Liquid Chromatographic Determination of Phenolic Impurities in Technical MCPA Using Electrochemical Detection (Coulometric Mode)

1988 ◽  
Vol 71 (2) ◽  
pp. 325-327
Author(s):  
Yuk Y Wigfield ◽  
Monique Lanouette
Keyword(s):  
Acetic Acid ◽  
Flow Rate ◽  
Chromatographic Determination ◽  
Gradient System ◽  
Mobile Phases ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Solvent Systems ◽  
Liquid Chromatographic

Abstract Fifteen samples of technical 4-chloro-2-methylphenoxy acetic acid (MCPA) from 6 manufacturers were analyzed for the presence of 13 different phenolic impurities. Reverse-phase liquid chromatography with an electrochemical (coulometric mode) detector was used for qualitative and quantitative determinations. The phenols were separated using a 40-70% methanol and 60-30% 0.02M KH2P04 (pH 4.0) 35 min gradient system on a Spheri-5-RP-18 column. Confirmation of the phenols present was done by retention time comparison with the corresponding standards, using 2 other isocratic mobile phases, methanol-0.2M acetic acid (60 + 40) at a flow rate of 1.3 mL/min and acetonitrile-0.02M KH2P04 (45 + 55) (pH 3.0) at a flow rate of 0.90 mL/min. The similarity of results on 3 different solvent systems demonstrates the absence of any interfering responses. 2-Methyl-4-chlorophenol (average 0.168%) and 2-methyl- 4,6-dichlorophenol (average 0.004%) were detected in all 15 samples. 3-Methylphenol (0.002%) and 2,6-dimethyl-4-chlorophenol (0.002%) were detected in one sample only. The minimum detectable amount ranged from 0.1 to 0.6 ng, depending on the phenol. This corresponds to less than 0.002% when expressed relative to the weight of sample. The coefficient of variation for multiple analyses of the same sample (n = 6) is 1% for 2-methyl-4-chlorophenol and 3% for 2-methy 1-4,6- dichlorophenol.

Reverse Phase Liquid Chromatographic Determination of Chlorophacinone and Diphacinone in Bait Formulations

1982 ◽  
Vol 65 (4) ◽  
pp. 927-929
Author(s):  
Brian R Bennett ◽  
Gregory S Grimes
Keyword(s):  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Chromatographic Determination ◽  
Reverse Phase ◽  
Target Concentration ◽  
External Standard ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract Chlorophacinone and diphacinone are extracted at the 0.005% level from grain or paraffinized baits with glacial acetic acid. The target concentration is 0.01 mg/mL. The filtered supernate is chromatographed on a Partisil PXS ODS10/25 liquid chromatography column with premixed and degassed glacial acetic acid-tetrahydrofuran-water (14 + 2 + 9) and detected at 288 nm. The concentration is calculated by using an external standard. The recovery from spiked samples averaged 96.6% for both analytes. The response is linear from 0.001 to 0.040 mg/mL. The coefficient of variation of within-day replicates ranged from 1.1 to 2.5%.

Liquid Chromatographic Determination of Acetic Acid in Foods

1984 ◽  
Vol 67 (5) ◽  
pp. 885-887
Author(s):  
Samy H Ashoor ◽  
Jim Welty
Keyword(s):  
Acetic Acid ◽  
Flow Rate ◽  
Mobile Phase ◽  
Chromatographic Determination ◽  
Uv Detector ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method has been developed for the determination of acetic acid in vinegar and other foods. The LC system includes an Aminex HPX-87H column and a UV detector set at 210 nm. The mobile phase is 0.009N H2S04 at a flow rate of 0.7 mL/min. The method is simple and specific for acetic acid. Recoveries of acetic acid from a variety of products ranged from 93.3 to 102% with coefficients of variation from 2.4 to 4.6%.

Use of Post-Column Derivatization in Liquid Chromatographic Determination of Sulfamethazine and Sulfathiazole in Feeds and Feed Premixes

1982 ◽  
Vol 65 (4) ◽  
pp. 823-827 ◽  
Author(s):  
Rodger W Stringham ◽  
Elizabeth C Mundell ◽  
Robert L Smallidge
Keyword(s):  
Acetic Acid ◽  
Colorimetric Method ◽  
Chromatographic Determination ◽  
Mobile Phases ◽  
Column Eluate ◽  
Liquid Chromatographic Determination ◽  
Sample Range ◽  
Liquid Chromatographic ◽  
Method Analysis

Abstract Sulfonamide drugs are extracted from feed and feed premixes by shaking with 0.15N HC1 in 25% methanol. The extract is diluted, clarified, and chromatographed on a reverse phase Cis column. Mobile phases used are methanol-2% acetic acid (35 + 65) and acetonitrile-2% acetic acid (18 + 82) for sulfamethazine (SMT) and sulfathiazole (STZ), respectively. A solution of dimethylaminobenzaldehyde (DMAB) is added to the column eluate and the resulting sulfonamide- DMAB complex is detected at 450 nm. The method was tested for linearity, recovery, and precision across a broad sample range. Recovery was 100.6 ± 2.3% and 96.3 ± 1.6% for STZ and SMT, respectively. Linearity was excellent (r2 = 0.9985 for STZ and r2 = 0.9996 for SMT) as was within-day precision (RSD = 2.00% for STZ and 1.52% for SMT). The method was compared with the Bratton-Marshall colorimetric method. Analysis of 14 STZ and 15 SMT samples failed to detect any bias between the 2 methods. Some practical aspects of the use of this technique are discussed.

Liquid Chromatographic Determination of Chlorinated Phenol Impurities in Technical Pentachlorophenol Using Electrochemical Detection (Coulometric Mode)

1984 ◽  
Vol 67 (3) ◽  
pp. 494-497 ◽  
Author(s):  
Monique Lanouette ◽  
William P Cochrane ◽  
Jojinder Singh
Keyword(s):  
Chromatographic Determination ◽  
Gradient System ◽  
Chlorinated Phenols ◽  
Qualitative And Quantitative ◽  
Sodium Pentachlorophenate ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic ◽  
Minimum Detectable Amount

Abstract Fourteen technical pentachlorophenol and 3 sodium pentachlorophenate samples were obtained from several manufacturers and analyzed for the presence of various chlorinated phenolic impurities. Reverse phase liquid chromatography with an electrochemical (coulometric mode) detector was used for qualitative and quantitative determinations. Nineteen chlorinated phenols were separated using a 50–70% methanol and 50–30% 0.02M KH2P04 (pH 4.0) 35 min gradient system on a Spheri-5 RP-18 column. 2,4-Dichlorophenol (average 0.07%); 3,5-dichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, 3,4,5-trichlorophenol (each <0.03%); 2,3,5,6-tetrachlorophenol (average 0.009%); 2,3,4,6-tetrachlorophenol (average 4.47%); 2,3,4,5-tetrachlorophenol (<0.025%) were detected as contaminants in the various samples. The minimum detectable amount ranged from 0.1 to 10 ng, depending on the chlorophenol.

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.

Liquid Chromatographic Determination of Carminic Acid in Yogurt

1989 ◽  
Vol 72 (2) ◽  
pp. 231-234 ◽  
Author(s):  
Mercedes Jalón ◽  
Majesús Peńa ◽  
Julián C Rivas
Keyword(s):  
Chromatographic Determination ◽  
Carminic Acid ◽  
Reverse Phase ◽  
Liquid Chromatographic Method ◽  
Relative Standard ◽  
Array Detection ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A reverse-phase liquid chromatographic method is described for the determination of carminic acid in yogurt. A C18 column is used with acetonitrile-1.19M formic acid (19 + 81) as mobile phase and diode array detection. Sample preparation includes deproteinization with papain and purification in a polyamide column. The relative standard deviation for repeated determinations of carminic acid in a commercial strawberry-flavored yogurt was 3.0%. Recoveries of carminic acid added to a natural-flavored yogurt ranged from 87.2 to 95.3% with a mean of 90.2%. The method permits measurement of amounts as low as 0.10 mg/kg.

Rapid Method for Extraction and Reverse Phase Liquid Chromatographic Determination of Paraquat Residues in Water

1983 ◽  
Vol 66 (3) ◽  
pp. 663-666
Author(s):  
Ijaz Ahmad
Keyword(s):  
High Performance ◽  
Chromatographic Determination ◽  
High Performance Liquid Chromatographic ◽  
Reverse Phase ◽  
Ultraviolet Detection ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Low Levels ◽  
Liquid Chromatographic

Abstract A simple and fast analytical method is described for the quantitative determination of low levels of paraquat residues in water. The method involves extraction and concentration of paraquat in water by using a C18 Sep-Pak cartridge followed by reverse phase high performance liquid chromatographic determination with ultraviolet detection at 257 nm. Recoveries of paraquat from spiked samples were above 93% with a coefficient of variation of 6.1%. The method can be used for water samples with paraquat concentrations as low as 0.05 ppm.

Liquid Chromatographic Determination of Thiamine in Rodent Feed by Postcolumn Derivatization and Fluorescence Detection

1995 ◽  
Vol 78 (2) ◽  
pp. 307-309 ◽  
Author(s):  
Theresa A Gehring ◽  
Willie M Cooper ◽  
Claude L Holder ◽  
Harold C Thompson
Keyword(s):  
Chromatographic Determination ◽  
Reversed Phase ◽  
Detector Response ◽  
Fluorescence Excitation ◽  
Liquid Chromatographic Method ◽  
Essential Nutrient ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method was developed for determination of the essential nutrient thiamine (vitamin Bi) in rodent feed. Thiamine was extracted with hydrochloric acid, separated by reversed-phase liquid chromatography, derivatized postcolumn to thiochrome with potassium hydroxide and potassium ferricyanide, and detected by fluorescence. Excitation and emission wavelengths were 370 and 430 nm, respectively. Detector response was linear in the range of 2.58 to 15.5 ng of thiamine injected. Instrument detection limit was 5 pg of thiamine injected.

Reversed-Phase Liquid Chromatographic Determination of Hypoglycin A (HG-A) in Canned Ackee Fruit Samples

1994 ◽  
Vol 77 (5) ◽  
pp. 1175-1179 ◽  
Author(s):  
Ghulam Sarwar ◽  
Herbert G Botting
Keyword(s):  
Amino Acids ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Precolumn Derivatization ◽  
Edible Portion ◽  
Fruit Samples ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A reversed-phase liquid chromatographic (LC) method involving precolumn derivatization with phenylisothiocyanate (PITC) was developed for determining levels of hypoglycin A (HG-A) in canned ackee fruit samples. HG-A was extracted by homogenizing the drained fruit in 80% ethanol. By using a Waters Pico-Tag amino acid analysis 15-cm-long column (which is also used for analyzing protein hydrolysates and biological samples) and an LC system, the baseline separation of HG-A from other amino acids was completed in about 6 min. The total time for analysis and equilibration was 16 min. HG-A levels in the edible portion of fruit in 18 cans varied from 18.27 to 87.50 mg HG-A/can. Recoveries of added standard HG-A averaged 101%. To our knowledge, this is the first report of the use of this method to determine HG-A in ackee fruit.

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