[Determination of bicozamycin in livestock products and seafoods by liquid chromatography-tandem mass spectrometry].

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for trace residue determination of bicozamycin (BZM) in livestock products and seafoods. BZM was extracted from a sample with acetonitrile-water (4 : 1), followed by a two-stage SPE enrichment and cleanup. The first stage involved a styrene-divinylbenzene copolymer cartridge (GL-Pak PLS-2), and the second stage involved a divinylbenzene-N-vinylpyrrolidone copolymer cartridge (Oasis HLB). The LC separation was performed on a C18 column using 0.01% formic acid-methanol (8 : 2) as the mobile phase and MS detection with negative ion electrospray ionization. The mean recoveries from swine muscle, liver, yellowtail, and milk fortified at the minimum residue limit (MRL) levels and 0.01 microg/g were >70%, and the relative standard deviations (RSDs) were <20%. Limits of quantitation (LOQs) ranged from 0.002 to 0.005 microg/g.

[Simultaneous determination of sedecamycin and terdecamycin in livestock products by LC/MS].

A simple and rapid LC/MS method for simultaneous determination of sedecamyin (SCM) and terdecamycin (TDM) in livestock products has been developed. SCM and TDM were extracted with acetonitrile. The extract was washed with n-hexane and then evaporated to dryness. The residue was dissolved in methanol, and injected into the LC/MS. The mass spectrometer was operated in the positive electrospray ionization (ESI) mode. LC separation was performed on a high-pH-resistant C18 column with 10 mmol/L carbonic acid-ammonia buffer (pH 10.0)-acetonitrile as a mobile pahse. The recoveries from swine muscle and liver fortified at the levels of 0.01 and 0.05 microg/g were 77-88%, and those from poultry muscle and liver fortified at the levels of 0.01 and 0.3 microg/g were 51-93%. The quantitation limits of SCM and TDM were 0.008 microg/g and 0.005 microg/g, respectively.

Determination method for ractopamine in swine and cattle tissues using LC/MS.

Simple and reliable methods using LC/MS have been developed for the determination of the beta-agonist ractopamine in swine and cattle tissues. Ractopamine was extracted with ethyl acetate from muscle and liver, and the ethyl acetate layer was evaporated to dryness. The residue was purified by partition with acetonitrile/n-hexane. In the case of fat, ractopamine was extracted and purified by partition with acetonitrile/n-hexane. The resulting acetonitrile solutions were evaporated to dryness. The residue was dissolved in methanol, and subjected to LC/MS. The LC separation was performed on a Wakosil-II 3C18HG column (150 x 3 mm i.d.) in isocratic mode with 0.05% trifluoroacetic acid-acetonitrile (80:20) as a mobile phase at a flow rate of 0.4 mL/min. The MS detection was performed in the selected ion recording (SIR) mode, with detection of the M + H+ ion of ractopamine (m/z 302) produced by electrospray ionization (ESI). The mean recoveries of the drug from swine muscle (0.01 microg fortified), fat (0.01 microg fortified) and liver (0.04 microg/g fortified) were 99.7%, 99.5% and 100.8%, and those from cattle samples were 108.3%, 97.0% and 109.4%, respectively. The relative standard deviations (RSDs) ranged from 0.1% to 9.5%. The limit of quantification (LOQ) of the drug was 1 ng/g.

[Analysis of chloramphenicol in honey and royal jelly by LC/MS/MS].

A sensitive and selective method using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was developed for the determination of chloramphenicol (CAP) in honey and royal jelly. Mass spectral acquisition was performed in the negative mode by applying multiple reaction monitoring. In LC separation, Mightyl RP-18GP and 10 mmol/L ammonium acetate-acetonitrile were used as the column and mobile phase, respectively. CAP in honey samples was diluted with water, while CAP in royal jelly was extracted with 1% metaphosphoric acid-methanol (4 : 6). The solutions were cleaned up with an Oasis HLB cartridge. The quantification limits of CAP in honey and royal jelly were 0.3 ng/g and 1.5 ng/g, respectively. The recoveries of CAP from both honey and royal jelly at the quantification limits were over 92%. Twenty honey products and seven royal jelly products were analyzed by the developed method. CAP was detected in one honey product at 0.6 ng/g and in six royal jelly products at the level of 1.5-17.8 ng/g. These results show that the developed method has satisfactory sensitivity selectivity and is useful for the determination of CAP residues in honey and royal jelly.

[Analysis of tetracyclines in honey and royal jelly by LC/MS/MS].

A simple and accurate method using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed for the determination of tetracyclines (TCs), i.e., oxytetracycline (OTC), chlortetracycline (CTC) and tetracycline (TC), in honey and royal jelly. Mass spectral acquisition was performed in the positive mode. In LC separation, L-column ODS and 0.01% formic acid-acetonitrile were used as the column and mobile phase, respectively. TCs in a honey sample were diluted with water, while TCs in royal jelly were extracted with 2% metaphosphoric acid-methanol (6:4). They were cleaned up with Oasis HLB and Sep Pak C18 cartridges, respectively. The quantification limits of TC, OTC, and CTC were 5, 5, and 10 ng/g, respectively, while those in royal jelly were 25, 25, and 50 ng/g, respectively. The recoveries of TCs from both honey and royal jelly were 75-120%.

[Determination of carbadox metabolites, quinoxaline-2-carboxylic acid and desoxycarbadox, in swine muscle and liver by liquid chromatography/mass spectrometry].

A sensitive and selective method using liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) for the determination of carbadox metabolites, quinoxaline-2-carboxylic acid (QCA) and desoxycarbadox (Desoxy-CDX), in swine muscle and liver has been developed. The LC separation was performed on a Cadenza CD-C18 column (10 cm x 2 mm i.d.) with a gradient system of 0.01% acetic acid-acetonitrile as the mobile phase at a flow rate of 0.2 mL/min. Negative ionization produced the [M-H]- molecular ion of QCA. On the other hand, the positive mode produced the [M+H]+ ion of Desoxy-CDX. The calibration graphs for QCA and Desoxy-CDX were rectilinear from 0.01 to 0.5 ng with selected ion monitoring (SIM). The drugs were extracted with 0.3% metaphosphoric acid-methanol (7:3), and the extracts were cleaned up on an Oasis HLB cartridge (60 mg) and by liquid-liquid extraction. The recoveries of QCA and Desoxy-CDX from swine muscle and liver fortified at 2.5 and 5 ng/g were 70.2-86.3%, and the detection limits were 1 ng/g for both drugs.

[Simple determination of residual anticoccidial drugs (diclazuril and nicarbazin) in chicken tissues by HPLC].

A simple and rapid determination of anticoccidial drug residues, diclazuril (DCZ) and nicarbazin (NCZ), in chicken tissues has been developed. DCZ and NCZ were extracted with acetonitrile from chicken liver, muscle, and fat. The extract was rinsed with n-hexane saturated with acetonitrile and then evaporated. The residue was dissolved in 1.4 mL of acetonitrile-methanol (1:1), then 1.0 mL of n-hexane saturated with acetonitrile-methanol (1:1) was added, and the mixture was partitioned by the addition of 0.6 mL of water. DCZ and NCZ in the aqueous layers were determined by HPLC on an Xterra RP-18 column with acetonitrile-0.5% ammonium acetate containing 0.01 mol/L tetra-n-butylammonium hydrogen sulfate (43:57) as the mobile phase. The mean recoveries (n = 5) of DCZ and NCZ spiked in chicken tissues at the maximum residue levels were 92.0-95.6% (CV 2.4-3.0%) and 87.3-89.4% (CV 1.7-2.8%), respectively. The detection limits of DCZ and NCZ were 0.01 and 0.004 microgram/g, respectively.