Determination of albendazole and its major metabolites in the muscle tissues of Atlantic salmon,tilapia, and rainbow trout by high performance liquid chromatography with fluorometric detection

A liquid chromatographic procedure for the determination of albendazole ([5-(propylthio)-1H-benzimidazol-2yl]carbamic acid methyl ester) and its major metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole-2- aminosulfone in rainbow trout, tilapia, and salmon muscle with adhering skin tissue is described. The muscle tissue samples are made alkaline with potassium carbonate and extracted with ethyl acetate. The extracts are further subjected to cleanup by utilizing a number of liquid-liquid extraction steps. After solvent evaporation, the residue is reconstituted in mobile phase and chromatographed. The chromatography is carried out on a reversed phase Luna C(18) column, using acetonitrile/methanol/buffer as a mobile phase and a fluorescence detector. The average recoveries from the fortified muscle tissue of the three fish species for albendazole (25-100 ppb), albendazole sulfoxide (15.5-62 ppb), albendazole sulfone (1-10 ppb), and albendazole-2- aminosulfone (10-100 ppb) were 94, 77, 82, and 67%, respectively. The average CV for each compound was < or =10%. The procedure was validated and then applied to the determination of albendazole and its three major metabolites in the muscle tissue of the three fish species obtained after orally dosing with albendazole.     

Effect of exposure to soil-bound polycyclic aromatic hydrocarbons on milk contaminations of parent compounds and their monohydroxylated metabolites

The aim of this study was to determine the transfer kinetics of soil-bound polycyclic aromatic hydrocarbons to milk in lactating cows. Soil (500 g/day) fortified with fluorene (104 microg/g dry soil), phenanthrene (82 microg/g), pyrene (78 microg/g), and benzo[a]pyrene (33 microg/g) was administered to three dairy cows via a rumen cannulas for 28 consecutive days. Parent compounds and their major metabolites in milk were measured using gas chromatography-mass spectrometry. Secretion of parent compounds in milk did not increase significantly (P > 0.05) over the control values measured before supply. Target monohydroxylated metabolites were not detected in control samples, but 2-hydroxy fluorene, 3-hydroxy phenanthrene, and 1-hydroxy pyrene were present in milk by the second day of dosing. The highest concentrations of metabolites in milk (31-39 ng/mL) were for 1-hydroxy pyrene at days 7 and 14 of dosing. The observed plateaus for 3-hydroxy phenanthrene and 2-hydroxy fluorene were lower (respectively, 0.69 and 2.79 ng/mL) but significantly increased in comparison to the control samples. Contrarily, 3-hydroxy benzo[a]pyrene was not detected in milk at any sampling time. These results suggested a notable metabolism of the parent compounds after their extraction from soil during the digestive transfer. Thus, the metabolization of fluorene and pyrene can lead to higher concentrations of metabolites than of parent compounds in milk. Despite the absence of a significant transfer of parent PAHs to milk, the appearance of metabolites raises the questions of their impact on human health.     

Simplified multiresidue method for liquid chromatographic determination of N-methyl carbamate insecticides in fruits and vegetables

A simplified method is described for determining 7 N-methyl carbamates (aldicarb, carbaryl, carbofuran, methiocarb, methomyl, oxamyl, and propoxur) and 3 related metabolites (aldicarb sulfoxide, aldicarb sulfone, and 3-hydroxy carbofuran) in fruits and vegetables. Residues are extracted from crops with methanol; coextractives are then separated by gel permeation chromatography (GPC) or GPC with on-line Nuchar-Celite cleanup for crops with high chlorophyll and/or carotene content (e.g., cabbage and broccoli). Carbamates are separated on a reverse-phase liquid chromatography column, using a methanol-water gradient mobile phase. Separation is followed by postcolumn hydrolysis to yield methylamine, and the formation of a fluorophore with o-phthalaldehyde and 2-mercaptoethanol prior to fluorescence detection. Recovery data were obtained by fortifying 5 different crops (apples, broccoli, cabbages, cauliflower, and potatoes) at 0.05 and 0.5 ppm. Recoveries averaged 93% at both fortification levels except for the very polar aldicarb sulfoxide for which recoveries averaged around 52% at both levels. The coefficient of variation of the method at both levels is less than 5% and the limit of detection, defined at 5 times baseline noise, varies between 5 and 10 ppb, depending on the compound.     

Liquid chromatographic determination of zearalenone and alpha- and beta-zearalenols in milk

Previous research has demonstrated transmission of zearalenone and alpha- and beta-zearalenols into the milk of cows and other animals. Since human intake of zearalenone and its metabolites via milk is an unknown factor in risk assessment of zearalenone and because appropriate methodology for their determination in milk is not available, a rapid and sensitive analytical method has been developed. Essentially, the method includes extraction with basic acetonitrile, acidification, partition into methylene chloride on a hydrophilic matrix, cleanup on an aminopropyl solid phase extraction column, and reverse-phase liquid chromatography with fluorescence detection. Recoveries from milk averaged 84% for zearalenone, 93% for alpha-zearalenol, and 90% for beta-zearalenol at spiking levels of 0.5 to 20 ng/mL. As little as 0.2 ng/mL of zearalenone and alpha-zearalenol and 2 ng/mL of beta-zearalenol can be detected in milk. These 3 compounds are stable in refrigerated milk for at least 2 weeks and in milk brought to boiling. Enzymes (beta-glucuronidase and aryl sulfatase) may be added to milk prior to extraction to hydrolyze any conjugates.     

Analysis of fenbendazole residues in bovine milk by ELISA

Fenbendazole residues in bovine milk were analyzed by ELISAs using two monoclonal antibodies. One monoclonal antibody (MAb 587) bound the major benzimidazole anthelmintic drugs, including fenbendazole, oxfendazole, and fenbendazole sulfone. The other (MAb 591) was more specific for fenbendazole, with 13% cross-reactivity with the sulfone and no significant binding to the sulfoxide metabolite. The limit of detection of the ELISA method in the milk matrix was 7 ppb for MAb 587 and 3 ppb for MAb 591. Fenbendazole was administered in feed, drench, and paste form to three groups of dairy cattle. Milk was collected immediately before dosing and then every 12 h for 5 days. The ELISA indicated that residue levels varied widely among individual cows in each group. Fenbendazole levels peaked at approximately 12-24 h and declined rapidly thereafter. Metabolites were detected at much higher levels than the parent compound, peaked at approximately 24-36 h, and declined gradually. Residue levels were undetectable by 72 h. The ELISA data correlated well with the total residues determined by chromatographic analysis, but the use of the two separate ELISAs did not afford an advantage over ELISA with the single, broadly reactive MAb 587. The ELISA method could be used to flag high-residue samples in on-site monitoring of fenbendazole in milk and is a potential tool for studying drug pharmacokinetics.     

Identification of cephapirin metabolites and degradants in bovine milk by electrospray ionization--ion trap tandem mass spectrometry

Liquid chromatography-ion trap tandem mass spectrometry (LC-MS/MS) with electrospray ionization was used to identify cephapirin metabolites and degradants in milk from cows dosed with cephapirin. The milk was extracted according to a previously published procedure. Structures for various components were tentatively identified by their molecular weight, product ion mass spectra, and/or correspondence to standard mass spectra. These components may have occurred as metabolites or as degradants that occurred on storage or during extraction. Compounds identified in the milk included cephapirin, desacetylcephapirin, cephapirin lactone, hydrolyzed cephapirin, and a reduced cephapirin lactone that has not previously been reported. Methylcephapirin was also identified, possibly as a trace contaminant in the formulation. Analysis of incurred milk extracts showed that cephapirin and desacetylcephapirin are the major residues in milk. Desacetylcephapirin residues persisted about as long as the parent drug. The detection limit for both residues by LC-MS/MS was approximately 1 ng/mL in milk. These results have implications for microbiological methods or rapid test kits, if such methods or kits respond to cephapirin metabolites and degradants present in the milk.     

Determination of nitrofuran residues in milk of dairy cows using liquid chromatography-tandem mass spectrometry

An analytical method has been developed for the determination of total bound and extractable residues of the nitrofuran drugs furazolidone, nitrofurazone, furaltadone, and nitrofurantoin in milk of dairy cows. The method involves overnight acid hydrolysis and simultaneous derivatization of the released side chains with 2-nitrobenzaldehyde. During hydrolysis, the bound metabolites are hydrolyzed to the side chains. After pH adjustment and solid-phase extraction cleanup, the derivatives are detected and quantitated using a liquid chromatography-tandem mass spectrometry system with an atmospheric pressure chemical ionization interface. Validation of the method is accomplished by fortifying control milk with a mixture of side chains at 1, 2, and 4 ng/g. Internal standards are added at the beginning of the procedure to compensate for matrix effects and recovery losses. Method accuracies range from 83 to 104% with coefficients of variation less than 13% for all four analytes. The limits of detection are相似文献   

Metabolism of [(14)c]chlorantraniliprole in the lactating goat

Metabolism of [(14)C]chlorantraniliprole {3-bromo-N-[4-chloro-2-methyl-6-[(methylamino)carbonyl]phenyl]-1- (3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxamide} was investigated in a lactating goat following seven consecutive daily single oral doses. Each dose was equivalent to 10.4 mg/kg of feed. There was no significant transfer of residues of either chlorantraniliprole or its metabolites into fat, meat, or milk. Chlorantraniliprole and its metabolites accounted for 93.57% of the administered dose and were eliminated primarily in the excreta. Residues in meat, milk, liver, and kidney together accounted for ca. 1.5% of the administered radioactivity. A total of 19 metabolites including 3 glucuronide conjugates and intact chlorantraniliprole were identified in the feces, urine, or tissues by comparison of their HPLC retention times, mass spectral fragments (LC-MS/MS), or multiple reaction monitoring (MRM) transitions to authentic synthesized standards. The major metabolic pathways of [(14)C]chlorantraniliprole in the goat were N-demethylation, methylphenyl hydroxylation, and further oxidation to the carboxylic acid; loss of water from the N-hydroxymethyl group to yield various cyclic metabolites; and hydrolysis of N-methyl amides to form benzoic acid derivatives. Minor metabolic reactions involved cleavage of the amide bridge between the phenyl and heterocyclic rings of chlorantraniliprole.     

Naturally occurring estrogens in processed milk and in raw milk (from gestated cows)

The occurrence of the steroid hormones estrone (E1), 17alpha-estradiol (alphaE2), 17beta-estradiol (betaE2), and estriol (E3) in processed bovine milk with different fat contents and in raw milk from (non)gestated cows was investigated. Following liquid extraction, optional enzymatical deconjugation, C18 solid-phase extraction, and derivatization, estrogens were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Free and deconjugated E1 (6.2-1266 ng/L) was the major estrogen followed by alphaE2 (7.2-322 ng/L) and betaE2 (5.6-51 ng/L), whereas E3 was detected regularly at the detection limit of 10 ng/L. The lowest and highest concentrations were determined in raw milk from nonpregnant and from cows in the third trimester of gestation, respectively. The estrogen concentration in processed milk coincides with that of raw milk between first and second trimesters, reflecting the contribution of lactating pregnant cows to the final consumable product. The daily intake of total investigated estrogens through milk is 372 ng, which is dramatically more than currently recognized.     

Laboratory studies on the leaching of aldicarb through a tropical soil from Belize,Central America

Studies in temperate regions indicate that the carbamate insecticide aldicarb and its metabolites leach readily through agricultural soils into groundwater. However, little is known about the fate of this nematicide in tropical regions, where its leaching potential may be even greater because of high annual rainfall and the acidic nature and low organic content of many tropical soils. Examination of the leaching behaviour of aldicarb and its metabolites in columns containing soil from Belize, Central America, indicated that total carbamate residues (TCR) could rapidly reach concentrations > 15 mg L^?1 in porewater 1 m below the soil surface within 70 days of application. These values are well in excess of the US EPA Health Advisory level of 0.01 mg L^?1. TCR retention within a given depth interval in the soil columns relative to incoming TCR flux was greatest between 0 and 0.1 m, reflecting high organic matter contents in the upper soil. Retention below 0.1 m was relatively consistent with depth, while differences in relative retention between columns were due to a greater duration of leaching for the second column. Aldicarb was rapidly oxidized to aldicarb sulfoxide and aldicarb sulfone in these soils. The high concentration and mobility of TCR in this acidic soil is attributed to the transformation of the parent compound to the sulfoxide metabolite, which has a lower degradation rate and organic carbon partioning coefficient than aldicarb.     

Residues of methamidofos, malathion, and methiocarb in greenhouse crops

The diminution of methamidofos, malathion, and methiocarb in different crops grown in greenhouses has been studied, including the presence of metabolites such as malaoxon, methiocarb sulfoxide, and methiocarb sulfone. The analytical method is based on dichloromethane extraction and GC-PFPD analysis. It has been validated establishing performance parameters such as recovery rates, precision, linear ranges, and limits of detection and quantification, which are low enough for ensuring that their corresponding MLRs can be adequately quantified. Samples of treated cucumbers and peppers grown in greenhouses were collected and analyzed during a 15-day period for obtaining the diminution rates of methamidofos and malathion. The behavior of methiocarb in treated green beans and tomatoes has been studied using analysis of variance (ANOVA) as the statistical tool, for establishing the influence of crop, season, application dose, and greenhouse design.     

Fate of a phenylpyrazole in vegetation and soil under tropical field conditions

The fate of fipronil, a phenylpyrazole insecticide, and its metabolites under tropical conditions was studied in soil and in vegetation after treatment for locust control. Two different plots were treated with a formulation of fipronil at doses of 5 and 10 g of active ingredient ha(-)(1), respectively. Vegetation and soil at depths of 0-5 and 5-20 cm were sampled for up to 2 months after treatment. After extraction and purification on fipronil immunoaffinity cartridges, residues were analyzed by gas chromatography using electron capture and mass detectors. In soil, a rapid initial decrease of fipronil was observed with a rapid formation of the sulfone and the photodegradate; the amide and the sulfide were not detected. In vegetation, a rapid initial decrease of fipronil was also observed with a rapid formation of mostly the sulfone; the photodegradate and the sulfide were also detected but at much lower concentrations. The metabolites resulting from the degradation of fipronil were similar in both soil and vegetation, but their relative concentrations were different.     

异位酸饲料添加剂对奶牛产奶的作用

50头经产的黑白花奶牛200天的试验表明,在基础日粮中添加异位酸的试验牛,平均每头每日产奶量比喂基础日粮的对照牛多1.01公斤,增加5.14%(P<0.01);折算成标准奶,每头每日比对照牛多产1.41公斤,增加7.84%(P<0.01)。乳脂、乳蛋白和乳中干物质的含量分别提高4.43%,1.31%和2.68%。试验牛产1公斤标准奶所需要的奶牛能量单位和粗蛋白质比对照牛低。两组牛的健康状况和繁殖性能相似。     

Liquid chromatographic determination of N-methylcarbamate insecticides and metabolites in crops. II. Analytical characteristics and residue findings

Four laboratories obtained 177 carbamate recovery values using a liquid chromatographic method. The average recovery of 11 carbamates (aldicarb, aldicarb sulfone, bufencarb, carbaryl, carbofuran, 3-hydroxy carbofuran, 3-keto carbofuran, methiocarb, methiocarb sulfoxide, methomyl, and oxamyl) from 14 crops was 99% with a coefficient of variation of 8% (0.03-1.8 ppm fortification levels). No statistical difference in recovery was found between oxime and phenyl carbamates, or between parent and metabolite carbamates. Average recovery of aldicarb sulfoxide was 59% due to loss in the liquid-liquid partitioning because of the polarity of this compound. A fifth laboratory contributed 34 carbamate recoveries (average 99%) on table-ready food products for 4 carbamates. Bendiocarb, dioxacarb, isoprocarb, and propoxur are also quantitatively recovered through the method. Previously reported carbamate and noncarbamate recovery data are also discussed. In the Food and Drug Administration's (FDA) analysis of 319 samples (mainly crops), 86 (27%) were found to contain residues of carbamate insecticides and/or toxic carbamate metabolites. Carbaryl and methomyl were the most common carbamate residues found on the food products excluding the aldicarb sulfone and sulfoxide residues found on potatoes. In one FDA Total Diet Program "market basket", 11 of 69 table-ready food commodities contained from 0.005 to 0.094 ppm carbamate residues. Carbaryl was the most prevalent residue. Several laboratories reported adverse effects on the determinative system when inadequately purified reagents were used.     

Electron capture gas chromatographic determination of traces of formaldehyde in milk as the 2,4-dinitrophenylhydrazone

A quantitative method is described for the determination of formaldehyde in milk by packed-column gas chromatography and electron capture detection. Aldehyde derivatization was carried out in situ with 2,4-dinitrophenylhydrazine followed by extraction and analysis using an external standard. Average recoveries of 96.3 +/- 1.6% were characteristic of the chromatographic method with an estimated detection limit of 0.026 mg/kg. The technique was applied to determination of formaldehyde in milk from cows consuming a formalin-treated feedstuff.     

苹果酸对泌乳早期奶牛泌乳性能和代谢产物的影响

选用28头经产奶牛,根据泌乳期、上一泌乳期305d的产奶量和预产期,采用随机区组设计分为4组,研究苹果酸(07、0、140和210g/d)对泌乳早期奶牛采食量、泌乳性能、血液代谢产物和尿酮浓度的影响。结果表明:日粮添加苹果酸对奶牛的采食量、乳脂率、乳蛋白率、乳糖率和乳干物质率无显著影响,140g/d组和210g/d组产奶量和饲料转化效率显著高于对照组(P<0.05)。添加苹果酸后,140g/d组和210g/d组血浆葡萄糖浓度显著高于对照组(P<0.05),而血浆游离脂肪酸和β-羟丁酸浓度显著低于对照组(P<0.05);140g/d组和210g/d组尿酮浓度显著低于对照组和70g/d组(P<0.05)。根据试验结果,苹果酸适宜添加量为140g/d。     

Investigation of the persistence of nitroxynil residues in milk from lactating dairy cows by ultra performance liquid chromatography tandem mass spectrometry

Nitroxynil is an anthelmintic used in the treatment of liver fluke. In this study, six dairy cows were treated during lactation with Trodax, a 34% solution containing nitroxynil as its N-ethylglucamine salt, indicated for the treatment of fascioliasis in cattle and sheep. Samples were collected twice daily for 16 days and later at weekly intervals up to 58 days post-treatment. Nitroxynil residues were extracted from milk samples using acetonitrile; magnesium sulfate and sodium chloride were added to induce liquid-liquid partitioning and purified by dispersive solid phase extraction for clean-up. Nitroxynil was determined by ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) in negative ionization mode. The limit of detection (CCα) of the method is 0.24 μg/kg. Maximum concentration of nitroxynil in the samples was in the range of 688-1358 μg/kg, with levels persisting for 58 days in four of the six lactating cows. Incurred nitroxynil samples were treated with sulfatase and β-glucuronidase from Helix pomatia ; the results indicated the presence of glucuronide conjugates in samples at early withdrawal times. At later withdrawal times the concentration of free nitroxynil was lower than the concentration in the control samples, indicating potential degradation during enzymatic treatment.     

Determination of depletion and statistical distribution of morantel-related residues in bovine milk following administration of morantel tartrate to dairy cows

Residue depletion studies were conducted in dairy cattle to monitor morantel-related residues in milk following oral administration of morantel tartrate (Rumate. Eleven lactating cows of various ages, periods of lactation, and known milk production were orally dosed with the bolus formulation of morantel tartrate with an actual dose range of 8.4-9.8 mg/kg body weight. Representative samples of milk were collected at 10-14 h intervals post-dose, and subsamples were assayed for the major and minor hydrolysis products of morantel-related residues, MAPA and CP-20,107. Residues assayed as precursors of MAPA peaked at the second milking (24 h post-dose) and were below 25 ppb (range: less than 12-24 ppb). Precursors of CP-20,107, which confirm the identity of morantel, also peaked at 24 h post-dose (range: 2.1-3.3 ppb) and declined rapidly thereafter. A statistical model was used to project the level of residues at the upper limit of 99% of the total target animal (i.e., dairy cattle) population with 95% confidence. The calculated peak levels from this model were 50 and 5.0 ppb for morantel-related residues convertible to MAPA and CP-20,107, respectively.     

Determination of altosid insect growth regulator in waters, soils, plants, and animals by gas-liquid chromatography.

Residues of isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate (Altosid) insect growth regulator are determined in waters, soils, plants, milk, eggs, fish, shellfish, poultry and cattle tissues, blood, urine, and feces. Acetonitrile is the primary extraction solvent for all samples. Residues are extracted by high-speed blending followed by vacuum filtration. Fatty extracts are subjected to cold-temperature precipitation and filtration. Samples are cleaned up by petroleum ether partitioning and Florisil and neutral alumina chromatography. The concentrated eluants are analyzed by gas-liquid chromatography (GLC) on columns of differing polarity, using hydrogen flame ionization detectors. The identity of suspected residues is confirmed by additional GLC and by mass fragmentography. The lower limits of detection were: water samples, 0.0004-0.001 ppm; soils, blood, and urine, 0.001 ppm; forage grasses, forage legumes, and rice foliage, 0.005 ppm; and milk, eggs, fish, shellfish, poultry and cattle tissues, and feces, 0.010 ppm.     

奶牛产奶量与乳中孕酮、雌二醇含量关系的研究

用放射免疫法测定了50头荷斯坦牛产后23d内及发情前后12d内乳中的孕酮(P)和雌二醇(E2)的含量。结果表明:产奶量≤2000kg时,P和E2的平均含量分别为(0.70±0.30)ng/ml和(134±240)pg/ml;产奶量为2001-2500kg时,P和E2的平均含量分别为(0.55±0.17)ng/ml和(100±111)pg/ml;产奶量为2501-3000kg时,P和E2的平均含量分别为(0.45±0.17)ng/ml和(44±24)pg/ml;产奶量为2001-2500kg时,P和E2的平均含量为(0.50±0.19)ng/ml和(94±182)pg/ml。发情前后12d内,产奶量≤2000kg,P和E2的平均含量分别为(1.74±1.13)ng/ml和(40±15)pg/ml;产奶量为2001-2500kg时,P和E2的平均含量分别为(1.85±0.64)ng/ml和(47±11)pg/ml;产奶量为2501-3000kg时,P和E2的平均含量分别为(1.98±1.26)ng/ml和(42±12)pg/ml;产奶量为2001-2500kg时,P和E2的平均含量分别为(2.41±1.10)ng/ml和(49±13)pg/ml。不同产奶量(90d内总产量)的奶牛其产后乳中孕酮及雌二醇含量之间的差异均达极显著(P<0.01)。而不同产奶量的奶牛其发情前后孕酮、雌二醇含量差异不显著(P>0.05)。