paluch ◽  
Joanna Kozak ◽  
Karolina Mermer ◽  
Iwona Molęda ◽  
Marcin Wieczorek ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Tartaric Acid ◽  
Steam Distillation ◽  
Detection System ◽  
Titratable Acidity ◽  
Volatile Acidity ◽  
Relative Standard ◽  
Titration System ◽  
Better Than

Novel integrated flow-based steam distillation and titration system with spectrophotometric detection was developed for determination of volatile acidity in wines. Using the system, the distillation procedure was carried out in an automatic manner, starting with introducing into a heated steam distillation module a sample and subjecting it to steam distillation. Under selected conditions, all the analyte was transferred to the distillate; therefore, the system did not require calibration. The collected distillate and titrant were introduced into the next monosegments in varying proportions, in accordance with the developed titration procedure, and directed to the detection system to record the titration curve. The titration was stopped after reaching the end point of titration. Procedures for distillation and titration were developed and verified separately by distillation of acetic acid, acetic acid in the presence of tartaric acid as well as acetic acid, tartaric acid, and titratable acidity, with precision (relative standard deviation) and accuracy (relative error) for both procedures lower than 6.9 and 5.6%, respectively. The developed steam distillation and titration systems were used to determine volatile acidity in samples of white and rosé wines separately and as the integrated steam distillation and titration system, both with precision lower than 9.4% and accuracy better than 6.7%.

Conductometric and Colorimetric Determination of Volatile Acidity of Vinegars by Flow-Injection Analysis

1991 ◽  
Vol 74 (2) ◽  
pp. 346-350 ◽  
Author(s):  
Matthieu Tubino ◽  
Flavio G Barros
Keyword(s):  
Acetic Acid ◽  
Colorimetric Determination ◽  
Bromocresol Purple ◽  
Water Stream ◽  
Ptfe Membrane ◽  
Volatile Acidity ◽  
Relative Standard ◽  
Significant Difference ◽  
Membrane Separator

Abstract Recent methods for determination of the volatile acidity of vinegars are relatively slow (about 40 mln) and involve techniques subject to a variety of errors (ca 2.5%). The present paper describes a method that provides results in a shorter time (ca 2 mln, Including dilution), with a smaller relative error rate (ca 1%). Conductometric analysis consists of the Injection of the sample In a deionlzed water stream that then flows past a PTFE membrane separator. Acetic acid diffuses through the membrane to another deionlzed water stream that passes through a conductivity cell. Colorimetric analysis also consists of sample injection into a deionlzed water stream that passes through the same PTFE membrane separator. However, the acetic acid diffuses into a bromocresol purple solution stream at pH 7. This solution passes through a flow cell In a spectrophotometer set at 540 nm. Before injection, samples were treated with hydrogen peroxide to ensure complete oxidation of sulfite to sulfate. Results of the proposed method were also compared with another similar method. At a 95% confidence level, the statistical t-test Indicates no significant difference between them. Typical estimates of the relative standard deviations obtained with the new methods are ca 1%. Analyses were performed with red and white wine vinegars.

scholarly journals Determination of titratable acidity in white wine

2007 ◽  
Vol 52 (2) ◽  
pp. 169-184 ◽  
Author(s):  
Milos Rajkovic ◽  
Ivana Novakovic ◽  
Aleksandar Petrovic
Keyword(s):  
Tartaric Acid ◽  
Potentiometric Titration ◽  
Ph Value ◽  
Titratable Acidity ◽  
White Wine ◽  
Selective Electrode ◽  
Alcohol Fermentation ◽  
Standard Methods ◽  
Illegal Acts

The amount of titration acid in must is in the largest number of cases with in the range 5.0-8.0 g/dm3. Wines, as a rule, contain less acids than must, and according to Regulations, titratable acidity is in the range of 4.0-8.0 g/dm3 expressed in tartaric acid, because a part of tartaric acid is deposited in the form of salts (tartar or argol) during alcohol fermentation. For wines that contain less than 4 g/dm3 of titratable acids there arises a suspicion about their origin, that is, that during the preparation some illegal acts were done. Because of that, the aim of this paper is to determine titratable acidity in white wine, using standard methods of determination, which are compared with the results received by potentiometric titration using ion-selective electrode. According to the received results it can be seen that wine titration with indicator gives sufficient reliable values of wine titration acidity. However, as potentiometric titration at pH value 7.00 is more reliable and objective method, the values of titratable acids content in wine, expressed through tartaric acid, are given according to this result. The analysis of differential potentiometric curves shows that these curves can give us an answer to the question of the presence of a larger amount of other nonorganic substances, which have already existed in wine. However, none of the used methods gives absolutely reliable answer what substances are present in analysed samples.

Gas Chromatographic-Thermal Energy Analysis Method for Determination of Volatile N-Nitrosamines in Baby Bottle Rubber Nipples: Collaborative Study

1987 ◽  
Vol 70 (1) ◽  
pp. 64-68 ◽  
Author(s):  
J Ian Gray ◽  
Michael A Stachiw
Keyword(s):  
Thermal Energy ◽  
Energy Analysis ◽  
Collaborative Study ◽  
Internal Standard ◽  
Analytical Techniques ◽  
The United States ◽  
Baby Bottle ◽  
Relative Standard ◽  
Better Than

Abstract A collaborative study was conducted on the U.S. Food and Drug Administration (FDA) dichloromethane extraction method for determining volatile N-nitrosamines in baby bottle rubber nipples. Following dichloromethane extraction, A'-nitrosamines were determined by gas chromatography-thermal energy analysis. Six pairs of blind duplicate rubber nipple samples representing 6 lots were analyzed by 11 collaborating laboratories. All samples were portions taken from equilibrated composites of cut-up rubber nipples obtained from manufacturers in the United States. Recoveries of the internal standard (N-nitrosodipropylamine) at approximately 20 ppb ranged from 10 to 120%. Reproducibility relative standard deviations (RSDJ were between 35 and 45% for N-nitrosamine levels from 10 to 20 ppb. However, when data from laboratories with recoveries less than 75% were excluded (this is now specified in the method), RSD„ values were between 11 and 32% for N-nitrosamine levels from 6 to 26 ppb. Values were consistent with or better than those reported for other analytical techniques designed to quantitate trace contaminants at the low ppb level, e.g., afiatoxin in foods. The method has been adopted official first action for the quantitation of volatile N-nitrosamines in baby bottle rubber nipples.

Reverse Phase Liquid Chromatographic Determination of Some Food Additives

1987 ◽  
Vol 70 (3) ◽  
pp. 578-582 ◽  
Author(s):  
Madduri Veerabhadrarao ◽  
Mandayam S Narayan ◽  
Omprakash Kapur ◽  
Chilukuri Suryaprakasa Sastry
Keyword(s):  
Acetic Acid ◽  
Benzoic Acid ◽  
Mobile Phase ◽  
Direct Method ◽  
Food Additives ◽  
Acid Water ◽  
Relative Standard ◽  
Acetic Acid Water ◽  
Liquid Chromatographic

Abstract Liquid chromatographic methods are described for the separation and determination of non-nutritive sweeteners, namely, acesulfame, aspartame, saccharin, and dulcin; preservatives such as benzoic acid and p-hydroxybenzoic acid; and caffeine and vanillin in ready-toserve beverages, ice candy, ice cream, squash beverage, tomato sauce, and dry beverage mix samples. These additives are separated on a ^Bondapak C18 column using methanol-acetic acid-water (20 + 5 + 75) as mobile phase and detected by UV absorption at 254 nm. Caffeine, vanillin, dulcin, and benzoic acid can be analyzed quickly by using a mobile phase of methanol-acetic acid-water (35 + 5 + 60). Aspartame can be separated in the presence of caffeine and vanillin by using the mobile phase pH 3 acetate buffer-methanol (95 + 5). Retention factors and minimum detectable limits are described. The percentage error and the percent relative standard deviation for 6 replicate samples ranged from 0.3 to 2.8 and from 1.64 to 3.60, respectively. Recovery of additives added to the foods named and analyzed by the direct method and by extraction ranged from 98.0 to 100.6% and from 91.6 to 101.8%, respectively. The proposed LC techniques are simple, rapid, and advantageous because all the additives can be detected in a single step, which makes it useful for the routine analysis of various food products.

scholarly journals IMPORTANCE OF THE OXIDATION REACTION OF SODIUM METAPERIODATE FOR SPECTROPHOTOMETRIC ASSAY OF RESERPINE

2004 ◽  
Vol 72 (2) ◽  
pp. 121-129
Author(s):  
D. K. Singh ◽  
Archana Sahu
Keyword(s):  
Acetic Acid ◽  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Spectrophotometric Method ◽  
Oxidation Reaction ◽  
Spectrophotometric Assay ◽  
Sodium Metaperiodate ◽  
Relative Standard ◽  
Sensitive Spectrophotometric Method

A new simple, accurate and reasonably sensitive spectrophotometric method is described for the determination of reserpine based on the oxidation with sodium metaperiodate in the presence of acetic acid and coupling with 3-methyl-2-benzo thiazolinone hydazone hydrochloride (MBTH) to form highly blue coloured product showing maximum absorbance at 630 nm. Beer's law is obeyed in the range 0.2–1.6 µg ml−1. The relative standard deviation was found to be less than 1%. The proposed method can be applied for the estimation of reserpine in tablets with no evidence of interference from excipients.

scholarly journals Changes of organic acids and phenolic compounds contents in grapevine berries during their ripening

2013 ◽  
Vol 11 (10) ◽  
pp. 1575-1582 ◽  
Author(s):  
Irena Jančářová ◽  
Luděk Jančář ◽  
Alice Náplavová ◽  
Vlastimil Kubáň
Keyword(s):  
Phenolic Compounds ◽  
Tartaric Acid ◽  
Alkaline Solution ◽  
Spectrophotometric Method ◽  
Total Content ◽  
Titratable Acidity ◽  
Colored Complex ◽  
Total Titratable Acidity ◽  
Phenolic Substances

AbstractChanges of total content of phenolic substances, alteration in total titratable acidity and differences in tartaric acid content in grapes of four white (Müller-Thurgau — MT, Pinot Blanc — Rulandské bílé in Czech, RB, Sauvignon (Sg), and Muscat Ottonel — Muškát Ottonel in Czech, MO) and two blue (Dornfelder — Df and Blue Frankish — Frankovka in Czech, Fr) grapevine varieties throughout their growth, ripening and maturing (July–November). Potentiometric titration was applied for the determination of total titratable acids in grapes (expressed as tartaric acid equivalents in g L−1). A spectrophotometric method according Rebelein based on the formation of a colored complex of ammonium metavanadate and tartaric acid was used for determination of tartaric acid in green juice made by pressing unripe grapes. A spectrophotometric method based on reduction of phosphomolybdato-tungsten complex in alkaline solution using Folin-Ciocalteau reagent was applied for determination of total content of phenolic substances (TCP).

4-Amino-Benzo[F]Isoindole-1,3-Dione Derivatives As Turn-On Fluorescent Indicators For Water Determination In Acetonitrile

2018 ◽  
pp. 183-191
Author(s):  
R. Linnik ◽  
I. Levkov ◽  
A. Chemnyi ◽  
O. Radchenko ◽  
Z. Voitenko ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Linear Response ◽  
Emission Peak ◽  
Water Determination ◽  
Fluorescent Indicators ◽  
Turn On ◽  
Peak Intensity ◽  
Relative Standard ◽  
Acetonitrile Solutions

4-Amino-9-(2,5-dioxo-pyrrolidin-1-phenyl-3-yl)-1-phenyl-benzo[f]isoindole-1,3-dione (1) and 4-amino-9-(2,5- dioxo-1-(4-methylphenyl)-pyrrolidin-3-yl)-1-(4-methylphenyl)-benzo[f]isoindole-1,3-dione (2) were studied as fluorescent indicators for water determination in acetonitrile. The intensity of fluorescence of these compounds in acetonitrile solutions increases in presence of water along with red shift of the emission peak. Intensity-based and wavelength-based procedures of water determination in acetonitrile are suggested with detection limit of 0.2 % (v/v) H2O in both cases. The linear response covers a concentration range of 0.2–20 % (v/v). The relative standard deviation at 1 % (v/v) water content is 0.20. The interferences of acetic acid, ammonia and metal ions have been studied. Ammonia and acetic acid don’t interfere with the determination of water by wavelength-based fluorescence technique. In intensity-based mode the determination of water is possible at concentration of these impurities up to 0.25 and 0.02 mol·L -1, respectively. Cu(II) ions have almost no effect on fluorescence of indicators up to 1·10 -5 mol·L -1 ; Zn (II) ions enhance fluorescence of 1 at concentration ≥ 5·10-6 mol·L-1 . The 4-amino-benzo[f]- isoindole-1,3-dione-based fluorescent indicators are pH-insensitive.

Sequential determination of titratable acidity and tartaric acid in wines by flow injection spectrophotometry

The Analyst ◽  
1998 ◽  
Vol 123 (4) ◽  
pp. 661-664 ◽  
Author(s):  
Antoacute;nio O. S. S. Rangel ◽  
Ildikoacute; V. Toacute;th
Keyword(s):  
Tartaric Acid ◽  
Flow Injection ◽  
Titratable Acidity ◽  
Sequential Determination

scholarly journals Smartphone-based molecularly imprinted sensors for rapid detection of thiamethoxam residues and applications

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0258508
Author(s):  
Sihua Peng ◽  
Aqiang Wang ◽  
Yuyang Lian ◽  
Xi Zhang ◽  
Bei Zeng ◽  
...  
Keyword(s):  
Pesticide Residues ◽  
Rapid Detection ◽  
Rapid Determination ◽  
Detection System ◽  
Residue Analysis ◽  
Differential Pulse ◽  
Detection Technology ◽  
Screen Printed Carbon Electrode ◽  
Relative Standard

In order to achieve rapid detection of thiamethoxam residues in mango, cowpea and water, this study modified the screen printed carbon electrode (SPCE) to make a specific molecular imprinting sensor (Thiamethoxam-MIP/Au/rGO/SPCE) for thiamethoxam. An integrated smartphone platform was also built for thiamethoxam residue analysis. The performance of the complete system was analyzed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The system was then applied for the rapid determination of thiamethoxam residues in water, mango and cowpea samples. The results showed that the molecular sensor showed good linearity in the range 0.5–3.0 μmol/L of thiamethoxam. The detection limit of thiamethoxam was 0.5 μmol/L. Moreover, the sensor had good reproducibility and anti-interference performance. The average recovery rates of the pesticide residues in water, mango and cowpea samples were in the range of 90–110% with relative standard deviations < 5%. The rapid detection system for thiamethoxam residue constructed in this study was simple, reliable, reproducible and had strong anti-interference. It has broad application prospects in the field detection of thiamethoxam residue, and serves as a valuable reference for the further development of rapid detection technology of pesticide residues in the field of environment and food safety.

Liquid Chromatographic Determination of Ochratoxin A in Coffee Beans and Coffee Products

1986 ◽  
Vol 69 (6) ◽  
pp. 960-964 ◽  
Author(s):  
Hisaya Terada ◽  
Haruo Tsubouchi ◽  
Katsuhiko Yamamoto ◽  
Kazuo Hisada ◽  
Yoshio Sakabe
Keyword(s):  
Ochratoxin A ◽  
Chromatographic Determination ◽  
Instant Coffee ◽  
Coffee Beans ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Better Than

Abstract A liquid chromatographic method for the determination of ochratoxin A in coffee beans (green and roast), instant coffee, and coffee drink is described. The sample is subjected to extraction with methanol-1% aqueous sodium bicarbonate (1 + 1) and C18 cartridge cleanup. The extract is chromatographed on a Nucleosil 5C18 column with a mobile solvent of acetonitrile-water-0.2M phosphate buffer pH 7.5 (50 + 47 + 3) containing 3mM cetyltrimethylammonium bromide as an ionpair reagent. Ochratoxin A is detected with a fluoromcter (excitation 365 nm, emission 450 nm). The sensitivity was increased 20-fold by using ion-pair resolution. The detection limits corresponded to 2 μg/kg for coffee beans, 5 μg/kg for instant coffee, and 0.2 μg/kg for coffee drink. The recoveries from coffee products were generally better than 80.7% and the relative standard deviations were 3.43-5.93%. The peak coinciding with ochratoxin A can be confirmed by treatment using alcohol (methanol, ethanol, or n-propanol) and H2S04.

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