Yukio Matsuki

Improved methodology for the simultaneous detection of the trichothecene mycotoxins deoxynivalenol and nivalenol in cereals

A simple and sensitive method has been developed for the analysis of two trichothecene mycotoxins (deoxynivalenol and nivalenol) in cereals. These toxins were extracted with acetonitrile/water (3:1), defatted with n-hexane and purified by a two-step chromatographic procedure using Florisil and Sep-pak columns. The amounts of deoxynivalenol (DON) and nivalenol (NIV) in the column eluates were quantitated by gas chromatography with electron capture detector and gas chromatography-mass spectrometry (selected ion monitoring). The limits of detection of the method were 2.0 micrograms/kg for DON and NIV with recoveries of the toxins spiked into polished rice, wheat and corn at 300 micrograms/kg averaging 87% and 86% respectively.

Rapid and sensitive determination of zearalenone in cereals by high-performance liquid chromatography with fluorescence detection

Zearalenone, an estrogenic mycotoxin of Fusarium species, in cereals can be extracted with acetonitrile-water (3:1), purified on a Florisil column, resolved by high-performance liquid chromatography (HPLC) with a Nucleosil 50-10 column using 90% water-saturated chloroform-cyclohexane-acetonitrile-ethanol (50:15:2:1) and quantitated by fluorescence measurement. This method is rapid, simple and reproducible, and detects zearalenone in wheat, barley, corn and other cereals with picogram sensitivity. A combination of this HPLC method with a gas-liquid chromatographic method for trichothecenes may be applied to the simultaneous detection of Fusarium mycotoxins (zearalenone, nivalenol and deoxynivalenol) in cereals.

A survey of the occurrence of nivalenol, deoxynivalenol and zearalenone in foodstuffs and health foods in Japan

By adopting a rapid and sensitive method for simultaneous detection of nivalenol (NIV), deoxynivalenol (vomitoxin, DON) and zearalenone (ZEN), the natural occurrence of these mycotoxins in Japan in retail marked cereal flours, popcorn and health foods (totalling 76 samples) was surveyed. Significant contamination by NIV and DON was observed in commercial wheat and barley flours, and partially milled grains which are consumed as rice ingredients. Of particular interest was the presence of DON in popcorn imported from the United States, and the high-level contamination of NIV and ZEN in jobs-tears (Hatomugi in Japanese), a widely marketed health food.

A limited survey of Fusarium mycotoxins nivalenol, deoxynivalenol and zearalenone in 1984 UK harvested wheat and barley

A limited survey for the occurrence of nivalenol (NIV), deoxynivalenol (DON) and zearalenone (ZEN) in 1984 UK-grown cereals (31 samples) have been carried out using a new procedure, which is a rapid and sensitive method for Fusarium mycotoxins. NIV, DON and ZEN were detected in 17 (55%), 20 (65%) and 4 (13%) out of 31 samples, and average levels in positive samples were 101 micrograms/kg, 31 micrograms/kg and 1 microgram/kg, respectively. Additional surveys on two wheat and eight barley samples harvested in Scotland have shown that 30%, 60% and 100% of the samples were contaminated with NIV, DON and ZEN, respectively. The contents averaged 391 micrograms/kg of NIV, 39 micrograms/kg of DON and 9 micrograms/kg of ZEN. The results of this survey show that UK-grown cereals were significantly contaminated with NIV, DON and ZEN in a similar way to that observed in Japan, Korea and China. This is the first evidence of the natural occurrence of NIV in UK cereals.

Examination of Chinese and U.S.S.R. cereals for the fusarium mycotoxins, nivalenol, deoxynivalenol and zearalenone

Cereals, foods and feeds sampled in Taiwan, China and the U.S.S.R. were contaminated with nivalenol, deoxynivalenol and zearalenone. The frequencies and levels of contamination are similar to those observed in the cereals of Japan and Korea. This is the first report on the natural occurrence of nivalenol, deoxynivalenol and zearalenone in Chinese and U.S.S.R. cereals, foods and feeds.

Application of gas chromatography for the separate determination of free and combined sulphites in foods. I.

ZusammenfassungSchweflige Säure in Lebensmitteln — sowohl freie als auch gebundene läßt sich gaschromatographisch bestimmen.Dazu wird die freie schweflige Säure mit 0,1 m-Weinsäure, die gesamte schweflige Säure mit einem alkalischen Extraktionsmittel, das Seignettesalz und Eisen(II)-sulfat enthält, extrahiert und das SO2 aus dem Extrakt mittels Phosphorsäure freigesetzt. Das Dampfraum-Gas wird in einem Gaschromatographen mit flammenphotometrischem Detektor analysiert.Die Wiederfindungsrate von Sulfit, das getrockneter Ananas, getrockneten Aprikosen, Weiß- und Rotwein zugesetzt wurde, betrug beim freien SO2 zwischen 92,5 und 104,0%, beim gebundenen SO2 zwischen 93,5 und 98% bei einer unteren Nachweisgrenze von 0,5 ppm.SummaryA combination of head-space technique and FPD gas chromatography was applied to the separate determination of free and combined sulphite in foods.0.1 M-Tartaric acid was chosen as an excellent extractant for the selective extraction of free sulphite in the presence of combined sulphite, whilst (N) alkaline extractant containing potassium-sodium tartarate and ferrous sulphite (deoxidant) liberated free and combined sulphite completely.Sulphite was released from each solution in the following way. To 1 ml of filtered solution, 5 ml of 10% phosphoric acid was added, the mixture was shaken vigorously for 10 s kept for 10 min at 0 °C, then again shaken vigorously for 10 s. An aliquot of the head-space gas thus obtained was immediately injected into a FPD gas chromatograph.Recoveries of 10–20 ppm of free sulphite and 100–200 ppm of combined sulphite from dried pineapple, dried apricot, white and red wines were 92.5–104.0 and 93.5–98.0%, respectively, the detection limit being 0.5 ppm.

Establishment of a modified rankine method for the separate determination of free and combined sulphites in foods. III

ZusammenfassungDie Rankine-Methode wurde bedeutend verbessert. Ein Umtausch der Aspiration mit Blasensystem trug beträchtlich zur Vereinfachung des Bestimmungsverfahrens bei, und die Reproduzierbarkeit wurde verbessert. Luft (Fließrate 1,01/min) wurde als Blasengas benutzt, da der Gebrauch von Inertgas für die Wiederfindungsrate unbedeutend ist.Natriumhydrogensulfit (freies Sulfit) und drei Arten gebundener Sulfite (Acetaldehydhydrogensulfit, Pyruvathydrogensulfit undd-Mannosehydrogensulfit) dienten dazu, die geeignetsten Bedingungen für die getrennte Bestimmung der freien und gebundenen Sulfite zu ermitteln.Freies Sulfit wurde bei 0 °C durch 30 min Durchblasen vertrieben. Hierbei ging kein gebundenes Sulîit verloren. Die Phosphorsäurekonzentration war wichtig für die Freisetzung des Sulfites. Wenn man 25%ige Phosphorsäure verwendet, werden > 99% freien Sulfites beim Durchblasen in der Kälte vertrieben, während > 99% gebundenen Sulfites durch nachheriges 10 min langes Erhitzen wiedergewonnen werden.Die modifizierte Rankine-Methode wurde weiterhin für konzentrierte Säfte verwendet.SummaryConsiderable improvements were made to the original Rankine method. Replacement of aspiration with an injection system contributed a great deal to the simplification of procedure, being accompanied with an increase in reproducibility. Air (flow rate 1.01/min) was used for injection because the use of inert gas gave little increase in recovery rate.Sodium bisulphite (free sulphite) and three kinds of combined sulphite compound (bisulphite adducts of acetaldehyde, pyruvic acid and D-mannose) were used to find the most suitable conditions for the separate determination of free and combine sulphites.Free sulphite was expelled from the sample by bubbling at 0 °C for 30 min. It was confirmed that no combined sulphite was dissociated under these conditions. The phosphoric acid concentration had an important role in the liberation of sulphite. When 25% phosphoric acid was used, more than 99% of free sulphite was expelled by cold bubbling and more than 99% of combined sulphite was recovered by heating afterwards for 10 min.The scope of the modified Rankine method was also extended to the determination of sulphite in concentrated orange juice.

Comparative determination of free and combined sulphites in foods by the modified rankine method and flame photometric detection gas chromatography. V.

ZusammenfassungEs wurde eine vergleichende Sulfitbestimmung in verschiedenen Lebensmitteln mit Hilfe der modifizierten Rankinemethode (MR), der Gaschromatographie und der Monier-Williams-Methode durchgeführt. Die Ergebnisse stimmen gut überein, wobei die Monier-Williams-Methode geringfügig höhere Werte erbrachte. Diese Methode wird durch schwefelhaltige Lebensmittelinhaltsstoffe empfindlich gestört.Des weiteren wurde in verschiedenen Lebensmitteln die Relation von freiem zu gebundenem Sulfit ermittelt. Dabei stellte sich heraus, daß in den meisten Lebensmitteln 65% des Sulfits in gebundener Form vorliegen. Sowohl MR-Methode als auch Gaschromatographie erlauben eine getrennte Bestimmung von freiem und gebundenem Sulfit. Da beide Methoden einfach und schnell durchzuführen sind, eignen sie sich für die Routinebestimmung.SummaryApplication of the modified Rankine (MR), GLC and present official Monier-Williams methods to the determination of sulphites in a variety of foods was attempted. Generally, sulphite contents determined by these three methods were in good agreement although the values obtained by the modified Monier-Wiliams method were slightly higher than by the other two. A marked interfering effect of other sulphur compounds was observed in the case of determinations by the Monier-Williams method. On the other hand, the determined sulphite values by the MR and GLC methods were independent of the coexisting sulphur compounds. The ratios of free or combined sulphites to total sulphites were compared among the two methods, and in most foods tested the rations of combined to total sulphites were not less than 65%. We conclude that both the MR and GLC methods are valid for the separate determination of free and combined sulphites in most foods, and these two methods will be preferred for routine analysis because of their simplicity and speed.

On the combination of sulphite with food ingredients (aldehydes, ketones and sugars). II.

ZusammenfassungEs wird die Darstellung der Bisulfit-Anlagerungsverbindungen von Acetaldehyd, Brenztraubensäure undd-Mannose beschrieben. Die Reinheit der gen. Verbindungen beträgt 99%.fünfAn Hand dieser Verbindungen wird überprüft, welche von fünf Standardmethoden zur Sulfitbestimmung in Lebensmitteln für die Bestimmung des gebundenen Sulfits geeignet ist. Hierbei ergeben die abgeänderte Monier-Williams-Methode, die Jodometrie und die Wasserdampfdestillation/Colorimetrie befriedigende Ergebnisse, während die Mikrodiffusion und die direkte Colorimetrie ungeeignet erscheinen.Die gen. Anlagerungsverbindungen bilden sich bei Zimmertemperatur im schwach sauren bis schwach alkalischen Milieu innerhalb kurzer Zeit. In einer äquimolaren Lösung aus Acetaldehyd bzw. Brenztraubensäure und Natriumhydrogensulfit liegt nach kurzer Zeit 50% des Sulfits als Anlagerungsverbindung vor.SummaryThree kinds of combined sulphites (bisulphite adducts of acetaldehyde, pyruvic acid and D-mannose), different in combination strength, were prepared to provide a model system for comparative studies on the accuracy of several determination methods for combined sulphites. The purity of the combined sulphites, obtained either as crystals or amorphous powder, was shown to be not less than 99%.Five methods, formerly applied on the determination of residual sulphites in foods, were subjected to the determination of these combined sulphites. A modified Monier-Williams method, iodimetry and distillation-colorimetry were effective for the determination of combined sulphite, whilst a microdiffusion method and direct colorimetry (by use of mercuric chloride) were shown to be inadequate for the determination of combined sulphite.Three combined sulphites were shown to be produced by the reaction between free sulphite and acetaldehyde, pyruvic acid or D-mannose at room temperature within a short time in the weak acid to slightly alkaline pH range. About 50% of combined sulphite were produced by the reaction of equimolar amounts of sodium bisulphite and acetaldehyde or pyruvic acid.

Colorimetric microdetermination of sulphites in foods by use of the modified rankine apparatus. IV.

ZusammenfassungGeringe Sulfitmengen in Lebensmitteln (geschälte Garnelen, gezuckerte Bohnen) können colorimetrisch bestimmt werden. Die neuentwickelte Methode beruht auf einer Kombination von colorimetrischer Bestimmung mittels p-Rosanilin und der Bestimmungsmethode nach Rankine. Auf diese Weise lassen sich Gehalte von 2 μg noch genau bestimmen. Bei der Farbentwicklung wurde das giftige Quecksilbertetrachlorid durch 0.1 n-NaOH ersetzt, anstelle von Luft Stickstoff als Trägergas verwendet und somit eine Oxydation des Sulfits während der Bestimmung vermieden. Da Nitrit und Aldehyde die Farbentwicklung stören, wurde ihr Einfluß durch Dimedon und Natriumazid ausgeschaltet.SummaryDetection and determination of traces of sulphites in foods was attempted by use of the modified Rankine apparatus and pararosaniline colorimetry. Replacement of alkaline titration reported previously by pararosaniline colorimetry lowered the absolute detection limit from 30 μg (titration method) to 2 μg. In view of clean analysis, in the color developing system, 0.1 N-sodium hydroxide was used in place of mercuric chloride solution commonly used as an absorbant of sulphites. In order to prevent oxidative decomposition of sulphites during operation, nitrogen gas was used as carrier instead of air. Dimedone and sodium azide were used for the elimination of aldehydes and nitrites, respecitvely, in the sample, which will disturb the color development of sulphites with pararosaniline-formaldehyde reagents. With this improved method, it was possible to determine the residual sulphites in frozen peeled shrimps, sugared beans and other foods with low sulphite contents accurately.