Multiresidue method for isolation and liquid chromatographic determination of seven benzimidazole anthelmintics in milk

A multiresidue method for the isolation and liquid chromatographic determination of 7 benzimidazole anthelmintics (thiabendazole, oxfendazole, para-hydroxyfenbendazole, fenbendazole sulfone, mebendazole, albendazole, and fenbendazole) in milk is presented. Blank or benzimidazole-spiked milk samples (0.5 mL) were blended with octadecylsilyl (C-18, 18% load, end-capped) derivatized silica packing material. A column made from the C-18/milk matrix was first washed with hexane (8 mL), and then the benzimidazoles were eluted with methylene chloride-ethyl acetate (1 + 2, v/v; 8 mL). The eluate contained benzimidazole analytes which were free from interfering compounds as determined by UV detection (photodiode array, 290 nm). Correlation coefficients of standard curves for individual benzimidazoles isolated from spiked samples were linear (0.989 +/- 0.003 to 0.998 +/- 0.001) with recoveries ranging from 70 +/- 9% to 107 +/- 2% for the concentration range (62.5-2000 ng/mL) examined. The inter-assay variabilities ranged from 4 +/- 1% to 9 +/- 7% with intra-assay variabilities of 3-6%.     

Matrix solid phase dispersion (MSPD) isolation and liquid chromatographic determination of furazolidone in pork muscle tissue

A method for the isolation and liquid chromatographic (LC) determination of furazolidone in pork muscle tissue is presented. Blank or furazolidone-fortified pork muscle tissue samples (0.5 g) were blended with octadecylsilyl (C18, 18% load, endcapped, 2 g) derivatized silica. A column made from C18/pork matrix was first washed with hexane (8 mL), followed by elution of furazolidone with ethyl acetate. The ethyl acetate extract was then passed through an activated alumina column. The eluate contained furazolidone that was free from interfering compounds when analyzed by LC with UV detection (photodiode array, 365 nm). Detector response with increasing concentrations of furazolidone isolated from fortified samples was linear (r = 0.998 +/- 0.002) with an average percentage recovery of 89.5 +/- 8.1% for the concentration range (7.8-250 ng/g) examined and resulted in a minimum detectable limit of 390 pg on column, and a detector response of more than 5 times baseline noise. The inter-assay variability was 9.9 +/- 5.4% with an intra-assay variability of 1.5%.     

Matrix solid phase dispersion isolation and liquid chromatographic determination of sulfadimethoxine in catfish (Ictalurus punctatus) muscle tissue

A method for the isolation and liquid chromatographic determination of sulfadimethoxine in catfish (Ictalurus punctatus) muscle tissue is presented. Blank control and sulfadimethoxine-fortified fish muscle tissue samples (0.5 g) were blended with octadecyisilyl (C18, 40 micrograms, 18% load, endcapped) derivatized silica packing material. A column made from the C18/fish tissue blend was first washed with hexane (8 mL), following which the sulfadimethoxine was eluted with dichloromethane (8 mL). The eluant contained sulfadimethoxine analyte that was free from interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array, 270 nm). Standard curves for sulfadimethoxine isolated from fortified samples were linear (0.999 +/- 0.001) with an average relative percentage recovery of 101.1 +/- 4.2% for the concentration range (50, 100, 200, 400, 800, and 1600 ng/g) examined using sulfamethoxazole as the internal standard. The interassay variability was 10.7 +/- 8.2% with an intra-assay variability of 2.2%.     

Matrix solid phase dispersion isolation and liquid chromatographic determination of oxytetracycline in catfish (Ictalurus punctatus) muscle tissue

A method for isolation and liquid chromatographic determination of oxytetracycline in catfish (Ictalurus punctatus) muscle tissue is presented. Blank control and oxytetracycline-fortified fish muscle tissue samples (0.5 g) were blended with octadecylsllyl (C18, 40 microns, 18% load, endcapped) derivatized silica packing material (2 g) containing 0.05 g each of oxalic acid and disodium ethylenediaminetetraacetate. A column made from the C18/fish tissue matrix was first washed with hexane (8 mL), following which the oxytetracycline was eluted with acetonitrile-methanol (1 + 1, v/v) containing 0.06% w/v each of butylated hydroxyanisole and butylated hydroxytoluene. The eluate contained oxytetracycline analyte that was free from interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array set at 365 nm). Standard curves for oxytetracycline isolated from fortified samples were linear (0.998 +/- 0.002) with an average absolute percentage recovery of 80.9 +/- 6.6% for the concentration range (50, 100, 200, 400, 800, 1600, and 3200 ng/g) examined. The interassay variability was 11.3 +/- 5.2% with an intra-assay variability of 1.1%.     

Matrix solid-phase dispersion (MSPD) isolation and liquid chromatographic determination of oxytetracycline, tetracycline, and chlortetracycline in milk

A multiresidue method for the isolation and liquid chromatographic determination of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) antibiotics in milk is presented. Blank and tetracycline (OTC, TC, and CTC) fortified milk samples (0.5 mL) were blended with octadecylsilyl (C18, 40 microns, 18% load, endcapped, 2 g) derivatized silica packing material containing 0.05 g each of oxalic acid and disodium ethylenediaminetetraacetic. A column made from the C18/milk matrix was first washed with hexane (8 mL), following which the tetracyclines were eluted with ethyl acetate-acetonitrile (1 + 3; v/v). The eluate contained tetracycline analytes that were free from interfering compounds when analyzed by liquid chromatography with UV detection (photodiode array, 365 nm). Correlation coefficients of standards curves for individual tetracycline isolated from fortified samples were linear (from 0.982 +/- 0.009 to 0.996 +/- 0.004) with average percentage recoveries from 63.5 to 93.3 for the concentration range (100, 200, 400, 800, 1600, and 3200 ng/mL) examined. The inter-assay variability ranged from 8.5 +/- 2.4% to 20.7 +/- 13.0% with an intra-assay variability of 1.0-9.3%.     

Matrix solid phase dispersion (MSPD) extraction and gas chromatographic screening of nine chlorinated pesticides in beef fat

A multiresidue technique is presented for the extraction and quantitative gas chromatographic screening of 9 insecticides (lindane, heptachlor, aldrin, heptachlor epoxide, p,p'-DDE, dieldrin, endrin, p,p'-TDE, and p,p'-DDT) as residues in beef fat. Beef fat was fortified by adding the 9 insecticides, plus dibutyl chlorendate as internal standard, to 0.5 g portions of beef fat and blending with 2 g C18 (octadecylsilyl)-derivatized silica. The C18/fat matrix blend was fashioned into a column by adding the blend to a 10 mL syringe barrel containing 2 g activated Florisil. The insecticides were then eluted from the column with 8 mL acetonitrile, and a 2 microL portion of the acetonitrile eluate was then directly analyzed by gas chromatography with electron capture detection. Unfortified blank controls were treated similarly. The acetonitrile eluate contained all of the pesticide analytes (31.25-500 ng/g) and was free of interfering co-extractants. Correlation coefficients for the 9 extracted pesticide standard curves (linear regression analysis, n = 5) ranged from 0.9969 (+/- 0.0021) to 0.9999 (+/- 0.0001). Average relative percentage recoveries (85 +/- 3.4% to 102 +/- 5.0%, n = 25 for each insecticide), inter-assay variability (6.0 +/- 1.0% to 14.0 +/- 6.7%, n = 25 for each insecticide), and intra-assay variability (2.5-5.1% n = 5 for each insecticide) indicated that the methodology is acceptable for the extraction, determination, and screening of these residues in beef fat.     

Simultaneous liquid chromatographic screening of five coccidiostats in chicken liver

A reverse-phase liquid chromatographic (LC) method is described for simultaneously determining 5 coccidiostats--aklomide, dinsed, ethopabate, nitromide, and zoalene in chicken liver. The method entails blender extraction of 10 g liver with ethyl acetate, column chromatography through Sephadex LH-20 and neutral alumina, and LC analysis on a C18 column with UV detection at 260 nm. The drugs were eluted from Sephadex with methanol-benzene (10 + 90), from alumina with methanol-dichloromethane (10 + 90), and from C18 with acetonitrile-water (linear gradient: 25% acetonitrile for 10 min, increasing to 55% over 15 min; flow rate 1 mL/min). Liquid chromatography was completed in 40 min and calculations were based on peak height measurements. Average recoveries of the coccidiostats from fortified liver ranged from 72 to 97%, except for dinsed, which showed a relatively constant average recovery of 57%. The detection limit for the standards was 2.5 ng on column. Levels as low as 50 ng/g were detected in fortified liver samples.     

Multiresidue matrix solid phase dispersion (MSPD) extraction and gas chromatographic screening of nine chlorinated pesticides in catfish (Ictalurus punctatus) muscle tissue

A multiresidue technique for extraction and gas chromatographic screening of 9 insecticide (lindane, heptachlor, aldrin, heptachlor epoxide, p,p'-DDE, dieldrin, endrin, p,p'-TDE, and p,p'-DDT) residues in catfish (Ictalurus punctatus) muscle tissue is presented. The 9 insecticides, plus dibutyl chlorendate internal standard, were fortified into catfish muscle tissue (0.5 g) and blended with 2 g C18 (octadecylsilyl derivatized silica reverse-phase material). The C18/muscle tissue matrix blend was fashioned into a column by adding the blend to a 10 mL syringe barrel containing 2 g activated Florisil. The insecticides were then eluted from the column with acetonitrile (8 mL), and a portion (2 microL) of the acetonitrile eluate was then directly analyzed by gas chromatography with electron capture detection. Unfortified blank controls were treated similarly. The resultant extracts contained pesticide analytes (31.25-500 ng/g) free of interfering compounds when analyzed. Correlation coefficients for the 9 extracted pesticide standard curves (linear regression analysis, n = 5) ranged from 0.9967 (+/- 0.0018) to 0.9999 (+/- 0.0001). Average percentage recoveries (82 +/- 4.8% to 97 +/- 3.6%, n = 25 for each insecticide), interassay (5.0 +/- 2.7% to 16.9 +/- 6.5%, n = 25 for each insecticide) and intraassay (1.8 to 4.7%, n = 5 for each insecticide) variabilities were indicative of an acceptable methodology for the analysis and screening of these residues in catfish muscle tissue.     

超高效液相色谱-串联质谱法测定牛奶和奶粉中五种苯并咪唑类药物

为建立牛奶及奶粉中5种苯并咪唑类药物(阿苯达唑、芬苯达唑、奥芬达唑、噻苯达唑、苯硫氨酯)简便、准确的分析检测方法,以固相萃取为净化手段,采用Acquity UPLC^® BEH C₁₈(100 mm×2.1 mm,1.7 μm)色谱柱进行分离,电喷雾离子源(ESI⁺),多反应监测(MRM)模式检测。结果表明,5种苯并咪唑类药物在1~500 μg·L^-1范围内呈线性相关,相关系数(r)均大于0.996,加标平均回收率介于91.7%~97.8%之间,相对标准偏差(RSD)在1.4%~6.5%之间,基质效应均小于15%。5种药物的检出限均在0.1~3 μg·kg^-1范围内,定量限均在0.5~10 μg·kg^-1范围内。该方法操作简单、快速且灵敏度高,重现性好,能够用于牛奶及奶粉5种苯并咪唑类药物的同时测定。     

Liquid chromatographic determination of flucytosine in capsules: collaborative study

A liquid chromatographic method for the determination of flucytosine in capsules was collaboratively studied by 7 laboratories. The method uses a C18 reverse phase column, water-methanol-acetic acid mobile phase containing 1-octanesulfonic acid sodium salt, p-aminobenzoic acid as internal standard, and photometric detection at 285 nm. The mean recovery value (+/- SD) of flucytosine from a synthetic formulation representing capsules was 99.2 +/- 1.72% (CV = 1.73%). Composited samples of 250 and 500 mg commercial capsules gave assay values of (mean +/- SD) 103.17 +/- 2.21 and 99.29 +/- 1.29% of declared, respectively. CV values were 2.15 and 1.30%. Reproducibility and repeatability CVs were 2.19 and 1.50%, respectively, for the 250 mg capsules, and 1.34 and 0.63%, respectively, for the 500 mg capsules. The method has been adopted official first action.     

Methodology for the analysis of benzimidazole anthelmintics as drug residues in animal tissues

Methodology for the analysis of 8 benzimidazoles as residues in bovine liver is reported. Spiked tissues were extracted by homogenization in saline and ammonium hydroxide and blending with diatomaceous earth. This matrix was packed into a column, and the benzimidazoles were eluted with ethyl acetate. After the sample was further purified, benzimidazoles were separated and quantitated by liquid chromatography with ultraviolet detection (290 nm). Liver tissue samples obtained from cattle which had undergone a drug depletion study of fenbendazole administered per os were analyzed using these methods. The results of these analyses and the application of this approach to multiresidue analysis of drugs in animal tissues are discussed.     

Rapid assay for analyzing biogenic amines in cheese: matrix solid-phase dispersion followed by liquid chromatography-electrospray-tandem mass spectrometry

A new rapid and sensitive method based on matrix solid-phase dispersion (MSPD) followed by liquid chromatography-electrospray-tandem mass spectrometry was devised for the determination of biogenic amines at trace levels in cheese samples. The method required 0.25 g of sample, CN-bonded silica as a dispersant sorbent, and a formic acid aqueous solution/methanol mixture as an eluting solvent. Extraction recoveries from soft cheese products were calculated in the 98 +/- 4-110 +/- 6% range. A procedure based on solid-phase extraction was also evaluated for the extraction of these compounds in cheese. Chromatographic separation was performed using a C18 column with an aqueous ammonium acetate/methanol mixture as the mobile phase under gradient conditions. The method was validated in terms of detection limits (LOD), quantitation limits (LOQ), linearity, recovery, precision, and trueness. Results in the 0.05-0.25 mg kg(-1) range were obtained for the LOD of histamine, tyramine, and beta-phenylethylamine in soft cheese samples. Linearity was established over 2 orders of magnitude. Excellent precision in terms of intra-day repeatability was calculated (RSD% < 5). The applicability of the method to the determination of biogenic amines in cheese products was demonstrated.     

Liquid chromatographic determination of sulfamoyldapsone in swine tissues

A liquid chromatographic (LC) method is described for the quantitative determination of sulfamoyldapsone (2-sulfamoyl-4,4'-diaminodiphenyl sulfone) in swine muscle, liver, kidney, and fat. Sulfamoyldapsone was extracted from tissues with acetonitrile saturated with n-hexane. The extract was washed with n-hexane saturated with acetonitrile, concentrated, and cleaned up by alumina column chromatography. Sulfamoyldapsone was separated on an ODS column by using acetonitrile-methanol-water (6 + 18 + 76) and was detected at 292 nm. Overall average recovery of sulfamoyldapsone added to tissues at levels of 0.1 and 0.5 microgram/g was 93.3% +/- 6.0. Detection limit was 0.02 microgram/g in these tissues.     

Isolation and gas chromatographic determination of chlorsulfuron in milk

A method for the isolation and gas chromatographic determination of chlorsulfuron in milk is presented. Blank or chlorsulfuron-spiked milk samples were blended into C-18 (octadecylsilyl derivatized silica, ODS) packing material. A column made from the C-18/milk matrix was washed with hexane after which chlorsulfuron was eluted with dichloromethane (DCM). The DCM eluate contained chlorsulfuron which was free from interfering co-extractants when analyzed by gas chromatography utilizing a nitrogen/phosphorus detector. Chlorsulfuron was found to undergo a thermally induced decomposition to give 2-amino-4-methoxy-6-methyl-1,3,5-triazine, which was detected and quantitated by this method. Standard curves for these analyses were linear (r = 0.992 +/- 0.004, n = 5), with an average percentage recovery of 91.6 +/- 10.8%, over the concentration range examined (62.5-2000 ng/mL). The inter- and intra-assay variabilities were 11.6 +/- 7.5% and 6.2%, respectively.     

Determination of niclosamide residues in rainbow trout (Oncorhynchus mykiss) and channel catfish (Ictalurus punctatus) fillet tissue by high-performance liquid chromatography

Bayluscide [the ethanolamine salt of niclosamide (NIC)] is a registered piscicide used in combination with 3-(trifluoromethyl)-4-nitrophenol (TFM) to control sea lamprey populations in streams tributary to the Great Lakes. A high-performance liquid chromatography (HPLC) method was developed for the determination of NIC residues in muscle fillet tissues of fish exposed to NIC and TFM during sea lamprey control treatments. NIC was extracted from fortified channel catfish and rainbow trout fillet tissue with a series of acetone extractions and cleaned up on C(18) solid-phase extraction cartridges. NIC concentrations were determined by HPLC with detection at 360 and 335 nm for rainbow trout and catfish, respectively. Recovery of NIC from rainbow trout (n = 7) fortified at 0.04 microg/g was 77 +/- 6.5% and from channel catfish (n = 7) fortified at 0.02 microg/g was 113 +/- 11%. NIC detection limit was 0.0107 microg/g for rainbow trout and 0.0063 microg/g for catfish. Percent recovery of incurred radioactive residues by this method from catfish exposed to [(14)C]NIC was 89.3 +/- 4.1%. Percent recoveries of NIC from fortified storage stability tissue samples for rainbow trout (n = 3) analyzed at 5 and 7.5 month periods were 78 +/- 5.1 and 68 +/- 2.4%, respectively. Percent recoveries of NIC from fortified storage stability tissue samples for channel catfish (n = 3) analyzed at 5 and 7.5 month periods were 88 +/- 13 and 76 +/- 21%, respectively.     

Determination of anthocyanidins in berries and red wine by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for the determination of anthocyanidins from berries and red wine is described. Delphinidin, cyanidin, petunidin, pelargonidin, peonidin, and malvidin contents of bilberry (Vaccinium myrtillus), black currant (Ribes nigrum), strawberry (Fragaria ananassa cv. Jonsok), and a Cabernet sauvignon (Vitis vinifera) red wine were determined. The aglycon forms of the anthocyanins present in the samples were revealed by acid hydrolysis. A reversed phase analytical column was employed to separate the anthocyanidins before identification by diode array detection. The suitability of the method was tested by determining the recovery (95-102% as aglycons and 69-104% from glycosides) for each anthocyanidin. Method repeatability was tested by charting the total aglycon content of two samples over a period of 14 analyses and determining the coefficients of variation (1.41% for bilberry and 2.56% for in-house reference material). The method developed proved thus to be effective for reliable determination of anthocyanidins from freeze-dried berry samples and red wine. The total anthocyanidin content of the tested samples was as follows: in-house reference material, 447 +/- 8 mg/100 g; strawberry, 23.8 +/- 0.4 mg/100 g; black currant, 135 +/- 3 mg/100 g; bilberry, 360 +/- 3 mg/100 g; and Cabernet sauvignon red wine, 26.1 +/- 0.1 mg/100 mL.     

Liquid chromatographic determination and stability of the Fusarium mycotoxin moniliformin in cereal grains

Moniliformin is a mycotoxin produced by Fusarium subglutinans and other Fusarium species. A rapid, liquid chromatographic method for its determination in corn and wheat is described. Samples are extracted in acetonitrile-water (95 + 5); following defatting with n-hexane, an aliquot of the extract is evaporated and cleaned up on small C18 and neutral alumina columns successively. Reverse-phase liquid chromatography (LC) is conducted on a C18 column with 10 or 15% methanol or acetonitrile in aqueous ion-pair reagent as mobile phase, with detection by ultraviolet absorption at 229 and 254 nm. Average recoveries of moniliformin (potassium salt) added to ground corn and wheat at levels of 0.05-1.0 micrograms/g were 80% (n = 20) and 85% (n = 12), respectively, and the limit of detection was ca 0.01-0.18 micrograms/g, depending on LC conditions. Analysis of 24 samples of wheat, 4 samples of rye, and 12 samples of corn showed moniliformin in only 2 corn samples (0.06 and 0.2 micrograms/g). Moniliformin was also detected in a sample of artificially damaged (slashed) corn (0.2 micrograms/g) and selected kernels of corn that were field-inoculated with F. subglutinans and F. moniliforme (50 micrograms/g and 0.5 micrograms/g, respectively). In stability studies, moniliformin (potassium salt, 1 microgram/g) in ground corn and ground wheat heated at 50, 100, and 150 degrees C for 0.5-2 h decomposed moderately, e.g., 55% remained in corn after 0.5 h at 100 degrees C.     

Development of multiresidue analysis for twenty phthalate esters in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-gas chromatography-tandem mass spectrometry

A novel multiresidue analysis method is developed for the determination of twenty phthalate esters at the μg/kg level in edible vegetable oils by microwave-assisted extraction-gel permeation chromatography-solid phase extraction-high resolution gas chromatography-tandem mass spectrometry (MAE-GPC-SPE-HRGC-MS/MS). The samples were extracted with methanol under microwave incubation. Cleanup was carried out with GPC followed by a further C18 SPE column and then separated by the HP-5MS capillary column under a temperature program. The eluents were qualitatively and quantitatively determined by tandem mass analyzer with selected reaction monitoring (SRM) type and positive ion mode. The calibration curves showed good linearity in the range 5 μg/kg to 2.50 mg/kg with correlation coefficients larger than 0.999. Low detection limits (LODs) of 0.218-1.367 μg/kg and quantification limits (LOQ) of 0.72-4.51 μg/kg were achieved. The mean recoveries were in the range from 93.04% to 104.6% at 5, 15, and 40 μg/kg spiked levels, and the relative standard deviations (RSDs) were in the range of 1.01% and 5.26% (n = 7). This method could potentially overcome the interference from large amounts of lipids and pigment. The real sample test showed this method can be used for sensitive and accurate determination and confirmation of phthalate ester residues in high-fat and complex samples.     

Liquid chromatographic determination of miconazole nitrate in creams and suppositories

A rapid method has been developed for the determination of miconazole nitrate in creams and suppositories. The sample is dissolved in ethanol, diluted in acetonitrile-water (1 + 1), and injected onto a C18 column. The mobile phase consists of 55% acetonitrile, a triethylammonium phosphate buffer, and an ion-pairing agent. The total run time is less than 4 min, and the active ingredient is determined using absorbance detection at 214 nm. The mean recovery of miconazole from spiked placebo samples was 99.7 +/- 0.7% for the cream samples at the 2% level and 98.8 +/- 0.3% for the suppository samples at the 4% level.     

Improved HPLC method for the determination of curcumin,demethoxycurcumin, and bisdemethoxycurcumin

Commercially available curcumin, a bright orange-yellow color pigment of turmeric, consists of a mixture of three curcuminoids, namely, curcumin, demethoxycurcumin, and bisdemethoxycurcumin. These were isolated by column chromatography and identified by spectroscopic studies. The purity of the curcuminoids was analyzed by an improved HPLC method. HPLC separation was performed on a C(18) column using three solvents, methanol, 2% AcOH, and acetonitrile, with detection at 425 nm. Four different commercially available varieties of turmeric, namely, Salem, Erode, Balasore, and local market samples, were analyzed to detect the percentage of these three curcuminoids. The percentages of curcumin, demethoxycurcumin, and bisdemethoxycurcumin as estimated using their calibration curves were found to be 1.06 +/- 0.061 to 5.65 +/- 0.040, 0.83 +/- 0.047 to 3.36 +/- 0.040, and 0.42 +/- 0.036 to 2.16 +/- 0.06, respectively, in four different samples. The total percentages of curcuminoids are 2.34 +/- 0.171 to 9.18 +/- 0.232%.