Determination of halquinol residual levels in animal-derived food products using liquid chromatography-tandem mass spectrometry.

A reliable and highly sensitive detection method based on liquid chromatography coupled with triple quadrupole electrospray tandem mass spectrometry (LC-MS/MS) analysis has been developed for determination and quantification of halquinol, including 5,7-dichloroquinolin-8-ol and 5-chloroquinolin-8-ol. The target analytes were extracted from porcine muscle, egg, milk, eel, flatfish and shrimp using a mixture of acetonitrile and ethyl acetate followed by liquid-liquid purification with n-hexane. The analytes were separated on an Agilent Eclipse XDB-C18 reversed-phase analytical column using 0.05% formic acid in distilled water and acetonitrile as mobile phases. Good linearity from six-point matrix-matched calibration was obtained with correlation coefficients (R2 ) ≥ 0.9904. Recoveries from three spiking levels (5, 10 and 20 µg/kg) ranged between 70.6 and 101.7% in various matrices with relative standard deviations ≤8.6%. Samples acquired from markets located in Seoul, Republic of Korea, tested negative for the target analytes. In conclusion, the proposed method is versatile and precise for the routine detection of halquinol residual levels in animal-derived food products intended for human consumption.

Validation of a UPLC-PDA method to study the content and stability of 5-chloro 8-hydroxyquinoline and 5,7-dichloro 8-hydroxyquinoline in medicated feed used in swine farming.

A new, rapid, simple and specific method to determine 5-chloro 8-hydroxyquinoline (5-HQ) and 5,7-dichloro 8-hydroxyquinoline (5,7-HQ) stability in swine feed was optimized and validated. A system consisting of an ACQUITY UPLC BEH C18 column (1.7 µm, 2.1 mm × 100 mm), a mobile phase of acetonitrile-0.1% o-phosphoric acid (55:45 v/v) with a 0.5 mL/min flow rate, and a PDA detector (247 nm) were used. The retention times of 5-HQ and 5,7-HQ, were 0.77 min and 1.6 min, respectively. The pure drug was subjected to acid and alkali hydrolysis, chemical oxidation and UV light degradation to perform forced degradation studies. 5,7-HQ was more susceptible to degradation than 5-HQ. The figures of merit of the method (linearity, accuracy, precision, and robustness) were determined. The method was successfully applied to estimate the stability of both analytes in medicated feed.

Simultaneous analysis of spectinomycin, halquinol, zilpaterol, and melamine in feedingstuffs by ion-pair liquid chromatography-tandem mass spectrometry.

A method for the simultaneous analysis of veterinary drug residues (spectinomycin, halquinol, and zilpaterol) and contaminants (melamine) in feedingstuffs by liquid chromatography-tandem mass spectrometry was developed. Method performance for all analytes was evaluated by reversed-phase liquid chromatography, reversed-phase with altered chemical equilibrium, and hydrophilic interaction (HILIC) as chromatographic modes. Validation was in accordance to Commission Decision 657/2002/CE, by considering the best chromatographic approach. Ion-pair liquid chromatography with C18 as stationary phase led to the lowest random uncertainties, effective analyte separation and shorter time of analysis. Low precision deviations and good recovery rates were obtained and thus method reliability and sensitivity could be consolidated. Method applicability was evaluated by the analysis of samples of feedingstuffs, such as cattle, pig, and poultry feeds, feed ingredients of both animal and vegetable origins, and mineral feeds. Some samples showed quantifiable concentrations of halquinol and zilpaterol, reinforcing the importance of this new analytical control method.

Reverse-phase high-performance liquid chromatographic determination of halogenated 8-hydroxyquinoline compounds in pharmaceuticals and bulk drugs.

A reverse-phase high-performance liquid chromatographic (HPLC) method was developed for determining iodochlorhydroxyquin, 5,7-dichloro-8-hydroxyquinoline, and 5,7-diiodo-8-hydroxyquinoline in creams, ointments, shampoos, tablets, and bulk drugs. A column packed with 10-micron phenyl-silica and a mobile phase of 0.001 M NiCl2 in acetonitrile-methanol-water (30:20:50) was used to separate the nickel complexes of the three drugs, with detection at 273 nm. Analysis of creams, ointments, shampoos, and tablets gave results close to the label declarations. Recovery of standard material added to samples was greater than or equal to 98%. Linearity of response was shown over a range of 30-150% of label claim for standards of the three drug substances. Multiple analyses of iodochlorhydroxyquin and diiodohydroxyquinoline bulk drugs showed purities of 99.96 and 98.77% with CV of 1.17 and 0.73%, respectively. The HPLC method offers an alternative to current USP procedures, which lack stability-indicating and specificity characteristics.

Fluorimetric determination of chloroxine using manual and flow-injection methods.

A reliable and highly sensitive method is described for the determination of chloroxine in pharmaceutical preparations. It involves the formation of a complex between chloroxine and aluminum(III) in a micellar medium. The complex is a very fluorescent species, and there is a linear relationship between chloroxine concentration and fluorescence intensity over the range 2.0 x 10(-8)-5.1 x 10(-5) mol l-1. The limit of detection is 5 x 10(-9) mol l-1. The method can be easily adapted to a flow system using a three-channel manifold, the peak height being proportional to the chloroxine concentration over the range 5.6 x 10(-7)-5.6 x 10(-5) mol l-1. Manual and flow-injection procedures permit the determination of chloroxine in the presence of chlorquinaldol, and have been successfully applied to the determination of chloroxine in pharmaceutical preparations.

Rapid microbiological assay for chlorhydroxyquinoline that uses a cryogenically stored inoculum.

A rapid microbiological assay for chlorhydroxyquinoline is described. It is a turbidimetric procedure that uses Streptococcus faecalis as the test organism. Results are available within 5 h. Data are presented to show the advantages of using a cryogenically stored inoculum over an inoculum prepared on a daily basis.