Detection of antibiotics in chicken eggs obtained from supermarkets in Ho Chi Minh City, Vietnam.

The residual levels of antibiotics in Vietnamese eggs were monitored from 2014 to 2015. A total of 111 egg packages, distributed by 11 different companies, were collected from supermarkets in Ho Chi Minh City and the levels of 28 antibiotics were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) screening method. Sixteen samples tested positive for antibiotics; a total of eight compounds (enrofloxacin, ciprofloxacin, norfloxacin, sulfadimethoxine, sulfamethazine, sulfamonomethoxine, tilmicosin and trimethoprim) were detected.

Monitoring of Antibiotic Residues in Aquatic Products in Urban and Rural Areas of Vietnam.

Antibiotic residues in aquatic products in Vietnam were investigated. A total of 511 fish and shrimp samples were collected from markets in Ho Chi Minh City (HCMC), Thai Binh (TB), and Nha Trang (NT) from July 2013 to October 2015. The samples were extracted with 2% formic acid in acetonitrile and washed with dispersive C18 sorbent.

[Validation Study for Analytical Method of Diarrhetic Shellfish Poisons in 9 Kinds of Shellfish].

A method was developed for the simultaneous determination of okadaic acid, dinophysistoxin-1 and dinophysistoxin-2 in shellfish using ultra performance liquid chromatography with tandem mass spectrometry. Shellfish poisons in spiked samples were extracted with methanol and 90% methanol, and were hydrolyzed with 2.5 mol/L sodium hydroxide solution.

Rapid and easy multiresidue method for the analysis of antibiotics in meats by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

This study involved the development of a multiresidue method for the rapid analysis of 43 antibiotics in meats using ultrahigh-performance liquid chromatography-tandem mass spectrometry. This method was performed using dispersive-solid phase extraction, which is able to analyze 20 samples within 2 h. All compounds were determined simultaneously on a C18 separation column with gradient elution.

Antibiotic residue monitoring results for pork, chicken, and beef samples in Vietnam in 2012-2013.

A monitoring plan of residual antibiotics in food of animal origin was conducted in Vietnam from 2012 to 2013. Meat samples were collected from slaughterhouses and retail stores in Ho Chi Minh City and Nha Trang. A total of 28 antibiotics were analyzed using a LC-MS/MS screening method.

[Trial for estimating the concentration of pesticide residues in the ingredients of processed foods].

If pesticide residues are detected at over the uniform limit (0.01 ppm) in processed foods, the maximum residue limits of pesticides in each ingredient should be considered. For that purpose, analysis of pesticide residues in the ingredients would be required, but in many cases it is difficult to obtain ingredients from the same lot, or the processed foods may have been manufactured overseas.

[Simultaneous determination of veterinary drugs in livestock products using dispersive and cartridge column solid-phase extraction by LC-MS/MS].

A method using dispersive and cartridge column solid-phase extraction (SPE) was developed for the simultaneous determination of veterinary drugs in livestock products by LC-MS/MS. The samples were extracted with 85% acetonitrile and cleaned up using dispersive and cartridge column SPE. Recoveries of 70 analytes fortified at the levels of 0.

[Validation study on a rapid multi-residue method for determination of pesticide residues in vegetables and fruits by LC-MS/MS].

A validation study was conducted on a rapid multiresidue method for determination of pesticide residues in vegetables and fruits by LC-MS/MS. Pesticide residues in the vegetables or fruits were extracted with acetonitrile in a disposable tube using a homogenizer, followed by salting out with anhydrous magnesium sulfate and sodium chloride in the presence of citrate salts for buffering. The extract was purified with a double-layered cartridge column (graphite carbon black/primary secondary amine silica gel; GCB/PSA).

[Preparation of samples for proficiency testing of pesticide residue analysis in processed foods].

To conduct proficiency testing for the analysis of pesticide residues in processed foods, fortified samples of retort curry and pancake were examined. In the case of retort curry, heating and mixing were necessary at the time of preparation to provide a homogenous analytical sample. A mixture of 4 carbamates and 11 organophosphorus pesticides was spiked and 14 of them showed consistent results in the samples.

[Multiresidue method for determination of pesticide residues in processed foods by GC/MS/MS].

A rapid and simple multiresidue method has been established for determination of pesticide residues in processed foods by GC/MS/MS. The pesticides were extracted with ethyl acetate, and were cleaned up with a double-layered SPE cartridge column (graphite carbon black/PSA silica gel). Recovery tests of 258 pesticides from five kinds of processed foods (dumpling, curry, French fries, fried chicken, fried fish) were performed at two different fortification levels of 0.

[Multiresidue method for determination of pesticide residues in processed foods by GC/MS].

A rapid and simple multiresidue method has been established for determination of pesticide residues in processed foods by GC/MS. The pesticides were extracted with ethyl acetate in the presence of anhydrous MgSO(4) in a disposable tube, using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids.

Simple and rapid analysis of aristolochic acid contained in crude drugs and Kampo formulations with solid-phase extraction and HPLC photodiode-array detection.

Simple and rapid analysis of aristolochic acid (AA) in crude drugs and Kampo extracts using a solid-phase extraction method and HPLC-PDA analysis was investigated. Extraction of AA from samples was accomplished by adding methanol containing 1% ammonia. The addition of ammonia ionized the AA of acidic substances so that they adhered to an acrylamide copolymer of a strong anion exchange resin (Sep-Pak QMA) coupled to diol silica easily.

[Determination of melamine in Chinese-made processed food].

A method using liquid chromatograph coupled with tandem mass spectrometer (LC/MS/MS) was developed for the determination of melamine in processed food. After extraction with 50% acetonitrile and clean-up with PSA and SCX, the quantification limit of melamine in processed food was 0.5 microg/g.

[Determination of pesticides in Chinese dumplings using liquid chromatography-tandem mass spectrometry].

A rapid and easy multiresidue method for determination of pesticide residues in Chinese dumplings using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Pesticide residues were extracted with ethyl acetate in the presence of anhydrous magnesium sulfate in a disposable tube using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids.

A rapid and easy multiresidue method for the determination of pesticide residues in vegetables, fruits, and cereals using liquid Chromatography/tandem mass spectrometry.

The applicability of a rapid and easy multiresidue method for determination of pesticide residues in agricultural products by using liquid chromatography/tandem mass spectrometry (LC/MS/MS) was examined. Pesticide residues were extracted with acetonitrile in a disposable tube using a homogenizer, followed by salting out with anhydrous magnesium sulfate and sodium chloride. The extract was purified with a double-layered cartridge column (graphite carbon black/primary-secondary amine silica gel).

Simultaneous analysis of 260 pesticide residues in agricultural products by gas chromatography/triple quadrupole mass spectrometry.

A method for simultaneous analysis of about 260 pesticides by gas chromatography coupled to tandem mass spectrometry (GC/MS/MS) with a triple quadrupole analyzer (QqQ) has been studied. The pesticides were extracted with acetonitrile and cleaned up by a bilayer cartridge. A single injection method was developed for the monitoring of all of the targeted pesticides.

Simultaneous analysis of 17 organochlorine pesticides in natural medicines by GC/MS with negative chemical ionization.

Many methods for the determination of pesticide residues in food have been reported. Although natural medicines should be confirmed to be as safe as food, few methods for the determination of pesticide residues in natural medicines have been reported. In this study, 17 organochlorine pesticides were detected in natural medicines using GC/MS with negative chemical ionization (NCI).

Simultaneous analysis of 10 pyrethroid pesticides in natural medicines by GC/MS with negative chemical ionization.

Many methods for the determination of pesticides residues in food have been reported. Although natural medicines should be confirmed as safe as food, only a few methods for the determination of pesticide residues in natural medicines have been reported. In this study, 10 pyrethroid pesticides were detected in natural medicines by GC/MS with negative chemical ionization (NCI).

Determination of neonicotinoid pesticide residues in vegetables and fruits with solid phase extraction and liquid chromatography mass spectrometry.

A rapid and simple extraction method for the simultaneous analysis of five neonicotinoid insecticides has been developed. Twelve different fruit and vegetable matrixes were extracted with methanol and cleaned up using a graphitized carbon solid phase extraction cartridge loading with a 20% methanol solution. The concentrated eluate after methanol elution was then analyzed for pesticide residues by liquid chromatography/mass spectrometry in the APCI positive mode.

Determination of seventeen pesticide residues in agricultural products by LC/MS.

Residues of 17 pesticides in agricultural products were determined by LC/MS with an atmospheric pressure chemical ionization (APCI) interface in both positive and negative ion modes. Pesticides were extracted with acetonitrile, and the extracts were cleaned-up with a primary and secondary amine (PSA) mini-column eluted with acetone-hexane (1:1). Rice, orange and potato were spiked with the 17 pesticides at 0.