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.     

Liquid chromatographic determination of chlortetracycline hydrochloride in ruminant and poultry/swine feeds.

A liquid chromatographic (LC) method is described for the determination of chlortetracycline hydrochloride (CTC) in poultry/swine and ruminant feeds in the 10-100 ppm range and in premix. CTC is extracted from ground feed/premix with acidified acetone, and the extract is filtered through a Millex-HV filter or disposable C18 column. The filtrate is partitioned with methylene chloride when additional cleanup is necessary. A Nova-Pak C18 column is used for LC separation with determination at 370 nm. The average recovery of CTC from premix was 95% with a standard deviation (SD) of 1.70 and a coefficient of variation (CV) of 1.79%. The overall average recovery from feeds was 77% with an SD of 3.18 and a CV of 4.10%.     

Spectrophotometric determination of pyrantel tartrate in swine feeds by method of standard additions: collaborative study

The spectrophotometric method for pyrantel tartrate in swine feeds was collaboratively studied. Twenty-seven laboratories assayed feeds containing 0.0103, 0.0965, and 0.7902% pyrantel tartrate. Repeatability (sigmao) and reproducibility (sigmax) standard deviations were: sigmao = 0.00068%, sigmax = 0.00105% (10% of grand mean) for 0.0103% pyrantel tartrate level; sigmao - 0.0065%, sigmax = 0.0090% (10% of grand mean) for 0.0965% pyrantel tartrate level; and sigmao = 0.0415%, sigmax = 0.0743% (10% of grand mean) for 0.7902% pyrantel tartrate level. The mean theoretical recovery values for feeds containing 0.0103, 0.0965, and 0.7902% were 100, 97, and 96%, respectively. The method was adopted as official first action for feeds or concentrates containing 0.0106-0.8811% pyrantel tartrate.     

Rapid liquid chromatographic determination of dimetridazole and ipronidazole in swine feed

A simple and rapid method is described for the determination of dimetridazole (DMZ) and ipronidazole (IPR) in swine feeds at various levels (0.11-110 ppm). The drugs are released from feed by prewetting with a buffer, followed by extraction with either methanol or methylene chloride, depending on the drug level; if necessary, an acid-base cleanup is used before the liquid chromatographic analysis. The analytes are separated on a C18 column and monitored at 320 nm for detection and quantitation. Recoveries of DMZ from several feed formulations averaged 108% at the 92.8 ppm level with a standard deviation (SD) of 4.00% and a coefficient of variation (CV) of 3.70%, 101% at the 11.2 ppm level with an SD of 11.9% and a CV of 11.8%, and 100% at the 0.112 ppm level with an SD of 9.27% and a CV of 9.25%. Recoveries of IPR averaged 77.1% at the 12.9 ppm level with an SD of 1.75% and a CV of 2.27%; IPR recoveries averaged 35.2% at the 0.129 ppm level with an SD of 3.39% and a CV of 9.63%.     

Determinations of residual furazolidone and its metabolite, 3-amino-2-oxazolidinone (AOZ), in fish feeds by HPLC-UV and LC-MS/MS, respectively

The antibacterial drug furazolidone belonging to the group of nitrofuran antibacterial agents has been widely used as an antibacterial and antiprotozoal feed additive for poultry, cattle, and farmed fish in China. During application a large proportion of the administered drug may reach the environment directly or via feces. Although the use of furazolidone is prohibited in numerous countries, there are indications of its illegal use. It is known that furazolidone can be rapidly metabolized to 3-amino-2-oxazolidinone (AOZ) in the body of the target organism. In this study, a total of 21 fish feed samples, including 17 commercial fish feeds from local markets in China (representing 15 different formulations) and 4 fish feeds obtained from Germany and Turkey, respectively, are analyzed to determine whether the drug is still illegally used or commercially available feeds are contaminated by this drug. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) methods have been implemented to determine furazolidone and its metabolite AOZ in fish feeds containing animal protein, respectively. An efficient and convenient cleanup method for the determination of furazolidone in fish feeds is developed, and a simple cleanup method for the determination of AOZ is used. Method recoveries for samples used were determined as 87.7-98.3% for furazolidone at two spike levels of 2.0 and 5.0 ng g-1 and as 95.6-102.8% for AOZ at spike levels of 0.4 and 0.8 ng g-1. Limits of detections were 0.4 ng g-1 for furazolidone and 0.05 ng g-1 for AOZ. The established methods are therefore suitable for the determination of furazolidone and its metabolite AOZ in fish feeds at trace contamination levels. Using the established methods, all fish feed samples have been proved to be furazolidone negative; however, AOZ is tested in 16 of 17 fish feeds obtained from local markets in the Hubei province of China, with a positive rate as high as 94.1%.     

Determination of morantel-related residues in bovine milk by electron capture gas chromatography

A gas chromatographic assay was developed to determine major residues of morantel in bovine milk over a range that is suitable for monitoring residues of the drug. The method is based on hydrolysis of the N-methyl-tetrahydropyrimidine portion of morantel and its metabolites to N-methyl-1,3-propanediamine, and converting the diamine to an N,N-bis-(2-nitro-4-trifluoromethylphenyl) derivative. The addition of an internal standard, the N-desmethyl-N-ethyl homolog of pyrantel, to the milk sample circumvents any potential problem that could arise from variable reaction yields, and eliminates the true recovery as a factor affecting the accuracy and precision of the procedure. The concentrations of the derivatives are determined by pulsed electron capture gas chromatography over a linear dynamic range that is equivalent to 12.5-50 ppb morantel. The method was evaluated at the 0, 12.5, 25, and 50 ppb levels in fortified bovine milk, and in a withdrawal sample containing physiologically incurred morantel residues. Mean values of 14 +/- 1.7, 24 +/- 3.7, and 47 +/- 6.9 were found for the fortified samples, approximately 3 ppb for control milk, and 16 +/- 1.7 ppb for the withdrawal sample.     

Liquid chromatographic determination of morphine sulfate and some contaminants in injections and bulk drug material

A liquid chromatographic (LC) procedure is described for the assay of morphine sulfate in bulk drug material and injection solutions. The bulk drug and injection samples are prepared by direct dilution with LC mobile solvent. The average bulk drug purity (5 manufacturers) determined by the LC method was 99.9% with a difference of 0.1% from the average purity (anhydrous) found by the official USP XX procedure. The average LC recovery (19 studies) of morphine sulfate added to injection samples was 99.4% with a coefficient of variation (CV) of 1.14%. Morphine sulfate content was determined in triplicate for 53 injection samples (1-15 mg morphine sulfate/mL) formulated by 6 manufacturers, using the proposed LC procedure. Individual sample CV (n = 3) averaged 1.14%. The LC method is simple and specific for morphine sulfate. Major degradation products, preservatives, and some contaminants and related compounds are separated during LC.     

Monitoring of feeds selenium status in a southeast region of Romania

One hundred and eighty-five samples of feeds (hays, green plants, and concentrate feed) from households covering 41 localities in Dobrudja, a southeast region of Romania, were collected and analyzed for selenium (Se) content by spectrofluorometry with 2,3-diaminonaphthalene. Only 6.5% of the samples analyzed were, in terms of the feed Se content, considered appropriate (i.e., 0.15-0.30 ppm), within the normal range. The remaining 93.5% proved to be Se deficient; the results fell into the 0.001-0.150 ppm range. Consequently, the samples were divided into three deficiency groups based on the content recorded as follows: severe for 3.2% (Se below 0.01 ppm), critical for 84.9% (Se in the 0.01-0.1 ppm range), and marginal for 5.4% (Se in the 0.1-0.15 ppm range). Conclusively, the Dobrudja feeds may be said to be generally Se deficient, which requires prophylactic and therapeutic measures to correct animal selenium deficiency.     

High pressure liquid chromatographic determination of arprinocid in feed.

Arprinocid [9 - (2 - chloro - 6 - fluorophenylmethyl)-9H-purin-6-amine] is determined in feed by high pressure liquid chromatography with a silica column and ultraviolet detection. The drug is extracted from the feed into chloroform in the presence of pH 7 phosphate buffer, transferred to 0.1N HCl, and separated from interfering substances by partitioning with hexane. The acidic solution is neutralized, and the analyte is extracted into chloroform for injection into the chromatograph. This procedure has been applied to feeds containing 0.0030--0.0090% arprinocid with a precision of less than 5% relative standard deviation at the 0.0060% formulated concentration level. The results of this chromatographic procedure also correlate with those from a colorimetric analysis.     

Improving the fatty acid profile of fairy shrimp, Streptocephalus dichotomus, using a lipid emulsion rich in highly unsaturated fatty acids

Fatty acids are the largest component of lipids and have become a useful tool in the determination of live feeds to a variety of cultured species. Bioencapsulation is a technique which allows high-level incorporation of desired components (i.e., fatty acids, vitamins, antibiotics, etc.) in live feeds, which in turn can be supplemented to the consumer organisms. The procedure described in the present study serves as a platform of technology for enriching the Streptocephalus dichotomus. Uptake of two enrichment diets (ALGAMAC2000 and DHA-SELCO) by adult S. dichotomus was investigated. The fatty acid profile supports the hypothesis that the enrichment diet increases the level of essential fatty acids, such as linolic, linolenic, eicosapentenoic, and docosahexaenoic acids. The average content (percent of total fatty acids detected) of the enriched organism by different highly unsaturated fatty acid (HUFA) products were as follows: ALGAMAC2000 showed 14-22% saturated fatty acid (SFA), 17-18% monounsaturated fatty acid (MUFA), 28-41% polyunsaturated fatty acid (PUFA), 23-34% n-3, and 4.9-7.5% n-6, whereas DHA-SELCO showed about 20-23% SFA, 20-26% MUFA, 38% PUFA, 28-31% n-3, and 7.5-10% n-6. Our present investigation proves that both HUFA-rich diets appear to be an appropriate enrichment diet, and further provides an additional rationale for using fairy shrimp as a maturation diet for any cultivable freshwater organism.     

Liquid chromatographic determination and identification of morantel-related residues as precursors of 3-(3-methyl-2-thienyl) acrylic acid (CP-20,107) in bovine milk

A simple liquid chromatographic (LC) method was developed to determine and identify incurred morantel-related residues in bovine milk by converting them to 3-(3-methyl-2-thienyl) acrylic acid (CP-20, 107). Key techniques in this method involve short-term digestion of milk in HCl to release residues convertible to CP-20, 107, isolation and alkaline hydrolysis of these precursors to CP-20, 107, and recovery of the product for LC analysis. Photochemical conversion of CP-20, 107 to its cis-isomer and separation by LC identifies the residue. A homolog (pyrantel), which is used as an internal standard, is hydrolyzed to 3-(2-thienyl) acrylic acid. These acrylic acid isomers are readily resolved by LC. The method was evaluated over the 1-4 ppb (ng/mL) range for accuracy and precision to assess its utility for withdrawal studies. Bovine milk supplemented with morantel at 1, 2, and 4 ppb and assayed in replicate (n = 7-8) over 4 trials gave mean values and standard deviations of 1.0 +/- 0.11, 2.0 +/- 0.24, and 4.0 +/- 0.44 ppb, respectively. A milk specimen containing physiologically incurred residues of morantel assayed 2.1 +/- 0.19 ppb in replicate (n = 5).     

Determination of gentian violet, its demethylated metabolites, and leucogentian violet in chicken tissue by liquid chromatography with electrochemical detection

A method is presented for determination of residues of gentian violet (GV), its demethylated metabolites (pentamethyl and tetramethyl), and leucogentian violet (LGV) in chicken tissue. The analytes are extracted from tissue with acetonitrile/buffer and partitioned into methylene chloride. Polar lipids are removed on an alumina column followed by partitioning into methylene chloride from a citrate buffer. The compounds of interest are isolated on a disposable carboxylic acid cation exchange column and then eluted with 0.02% HCl in methanol. GV, its metabolites, and LGV are determined by liquid chromatography using isocratic elution with a buffered mobile phase from a cyano column and amperometric electrochemical detection at +1.000 V. Average recoveries of GV and LGV from commercially purchased chicken liver fortified with 20 ppb of each compound were 92% [standard deviation (SD) = 7, coefficient of variation (CV) = 7.6%] and 86% (SD = 7, CV = 8.1%), respectively. Average recoveries of GV, LGV, the pentamethyl metabolite, and 1 of the tetramethyl metabolites from control chicken liver (provided by the Center for Veterinary Medicine) fortified with 20 ppb of each compound were 80% (SD = 7, CV = 8.8%), 76% (SD = 3, CV = 3.9%), 83% (SD = 6, CV = 7.2%), and 76% (SD = 8, CV = 10.5%), respectively. Mean results from 10 analyses of residue-incurred chicken liver were 31 ppb GV (SD = 3, CV = 9.7%), 34 ppb pentamethyl metabolite (SD = 3, CV = 8.8%), and 40 ppb tetramethyl metabolite(s) (SD = 2, CV = 5.0%), for an average value of 105 ppb total residues (SD = 6, CV = 5.7%); no LGV was found. Data are also presented to show applicability of the method to muscle tissue.     

Determination of tannin in green tea infusion by flow-injection analysis based on quenching the fluorescence of 3-aminophthalate

A flow-injection analytical system was developed to determine tannin content in green tea infusions. The flow-injection system is based on measuring the quenching effect of tannin on the fluorescence of 3-aminophthalate. Fluorophore was obtained by auto-oxidation of luminol during solution preparation. System performance was satisfactory for routine analysis (sample throughput >20 h(-1); linear dynamic range for tannic acid, 0.005-0.3 mg/mL; linear dynamic range for green tea tannin, 0.02-1.0 mg/mL; CV < 3%). The flow-injection method is immune from interference by coexisting ascorbate in green tea infusion. Analytical results were verified by the ferrous tartrate method, the Japanese official analytical method.     

酒石酸对黏粒矿物上酸性磷酸酶吸附及活性的影响

采用平衡批处理法,研究了模拟根系分泌物——酒石酸溶液的浓度(0~80 mmol L-1)、pH(2.5~7.0)对酸性磷酸酶在针铁矿、高岭石及黄棕壤和砖红壤胶体(<2μm)上的吸附及比活性影响。结果表明,当酒石酸浓度由0 mmol L-1(作为对照)升高至80 mmol L-1时,酸性磷酸酶在供试土壤胶体和矿物表面的吸附量先急剧降低(0~5mmol L-1之间),后逐渐达到平衡;以羟基化表面为主的针铁矿对酸性磷酸酶的吸附百分率受酒石酸浓度的影响最大,吸附百分率从对照的96.2%降至80 mmolL-1酒石酸浓度时的33.7%,其他以层状铝硅酸盐矿物为主的供试土壤胶体和高岭石则受影响较小,吸附百分率从对照的76.3%~60.6%降至80 mmol L-1酒石酸浓度时的56.2%~41.6%。酸性磷酸酶在酒石酸体系中的最大吸附pH点均在该酶的等电点酸侧,这可能与酒石酸对矿物表面的电荷性质改变有关;酒石酸体系中,针铁矿上酸性磷酸酶的比活性远高于其它供试土壤胶体,该酶的最适比活性点随胶体类型的不同而无变化或有所高移。     

Determination of ochratoxin A in animal feed and cereal grains by liquid chromatography with fluorescence detection

A liquid chromatographic (LC) method is described for determination of ochratoxin A in animal feeds and cereal grains. Samples are initially extracted with chloroform-ethanol (8 + 2) and 5% acetic acid in water. Extracts are purified using a silica gel cartridge followed by a cyano cartridge. The samples are evaporated, diluted to a known volume, and analyzed using a 10 cm column of 3 micron C18 and a fluorescence detector. The method was applied to a variety of animal feeds and cereal grains at levels of 1.0-0.005 ppm added ochratoxin A. The overall recovery was 90.6% +/- 3.6.     

High-speed liquid chromatographic determination of monensin, narasin, and salinomycin in feeds, using post-column derivatization

A high-speed liquid chromatographic (LC) method using post-column derivatization is described for the determination of monensin, narasin, and salinomycin in a variety of animal feeds. The ionophores are extracted with hexane-ethyl acetate (90 + 10). A portion of the sample is evaporated, diluted to a known volume, and analyzed using a 6 cm 3 microns C18 column and an absorbance detector after post-column reaction with vanillin. The method has been applied to poultry and swine feeds with levels of 3-100 ppm added antibiotic. A comparison was also carried out with medicated poultry feed and beef feed lot supplement samples previously analyzed by 2 separate bioassay methods for monensin and salinomycin, respectively. Recoveries for the LC method ranged from 92.1 to 103% with an average recovery of 98.1% and a coefficient of variation of 3.65%.     

Residue analysis of tetracyclines and their metabolites in eggs and in the environment by HPLC coupled with a microbiological assay and tandem mass spectrometry

Tetracyclines are widely used in farm animals. This can cause drug residues in products of animal origin and, after excretion of these substances, in animal slurry and in soil fertilized with that slurry. In this paper, we present a method based on a microbiological assay coupled with HPLC for the detection of oxytetracycline, tetracycline, and chlortetracycline in eggs. After a simple liquid extraction of the samples and HPLC separation, fractions were collected on microtiter plates, and the tetracyclines were analyzed using the Staphylococcus aureus assay. This method was able to identify residues of tetracyclines in eggs at a level set by regulatory agencies (i.e., 200 microg/kg). In addition, it was shown that the described microbiological method can be used as a screening assay for the detection of tetracyclines and possible biologically active metabolites in animal slurry and soil samples. Employing the same extraction procedure, it was demonstrated that LC-MS-MS allowed the quantification of 20-400 microg/kg in eggs with recoveries ranging from 71 to 109% and RSDs of 3-15%.     

Liquid chromatographic determination of oxfendazole in swine feeds

A relatively simple analytical method is presented for determination of oxfendazole (2-(methoxycarbonylamino)-5-phenylsulfinyl-benzimidazole) at levels as low as 0.012% in swine feeds, using cation exchange liquid chromatography (LC). The sample was extracted with a solvent mixture of methanol-glacial acetic acid (90 + 10) at 45 degrees C, using a gyrorotory shaker. Plant pigments and other feed excipients were removed using zinc acetate treatment and pH-controlled extraction. Oxfendazole was further separated from the remaining interferences and quantitatively determined by LC on a Partisil SCX column with acetonitrile-0.01M phosphate buffer as mobile phase. The method is stability-specific, linear, precise, and accurate at 80-120% labeled strength (relative standard deviation 0.9-1.7 with mean recovery of 98-99%). Supporting data at a level of 0.0135% oxfendazole in swine feed indicated that this method is capable of complete recovery of oxfendazole from medicated swine feeds.     

Removal of Metaldehyde Through Photocatalytic Reactions Using Nano-Sized Zinc Oxide Composites

In this study, we have reported the synthesis of new amino-substituted p-tert-butylcalix[4]arene (3) and its application for the removal of two carcinogenic azo dyes, i.e., Chicago Sky Blue (CSB) and Tropaeolin 000 (TP) from aqueous environment. The newly synthesized calix–ligand 3 is characterized by FT-IR and ¹H NMR spectroscopy as well as elemental analysis. The extraction efficiency of newly calix–ligand 3 for CSB and TP dyes from aqueous media was evaluated through liquid–liquid extraction experiments. The newly synthesized calix–ligand 3 showed outstanding extraction percentage and maximum percent extraction, i.e., 97 and 96 % of CSB and TP dyes was achieved at pH 9, respectively. During the extraction process, effect of various parameters was monitored and found that extraction is highly dependent on pH and salinity. Moreover, cyclic structure, cavity size, functional groups of the calixarene derivative, hydrophobicity, and the ionic property of guest molecules also affect the extraction efficiency. The comparative data prop up calix–ligand 3 as an effective extractant for both CSB and TP dyes.     

Determination of natamycin in cheese and cheese rind: interlaboratory collaborative study

A collaborative test on the determination of natamycin in cheese and cheese rind was conducted. Participants were from 37 laboratories in 13 countries. Eight samples, consisting of 4 duplicates, were investigated by a spectrometric method and a liquid chromatographic (LC) method. The spectrometric method gave good results (coefficient of variation [CV] = 12%) and the LC method with ultraviolet detection gave reasonable results (CV = 25%) for levels down to 15 mg/kg (0.9 mg/dm2). For very low levels, a preconcentration step is necessary, but even then quantitation is poor (CV = 35-37%) for both methods at 1.7 mg/kg, although the presence of natamycin can be detected qualitatively. For a level of 0.3 mg/kg, quantitation is poor (CV = 39%) for the LC method and impossible (CV = 60%) for the spectrometric method.