Determination of Aspartame and Its Major Decomposition Products in Foods

1993 ◽  
Vol 76 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Jacques Prodolliet ◽  
Milene Bruelhart
Keyword(s):  
Soft Drink ◽  
Food Additives ◽  
Reversed Phase ◽  
Food Samples ◽  
Phase Detection ◽  
Decomposition Products ◽  
Coefficients Of Variation ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract A liquid chromatographic procedure already evaluated in a preceding study for the analysis of acesulfam-K is also suitable for the determination of the intense sweetener aspartame in tabletop sweetener, candy, fruit beverage, fruit pulp, soft drink, yogurt, cream, cheese, and chocolate preparations. The method also allows the determination of aspartame’s major decomposition products: diketopiperazine, aspartylphenylalanine, and phenylalanine. Samples are extracted or diluted with water and filtered. Complex matrixes are centrifuged or clarified with Carrez solutions. An aliquot of the extract is analyzed on a reversed-phase μBondapak C18 column using 0.0125M KH2P04 (pH 3.5)-acetonitrile ([85 + 15] or [98 + 2]) as mobile phase. Detection is performed by UV absorbance at 214 nm. Recoveries ranged from 96.1 to 105.0%. Decomposition of the sweetener was observed in most food samples. However, the total aspartame values (measured aspartame + breakdown products) were within -10% and +5% of the declared levels. The repeatabilities and the repeatability coefficients of variation were, respectively, 1.00 mg/100 g and 1.34% for products containing less than 45 mg/100 g aspartame and 4.11 mg/100 g and 0.91 % for other products. The technique is precise and sensitive. It enables the detection of many food additives or natural constituents, such as other intense sweeteners, organic acids, and alkaloids, in the same run without interfering with aspartame or its decomposition products. The method is consequently suitable for quality control or monitoring.

Determination of Acesulfam-K in Foods

1993 ◽  
Vol 76 (2) ◽  
pp. 268-274 ◽  
Author(s):  
Jacques Prodolliet ◽  
Milene Bruelhart
Keyword(s):  
Fruit Juice ◽  
Soft Drink ◽  
Food Additives ◽  
Reversed Phase ◽  
Uv Absorbance ◽  
Phase Detection ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method was evaluated for the determination of the intense sweetener acesulfam-K in tabletop sweetener, candy, soft drink, fruit juice, fruit nectar, yogurt, cream, custard, chocolate, and biscuit commercial preparations. Samples are extracted or simply diluted with water and filtered. Complex matrixes need a clarification step with Carrez solutions. An aliquot of the extract is analyzed on a reversed-phase μBondapak C18 column using 0.0125M KH2PO4 (pH 3.5)-acetonitrile (90 + 10) as mobile phase. Detection is performed by UV absorbance at 220 nm. Recoveries ranged from 95.2 to 106.8%. With one exception, all analyzed values were within ±15% of the declared levels. The repeatabilities and the repeatability coefficients of variation were, respectively, 0.37 mg/100 g and 0.98% for products containing less than 40 mg/100 g acesulfam-K and 2.43 mg/100 g and 1.29% for other products. The same procedure also allowed detection of many food additives or natural constituents, such as other intense sweeteners, organic acids, and alkaloids, in a single run without interfering with acesulfam-K. The method is simple, rapid, precise, and sensitive; therefore, it is suitable for routine analyses.

Elimination of caffeine interference in HPLC determination of urinary nicotine and cotinine.

1989 ◽  
Vol 35 (7) ◽  
pp. 1456-1459 ◽  
Author(s):  
N T Thuan ◽  
M L Migueres ◽  
D Roche ◽  
G Roussel ◽  
G Mahuzier ◽  
...  
Keyword(s):  
Reversed Phase ◽  
Gas Liquid Chromatography ◽  
Tobacco Exposure ◽  
Coefficients Of Variation ◽  
Chromatographic Procedure ◽  
Phase Liquid ◽  
Liquid Chromatographic ◽  
Minimum Detectable Amount ◽  
Column Extraction

Abstract We report an analytical reversed-phase liquid-chromatographic procedure for quantifying nicotine and cotinine in urine, taking into account the presence of interfering caffeine frequently encountered in such specimens. These analytes are extracted from the alkalinized urine with chloroform. After evaporation of the chloroform, the residue is dissolved in methanol and injected into a chromatographic C18 column. Extraction recoveries averaged 80% to 97%. Chromatographic conditions were investigated to obviate caffeine interference. The proposed eluent mobile phase is a polar mixture of water, acetonitrile, methanol, and a pH 4 acetoacetate buffer (65/2/29/4 by vol) adjusted to pH 4.30 +/- 0.02 with triethylamine. High resolution and linearity were obtained for each analyte up to a concentration of 200 mg/L. The minimum detectable amount of each compound was 20 ng per injection, corresponding to 10 micrograms per liter of urine. Correlation with results of gas-liquid chromatography was excellent (r = 0.99). This simple, rapid procedure allows routine screening of tobacco exposure with acceptable precision: within- and between-run coefficients of variation were less than 2% and less than 5%, respectively.

Simultaneous Determination of Psychoactive Compounds in Foodstuffs Using Micellar Liquid Chromatography with Direct Injection

2014 ◽  
Vol 97 (2) ◽  
pp. 409-414 ◽  
Author(s):  
Hoonka Subhra ◽  
Dubey-Neeti Prakash ◽  
Durgbanshi Abhilasha ◽  
Esteve-Romero Josep ◽  
Bose Devasish
Keyword(s):  
Simultaneous Determination ◽  
Mobile Phase ◽  
Soft Drink ◽  
Direct Injection ◽  
Sodium Dodecyl ◽  
Reversed Phase ◽  
Food Samples ◽  
Micellar Liquid Chromatography ◽  
Liquid Chromatographic

Abstract A micellar liquid chromatographic procedure was developed for the simultaneous determination of threecommonly used stupefacients, lidocaine, ketamine and diazepam, using a C18 reversed-phase column. A micellar mobile phase 0.15 M sodium dodecyl sulfate and 6% (v/v) pentanol, pH 7, and UV detection at 230 nm were used to determine the three stupefacients in food samples. Using the selected mobile phase, the stupefacients were eluted in less than 10 min with linearity (r = 0.998), LOD (range: 0.004–0.03 ppm), LOQ (range: 0.004–0.03 ppm), intraday and interday precision (below 2.84%), and mean recoveries (range: 79.11–110.16%) in the different foodstuffs were in accordance with the internationally established acceptance criteria. Validation of the developed method was performed on the basis of International Conference on Harmonization validation guidelines. The optimized and validated micellar liquid chromatographic method was successfully applied in the determination of lidocaine, diazepam, and ketaminein a real food sample (mango drink) and in spiked food samples (banana, ladoo, soft drink, tea). The developed method could also be easily used by law enforcement laboratories and hospitals for routine analysis.

scholarly journals Determination of Ceftiofur in Bovine Milk by Liquid Chromatography

1996 ◽  
Vol 79 (4) ◽  
pp. 844-847 ◽  
Author(s):  
Patrick J Mcneilly ◽  
Valerie B Reeves ◽  
E J Ian Deveau
Keyword(s):  
Ammonium Acetate ◽  
Methanol Extract ◽  
Solid Phase ◽  
Bovine Milk ◽  
Reversed Phase ◽  
Acetate Solution ◽  
Coefficients Of Variation ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic

Abstract A liquid chromatographic procedure is described for determination of ceftiofur (CEF) residues in milk. Milk samples were diluted with ammonium acetate solution and extracted on a C18 solid-phase extraction (SPE) column. After the analyte was eluted from the SPE column with methanol, extract volumes were reduced under nitrogen, diluted to 2.0 mL with acetate buffer, and filtered. CEF was determined after separation of milk components by reversed-phase chromatography with UV detection at 293 nm. Recoveries of CEF from bovine milk fortified at 25,50, and 100 ppb were 86.1,90.8, and 92.0%, respectively, with coefficients of variation (CVs) of 6.4, 7.3, and 3.9%, respectively. Values of CEF obtained from analysis of milk containing 2 levels of biologically incurred residues were 26.1 and 67.3 ppb with CVs of 3.8 and 4.4%, respectively. The limits of detection and quantitation were estimated to be 4 and 7 ppb, respectively.

scholarly journals Rapid Determination of Ampicillin in Bovine Milk by Liquid Chromatography with Fluorescence Detection

1997 ◽  
Vol 80 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Catharina Y W Ang ◽  
Luo Wenhong
Keyword(s):  
Fluorescence Detection ◽  
Rapid Determination ◽  
Bovine Milk ◽  
Skim Milk ◽  
Reversed Phase ◽  
Coefficients Of Variation ◽  
Whole Milk ◽  
Liquid Chromatographic ◽  
Clear Supernatant

Abstract A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of am- picillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deprote- inized with trichloroacetic acid (TCA) and acetonitrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5,10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb.

Determination of Ractopamine Hydrochloride in Swine, Cattle, and Turkey Feeds by Liquid Chromatography with Coulometric Detection

1994 ◽  
Vol 77 (4) ◽  
pp. 840-847 ◽  
Author(s):  
Michael P Turberg ◽  
Thomas D Macy ◽  
Jerry J Lewis ◽  
Mark R Coleman
Keyword(s):  
Solid Phase ◽  
Reversed Phase ◽  
Free Base ◽  
Coulometric Detection ◽  
Solid Phase Extraction Cartridge ◽  
Coefficients Of Variation ◽  
Ractopamine Hydrochloride ◽  
Cattle Feeds ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method is described for the determination of ractopamine hydrochloride (LY31537) in swine, turkey, and cattle feeds in the 1.25–100 ppm range and in swine supplement at 100 ppm. Feed samples were extracted with acidified methanol. An aliquot of the feed extract was diluted with water and buffered to pH 10.5 ± 0.5 with sodium carbonate to convert ractopamine hydrochloride to a free base. The free base was extracted from the buffered sample with ethyl acetate. The extract was further purified on an acid-washed, silica solid-phase extraction cartridge. After conversion of the free base back to the salt form with pH 4.5 buffer, analytical separation and quantitation of ractopamine hydrochloride were accomplished on IBM phenyl and Whatman ODS reversed-phase columns with coulometric detection at +600 mV. Mean daily recovery levels ranged from 85 to 100% for feeds fortified at 1.25 to 100 ppm. The coefficients of variation ranged from 1 to 6% for feeds fortified at 2.5 to 100 ppm.

Improved liquid-chromatographic method for determination of serum cortisol.

1979 ◽  
Vol 25 (7) ◽  
pp. 1293-1296 ◽  
Author(s):  
P M Kabra ◽  
L L Tsai ◽  
L J Marton
Keyword(s):  
Limit Of Detection ◽  
Internal Standard ◽  
Serum Cortisol ◽  
Peak Height ◽  
Reversed Phase ◽  
Column Temperature ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Abstract We describe a specific and precise method for measuring concentrations of cortisol in serum or plasma by liquid chromatography. Cortisol, together with an internal standard, equilenin, is extracted from 1 mL of serum or plasma and analyzed isocratically on a reversed-phase column with a mobile phase of acetonitrile/phosphate buffer (30/70, by vol.), at a flow rate of 2.0 mL/min. The eluted cortisol is detected by its absorption at 254 nm and quantitated by peak height measurements. Each analysis requires no longer than 15 min at the optimum column temperature of 50 degrees C. The lower limit of detection for cortisol is about 2 ng/sample for a standard solution; sensitivity is routinely 5 micrograms/L of serum. Analytical recoveries exceeded 95%, with good day-to-day precision (coefficients of variation between 4 and 7%). Of more than 50 drugs and steroids tested for possible interference, only the steroids cortisone, prednisone, and prednisolone may interfere with the analysis of cortisol.

scholarly journals Liquid Chromatographic Determination of Tocopherols and Tocotrienols in Vegetable Oils, Formulated Preparations, and Biscuits

2000 ◽  
Vol 83 (3) ◽  
pp. 627-634 ◽  
Author(s):  
Josep Serra Bonvehi ◽  
Francesc Ventura Coll ◽  
Imma Alsina Rius
Keyword(s):  
Vitamin E ◽  
Vegetable Oils ◽  
Chromatographic Determination ◽  
Extraction Methods ◽  
Coefficients Of Variation ◽  
Chromatographic Procedure ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic ◽  
Interday Precision

Abstract A precise and selective liquid chromatographic procedure for determining tocopherol and tocotrienol isomers in vegetable oils, formulated preparations, and biscuits was developed and validated. The proposed method quantitates vitamin E in better conditions of recoverability and reproducibility than the standard saponification procedure. Tocopherols and tocotrienols were extracted in hexane from vegetable oils, passed through a silica Sep-pak, chromatographed on a μ-Bondapak C18 column with a mobile phase of methanol–water (95 + 5, v/v), identified at 292 nm, and detected with fluorescence procedure (excitation 296 nm, and emission 330 nm). The correlation coefficient on the calibration curve was 0.9995 over the range of 0.1 to 100 μg/mL. Overall recovery of vitamin E isomers was 93%; coefficients of variation for intra- and interday precision, <2.25%. The results obtained from extraction methods 1 (with saponification) and 2 (without saponification) were compared by ANOVA test. Significant differences appeared between vitamin E isomers (p ≤ 0.05).

scholarly journals Determination of Sulfamethazine in Swine and Cattle Feed by Reversed-Phase Liquid Chromatography with Post-Column Derivatization: Pre-Collaborative Study

2000 ◽  
Vol 83 (2) ◽  
pp. 255-259 ◽  
Author(s):  
Kendrick Albert ◽  
Robert L Smallidge
Keyword(s):  
Collaborative Study ◽  
Extraction Procedure ◽  
Internal Standard ◽  
Reversed Phase ◽  
Feed Additives ◽  
Official Method ◽  
Cattle Feed ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic

Abstract In-house validation of a liquid chromatographic method for determination of sulfamethazine in swine and cattle feed was performed to verify that the method was ready for collaborative study under AOAC INTERNATIONAL guidelines. In this method, sulfamerazine is added during the extraction procedure and is used as an internal standard to correct for variable recovery of sulfamethazine from a variety of swine and cattle feed matrixes. The determinative step involves the use of post-column derivatization with dimethylaminobenzaldehyde which reacts with the primary amine group on the sulfonamides. Detection is at 450 nm, a wavelength at which most co-extracted matrix materials and other feed additives do not absorb light. The results indicate that the method recovery, precision, and ruggedness meet normal criteria to be ready for a collaborative study. Fortification experiments over a range of sulfamethazine concentrations from 0.006 to 0.26% showed an overall recovery relative to the internal standard of 100 ± 2%. These studies include both swine and cattle feed matrixes. The mean recovery in the analysis of 3 beef cattle experimental feeds was 98.9%. The method results agreed with the AOAC INTERNATIONAL Official Method for colorimetric analysis of swine feed. Method precision was excellent during in-house validation studies, with coefficients of variation (CVs) ranging from about 0.5 to 3%. The method ruggedness was verified with an overall CV of 3.5%.

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