Naoto Furusawa

Matrix solid-phase dispersion extraction and high-performance liquid chromatographic determination of residual sulfonamides in chicken

Simultaneous determination of the six sulfonamides (SAs) sulfadiazine, sulfadimidine, sulfamonomethoxine, sulfamethoxazole, sulfadimethoxine and sulfaquinoxaline in chicken using matrix solid-phase dispersion (MSPD) with neutral aluminium oxide as an MSPD sorbent and high-performance liquid chromatography (HPLC) is presented. In the present MSPD, six SAs could be isolated by only one step, elution with a 70% (v/v) aqueous ethanol solution, without the sorbent conditioning and the sorbent-tissue matrix washing. For the HPLC determination, a LiChrospher 100 RP-8 and a mixture of 1% acetic acid solution (pH 3.0, in water)-acetonitrile-N,N-dimethylformamide (78:22:5, v/v/v) as the mobile phase with a photodiode array detector were used. Average recoveries were greater than 87.6% with relative standard deviations between 0.5 and 8.6%. The total time and amount of solvent required for the analysis of one sample were <1.5 h and <12 ml, respectively.

Isolation of tetracyclines in milk using a solid-phase extracting column and water eluent.

An isolating method using a solid-phase extraction (SPE) ISOLUTE(R) C8 endcapped syringe-column for routine monitoring of residual tetracyclines (TCs) (oxytetracycline (OTC), tetracycline (TC), chlortetracycline (CTC), and doxycycline (DC)) in cows milk is presented. In the simplest and most environmentally harmless method, milk samples could be applied directly to the SPE column, following which all TCs were eluted with water. No organic solvents were used at all. The purified sample was injected into a high-performance liquid chromatography (HPLC) with a photo-diode array detector (PDAD). For the HPLC determination/identification, a LiChrospher(R) 100 RP-8 endcapped column and a mobile phase of acetonitrile -7% (v v(-1)) acetic acid solution (in water) (35:65, v v(-1)) with a PDAD was used. The total time required for the analysis of one sample was <40 min. Average recoveries (spiked 0.1-1.0 mug ml(-1) each drug) and their standard deviations were >80 and <5%, respectively.

Rapid high-performance liquid chromatographic determining technique of sulfamonomethoxine, sulfadimethoxine, and sulfaquinoxaline in eggs without use of organic solvents

A determining technique of sulfonamides (SAs) (sulfamonomethoxine (SMM), sulfadimethoxine (SDM), and sulfaquinoxaline (SQ)) in eggs, without use of organic solvents, is developed utilizing a high-performance liquid chromatography (HPLC) interfaced with a photo-diode array detector. The sample preparation was performed by homogenizing with perchloric acid solution using a handy ultrasonic-homogenizer followed by a centrifugal ultra-filtration unit. An analytical column and an isocratic mobile phase for HPLC are a reversed-phase C4 column (150mm×4.6 mm i.d.) and 0.18 mol l−1 citric acid solution, respectively. The proposed technique was shown to be linear (r>0.998) over the concentration range 0.1–2.0 μg g−1. Average recoveries of three SAs (spiked 0.05, 0.1, 0.15, and 0.2 μg g−1) ranged from 80.3 to 88.4%, with relative standard deviations (R.S.D.s) between 3.4 and 5.8%. The practical detection limits and total time required for the analysis of one sample were < 0.05 μg g−1 and <30 min, respectively. In all the processes, no organic solvents were used at all.

Rapid high-performance liquid chromatographic identification/quantification of total vitamin C in fruit drinks

Abstract A rapid and simple analysis for the identification/quantification of l -ascorbic acid (AsA) in fruit drinks by high-performance liquid chromatography (HPLC) with a photo-diode array detector was developed. The presence of dehydroascorbic acid was reduced by dithiothreitol before HPLC analysis. A J’sphere® ODS-H80 column (250×4.6 mm 2 i.d.) with a mobile phase of 2% (v/v) acetic acid solution was used for the HPLC separation. AsA in sample could be identified by the retention time and absorption spectrum. The practical limit of detection was 10 μg/ml. The total time required for the analysis of one sample was less than half an hour.

Rapid liquid chromatographic determination of oxytetracycline in milk.

A simple method for the determination of residual oxytetracycline (OTC) in milk by high-performance liquid chromatography (HPLC) was developed. The sample preparation could be made without complex extraction and clean-up procedures. A LiChrospher 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photo-diode array detector was used. The average recoveries from spiked OTC (0.1, 0.5 and 1.0 microgram/ml) were in excess of 89.8% with coefficients of variation between 0.6 and 4.1%. The limit of detection was 0.05 microgram/ml. The total time required for the analysis of one sample was below 10 min.

Simplified determining procedure for routine residue monitoring of sulphamethazine and sulphadimethoxine in milk.

A simplified determining/identifying method for residual sulphamethazine (SMZ) and sulphadimethoxine (SDM) in milk by using a high-performance liquid chromatography (HPLC) with a photo-diode array detector was presented. Both sulphonamides in cows milk samples were extracted by only stirring with ethanol followed by an Ultrafree-MC/Biomax as a centrifugal ultra-filtration unit. For determination/identification of SMZ and SDM, a Mightysil RP-18 GP Aqua column and a mobile phase of 25% (v/v) ethanol solution (in water) with a photo-diode array detector was used. Average recoveries from spiked SMZ and SDM (10-1000 ng/ml each drug) were > or = 83% with the relative standard deviations between 1.4 and 3.7%. The limit of quantitation (LOQ) were calculated to be 5 ng/ml for SMZ and 10 ng/ml for SDM, respectively. The values were below the MRL/tolerance (SMZ, 25 ng/ml; SDM, 10 ng/ml). The total time and solvent required for the analysis of one sample were <35 min and <2 ml of only ethanol, respectively. No toxic solvents were used. The developed procedure was harmless to the human and environment.

Simultaneous high-performance liquid chromatographic determination of residual sulphamonomethoxine, sulphadimethoxine and their N4-acetyl metabolit

A rapid and sensitive method for the determination of residual sulphamonomethoxine, sulphadimethoxine and their N4-acetyl metabolites in beef, pork, chicken and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of these compounds was performed using a mixture of 90% (v/v) acetonitrile solution and hexane (5:4, v/v) to minimize the fat content followed by purification by alumina column chromatography. These extracts contained sulphonamide analytes which were free from interfering compounds when examined by HPLC using a LiChrosorb RP-18 column. The average recoveries from spiked meat and egg were in excess of 80% with relative standard deviations between 0.4 and 5.0%. The practical limits of detection were 0.01 ppm for all samples.

Cooking effects on sulfonamide residues in chicken thigh muscle

Abstract This paper presents the net change by cooking on residues of sulfadiazine (SDZ), sulfamethoxazole (SMX), sulfamonomethoxine (SMM) and sulfaquinoxaline (SQ) in chicken muscles. These sulfonamides (SAs) were fed to chickens at a dietary concentration of 100 mg/kg (each drug) for 7 successive days. On the 7th day of feeding, they were killed and thigh muscles were collected. Muscle was ground, mixed and formed into 10-g “meatballs”. SA residues were determined by high-performance liquid chromatography. By using the usual cooking methods, boiling, roasting and microwaving, the muscles containing SAs were treated for the specified times. Net residues in the muscles cooked by boiling were reduced 45–61% in 12 min. In roast cooking, the SMX, SMM and SQ residues, except for SDZ, were reduced 38–40% in 12 min. No significant reduction of SDZ was found. By the microwave cooking, the four SAs residues were reduced 35–41% in 1 min. Reducing half-lives of SAs in chicken muscles cooked were estimated as follows: 9.3 min for SDZ and 13.2 min for SMX, SMM and SQ in boiling; 18.3 min for SMX, SMM and SQ in roasting; 1.6 min for all the SAs in microwaving.

Simultaneous determination of sulfamonomethoxine, sulfadimethoxine, and their hydroxy/N4-acetyl metabolites with gradient liquid chromatography in chicken plasma, tissues, and eggs

A simultaneous determination of sulfamonomethoxine, sulfadimethoxine, and their hydroxy/N(4)-acetyl metabolites in chicken plasma, muscle, liver, and eggs using gradient high-performance liquid chromatography (HPLC) with a photo-diode array detector is developed. All the compounds are extracted by a handheld ultrasonic homogenizer with ethanol followed by centrifugation. The separation is performed by a reversed-phase C4 column with a gradient elution (ethanol:1% (v/v) acetic acid, v/v; 10:90-->20:80). Average recoveries from samples spiked at 0.1-1.0mugg(-1) or mugml(-1) for each drug were >90% with relative standard deviations within 4%. The limits of quantitation were <30ngg(-1) or ngml(-1).

Mutagenicity and DNA-damaging activity of decomposed products of food colours under UV irradiation

Five synthetic food colours Food Red Nos 3, 40 and 102 and Food Blue Nos 1 and 2, and their UV irradiated products were tested for mutagenic activity by means of the Ames test using Salmonella typhimurium strains TA98 and TA100. Food colours were irradiated with UV light for 14 days. Food Red Nos 3, 40 and 102 and Food Blue No. 1 were non-mutagenic before and after irradiation. UV irradiated products of Food Blue No. 2 were mutagenic in TA98 with or without S-9 mix. The mutagenic activity increased with increasing irradiation period, reached maximum potency on day 6, and then decreased. Moreover, Food Blue No. 2 showed DNA-damaging activity after 14 days of irradiation in rec-assay using Bacillus subtilis strains H17 and M45. The capillary electrophoresis was applied for the analysis of UV irradiated products of Food Blue No. 2. The original peak of Food Blue No. 2 was decomposed into seven peaks after UV irradiation.