scholarly journals Preparative Method for Isolating α-Zearalenol and Zearalenone Using Extracting Disk

1999 ◽  
Vol 82 (1) ◽  
pp. 90-94 ◽  
Author(s):  
George M Ware ◽  
Yuhong Zhao ◽  
Shia S Kuan ◽  
Allen S Carman
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Control Sample ◽  
Preparative Method ◽  
Reversed Phase ◽  
Fluorescence Detector ◽  
Coefficients Of Variation ◽  
Limit Of Quantitation ◽  
Standard Calibration ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method is described for the determination of zearalenol and zearalenone in corn. Zearalenol and zearalenone are extracted from corn with methanol–water (1+1) and cleaned up using a solid-phase extraction (SPE) disk, separatedon a reversed-phase analytical column, and detected with a fluorescence detector. The SPE disk concentrated and cleanly separated zearalenol and zearalenone from sample interferences. Standard calibration curves for zearalenol and zearalenone for the concentration range 25–500 ng/mL were linear. The small extract disk had a column capacity equivalent to 1 g extracted corn. Zearalenol and zearalenone were added at levels ranging from 10 to 2000 ng/g to a control sample that contained no detectable levels of zearalenol and zearalenone. Both toxins were recovered from spiked samples at 106.3 and 103.8%, with coefficients of variation of 7.6 and 13.0%, respectively. The method has an estimated reliable limit of detection and limit of quantitation around 10 and 40 ng/g for each toxin, respectively.

scholarly journals Liquid Chromatographic Analysis of Vitamin K1 in Milk-Based Infant Formula with Matrix Solid-Phase Dispersion

1999 ◽  
Vol 82 (5) ◽  
pp. 1140-1145 ◽  
Author(s):  
G William Chase ◽  
Ronald R Eitenmiller ◽  
Austin R Long
Keyword(s):  
Infant Formula ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Reversed Phase ◽  
Vitamin K1 ◽  
Matrix Solid Phase Dispersion ◽  
Phase Dispersion ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method for vitamin K1 in milk-based infant formula is described. The vitamins are extracted from infant formula by matrix solid-phase dispersion and quantitated by reversed-phase chromatography with fluorescence detection. Vitamin K1 is converted to the fluorescent hydroquinone with a postcolumn zinc reductive reactor. The limit of detection is 12 pg, and the limit of quantitation is 38 pg on-column. Linear responses were obtained in the range 0.55-22.1 ng/mL (r2 = 0.9998). Recoveries of vitamin K1 from an analyte-fortified blank material for milk-based infant formula averaged 91.7% (n = 25). The method provides a rapid, specific, and easily controlled assay for vitamin K1 in fortified infant formula.

Liquid Chromatographic Method for Rapid Determination of Total Avermectin B1 and 8,9-Z-Avermectin B1 Residues in Apples

1995 ◽  
Vol 78 (2) ◽  
pp. 419-422 ◽  
Author(s):  
Janice A Cobin ◽  
Nelson A Johnson
Keyword(s):  
Chromatographic Method ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Rapid Determination ◽  
Reversed Phase ◽  
Extraction Column ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method has been developed and validated for the rapid determination of avermectin B1 and 8,9-Z-avermectin B1 residues in apples. The avermectins are extracted from the crop matrix with an acetonitrile–water–hexane mixture; the extract is cleaned up on an aminopropyl solid-phase extraction column. The avermectins are derivatized with trifluoroacetic anhydride and analyzed by reversed-phase liquid chromatography with fluorescence detection. Recoveries of avermectins from apples fortified with about 2–77 ppb avermectin B1a or 2-27 ppb 8,9-Z-avermectin B1a averaged 85%. The limit of quantitation is 2 ppb (signal- to-noise [S/N] ratio, 12) and the limit of detection is 1 ppb (S/N ratio, 6) for each analyte. The assay is a simple, rapid, and sensitive method for monitoring the total amount of avermectin residues in apples.

scholarly journals Determination of Total Avermectin B1 and 8,9-Z-Avermectin B1 Residues in Wine by Liquid Chromatography

1996 ◽  
Vol 79 (5) ◽  
pp. 1158-1161 ◽  
Author(s):  
Janice A Cobin ◽  
Nelson A Johnson
Keyword(s):  
Liquid Chromatography ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Signal To Noise Ratio ◽  
Reversed Phase ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method was developed and validated for determination of avermectin Bi and 8,9-Z-avermectin B1 residues in wine. The sample is extracted with hexane-acetonitrile and the hexane layer containing the avermectins is concentrated/ purified on an aminopropyl solid-phase extraction (SPE) column. The purified extract is derivatized with trifluoroacetic anhydride and the derivatized avermectins are analyzed by reversed-phase liquid chromatography with fluorescence detection. Recoveries of avermectins from wine fortified with approximately 1-25 ng/g avermectin B1a or 8,9-Zavermectin B1a averaged 88 and 102%, respectively. The limit of quantitation is 1 ng/g (signal-to-noise ratio [S/N] > 10) and the limit of detection is 0.5 ng/g (S/N > 3) for each analyte. This procedure provides a simple, rapid, and sensitive method for monitoring the total amount of avermectin residues in wine.

scholarly journals Determination of Tilmicosin in Bovine Milk by Liquid Chromatography with Ultraviolet Detection

1996 ◽  
Vol 79 (3) ◽  
pp. 652-655 ◽  
Author(s):  
Maureen A Ngoh
Keyword(s):  
Liquid Chromatography ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Bovine Milk ◽  
Reversed Phase ◽  
Uv Detection ◽  
Solid Phase Extraction Cartridge ◽  
Coefficients Of Variation ◽  
Limit Of Quantitation ◽  
Control Milk

Abstract A method is described for determining tilmicosin in bovine milk by liquid chromatography with ultraviolet (UV) detection. Samples are defatted by centrifugation. The lower skim layer is cleaned on a C18 solid-phase extraction cartridge. The extract is concentrated and analyzed with a reversed-phase phenyl column with UV detection at 280 nm. The method was validated with control milk fortified at 50,100, and 200 ng/mL. Average recoveries (and intralaboratory coefficients of variation) were 97% (9%), 98% (5%), and 101% (3%), respectively. The limit of quantitation is approximately 20 ng/mL, and the limit of detection is approximately 13 ng/mL. The method was tested on milk from a cow dosed with tilmicosin.

scholarly journals Determination of Vitamin K1 in Medical Foods by Liquid Chromatography with Postcolumn Reduction and Fluorometric Detection

2000 ◽  
Vol 83 (4) ◽  
pp. 957-962 ◽  
Author(s):  
George M Ware ◽  
G William Chase ◽  
Ronald R Eitenmiller ◽  
Austin R Long
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Sodium Bicarbonate Solution ◽  
Reversed Phase ◽  
Mean Value ◽  
Fluorometric Detection ◽  
Vitamin K1 ◽  
Limit Of Quantitation ◽  
Medical Foods

Abstract A liquid chromatographic (LC) method is described for the determination of vitamin K1 in medical foods. The sample is enzymatically digested with lipase and α-amylase and extracted with 1% sodium bicarbonate solution–isopropanol (1 + 1). After C18 solid-phase extraction, vitamin K1 is separated by nonaqueous reversed-phase LC, converted to the hydroquinone by postcolumn zinc reduction, and quantitated by fluorescence detection. The limit of detection is 8 pg (3 σ), and the limit of quantitation is 27 pg (10 σ) on column. Linear response ranged from 0.1 to 1.0 ng vitamin K1 (r = 0.9999). The mean recovery (n = 38) for all spiking levels was 101.6 ± 2.85%. Analysis of Standard Reference Material 1846, Infant Formula, gave a mean value of 0.95 ± 0.088 mg vitamin K/kg (K or K1?)(n = 31) with a coefficient of variation of 9.26.

scholarly journals Liquid Chromatographic Determination of Benzylpenicillin and Cloxacillin in Animal Tissues and Its Application to a Study of the Stability at –20°C of Spiked and Incurred Residues of Benzylpenicillin in Ovine Liver

1996 ◽  
Vol 79 (3) ◽  
pp. 640-644 ◽  
Author(s):  
Hock-Eng Gee ◽  
Koon-Bay Ho ◽  
John Toothill
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Order Kinetic ◽  
Animal Tissues ◽  
Muscle Tissues ◽  
Coefficients Of Variation ◽  
The Stability ◽  
Kidney Liver ◽  
Liquid Chromatographic

Abstract A method was developed for determining benzylpenicillin and cloxacillin in animal tissues. Samples are extracted with acetonitrile, and the extract is cleaned up on a C18 solid-phase extraction (SPE) cartridge, derivatized, and quantitated by liquid chromatography with UV detection at 325 nm. The method was validated on spiked bovine kidney, liver, and muscle tissues. Kidney was spiked at 0.01,0.05, and 0.20 mg/kg; liver and muscle were spiked at 0.20 mg/kg. Recoveries were 75–100%, with coefficients of variation of 2–7%. The method was further validated on kidney, liver, and muscle tissues from 2 sheep dosed with Aquacaine G suspension (containing benzylpenicillin). Mean levels of benzylpenicillin in these tissues ranged from 0.02 to 4.06 mg/kg, with coefficients of variation of replicate analyses between 3 and 7%. The limit of detection was approximately 0.005 mg/kg for benzylpenicillin and cloxacillin in kidney, liver, and muscle tissues. This method was used to study the stability of both spiked and incurred residues of benzylpenicillin in ovine liver during storage at –20°C for 3 months. Assuming the rate of loss follows a first-order kinetic decay, the mean half-life of benzylpenicillin in liver is 62 days for spiked tissues and 71 days for tissues with incurred residues.

Determination of Ractopamine Hydrochloride in Swine and Turkey Tissues by Liquid Chromatography with Coulometric Detection

1995 ◽  
Vol 78 (6) ◽  
pp. 1394-1402 ◽  
Author(s):  
Michael P Turberg ◽  
Thomas D Macy ◽  
Jerry J Lewis ◽  
Mark R Coleman
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Free Base ◽  
Coulometric Detection ◽  
Solid Phase Extraction Cartridge ◽  
Coefficients Of Variation ◽  
Swine Liver ◽  
Ractopamine Hydrochloride ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method is described for determination of ractopamine hydrochloride (LY031537) in swine and turkey tissues. Liver, kidney, muscle, and fat samples were homogenized in methanol. An aliquot of the extract was evaporated, 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 a Bond Elut acid-washed silica solid-phase extraction cartridge. After converting the free base back to the salt form with pH 4.5 buffer, analytical separation and quantitation of ractopamine hydrochloride was performed on an IBM C18 column with coulometric detection at +600 mV. The limit of detection of the method was approximately 0.5 ppb as determined in swine liver. Overall recovery levels ranged between 75 and 100% for samples of liver, kidney, muscle, and fat fortified at 1 to 100 ppb. The coefficients of variation ranged from 2 to 18% for samples fortified at 1 to 100 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 Development and Validation of a RP-HPLC Method for the Estimation of Amlexanox in Oral Paste Dosage Form

2012 ◽  
Vol 10 (2) ◽  
pp. 67-70
Author(s):  
Abdullah Al Masud ◽  
Mohammad Saydur Rahman ◽  
Towfika Islam ◽  
Saki Sultana ◽  
Moynul Hasan ◽  
...  
Keyword(s):  
High Performance ◽  
Dosage Form ◽  
Dynamic Range ◽  
Limit Of Detection ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Hplc Method ◽  
Rp Hplc ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic

A simple, reproducible and efficient reversed phase high performance liquid chromatographic (RPHPLC) method has been developed for the estimation of a recently approved anti allergic drug, amlexanox in oral paste dosage form. The separations were carried out on a Zorbax Eclipse XBD, C18 column (150 x 4.6 mm; 5?m) at a flow rate of 1.50 ml/min. by using mobile phase comprising of mixed buffer (pH adjusted to 6.50) and methanol (50:50 v/v). The injection volume was 10 ?l and the peaks were detected at 244 nm. The linear dynamic range found to be in the concentration range of 15-35 ?g/ml and coefficient of correlation was found to be 0.999. The %RSD value was below 2.0 for intra-day and inter-day precision which indicated that the method was highly precise. The LOD (Limit of detection) and LOQ (Limit of quantitation) were found to be 3.8 ng/ml and 12.5 ng/ml, respectively which revealed that the method was highly sensitive. The percentage recovery of amlexanox ranged from 99.31 to 99.75%, indicating the accuracy of the method and absence of interference from the excipients present in the formulation. The proposed method was simple, fast, accurate and reproducible and hence can be applied for routine quality control operations of amlexanox in oral paste dosage form. Key words: Amlexanox, Anti allergic, RP-HPLC, LOD, LOQ. DOI: http://dx.doi.org/10.3329/dujps.v10i2.11782 Dhaka Univ. J. Pharm. Sci. 10(2): 67-70, 2011 (December)

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