Determination of Aminacrine Hydro-Chloride in Drug Preparations by TLC with Fluorescence Densitometry

Abstract

A densitometric TLC method was developed for quantification of aminacrine hydrochloride in creams, jellies, and suppositories. Aminacrine was extracted into acidic ethanol, diluted to a known volume, and separated by high performance silica gel TLC. The fluorescence of aminacrine zones in samples and standards was compared by in situ scanning. Recoveries of aminacrine from authentic samples ranged from 95.4 to 103.4%.     

Enhanced Preconcentration of Pesticides from Water Using the Goulden Large-Sample Extractor

Abstract

Recoveries of nine model pesticides measured in water samples ranging from 4 to 120 liters using the Goulden large-sample extractor and were similar to recoveries predicted by a continuous liquid-liquid extraction model. Recoveries from the largest volumes were affected by emulsion formation at high sample flow rates. Limits of detection using the Goulden extractor under optimized conditions were lower than those obtained from 1 liter serial batch extractions by factors inversely proportional to sample volumes for pesticides with logarithm of solvent/water partition coefficients greater than 2. Average limits of detection for the pesticides were 9ng/l for 10 liter samples and 1 ng/l for 120 liter samples. Extraction of large water samples with methylene chloride using the Goulden large-sample extractor is an alternative technique to extraction of water by using solid-phase sorbents.     

Quantification of Niacin and Niacinamide in Vitamin Preparations by Densitometric Thin Layer Chromatography

Abstract

A densitometric TLC method was developed for the determination of the B-3 vitamins niacin and niacinamide in commercial vitamin preparations. The method involves removal of excipients by ethanol precipitation, separation of the vitamins by high performance TLC on phosphor-containing silica gel layers, and in situ scanning of sample and standard zones. The per cent recoveries for niacinamide in vitamin products were 96 to 104% and for niacinamide added to products 99 and 102%. Recoveries of added niacin were 99 to 102%, but recoveries of niacin in products ranged from 0 to 74% of the label values. Additional ingredients did not interfere with the determination.     

Determination of Iprodione,Vinclozolin, and Procymidone as the Heptafluorobutyramides of 3,5-Dichloroaniline

Abstract

A method was developed for the determination of three fungicides in foods based on alkaline degradation to 3,5-dichloroaniline, isolation of the latter by steam distillation and measurement of the heptafluorobutyrate by gas chromatography. Recoveries averaged 91% from several commodities spiked at from 10–80ppb. The minimum detectable limit of 2.6ppb was attainable in grape, with similar limits found in strawberry, tomato and beans. The method was capable of determining degradation products formed as a result of cooking.     

Pressurized System and Microwave-Assisted Extraction for Rapid Analysis of Fiber in Animal Feedstuffs

Abstract

A pressurized system under microwave radiation and filter bags to contain the samples was proposed as an alternative to Neutral Detergent Fiber (NDF) determination in animal feed. After optimization by a 2³ factorial design, the procedure was applied to nine forage and cereal bran with different amounts of starch (supplied by proficiency testing at various nutrition laboratories). Recoveries from 93 to 110% (0.7 to 7.4 RSD) were obtained. The proposed system allows the NDF simultaneous extraction from 18 samples, increasing the samples throughput from 6 or 40 day^?1 to approximately 280 day^?1, with low consumption of energy and reagents, producing low amounts of residue.     

Determination of Allantoin in Drug Preparations by Quantitative High Performance TLC

Abstract

A densitometric TLC method was developed for the quantification of allantoin in creams and suppositories used to treat vaginal infections. Allantoin was extracted with water at elevated temperature, diluted to a known volume, and separated by HP silica gel TLC. Allantoin was detected by spraying with p-dimethylamine-benzaldehyde reagent. The absorption of standards and samples was compared by in situ scanning. Recoveries of allantoin from authentic samples ranged from 96–102%, except for one sample that assayed high. The accuracy of the method was demonstrated by standard addition analysis of this sample.     

Determination of Biphenyl in Citrus Fruits by Quantitative Thin-Layer Chromatography

Abstract

Residues of the fungicide biphenyl in citrus fruits have been determined by direct scanning of spots on phosphor-impregnated high performance silica gel TLC plates under UV light. Biphenyl was separated from fruit tissue by steam liquid-liquid extraction. Recoveries from spiked samples ranged from 92–99% at 100, 50, and 10 ppm levels. The precision of the TLC determination and overall procedure are shown to be adequate for residue analysis.     

Plasma Sample Cleanup for Catecholamines Analysis Using Weak Cation Exchange Solid Phase Extraction

Abstract

Norepinephrine and epinephrine were isolated from human plasma at picogram levels by solid phase extraction (SPE), on a proprietary weak cation exchange silica based packing. Plasma samples were spiked with catecholamines at two concentrations to simulate body response to varying levels of stress. Recoveries of norepinephrine and epinephrine at both concentrations exceeded 95%.

An analysis of catecholamines by ion pair high-performance liquid chromatography with amperometric detection is described.     

Determination of Arsenic in Beverages and Foods by Hydride Generation Atomic Absorption Spectroscopy

Abstract

The determination of the arsenic content of foods and beverages by a technique involving a magnesium nitrate aided dry ashing step followed by an arsine generation atomic absorption finish is described. Recoveries of various arsenic species added prior to ashing was excellent. Total arsenic concentrations found in samples of beverages ranged from less than 10 to 265 ppb and in foods from 20 to 9290 ppb. The sensitivity of the technique is approximately ten-fold better than obtainable with commercially available hydride generation atomic absorption units.     

Reliable System for the Analysis of Riboflavin in Foods by High Performance Liquid Chromatography and UV Detection

Abstract

A high performance liquid chromatographic (HPLC) method has been developed to determine riboflavin in food samples. A reverse phase C₁₈ column with ultraviolet detection was employed. Sample preparation included acid and enzimatic hydrolysis, followed by purification on Florisil and Sep-Pak cartridges. Recoveries of 98% were obtained. A detection limit of 0.4 ng/injection has been achieved.     

Determination of Coumarin in Vanilla Flavorings by Quantitative High Performance Thin Layer Chromatography

Abstract

High performance silica gel TLC was used to qualitatively and quantitatively determine coumarin in real and artificial vanilla flavorings. Coumarin was detected as a fluorescent or colored zone and quantified by scanning with a densitometer. Recoveries and reproducibility values are reported for fortified samples. The method was applied to a qualitative survey of domestic vanilla samples and quantification of coumarin in an adulterated foreign sample. The result of this determination was verified by standard addition analysis. The method was also applied to the determination of coumarin in a spiked wine sample.     

Multiresidue Analysis of Pesticides in Water from Rice Cultures by On-line Solid Phase Extraction Followed by LC-DAD

Abstract

An automated on-line solid phase extraction procedure followed by liquid chromatography with diode array detection was investigated for the determination of different classes of pesticides in water samples containing varied amount of humic substances. The different pesticides used were: carbendazin, carbofuran, atrazine, diuron, propanil, molinate, alachlor, parathion-ethyl, diazinon, trifluralin and the degradation products deisopropylatrazine and deethylatrazine. Humic substances extracted from a Brazilian sediment were used from 5 to 80 mg/l and their influence on recoveries was evaluated in neutral and acidic media. Recoveries higher than 70% were obtained for all the pesticides, from the preconcentration of 75 ml of aqueous sample fortified at 2 ng/ml using precolumns packed with PLRP-S. Good recoveries were obtained at neutral pH for most of the analytes up to 40 mg/l of humic acid. Only at 80 mg/l the recoveries were significantly affected, both at acidic and neutral pH. The method was applied to the determination of pesticides in river water spiked at 0.1 to 1 ng/ml. Detection limits obtained for water containing 10 mg/l of humic acid were between 0.05 and 0.3 ng/ml.     

Analysis of Fenitrothion and Metabolites in Stored Wheat

Abstract

A simple and rapid method for the analysis of fenitrothion and its metabolites, fenitrooxon, S-methyl fenitrothion, demethyl fenitrothion, demethyl S-methyl fenitrothion, 3-methyl-4-nitrophenol, and dimethyl phosphorothioic acid in stored wheat has been developed. Simultaneous analysis of the extract was conducted using FPD-GLC after derivatization with diazoethane except for 3-methyl-4-nitrophenol which was analyzed directly by EC-GLC. Recoveries of all compounds from wheat fortified at the levels from 0.1 to 5.0 ppm were greater than 90%.

The developed method was used to quantitatively determine major metabolites found in grain treated with fenitrothion and stored at 20°C for 12 months. Demethyl fenitrothion, 3-methyl-4-nitrophenol, and dimethyl phosphorothioic acid were the major breakdown products of fenitrothion found in stored wheat. Confirmation of these metabolites was carried out by chemical derivatization plus FPD-GLC and by TLC.     

Synthesis of Heterobicyclic Nitrogen Systems Bearing a 1,2,4-Triazine Moiety as Anticancer Drugs: Part IV

Some new isolated and fused heterobicyclic nitrogen systems such as thiazolidinone, imidazolone, pyrimidinone, quinazolone, as-triazolone, as-triazinones, tetrazino-as-triazines, and the related compounds 3,4-diaminotriazine and sulfa derivatives 2–27 have been synthesized via treatment of 4-amino-6-styryl-3-thioxo-1,2,4-triazin-5(2,4H)ones (1) with cyclic and acyclic oxygen and nitrogen compounds. The structures of the products have been established from their elemental and spectral analyses. Some new compounds exhibited significant anticancer activities, where compounds 11j > 2a > 6 and 11I > 14 > 11k showed a moderate activity toward leukemia, ovarian cancer, and non-small cell lung cancer.

     

High Performance Liquid Chromatographic Determination of Neomycin in Milk Using a Hisep Column

Abstract

A high performance liquid chromatographic (HPLC) method for the determination of neomycin in milk is described. Milk is passed directly through an amberlite CG-50 ion exchange resin column, and the neomycin which is retained on the column is derivatized with ortho-phthalaldehyde (OPA) reagent. The derivatized neomycin is eluted from the column with potassium borate buffer/methanol and analyzed by HPLC. A HISEP HPLC column with fluororoetric detection was used. Recoveries ranged from 94 to 102% in samples fortified between 0.1 to 5ppra levels. The detection limit is 50ppb.     

Determination of Captan,Folpet, and Captafol in Water,Apples, and Lettuce By Quantitative Thin-Layer Chromatography

Abstract

Captan, folpet, and captafol were determined in water, lettuce, and apples by TLC of extracts on preadsorbent silica gel layers, detection with silver nitrate reagent, and densitometric scanning. The fungicides were extracted from water on Chromosorb 102 raicrocolumns. Cleanup on a Florisil column was required for the food extracts. Recoveries from distilled and tap water ranged from 76–98% at 0.02 ppm and 81–94% at 0.007 ppm. Recoveries from lettuce ranged from 88–94% and from apples 84–90%, both at 0.25 ppm. The selectivity, sensitivity, and precision of the method are adequate for routine residue analysis.     

The Thin-Layer Chromatographic Separation of Halogenated Fumigants as Ammonium Halides and Their Subsequent Determination by Meca

Abstract

A method is described for the determination of several pesticides containing bromine and chlorine by molecular emission cavity analysis (MECA). The pesticides were decomposed in an oxygen flask and the combustion products dissolved in aqueous ammonia. The ammonium halides were separated by TLC using microcrystalline cellulose adsorbent. After scraping from the TLC plates and dissolving in water the separated components were quantitated by MECA using either the InBr (Λ_max = 376 nm) or the InCl (Λ_max = 360 nm) emission bands. Recoveries of over 96% were obtained. Soils fortified with l, 2-dibromo-3-chloropropane at levels of 5–25 ppm were extracted using shaking and distillation procedures. Subsequent analysis showed that the shaking extraction gave a recovery of 92% compared to 85% from acid refluxing.     

Determination of Halide Traces in Environmental Samples by Mass Spectrometric Isotope Dilution Analysis

Abstract

Since 1985, the Goulden large-sample extractor (GLSE) has been used to isolate a broad array of trace-organic contaminants from large volumes of water. In this study, field-applied quality control measures, including matrix and surrogate spikes and blanks, were used to monitor method performance from GLSE extraction through GC-MS analysis. The method was applied to the determination of multiple classes of pesticides isolated from 4- to 112-L filtered surface-water samples. Average recoveries of six surrogate compounds ranged from 84 ± 18% for [²H₁₀]diazinon to 15 ± 13% for 4,4′-[²H₈]DDT, the low recoveries for which were largely a result of unmonitored breakdown of this surrogate by the GC injection system. Field-matrix-spike samples were prepared by fortifying 10-L, 35-L, and 110-L filtered surface-water samples with 68 pesticides to amended concentrations of 11-to 50-ng/L each. Recoveries ranged from not detected to greater than 100%. Variability in pesticide recoveries from triplicate 10-L water samples collected at one site averaged 5.7% relative standard deviation and did not exceed 19%.     

Trace Enrichment and Atomic Absorption Spectrometric Determination of Lead,Copper, Cadmium and Nickel in Drinking Water Samples by Use of an Activated Carbon Column

Abstract

A simple method for atomic absorption spectrometric determination of lead, copper, cadmium and nickel in drinking water samples after preconcentration by sorbing 1-(2-pyridylazo) 2-naphthol (PAN) complex of these metals on an activated carbon column has been established. The metal/PAN complexes were quantitatively retained on the activated carbon in the pH range 6-8. Metals retained on the activated carbon column were completely eluted with 2M HCl in acetone. This method was applied to the determination of lead, copper, cadmium and nickel in drinking water samples and good results were obtained (Recoveries >95%, relative standard deviations <7%, relative error <3%).     

Liquid Chromatographic Determination of Dimetridazole and Ronidazole in Feeds

Abstract

A simple high performance liquid chromatographic (HPLC) procedure for the simultaneous determination of dimetridazole and ronidazole in turkey feeds is described. The drugs are extracted from feeds by carbon-tetrachloride/dimethylformamide (80:20) at 60°C during 30 mn and the extract is subjected to a partition by water. After centrifugation the eluate is chromatographed on a reverse phase column with ultaviolet detection at 316 nm. Recoveries from samples fortified at levels 2.02 to 7.07 ppm for ronidazole and 2.01 to 7.03 for dimetridazole were 99,6% ± 1,4 and 95,3% ± 1,8 (mean ± standard deviation), respectively.