Fluorometric Determination of Indole in Shrimp

1978 ◽  
Vol 61 (5) ◽  
pp. 1089-1091
Author(s):  
Carl Ponder
Keyword(s):  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Analytical Data ◽  
Methanol Solution ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Saturated Sodium Chloride Solution ◽  
Aoac Official ◽  
Liquid Chromatographic

Abstract A fluorometric method is described for determining indole in shrimp. The indole is extracted with n-hexane, partitioned into a methanol- saturated sodium chloride solution ( 9 + 1 ), and determined fluoromctrically. The detection limit of the method is 0.04 μg indole/g shrimp. Quantitative analytical data are presented for indole in samples of shrimp determined by the fluorometric method and the AOAC official colorimetric and gas-liquid chromatographic procedures. The correlation coefficient between the data of the fluorometric and colorimetric methods was 0.96. Indole recovered from 25 g samples of fresh shrimp spiked with 6 and 12 μg indole/25 g ranged from 97 to 106%. The fluorescence response is linear in the range of 1 to 25 μg indole/100 ml methanol solution and no significant change is noted in solutions kept in the dark 18 hr.

Capillary Gas Chromatographic Determination of Prometryn and Its Degradation Products in Parsley

1985 ◽  
Vol 68 (4) ◽  
pp. 750-753
Author(s):  
Promode C Bardalaye ◽  
Willis B Wheeler
Keyword(s):  
Sodium Chloride ◽  
Ethyl Acetate ◽  
Aqueous Phase ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Fused Silica ◽  
Saturated Sodium Chloride Solution

Abstract Residue analysis of the herbicide prometryn (2,4-bis(isopropylamino)- 6-methylthio-l,3,5-triazine) is widely known, but an analytical method for determining its metabolities or degradation products in addition to the parent chemical has not yet been reported in the literature. The procedure reported here is for the extraction and determination of prometryn and 2 metabolites, 2-amino-4-isopropylamino-6-methylthio- l,3,5-triazine and 2,4-diamino-6-methylthio-l,3,5-triazine, in parsley. Crops were extracted with 2-propanol followed by concentration of the extract and partitioning with a minimum amount of hexane in the presence of a large excess of water to remove most of the green pigment. The aqueous phase was divided into 2 equal halves: (A) Onehalf portion was partitioned with dichloromethane in the presence of saturated sodium chloride solution, the dichloromethane phase was separated, and the aqueous phase was discarded. The organic solvent was evaporated, and the contents were reconstituted in petroleum ether before prometryn analysis. (B) The other half was made slightly alkaline with ammonium hydroxide solution and was partitioned with ethyl acetate in the presence of saturated sodium chloride solution. The ethyl acetate phase was concentrated, centrifuged to remove any turbidity, and analyzed for the 2 metabolities above. Fused silica capillary gas chromatography (GC) with nitrogen-phosphorus (N-P) detection was used for quantitation. The limit of detection was 0.05 mg/kg for all the compounds examined. Recoveries from fortified parsley samples ranged from 59 to 73% at fortification levels of 0.05 to 1.0 mg/kg.

Indirect Fluorometric Determination of Lactic Acid in Wine

1993 ◽  
Vol 76 (5) ◽  
pp. 1017-1021 ◽  
Author(s):  
Giovanni Burini
Keyword(s):  
Lactic Acid ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
H2so4 Concentration ◽  
Time Value ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Liquid Chromatographic ◽  
Good Agreement

Abstract A sensitive, specific, and reliable fluorometric method for the determination of lactic acid in wine is described. After the wine sample was boiled and diluted, lactic acid was fluorometrically determined by evaluating the concentration of fluorophore derived from the reaction between acetaldehyde, a product of the oxidation of lactic acid, and 1,3-cyclohexanedione. The best oxidation conditions were a temperature of 90°C for 2 min and a Ce(SO4)2 concentration of 2 mg/mL in 0.5M H2S04. These values are not strictly critical, because the time value ranged from 1 to 2.6 min, temperature from 82 to 93.6°C, Ce(SO4)2 concentration from 1 to 2.6 mg/mL, and H2SO4 concentration from 0.125 to 0.72M; the values yielded fluorescence intensity decrements of <5% relative to the optimum. Six wine samples (3 red and 3 white) as well as those spiked with 1 and 2 g lactic acid/L were analyzed. The average recoveries ranged from 98.3 to 100.1%, with the relative standard deviation ranging from 1.3 to 3.4. The results of the fluorometric analyses compared with those obtained from the known liquid chromatographic method gave good agreement. The proposed method appears to be sensitive, specific, and reliable but not advantageous for routine analysis.

Gas-Liquid Chromatographic Determination of Technical Chlordane Residues in Food Crops: Interpretation of Analytical Data

1975 ◽  
Vol 58 (5) ◽  
pp. 1051-1061
Author(s):  
William P Cochrane ◽  
James F Lawrence ◽  
Young W Lee ◽  
Ronald B Maybury ◽  
Brian P Wilson
Keyword(s):  
Field Experiments ◽  
Stationary Phases ◽  
Analytical Data ◽  
Chromatographic Determination ◽  
Electron Capture Detection ◽  
Food Crops ◽  
Liquid Chromatographic Determination ◽  
Consistent Method ◽  
Liquid Chromatographic

Abstract An interlaboratory investigation of technical chlordane residues in food crops was carried out to determine the most practical and consistent method of reporting results. Using a technical chlordane reference standard, 8 gas chromatographic stationary phases were studied for their resolution capabilities. The best separations were obtained with SE-30 and its OV-1 equivalent. Using these columns and electron capture detection, potatoes and carrots from supervised field experiments were analyzed in duplicate and quantitated by using 4 methods of calculation. The data were statistically treated to determine the precision and bias for each method. Also, 1 sample was analyzed in duplicate on 2 different occasions by 6 laboratories to substantiate the initial conclusions. Based on the criterion of high precision it is suggested that a comparison of total area under the chromatogram of the sample with total area of a standard technical chlordane be the method of quantitation. Only peaks which are common to both standard and sample have any significance in this type of calculation.

Liquid Chromatographic Determination of Zoalene in Medicated Feeds

1984 ◽  
Vol 67 (5) ◽  
pp. 861-862 ◽  
Author(s):  
John Morawski ◽  
Glenn Kyle
Keyword(s):  
Colorimetric Method ◽  
Chromatographic Determination ◽  
Activated Alumina ◽  
Reverse Phase ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Aoac Official ◽  
Liquid Chromatographic ◽  
Medicated Feeds

Abstract A rapid, reliable separation and quantitation of zoalene (3,5-dinitroo-toluamide) from feeds is accomplished by using reverse phase liquid chromatography (LC) and ultraviolet detection. An extraction technique which is similar to the present AOAC official colorimetric method is used before chromatographic analysis. This extraction is followed by an activated alumina cleanup and LC to separate zoalene from feed matrix. The methodology was applied to a variety of spiked feed matrices, and yielded good recoveries. Liquid chromatographic results were shown to correlate with colorimetric determinations.

DETERMINATION OF TRACE AMOUNTS OF SILVER IN GALENA ORES

1960 ◽  
Vol 38 (9) ◽  
pp. 1488-1494 ◽  
Author(s):  
E. J. Bounsall ◽  
W. A. E. McBryde
Keyword(s):  
Aqueous Solution ◽  
Nitric Acid ◽  
Sodium Chloride ◽  
Hydrochloric Acid ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Silver Content ◽  
Aqueous Sodium Chloride Solution ◽  
Aqueous Sodium

An analytical method is described for the determination of microgram amounts of silver in galena ores, based on the "reversion" of silver dithizonate. Silver is separated from relatively large amounts of lead by extraction as dithizonate into chloroform from an aqueous 1:99 nitric acid solution. Separation from mercury, which is also extracted under these conditions and would, if present, interfere in the analysis, is achieved by reverting the dithizonate solution with a 5% aqueous sodium chloride solution which is also 0.015 molar in hydrochloric acid. Following dilution of this aqueous solution and adjustment of pH, silver is again extracted into chloroform as the dithizonate, and determined absorptiometrically. Analyses of a number of galena ore samples showed a precision of within 3% for a silver content ranging from 0.03 to 0.4%.Some other methods for isolating silver from these samples, which were tried but found unsatisfactory, are discussed.

Fluorometric Method for Determination of 1,2-Unsaturated Aldehydes in Autooxidized Lipids with 2,4-Diaminotoluene

1990 ◽  
Vol 73 (4) ◽  
pp. 590-594
Author(s):  
Teruhisa Hirayama ◽  
Shinji Miura ◽  
Mariko Araki ◽  
Yoshiko Takeo ◽  
Tetsushi Watanabe
Keyword(s):  
Methyl Oleate ◽  
Acidic Condition ◽  
Emission Wavelength ◽  
Excitation Wavelength ◽  
Fluorometric Method ◽  
Unsaturated Aldehydes ◽  
Liquid Chromatographic

Abstract A simple fluorometric method has been developed to determine 1,2-unsaturated aldehydes in autooxidized lipids. 1,2- Unsaturated aldehydes were allowed to react with 2,4-diamlnotoluene in acidic condition and the products, 7-amlno-6- methylqulnoline derivatives, were determined by a fluorometric procedure at 394 nm (excitation wavelength) and 494 nm (emission wavelength). Finally, 1902.9, 1738.8, and 2149.2 μg/g of 1,2-unsaturated aldehydes as 2-propenal were detected in 20-h autooxidized methyl oleate, methyl llnoleate, and methyl llnolenate, which contained 98.5, 223.2, and 355.6 μg/g, respectively, of thlobarblturlc acid reactive substances as malondialdehyde. In a preliminary liquid chromatographic LC determination of 2-propenal In autooxidized lipids, 29, 20, and 57 μg/g, respectively, of 2- propenal were detected In 20-h autooxidized methyl oleate, methyl llnoleate and methyl llnolenate. The 2-propenal can be detected as 7-amlno-6-methylqulnoline by using LC-fluorometrlc procedure at levels of 100 pg.

Liquid Chromatographic Determination of Sulfite in Grapes and Selected Grape Products

1989 ◽  
Vol 72 (6) ◽  
pp. 903-906
Author(s):  
Gracia A Perfetti ◽  
Frank L Joe ◽  
Gregory W Diachenko
Keyword(s):  
Chromatographic Determination ◽  
Reverse Phase ◽  
Nitrobenzoic Acid ◽  
Tetrabutylammonium Ion ◽  
Aqueous Formaldehyde Solution ◽  
Liquid Chromatographic Determination ◽  
Aoac Official ◽  
Liquid Chromatographic ◽  
Aqueous Formaldehyde

Abstract A liquid chromatographic (LC) method is described for the determination of sulfite in grapes and certain grape products. Sulfite is extracted from grapes with aqueous formaldehyde solution buffered at pH 5; free sulfite is converted to hydroxymethylsulfonate (HMS), which is extremely stable at pH 3-7. Subsequent heating to 80°C for 30 min converts reversibly bound forms of sulfite to HMS. The extract is then analyzed by reverse-phase ion-pairing liquid chromatography, using a Cjg column and a mobile phase of aqueous 0.005M tetrabutylammonium ion in 0.05M acetate, pH 4.7, and a flow rate of 1 mL/min. Aqueous KOH is added to the eluate to convert HMS to free sulfite, which is then treated with 5,5'-dithiobis[2-nitrobenzoic acid]. This reaction produces the 3-carboxy-4-nitrothiophenolate anion, which is determined by measurement of electronic absorption at 450 nm. For grapes spiked with HMS at 5-20 ppm (as S02), recoveries ranged from 92 to 112%, with a coefficient of variation of 4.6%. The method was also used to determine sulfite in various grape products. Results were comparable to those obtained by the AOAC official Monier-Williams method.

Rapid Fluorometric Determination of Benzo(a)pyrene in Foods

1982 ◽  
Vol 45 (2) ◽  
pp. 139-142 ◽  
Author(s):  
YASUHIDE TONOGAI ◽  
SHUNJIRO OGAWA ◽  
MASATAKE TOYODA ◽  
YOSHIO ITO ◽  
MASAHIRO IWAIDA
Keyword(s):  
Detection Limit ◽  
Peak Height ◽  
Excitation Wavelength ◽  
Activated Alumina ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Standard Curve ◽  
Layer Chromatography ◽  
Entire Procedure

A simple and rapid fluorometric method for determining benzo (a) pyrene in foods was developed. Benzo (a) pyrene is extracted from foods with n-hexane:ether mixture (4:1), purified through a column of activated alumina and determined fluorometrically. An excitation wavelength of 295 nm and emission wavelength of 403 nm were used for calculating concentrations of benzo (a) pyrene. The peak height at 403 nm and baseline between 392 and 418 nm were employed to derive a standard curve for quantitating benzo (a) pyrene. A calibration curve for between 0.04 – 4 ng/ml of benzo (a) pyrene was used. Recoveries of benzo (a) pyrene from 14 kinds of food spiked at levels of 20 and 2ppb were within the range of 79.5 – 93.8% and 50.0 – 80.6%, respectively. The entire procedure takes only one hour with the detection limit being 0.1 ppb. Benzo (a) pyrene detected was reconfirmed by thin-layer chromatography.

scholarly journals The determination of ammonia in soil

1920 ◽  
Vol 10 (1) ◽  
pp. 72-85 ◽  
Author(s):  
Donald J. Matthews
Keyword(s):  
Sodium Chloride ◽  
Chloride Solution ◽  
Calcareous Soil ◽  
Sodium Chloride Solution ◽  
Complete Recovery ◽  
Partial Decomposition ◽  
Definite Time

Ammonia can be recovered from soil with an efficiency of 98·5 to 99·5 per cent, in six hours in the apparatus described.For most purposes it is sufficient to aerate the soil for three hours.Highly dunged glasshouse soils undergo partial decomposition in the cold with magnesia. In such cases the soil should be aerated with magnesia and strong sodium chloride solution for a definite time, say three hours.The complete recovery of added ammonia from a calcareous soil is difficult unless the soil is finely ground.

ANTIMONY TRICHLORIDE – ETHANOL PRECIPITATION FOR THE FLUOROMETRIC DETERMINATION OF RIBOFLAVIN IN PORK

1947 ◽  
Vol 25f (2) ◽  
pp. 133-140 ◽  
Author(s):  
Jessie R. Lewis ◽  
Paul R. Gorham
Keyword(s):  
Antimony Trichloride ◽  
Fluorometric Method ◽  
Fluorometric Determination ◽  
Ethanol Precipitation

A fluorometric method suitable for routine analyses is presented in which interfering substances in papain–takadiastase extracts of pork are precipitated in the presence of 0.02% antimony trichloride and 47.5% ethanol. Antimony trichloride prevents the adsorption of riboflavin upon the precipitate. Recoveries of 95 to 100% are obtained. Determinations by this method correlate well with those obtained microbiologically: for eight samples of fresh pork, four cooked, and four uncooked, r =.94; for 20 samples of cured pork, four cooked, and 16 uncooked, r =.98.

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