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A method for simultaneous determination of 15 pesticides in cereals by HPLC with UV and FL detection was developed. The pesticides were extracted by SFE, defatted with Extrelut®+Sep-Pak® C18 and cleaned up with a Sep-Pak® Florisil cartridge. Pesticides were eluted from the cartridge with mixtures of 15 and 50% ether-n-hexane and 50% acetone-n-hexane.Extrelut® 3 was directly connected to the exhaust port of SFE to charge the extract. The amount of lipid extracted by SFE was smaller than that in the case of solvent extraction with acetone or acetonitrile. The large amount of lipid in the case of corn was further decreased by gel permeation chromatography (GPC) after Extrelut® 3. Separation of the Sep-Pak® Florisil eluate into three fractions was effective in providing a clue to the kinds of pesticide contained in the sample.

Twenty-one N-methylcarbamates (NMCs) and 12 metabolites or isomers in agricultural products were simultaneously determined. As extraction was accomplished with ethyl actate instead of dichloromethane, NMCs possessing a thioether group were partly oxidized to sulfoxides. They were quantified as total amount of oxidized and non-oxidized compounds. NMCs in food samples were extracted with acetone, then the acetone was evaporated off and sodium chloride was added before extraction with ethyl acetate. The extract was evaporated and the residue was partitioned between acetonitrile and n-hexane. The acetonitrile layer was evaporated and the residue was cleaned up on a Sep-Pak® aminopropyl cartridge. NMCs were determined by HPLC with post-column reaction and fluorescence detection. Recoveries of NMCs from 10 kinds of agricultural products including rice, onion and apple were 56.9 to 108.2%, except for butocarboxim sulfoxide, at fortification levels of 0.1 to 1ppm. Detection limits were 0.01ppm for major NMCs.

An analytical method for the neonicotinoid pesticide nitenpyram and its metabolites CPMA and CPMF was investigated. Agricultural products were extracted with acetone followed by re-extraction using an Extrelut® column and purification by silica gel column chromatography. CPMA and CPMF were so unstable that they were derived to a more stable compound, CPF, prior to re-extraction. It was necessary to remove acetone from the extract before reaction of CPMF, because a by-product was found and the recovery of CPF decreased in the presence of acetone. Nitenpyram was determined using HPLC, and CPF, using GC-FTD. Recoveries from fruits, vegetables, rice and tea were 66-85% for nitenpyram (0.2-0.8ppm added), and 64-120% for metabolites (0.5-2.0ppm added), except for CPMA in tea. Detection limits were 0.0025-0.01ppm for nitenpyram, and 0.025-0.1ppm for metabolites.

A method was established for simultaneous determination of 19 pesticides and their 4 metabolites in fresh fruits and vegetables by HPLC monitored by UV and FL. The pesticides were extracted with acetonitrile and partitioned with NaCl solution in an alkaline condition, then cleaned up with Bond Elut® SAX+PSA cartridges. The pesticides were eluted from the cartridges with a mixture of 5, 15 or 50% acetone-n-hexane and fractionated to fractions 1-3 depending on the type of sample.The pesticides and their metabolites spiked in samples at 0.2 or 0.5ppm gave satisfactory recoveries except for benomyl, TBZ, imazalil and thiophanate methyl. Detected pesticide peaks were confirmed by the use of a photodiode array detector, GC-NPD/FPD and GS/MS (TIC and SIM). NAC from apple, bitertanol from banana, and chlorpyrifos, OPP, TBZ, and imazalil from grapefruit were detected by the proposed method.

The fungicide tecloftalam and its metabolite tecloftalam-imide were individually determined. They were extracted from brown rice with acetone and re-extracted with ethyl acetate. The extract was partitioned between n-hexane and acetonitrile to remove oil, and then charged on a Sep-Pak Plus Florisil cartridge. Tecloftalam-imide was eluted with 50% diethyl ether-n-hexane and then tecloftalam was eluted with methanol. Tecloftalam-imide was determined on a gas chromatograph (GC) equipped with a capillary column DB-1 and an electron capture detector (ECD). Tecloftalam was converted into tecloftalam-imide by addition of acetic anhydride, and determined by GC-ECD. Recoveries of tecloftalam and tecloftalam-imide from rice spiked at levels of 0.2ppm were 89.3±1.9% and 82.6±1.5%, respectively. Detection limits were 0.01ppm in samples.

A rapid analysis of 5 kinds of triazine herbicides and 3 kinds of metabolites in agricultural products by FTD-GC was developed. The pesticides in vegetables and fruits were extracted with methanol, re-extracted with 20% ethyl acetate/n-hexane and then cleaned up on Sep-pak Silica. The pesticides in cereals and beans were extracted with acetonitrile and then cleaned up on Sep-pak Silica, after the removal of lipids with n-hexane.Recoveries of the pesticides ranged between 50.3 and 92.9% for vegetables and fruits, and between 62.6 and 78.6% for cereals and beans, except for metabolites of metribuzin and cyanazine.

The raw materials of processed foods were purchased at twelve places acccording to the “market basket” approach. The contents of 49 natural food additives in the purchased raw materials were analyzed. The amounts of chemically synthesized natural food additives used in food processing were calculated by subtracting the contents in raw materials from the contents in the processed foods. Total daily intake of chemically synthesized natural food additives from processed foods was suggested to be about 3g.

Three methods for the removal of lipids, i. e., the GPC method with a mixture of ethyl acetate-cyclohexane (1:1, v/v), the n-hexane/acetonitrile partition method, and the Extrelut-3/Sep-pak® C18 method, were compared in the analysis of pyrethroid pesticide residues in crops. Efficiencies of the removal of lipids in salad oil, brown rice and soybean were 51.0-77.4% by GPC, 61.6-96.4% by n-hexane/acetonitrile partition and 73.8-98.4% by the Extrelut-3/Sep-pak® C18 method. Recoveries of 10 pyrethroid pesticides from brown rice (fortified at 0.2-0.4ppm) were 72.2-130% by GPC, 62.5-100% by n-hexane/acetonitrile partition, and 61.5-96.3% by the Extrelut-3/Sep-pak® C18 method, respectively. Therefore, the Extrelut-3/Sep-pak® C18 method seems to be the most suitable for the removal of lipids in the analysis of pyrethroid pesticide residues in crops because of its efficiency and simplicity.

An improved method for determination of water-soluble chloride and water-soluble sulfate in food blue No. 1 aluminium lake (B-1 Lake) was developed. The reason for the very poor recovery of sulfate in B-1 Lake was found to be the adsorption of anions on the lake. In order to prevent sulfate adsorption, 0.1M phosphate buffer (pH7.0) was added. As the ratio of B-1 Lake to water decreased, the chloride content apparently increased. A constant value of chloride content in B-1 Lake (3.5%) was obtained by extrapolation.The preparation of test solution and the determination of Cl-, SO42- and I- in B-1 Lake were conducted as follows. Weigh 1.000g of Food B-1 Lake, add 10ml of 0.1M phosphate buffer (pH 7.0) and 90ml of water, and shake for 5 minutes in a mechanical shaker. After filtration, test the solution by ion-chromatography.A good recovery of sulfate was obtained by the proposed method. In a commercial B-1 Lake sample, chloride content was 3.2% and sulfate content was 2.7%, using this method. These values represent total contents of water-soluble chloride and water-soluble sulfate.

A method for determination of the starting materials, [7-hydroxy-1, 3, 6-naphthalenesulfonic acid (TS), G-salt (GS), R-salt (RS), Schaeffer's salt (SS) and naphthionic acid (NA)] and subsidiary colors, [ponceau 6R (P6R), amaranth (R-2) and fast red E (FRE)] in new coccine (R-102) was developed by use of HPLC. The following conditions were used for analysis: column, L-column ODS (4.6mm i. d.×250mm); eluent, gradient elution system of 0.02M ammonium acetate and acetonitrile (hold at 0.02M ammonium acetate for 5min, then 0-30% acetonitrile in 45min); detection for TS, GS, RS, SS and NA at 238nm and subsidiary colors at 510nm.Recoveries of each impurity from R-102 averaged 99.1-103.5%. Ten samples of commercial R-102 were analyzed by the present HPLC method and the impurites were as follows: TS, 0.005-0.044%; GS, 0.044-0.284%; NA, 0.013-0.196%; RS, N. D.; SS, N. D.; P6R, 0.008-0.169%; R-2, N. D. -0.279%; FRE, 0.007-0.100%. The detection limit was 0.001% for each impurity.

An HPLC method for determination of iprodione and its metabolite in agricultural products was developed. The residues were extracted from vegetables and fruit with acetone or from cereal and beans with acetonitrile, and then re-extracted into ethyl acetate. The extracts were cleaned up by Florisil column chromatography. The Florisil column was washed with 50ml of 50% ether in n-hexane, and iprodione and its metabolite were eluted with 50ml of 15% acetone in n-hexane. Recoveries of iprodione and its metabolite added to samples at 0.5ppm ranged from 70.3 to 105.0% (except from tea), and the detection limits were 0.02ppm.Tea gave low recoveries because iprodione and its metabolite were scarcely extracted from tea leaves with hot water. Iprodione dissolved in methanol gradually changed to its metabolite during storage at room temperature. Therefore the standard solution should be freshly prepared as occasion demands.

An analytical method for 15 chemicals including dimepiperate, thenylchlor, probenazole, bromobutide and debromo-bromobutide has been developed by modifying the Japanese official analytical method for 10 organonitrogen pesticides notified in September 1993.Ten grams of grain or 20g of vegetable or fruit was homogenized with acetone followed by extraction with ethyl acetate, and the extract was evaporated. In the case of grains, fat or oil was removed from the extract by n-hexane-MeCN partitioning. Then the extract was purified by Florisil column chromatography and concentrated to 5ml. The concentrations of pesticides were determined by FTD-GC. Esprocarb, diethophencarb and thiobencarb in wheat could not be determined by FTD-GC because of interfering peaks, so they were determined by GC/MS (SIM). The recoveries of 15 chemicals in ten kinds of fortified agricultural products were 65.9-103.4% when they were fortified at levels of 0.5ppm for probenazole and 0.1ppm for the others. Detection limits were 0.005 to 0.05ppm for each pesticide.

A method for preparation of sample solutions has been developed for determination of food coal-tar dyes in foods by using pronase. Twelve kinds of dyes were extracted with a mixture of 1% NH4OH and ethanol from foods which were hydrolyzed by pronase treatment. Then the extract was concentrated under vacuum, cooled in ice, treated with tetrabutylammonium hydroxide and cleaned up by using Sep-pak Plus tC18 cartridges. The dyes retained on the replaced cartridge were eluted with a mixture of methanol and tetrabutylammonium phosphate solution (pH 5.0), and determined by gradient high performance liquid chromatography with visible wavelength detectors.The recoveries of food coal-tar dyes were more than 76.0% from foods spiked at 1 and 10μg/g levels.

A separative determination method of benfuracarb, carbosulfan, carbofuran and 3-hydroxycarbofuran in agricultural products by GC and HPLC was developed. When benfuracarb and carbosulfan in raw extract or slightly cleaned-up extracts of foods were measured by GC, almost all of them was not recovered, though a corresponding amount of carbofuran was detected. On the other hand, when the same GC test solutions were measured by HPLC, benfuracarb and carbosulfan were quantitatively recovered regardless of the degree of cleanup (with or without Sep-pak Silica or Florisil) of the test solution.Accordingly, benfuracarb and carbosulfan in test solution coexisting with food components were decomposed to carbofuran during GC analysis, and the degree of the decomposition depended on the kind of foods. In order to prevent the decomposition, it was necessary to clean-up the test solutions for benfuracarb and carbosulfan sufficiently.

A method for preparation of sample solution for determination of nitrate and nitrite in vegetables, beef and their processed foods by colorimetry and suppressed ion chromatography (IC) with UV detection has been developed.Nitrate and nitrite were simultaneously extracted from foods with sodium borate solution at 80°, then the extracts were cooled and filtered through an ultrafilter (Molcut II). Nitrite was determined in the filtrate by colorimetry, and nitrate by IC. In the case of determination of nitrate in foods containing more than 3% sodium chloride, the salt was eliminated from the extracts by using an On Guard-Ag cartridge. The recoveries of nitrate were 90.0-102.0% from foods fortified at 5-1, 000μg/g, and those of nitrite were 84.2-101.0% from foods fortified at 5-50μg/g.

A determination method by HPLC for starting materials [sulfanilic acid (SA), G-salt (GS), R-salt (RS), Schaeffer's salt (SS)], intermediates [6, 6′-oxybis(2-naphthalenesulfonic acid) (DONS), 4, 4′-(diazoamino)-dibenzenesulfonic acid (DAADBSA)] and subsidiary colors [3-hydroxy-4-[(4-sulfophenyl)azo]-2, 7-naphthalenedisulfonic acid (RS-SA), 4-[(2-hydroxy-1-naphthalenyl)azo] benzenesulfonic acid (2N-SA), 6-hydroxy-5-(phenylazo)2-naphthalenesulfonic acid (SS-AN)] in sunset yellow FCF was developed. The following conditions were used for analysis: column, Inertsil ODS-2 (4.6mm i. d.×250mm); solvent, gradient elution system of 0.02M ammonium acetate and 40v/v% acetonitrile in 0.02M ammonium acetate; detection, SA, GS, RS, SS and DONS at 232nm, DAADBSA at 358nm and subsidiary colors at 482nm.Recoveries of each impurity from sunset yellow FCF averaged 99.4-102.2%. Sixteen samples of commercial sunset yellow FCF in Japan were examined, with the following results: SA, N. D. -0.170%; GS, N. D. -0.080%; RS, N. D. -0.050%; SS, N. D. -0.281%; DONS, N. D. -0.250%; DAADBSA, N. D. -0.210%; RS-SA, 0.024-3.54%; mixtures of SS-AN and 2N-SA (as SS-AN); 0.015-0.360%. The detection limit was 0.05μg/g for each impurity.

The factors affecting formation of hydrogen peroxide (H2O2) in coffee have been studied. H2O2 in coffee was identified by TLC and determined by using an oxygen electrode method and modified 4-aminoantipyrine colorimetry. H2O2 was not detected in green coffee beans, but was detected in coffee infusion. Coffee infusion or coffee solution prepared using a coffee maker contained less H2O2 than those prepared using a filfer or a beaker. The greater the degree of roasting, the greater was the formation of H2O2 in coffee beans. The formation of H2O2 was also influenced by temperature and light.Some components of coffee beans, saccharose, chlorogenic acid, glycine, caffeine, caffeic acid and quinic acid, did not contain H2O2, but when these components were roasted in the same manner as coffee beans and an infusion was prepared, H2O2 was formed. Formation of H2O2 from roasted caffeic acid was particularly marked.

A simple and rapid determination method for disulfoton (ethylthiomethon), its oxidative metabolites (disulfotonsulfon, dimetl onthiol, dimethonthiolsulfon) and trichlorfon in agricultural products was established.Those pesticides were extracted from samples with acetone, purified by coagulation, reextracted with dichloromethane into the organic layer and determined by GC. After trichlorfon was completely decomposed to dimethylphosphite (DMP: thermal decomposition product) on GC, disulfoton, its metabolites and DMP were separately determined by FPD-GC with a capillary column.Surveillance of these pesticides in 51 agricultural products which were purchased in Osaka on June, 1989, was carried out. Neither trichlorfon nor disulfoton and its metabolites were detected. Recoveries of trichlorfon and disulfoton added to the samples at 0.1ppm ranged from 60.4 to 93.5% and the detection limit of the five pesticides was 0.001ppm in samples by the proposed method.

In Japan, dehydroacetate and sorbate are authorized as additives to be used as antimicrobial agents for cheese.On the other hand, application of natamycin for the surface treatment of cheese is allowed in approximately 30 countries. In this investigation, we compared the effectiveness of natamycin and sorbate by treating Gouda-type cheese, specially manufactured for this purpose, with different concentrations of antimicrobials and with different methods of application. The results may be summarized as follows.1. Natamycin remains on the surface of the cheese not penetrating inside, while sorbate was shown to penetrate inwards, diffusing throughout the cheese.2. Natamycin showed low effectiveness at the concentration of 5μg/kg (when applied by the coating method), amounting to one-hundredth of that of sorbate.3. So far as application mode was concerned, coating was more effective than the dipping method, showing the same effect on cheese at about one-fifth concentration compared with the dipping method.4. When natamycin was applied by the coating method, it could be completely removed by scraping off 5mm of the exterior.5. The effectiveness of natamycin continued for as long as 8 weeks after application both by the coating and dipping methods, showing a selective effect on molds compared with sorbate. If cheese was not treated with either of the antimicrobials, molding began as early as at two weeks after manufacturing, becoming an obstacle to further ripening and storage of the cheese.6. Most of the molds on the cheese were identified as strains belonging to genus Penicillium, P. viridicatum and P. roquefortii being the most frequently isolated strains.

Determination of traces of sulfites in various foods was attempted by use of the modified Rankine apparatus and para-rosaniline-formaldehyde colorimetry.Dimedone solution and sodium azide solution, which were used for elimination aldehydes and nitrites, must be prepared freshly before use. The effects of interfering substances in samples on the color reaction could be corrected for by subtraction of the sample blank which was obtained by adding hydrogen peroxide to the sample solution before color development.The detection limit of this method was 0.05μg/ml SO2 in test solution, corresponding to 0.5μg/g SO2 in food samples.Sulfites in 51 kinds of foods were determined. This colorimetric microdetermination analytical method could be applied to almost all foods.

Boric acid in foods has been rapidly and simply determined by means of the curcumin color-developing reaction under non-aqueous conditions after chelate extraction of boric acid with 2-ethyl-1, 3-hexanediol (EHD).Boric acid in the sample was directly extracted into hexane-butyl acetate (4:1) solution containing 5% EHD under acid conditions, then 3ml of extract was used for the color-developing reaction. Boric acid in the extract was reacted with curcumin in glacial acetic acid and conc. sulfuric acid. After the reaction, water was added to the reaction mixture in order to decompose protonated curcumin (blank color), and then the reaction mixture was diluted with acetone to constant volume and the absorbance was measured at 550nm. More than 97.0% of spiked boric acid was recovered from 6 kinds of foods at the 10, 100 and 500μg/g level. The detection limit of boric acid was 0.3μg/g of sample.