Modified Monier-Williams Method Research Articles

Application of scanning electron microscopy-energy dispersive X-ray spectrometer to characterize the chemical composition of deposits on the surface of dried day lily

An innovative and simplified method to characterize the chemical composition of the residual sulphite deposits on dried day lily using scanning electron microscopy- energy dispersive X-ray spectrometer (SEM-EDS) was developed in this study. Granular deposits were observed by SEM on the surface of dried day lily overdosed with sulphiting agents. Laboratory scale model studies showed that soaking in 3% sodium bisulphite without subsequent washing may lead to the accumulation and precipitation of sodium bisulphite crystals. EDS analysis indicated that these deposits are sodium bisulphite. A strong correlation (R2 = 0.8994) was obtained between Sulfur/Carbon ratio calculated from SEM-EDS data and sulfur dioxide concentration determined by modified Monier-Williams method in day lily samples without crystals on the surface.

Determination of Sulphiting Agents in Raw and Processed Meat: Comparison Between a Modified Monier-Williams Method and the Direct Analysis by Ion Chromatography with Conductometric Detection

Sulphiting agents are a class of compounds that are used as preservatives since they release SO2 in food. Regarding meat products, the legislation restricts the use of these food additives, due to some toxic effects that they may have in humans. The most employed analytical procedure for the determination of sulphiting agents in foodstuffs is the Monier-Williams (M-W) method, but the reliability of this method was called into question by several authors. In this work, the M-W method was modified by replacing both the distillation unit to shorten the extraction time (from hours to 5 min) and the final titration with a chromatographic separation followed by conductometric detection of sulphate ion (m-M-W/IC-CD). This method was then validated, and the performance parameters were compared with those of the method based on the direct analysis of sulphite ion by ion chromatography with conductometric detection (DIC-CD). Linearity, accuracy at 40 and 80 mg kg−1 of SO2 and measurement uncertainty resulted comparable. Accuracy at 10 mg kg−1 of SO2 resulted higher for the m-M-W/IC-CD method, but this parameter could be influenced by traces of other sulphur-containing compounds that may be present in meat. The limit of determination of the m-M-W/IC-CD method was slightly higher than that obtained by the DIC-CD method. Finally, through spiking tests, it was proved that sulphide, 2-methyl-3-furanthiol and l-methionine cause “false-positive” responses, by using M-W-based methods.

원산지별 국내 유통 한약재의 이산화황 잔류실태 조사

국내에 유통되고 있는 국산과 수입산 한약재 11종 116건을 대상으로 잔류이산화황에 대한 모니터링을 수행한 결과 108건(93.1%)은 불검출이었고 6건(5.2%)는 이산화황 허용기준치 30 mg/kg을 초과하였고 2건은 30 mg/kg 미만으로 검출되었다. 116건의 이산화황 평균함량은 <TEX>$17.6{\pm}144.2mg/kg$</TEX>이고 최대 검출량은 구기자(1,546.3 mg/kg)이었고 중국산 현호색(66.6%)의 이산화황 검출 빈도가 가장 높게 나타났다. 국내산 한약재는 71건 중 1건(1.4%), 수입산 한약재는 45건 중 7건(15.6%)에서 이산화황이 검출되었고 국내산 1건(36.7 mg/kg)과 수입산 5건(118.1 mg/kg)이 허용기준치를 초과하여 국내산보다 수입산 한약재에 이산화황 잔류량이 많았다. 본 연구를 통해 이산화황 허용기준을 초과하는 부적합율은 다소 낮아지고 있지만 이산화황 허용기준을 초과하는 한약재들 중 일부 한약재에서는 잔류이산화황 함량이 높게 나타났고, 특히 국내산 약재에 비해 수입산 약재는 부적합율이 높게 나왔다. 한약재는 일반적으로 수세 및 가열과정을 거치므로 실제 섭취하는 형태의 탕액에서는 원재료보다 이산화황의 잔류량이 크게 감소하지만 완전히 제거되지는 않으므로 유통되는 한약재의 안전성 확립이 절실히 요구되어진다. 강화된 기준이 정착하여 안전한 한약재가 유통될 수 있도록 수입통관시 특별관리가 요구되며, 보다 적극적인 검사 요주의 품목에 대한 지속적인 잔류이산화황 모니터링이 필요할 것으로 사료된다. This study was carried out to investigate the residual sulfur dioxide residues (<TEX>$SO_2$</TEX>) in commercial medicinal herbs in Korea in 2013. Among a total of 116 samples of 11 different kinds of herbs, 71 samples (11 Kinds) were domestic, and 45 samples (10 Kinds) were imported. The residual contents of <TEX>$SO_2$</TEX> in the samples were determinated by a modified Monier-Williams method. Of the 116 samples, 6 samples (5.2%, 4 Kinds) failed to meet the regulations for sulfur dioxide residues of KFDA in medicinal herbs. Among 6 unsuitable samples, 1 samples (1.4%) were domestic, and 5 samples (11.1%, 3 Kinds) were imported. The highest amount of sulfur dioxide residues was 1546.3 mg/kg (Lycii Fructus) in the domestic samples. Regardless of region, <TEX>$SO_2$</TEX> contents were not found at Anemarrhenae Rhizoma, Citri Unshius Pericarpium, Eucommiae Cortex, Forsythiae Fructus, Gardeniae Fructus, Leonuri Herba and Lonicerae Folium et caulis. These data will be used as a basic data for the future legislation on the regulation and control of sulfur dioxide of herbal medicines.

국내 유통 한약재의 잔류이산화황 함량 모니터링

This study was conducted to investigate the residual contents of sulfur dioxide (SO2) in commercial medicinal herbs in Korea in 2012. Among a total of 136 samples of 16 different kinds of herbs, 86 samples (15 Kinds) were domestic, and 50 samples (14 Kinds) were imported. Sulfur dioxide in the samples was measured by a modified Monier-Williams method. Of the 136 samples, 17 samples (12.5%, 6 Kinds) failed to meet the regulations for sulfur dioxide residues of KFDA in medicinal herbs. Among 17 unsuitable samples (8.1%, 3 Kinds) were domestic, and 10 samples (20.0%, 6 Kinds) were imported. The highest amount of sulfur dioxide was 3,167.94mg/kg (Lycii Fructus) in the domestic samples. The detection frequency of sulfur dioxide by medicinal herb parts used, Rhizoma 25.7%, Flos 20.0%, Cortex 12.5%, Radix 15.3%, Fructus 7.6%, p-value 0.011. This results will be used as a basic data for the future legislation on the quality estimation and safety of medicinal herbs.

Critical Comparison between Modified Monier-Williams and Electrochemical Methods to Determine Sulfite in Aqueous Solutions

In the present work, known concentration of sulfite aqueous solutions in the presence and absence of gallic acid was measured to corroborate the validity of modified Monier-Williams method. Free and bound-sulfite was estimated by differential pulse voltammetry. To our surprise, the modified Monier-Williams method (also known as aspiration method) showed to be very inaccurate for free-sulfite, although suitable for bound-sulfite determination. The differential pulse approach, using the standard addition method and a correction coefficient, proved to be swift, cheap, and very precise and accurate.

Preliminary data on sulphite intake from the Korean diet

The purpose of this study was to provide the preliminary data on sulphite intake in the Republic of Korea. The sulphite intakes were estimated using individual dietary intake data from the Korean National Health and Nutrition Survey (KNHNS) carried out in 1998 ( n = 11 , 525 ; age > 1 ) and analytical results of sulphites in 24 foods. In order to determine the sulphite intake, 322 food samples in 24 food categories among foods considered to be representative sources of sulphites in the Korean diet were selected. These selected samples were analyzed by the modified Monier-Williams Method. The detection range of sulphites in 14 subcategories of food varied from<0.01 to 3.58 g kg −1. The range in a further 18 subcategories of food fell even below the detection limit level (<0.01 g kg −1). In addition, all detected levels were lower than the maximum levels allowed by Korean legislation. The sulphite intake for average consumers (which is a part of the real value) ranged from 0.0019 mg kg −1 of body weight day −1 (bwi day −1) to 0.0082 mg kg −1 of bwi day −1 and, as a portion of the acceptable daily intake (ADI), ranged from 0.3% to 1.2% in all age groups. The findings show that the major foods that contribute sulphites for average consumers are sugar, salt, flour, wine and orange juice. The calculated sulphite intake of the adult group (aged 30–64) was slightly higher than that of other age groups for average consumers. The calculated sulphite intake for 95th percentile consumers was 0.76 mg kg −1 of bwi day −1 and 109% expressed as a percentage of ADI. Wine was the major food contributing sulphite among the 95th percentile consumers. The results revealed that the calculated sulphite intakes for average consumers in Korea, even though part of a real value, were lower than the ADI set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA); on the other hand, the dietary intake of sulphites for 95th percentile was approximately 110% of the ADI. In order to reduce the sulphite intake below the ADI, consumers who are in the 95th percentile need to restrict their consumption of wine to less than two glasses per day (150 mL per glass), which causes the sulphite intake for 95th percentile consumers to fall to below 96% of the ADI.

유통 한약재의 이산화황 함유량에 관한 연구

This study was investigated the residual contents of sulfur dioxide on the 373 kinds of herbal medicine distributed from Korea, China, and Japan. A modified Monier-Williams method was described for the determination of <TEX>$SO_{2}$</TEX> contents in herbal medicines. The residual contents of <TEX>$SO_{2}$</TEX> were not detected at 221 products<TEX>$(59.8{\%})$</TEX> in total 373 products. Regardless of region, <TEX>$SO_{2}$</TEX> contents were not found at Farfarae Flos, Zizyphi Spinosi Semen, Castanea crenata, and Strychni Ignatii Semen. But it's found at Asparagi Radix, Codonopsitis Radix, Lilii Bulbus, and Kaempferiae Rhizoma of every region collected the samples. Also, <TEX>$SO_{2}$</TEX> contents were not detected at the herbal medicines which collected cultural fields of dometic. <TEX>$SO_{2}$</TEX> contents ranged 11<TEX>$\~$</TEX>3990 mg/kg(mean 152 mg/kg) at domestic samples, 11<TEX>$\~$</TEX>3440 mg/kg(mean 603 mg/kg) at imported samples. After treated with water wash and hot water extraction, the reduction rates of sulfur dioxide were appeared with <TEX>$24.4{\%}\~68.7{\%}\;and\;83.8{\%}\~100.0{\%},$</TEX> respectively. These data will be used to establish a criteron of residual sulfur dioxide in herbal medicines.

Determination of free, bound and total sulphites in foods by indirect photometry-HPLC

Sulphur dioxide and sodium, potassium, calcium salts of hydrogen-sulphite, disulphite and sulphite ions are extensively used as food additives for their technological efficacy and versatility. They are active as antimicrobial agents, enzyme inhibitors, antioxidants, structure modifiers, in the control of enzymatic and nonenzymatic browning reactions with stabilising and conditioning functions. In this study a modified Monier-Williams method has been utilised as a preparative procedure to obtain both the free and bound sulphite fractions. The two fractions have been analysed by HPLC with indirect photometric detection using a 250 × 4.6 mm LC-SAX column eluted with a solution of potassium hydrogen phthalate. Levels of 5–10 ppm of SO 2 in foods, corresponding to 30–60 ng injected are reliably detected by this method. The results confirm that the chromatographic method, unlike the Monier-Williams method, is able to avoid the potential interference of volatile substances derived from matrices or utilised chemicals.

Selective continuous flow–stopped flow–continuous flow determination of sulfite in White wines using immobilized sulfite oxidase on a rotating reactor

The sulfite ion in white wines has been selectively determined using the sulfite oxidase [EC 1.8.3.1] catalysis of sulfite oxidation in the presence of hexacyanoferrate(III) as the electron acceptor. The hexacyanoferrate(II) produced was detected amperometrically at a stationary Pt ring electrode (pH = 7.50; applied potential, +0.380 V versus Ag—AgCl; 3.0 mol l–1 NaCl). Ascorbic acid, the most serious interferent in the determination was eliminated before detection by passing the sample through a column with immobilized ascorbate oxidase [EC 1.10.3.3]. Application of the method of standard additions is also possible without the elimination of ascorbate. An unsegmented continuous flow stream passes the sample/reagent(s) through the column and directs it/them to the cell where contact is made with immobilized sulfite oxidase on a rotating disc. This disc is located at the bottom of the cell, while the Pt electrode is located at the top of the cell. The results of determinations using the proposed method correlate well with those of determinations conducted using the official Association of Analytical Chemists (AOAC) modified Monier–Williams method.

Determination of Sulfur Dioxide in Grapes: Comparison of the Monier-Williams Method and Two Ion Exclusion Chromatographic Methods

Results for determination of sulfur dioxide in grapes were compared by 3 methods: the modified Monier-Williams method, acid distillation/ion exclusion chromatography with electrochemical detection (AD/IEC-EC), and alkali extraction/ion exclusion chromatography with electrochemical detection (AE/IEC-EC). An unusual positive response was observed during the later stage of the Monier-Williams distillation of both control grapes and sulfited grapes. Development of volatile acidic compounds in parallel with this Monier-Williams response and darkening of sample was also observed by collection in an alkali trap and analysis using anion exclusion chromatography and photodiode array detection. No parallel increase in sulfite was observed by the more selective AD/IEC-EC method, which clearly demonstrated that the response observed during the later stage of the Monier-Williams method is a false positive, probably due to caramelization reaction products. Monier-Williams results for grapes containing ca 10 ppm sulfite were in reasonably good agreement with those by either the AD/IEC-EC or AE/IEC-EC methods, presumably because the false positive response in the Monier-Williams analysis compensated for the somewhat incomplete recovery of sulfite. The AE/IEC-EC method is recommended because it is rapid, sensitive, straightforward, and free from interference. Accurate results by Monier-Williams analysis could be obtained by limiting distillation to 60 min and correcting for recovery.

Optimized Monier-Williams Method for Determination of Sulfites in Foods: Collaborative Study

A collaborative study was conducted of the Food and Drug Administration (FDA)-optimized Monier-Williams method for determining sulfites in foods. Twenty-one industry and government laboratories participated in the study, which was jointly sponsored by the National Food Processors Association and FDA. Familiarization samples were shipped to each collaborator. Collaborators were permitted to proceed to the main study only after they demonstrated ability to perform the method to ensure that the study tested the performance of the method itself and not that of the individual laboratories. The study design involved 3 food matrixes (hominy, fruit juice, and protein [seafood]). Each matrix was prepared at 3 sulfite levels--the regulatory level, half the regulatory level, twice the regulatory level--and as a blank. All test samples were analyzed as blind duplicates, which gave each collaborator a total of 24 test portions. Collaborative recoveries gave a reproducibility (among-laboratories) coefficient of variation that ranged from 15.5 to 26.6% for sulfite determined as SO2 by weight in the 3 foods at the 10 ppm level. The optimized Monier-Williams method has been approved interim official first action to replace the AOAC modified Monier-Williams method, 20.123-20.125.

False positive and false negative reactions encountered in the use of sulfite test strips for the detection of sulfite-treated foods

The reliability of a qualitative test for sulfites in foods (Sulfitest sulfite test strips) was evaluated by comparison of the results obtained from the analysis of 90 food and beverage samples to results obtained by the quantitative, modified Monier-Williams method (the preferred procedure for sulfite analysis in foods of the Food and Drug Administration). The results obtained with the sulfite test strips compared favorably to the results of the Monier-Williams procedure when the sulfite test strips were used on sulfite-treated lettuce and raw or cooked potatoes. However, the strips yielded many false negative and false positive results with other types of foods. False positive results (strips indicated a substantial amount of sulfite when sulfite was not detectable by the Monier-Williams method) were obtained with fin fish, red meats, and poultry. False negative results (strips indicated the absence of sulfites when sulfite was detected at levels >10 ppm total sulfur dioxide by the Monier-Williams method) were obtained with dried fruits and wines under certain conditions of testing. The false negative responses with the test strips may result in the hazardous consumption of foods with high levels of sulfites, such as dried fruit or wine, by a sulfite-sensitive individual. The false positive responses would not be hazardous but could lead sensitive individuals to avoid foods that could be safely consumed. Although the strips may be useful for the detection of sulfites in certain foods, such as lettuce and potatoes, their use by sulfite-sensitive individuals cannot be recommended because of the confusion and potential hazards posed by the false negative and false positive responses.

A Direct HPLC Analysis of Total Sulfur Dioxide in Wine

A rapid (less than 25 min) method for determination of total sulfur dioxide (SO₂) in must or wine has been developed employing a Dionex 2010i ion chromatograph with anion exchange column and conductivity detector. A distillation step is avoided by diluting the filtered sample with 0.1 <i>N</i> NaOH:0.1% formaldehyde to an SO₂ level of 5 to 25 mg/L and eluting with a carbonate/bicarbonate buffer (pH 9.6). Recovery from sulfite-spiked must :samples by ion chromatography was 94% to 118%. High performance liquid chromatography-ion chromatography (HPLC-IC) analysis measured 83% to 110% total SO₂ compared to the official Modified Monier-Williams method, and the results were not significantly different (p &lt; 0.01 ). With attention to sample dilution and detector attenuation, sulfate, tartrate, and malate can be determined simultaneously, making this a useful technique for following SO₂ throughout winemaking, cellar treatment, and storage, as well as characterizing acid profiles.

The determination of sulphur dioxide in meats

Several methods were compared in determining sulphur dioxide in meat samples that contained no added sulphur dioxide but that had various pH values, in order to determine whether or not false positive results were obtained owing to the presence of hydrogen sulphide in the meat. The recovery of sulphur dioxide that had been added to meat samples was also studied.An iodimetric method gave false positive results for sulphur dioxide. A modified Monier-Williams method did not give false positive results, but it has limited sensitivity, giving a possible error of ±6·4 p.p.m. with a 10-g sample. The relative merits of each method are discussed.

The isolation of l-iduronic acid from the crystalline barium acid salt of heparin

The thrice-recrystallized barium acid salt of heparin was hydrolyzed by a modified Monier-Williams method with 72% sulfuric acid at 25°, followed by dilution and refluxing. The uronic acid fraction (13%) of the hydrolyzate was chromatographically shown to contain d-glucuronic acid, l-iduronic acid, and their lactones. The l-iduronolactone component was isolated, and characterized as the crystalline brucinium salt of its acid. It was established that the l-iduronic acid was derived neither from contaminant dermatan sulfate nor through C-5 epimerization of d-glucuronic acid. Previous hydrolytic conditions (which gave, in addition to 2-amino-2-deoxy- d-glucose, only d-glucuronic acid or d-glucose from purified heparin or its partially carboxyl-reduced derivatives, respectively) are now considered to have been too drastic to give all of the representative, degradation fragments.

Sulfur Dioxide Determination by Modified Monier-Williams Method

Abstract An alternative trapping system for the two U-tubes now incorporated in the modified Monier-Williams method for total sulfurous acid, 27.079, is recommended. This system is easy to use, permits the titration of distilled SO2 during the determination, and is cheaper and more durable than the U-tube system. The nonapplicability of 27.079 to dried onions, leeks, and cabbage is also discussed.