Development and certification of a reference material for Fusarium mycotoxins in wheat flour

Deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEN) are toxic secondary metabolites produced by several species of Fusarium fungi. These mycotoxins are often found together in a large variety of cereal-based foods, which are regulated by maximum content levels of DON and ZEN. To date, suitable certified reference materials (CRM) intended for quality control purposes are lacking for these Fusarium mycotoxins. In order to overcome this lack, the first CRM for the determination of DON, NIV and ZEN in naturally contaminated wheat flour (ERM®-BC600) was developed in the framework of a European Reference Materials (ERM®) project. This article describes and discusses the whole process of ERM®-BC600 development, including material preparation, homogeneity and stability studies, and an interlaboratory comparison study for certification. A total of 21 selected expert laboratories from different European countries with documented expertise in the field of mycotoxin analysis took part in the certification study using various gas and liquid chromatographic methods. The certified values and their corresponding expanded uncertainties (k?=?2) were assigned in full compliance with the requirements of ISO Guide 35 and are as follows: 102?±?11 μg?kg^?1 for DON, 1000?±?130 μg?kg^?1 for NIV and 90?±?8 μg?kg^?1 for ZEN.     

Metallothionein as a biomarker for mercury in tissues of rat fed orally with cinnabar

Cinnabar, as one of the most widely used mineral drugs in traditional Chinese medicines, has been proven to have prominent curative effects in clinical use for more than 2000 years. But the safety and toxicity of the drug has been under constant debate in clinic usage. Metallothionein (MT) contains about 30% of cysteine in the molecule, and plays an important detoxification role against heavy metals. In this study, it was used as a biomarker to assess mercurial accumulation in rats fed orally with cinnabar. After feeding rats with cinnabar by gastric gavage at different dosages and at different times, the distribution of heavy metals (including mercury, copper and zinc) and MT was investigated among rat tissues, including liver, kidney, heart, brain, testis and blood. Metals and MT determinations were carried out using inductively coupled plasma mass spectrometry (ICP‐MS) and a modified mercury saturation assay technique respectively. The results indicated that mercury was easily accumulated in the tissues of rats exposed to cinnabar, especially in kidney. For example: at a feeding dosage of 5 g kg^?1 (bw) for 4 weeks, the mercury concentrations in kidney were 13, 8.7, 21.6 and 26 times those in liver, testis, brain and heart respectively; and at 2.5 g kg^?1 (bw) for 2 weeks, the mercury concentrations in kidney were 21, 2.1, 3 and 21 times those in liver, testis, brain and heart respectively. In addition, mercury in kidney and liver of all cinnabar groups was significantly higher than that of the control group (P < 0.01). A high positive correlation observed between MT concentrations and mercury levels in both liver and kidney (R² = 0.9299, P < 0.02 for liver; R² = 0.9923, P < 0.0008 for kidney) indicated that MT could be used as a biomarker for mercury in tissues. Copyright © 2004 John Wiley & Sons, Ltd.     

Determination of arsenic by hydride generation with a long absorption cell for atomic absorption spectrometry

A method is described for the determination of arsenic involving hydride generation and atomic absorption spectrometry with an improved long graphite-tube furnace capable of considerably higher temperatures than the conventional quartz-tube heaters. Arsine is generated with sodium tetrahydroborate, held in a nitrogen-cooled trap and then swept with helium into an alumina tube (19 cm long) placed within the graphite furnace. The optimum conditions for determination of arsenic are given. The detection limit is 0.2 ng ml^?1 with RSD of 2–3%. Results for various NBS Standard Reference Materials agreed well with expected values and were as follows: orchard leaves, 10 ± 1 μg g^?1; tomato leaves, 0.28 ± 0.03 μg g^?1; bovine liver, 0.046 ± 0.005 μg g^?1.     

Determination of nivalenol and deoxynivalenol by liquid chromatography/atmospheric pressure photoionization mass spectrometry

Fusarium species, a plant pathogenic fungus of wheat and other cereals, produces toxic metabolites such as nivalenol (NIV) and deoxynivalenol (DON). Control of contamination by these toxins is very difficult, and a continuous survey of the occurrence is necessary for these toxins. Thus, the accurate and convenient determination of the cereals contaminated with these toxins is important for the supply of safe foods. A selective analytical method based on high‐performance liquid chromatography, combined with atmospheric pressure photoionization (APPI) mass spectrometry, has been developed for simultaneous determination of NIV and DON. The parameters investigated for the optimization of APPI were the ion source parameters fragmentor voltage, capillary voltage, and vaporizer temperature, and also mobile phase composition and flow rate. Furthermore, chemical noise and signal suppression of analyte signals due to sample matrix interference were investigated for APPI. The results indicated that APPI provides lower matrix effect and the correlation coefficient of NIV and DON in the range 0.2–100 ng · mL^?1 was above 0.999. Recoveries of NIV and DON in wheat ranged from 86 to 107% and limits of detection of NIV and DON were 0.20 ng · g^?1 and 0.39 ng · g^?1, respectively. In addition, the proposed method was applied for the analysis of naturally contaminated wheat samples. APPI was found to offer lower matrix effect and was a convenient technique for routine analysis of NIV and DON residues in wheat at trace levels. Copyright © 2009 John Wiley & Sons, Ltd.     

Use of a multifunctional column for the determination of deoxynivalenol in grains, grain products, and processed foods

Deoxynivalenol (DON), also known as vomitoxin, belongs to a class of naturally occurring mycotoxins produced by Fusarium spp. DON, 12, 13-epoxy-3,7 trihydroxytrichothec-9-en-8-one, is one of the most frequently detected mycotoxins in agricultural commodities worldwide. A method consisting of extraction, filtration, column cleanup, and RP-HPLC-UV separation and quantitation was validated for the determination of DON in grains (rice and barley), grain products (whole wheat flour, white flour, wheat germ, and wheat bran), and processed foods (bread, breakfast cereals, and pretzels). A 25 g test portion was extracted with 100 mL acetonitrile-water (84 + 16, v/v). After blending for 3 min, the supernatant was applied to a multifunctional column (MycoSep 225). The purified filtrate (2 mL) was evaporated to dryness and redissolved in the mobile phase. The toxins were then subjected to RP-HPLC-UV analysis. The accuracy and repeatability characteristics of the method were determined. Recoveries of DON added at levels ranging from 0.5 to 1.5 microg/g for all test matrixes were from 75 to 98%. SD and RSD(r) ranged from 0.7 to 11.6% and 0.9 to 12.7%, respectively. Within-laboratory HorRat values were from 0.1 to 0.7 for all matrixes analyzed. The method was found to meet AOAC method performance criteria for grains, grain products, and processed foods. The identity of DON in naturally contaminated test sample extracts was confirmed by HPLC/MS/MS analysis.     

Determination of arsenic species in a freshwater crustacean Procambarus clarkii

The arsenic species present in samples of the crayfish Procambarus clarkii caught in the area affected by the toxic mine‐tailing spill at Aznalcóllar (Seville, Southern Spain) were analyzed. The total arsenic contents ranged between 1.2 and 8.5 µg g^?1 dry mass (DM). With regard to the different species of arsenic, the highest concentrations were for inorganic arsenic (0.34–5.4 µg g^?1 DM), whereas arsenobetaine, unlike the situation found in marine fish products, was not the major arsenic species (0.16 ± 0.09 µg g^?1 DM). Smaller concentrations were found of arsenosugars 1a (0.18 ± 0.11 µg g^?1 DM), 1b (0.077 ± 0.049 µg g^?1 DM), 1c (0.080 ± 0.089 µg g^?1 DM), and 1d (0.14 ± 0.13 µg g^?1 DM). The presence of two unknown arsenic species was revealed (U1: 0.058 ± 0.058 µg g^?1 DM; U2: 0.12 ± 0.12 µg g^?1 DM). No significant differences were seen with respect to the total arsenic contents between the sexes. However, significant differences in the total arsenic contents were revealed between the area affected by the spill and the area not affected, the contents being greater in the affected area. Copyright © 2002 John Wiley & Sons, Ltd.     

Trace elements in sediments and bioaccumulation in European silver eels (Anguilla anguilla L.) from a Mediterranean lagoon (SE Italy)

Samples of surface sediments and tissues (liver and muscle) of commercially available European silver eels (Anguilla anguilla L.) collected from Varano lagoon (Italy) were analysed to determine trace element contents. Univariate and multivariate analyses were performed to highlight both the differences between sampling sites and the influence of channel discharges. Atomic ratios indices for sediment data and biological enrichment factors (BEF) for eel tissues were calculated in order to evaluate the enrichment factor due to human activities. The highest levels of As (11.9?µg?g^?1) and Zn (14.1?µg?g^?1) were observed in the south-eastern zone of the lagoon, which is influenced by urban and agricultural discharges. The low levels of Hg observed in this study (0.04?µg?g^?1) led us to exclude both natural and human local sources of this element. Trace element concentrations of all elements were lower in muscle than in liver tissue. Significant enrichment of Cu and Zn was found in livers.     

Analysis of Deoxynivalenol,Nivalenol, Zearalenone in Food by LC–APCI–MS

The detection of mycotoxins is an important task for analytical analysis, as they are a source of contaminants in foods today. The very small amounts of toxic mycotoxins (zearalenone, deoxynivalenol) make it important to determine the most reliable analytical methods. There are several options for the detection of mycotoxins, LC–API–MS techniques being the most common ones. The aim of the present determination is to give an overview on the application of LC–(API)-MS in the analysis of frequently occurring and highly toxic mycotoxins, such as deoxynivalenol, nivalenol and zearalenone, in organic foods. The limits of these three toxins in foods are very low: deoxynivalenol 1,250 μg kg^?1, nivalenol 0.9 μg kg^?1 of body weight, zearalenone 100 μg kg^?1.     

Validation and use of three complementary analytical methods (LC–FLS, LC–MS/MS and ICP–MS) to evaluate the pharmacokinetics, biodistribution and stability of motexafin gadolinium in plasma and tissues

Liquid chromatography–fluorescence (LC–FLS), liquid chromatography–tandem mass spectrometry (LC–MS/MS) and inductively coupled plasma–mass spectrometry (ICP-MS) methods were developed and validated for the evaluation of motexafin gadolinium (MGd, Xcytrin) pharmacokinetics and biodistribution in plasma and tissues. The LC–FLS method exhibited the greatest sensitivity (0.0057 μg mL⁻¹), and was used for pharmacokinetic, biodistribution, and protein binding studies with small sample sizes or low MGd concentrations. The LC–MS/MS method, which exhibited a short run time and excellent selectivity, was used for routine clinical plasma sample analysis. The ICP–MS method, which measured total Gd, was used in conjunction with LC methods to assess MGd stability in plasma. All three methods were validated using human plasma. The LC–FLS method was also validated using plasma, liver and kidneys from mice and rats. All three methods were shown to be accurate, precise and robust for each matrix validated. For three mice, the mean (standard deviation) concentration of MGd in plasma/tissues taken 5 hr after dosing with 23 mg kg⁻¹ MGd was determined by LC–FLS as follows: plasma (0.025±0.002 μg mL⁻¹), liver (2.89±0.45 μg g⁻¹), and kidney (6.09±1.05 μg g⁻¹). Plasma samples from a subset of patients with brain metastases from extracranial tumors were analyzed using both LC–MS/MS and ICP–MS methods. For a representative patient, ≥90% of the total Gd in plasma was accounted for as MGd over the first hour post dosing. By 24 hr post dosing, 63% of total Gd was accounted for as MGd, indicating some metabolism of MGd.     

A novel approach to decomposition of foodstuffs for stripping voltammetric determination of lead,cadmium and copper

Samples (ca. 0.3 g) are digested in 10-ml quartz vessels and the same vessel is used for anodic stripping voltammetry. Thus possible contamination during handling and dilution of the decomposed sample solution are avoided. A special design of column placed over the vessel provides digestion under reflux conditions without leakage and a glass cap fitted to another condenser enables the residual mineral acids (especially sulfuric acid) to be boiled out under low pressure conditions. The usual PTFE holder for electrodes and gas tubes is modified to facilitated insertion of the 10-ml vessel underneath. The system was checked on NBS standard reference materials (wheat flour and rice flour) and tested for the determinaton of Cd, Pb and Cu in baby foods. The limits of detection obtained for 3-min decomposition times were 0.3 ng g^?1, 4 ng g^?1 and 8 ng g^?1 for cadmium, lead and copper, respectively. The levels of these elements in various commercial baby foods are given.     

Study of the system manganese(VII)-3,7-bis(dimethylamino)-phenothiazin-5-ium chloride-water-1,2-dichloroethane Using UV-spectrophotometry

The system manganese(VII)-3,7-bis(dimethylamino)-phenothiazin-5-ium chloride (MB)-water-1,2-dichloroethane has been studied using UV-spectrophotometry. The molar absorptivity of the complex is (3.86 ± 0.06) × 10⁴ L mol^?1 cm^?1 at 290 nm and the system obeys Beer??s law in the range 0.1?C0.99 ??g mL^?1 Mn(VII). The detection limit (DL) and quantitation limit (QL) of Mn(VII) determination were found to be 0.0146 and 0.049 ??g mL^?1, respectively. The composition of the complex is established as MB: MnO ₄ ^? = 1: 1. Extraction investigations of the system discussed were carried out. The characteristic values for the extraction equilibrium and the equilibrium in the aqueous phase was determined: extraction constant K_ex = (1.12 ± 0.05) × 10⁵, distribution constant K_D = 75.61 ± 0.1 and association constant ?? = (1.48 ± 0.08) × 10³. A new method has been developed for the microdetermination of manganese(VII) in plants and steels.     

Determination of molar absorptivity coefficients for major type-B trichothecenes and certification of calibrators for deoxynivalenol and nivalenol

This paper presents results from the European Commission-funded project Doncalibrant, the objective of which was to produce calibrators with certified mass fractions of the Fusarium toxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-Ac-DON), 15-acetyldeoxynivalenol (15-Ac-DON), and nivalenol (NIV), in acetonitrile. The calibrators, available in ampoules, were sufficiently homogeneous, with between-bottle variations (s _bb) of less than 2%. Long-term stability studies performed at four different temperatures between −18 and 40 °C revealed no significant negative trends (at a confidence level of 95%). Molar absorptivity coefficients (in L mol⁻¹ cm⁻¹) were determined for all four toxins (DON: 6805 ± 126, NIV: 6955 ± 205, 3-Ac-DON: 6983 ± 141, 15-Ac-DON: 6935 ± 142) on the basis of a mini-interlaboratory exercise. The overall uncertainty of the calibrators’ target values for DON and NIV were evaluated on the basis of gravimetric preparation data and include uncertainty contributions from possible heterogeneity, storage, and transport. The Doncalibrant project resulted in the production of calibrators for DON (IRMM-315) and NIV (IRMM-316) in acetonitrile with certified mass fractions of 25.1 ± 1.2 μg g⁻¹ and 24.0 ± 1.1 μg g⁻¹, respectively. Both CRMs became commercially available from the Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) at the beginning of 2007.     

Suitability of a fully 13C isotope labeled internal standard for the determination of the mycotoxin deoxynivalenol by LC-MS/MS without clean up

Very often, the accuracy of quantitative analytical methods for the determination of mycotoxins by liquid chromatography (LC)-mass spectrometry (MS) and LC-MS/MS is limited by matrix effects during the ionization process in the MS source. Stable isotope labeled standards are best suited to correct for matrix effects and to improve both the trueness and the precision of analytical methods employing LC-MS and LC-MS/MS. This paper describes the successful use of fully ¹³C isotope labeled deoxynivalenol [(¹³C₁₅)DON] as an internal standard (IS) for the accurate determination of DON in maize and wheat by LC electrospray ionization MS/MS. To show the full potential of (¹³C₁₅)DON as IS, maize and wheat extracts were analyzed without further cleanup. Subsequent to calibration for the LC-MS end determination, DON was quantified in matrix reference materials (wheat and maize). Without consideration of the IS, apparent recoveries of DON were 29±6% (n=7) for wheat and 37±5% (n=7) for maize. However, the determination of DON in the reference materials yielded 95±3% (wheat) and 99±3% (maize) when (¹³C₁₅)DON was used as an IS for data evaluation.     

Direct multielement determination of trace elements in boron carbide powders by direct current arc atomic emission spectrometry using a CCD spectrometer

The use of direct current arc atomic emission spectrometry (DC-arc-AES) with a CCD spectrometer for the direct determination of the trace impurities Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr in three well characterized boron carbide powders is described. The detection limits obtained by the procedure were found to be between 0.2 (Mg) and 25 (Na) ??g?g^?1 for the above elements. Three boron carbide powder samples with trace element concentrations between 0.9 (Cu) and 934 (Si) ??g?g^?1 for Al, Ca, Cr, Cu, Fe, Mg, Mn, Na, Ni, Si, Ti, and Zr ?? including the standard reference material ERM?-ED102 ?? were analyzed by DC-arc-AES. The relative standard deviations for 9 measurements when using 5.0?±?0.3?mg of the respective samples were found to vary from 6.2 to 27% for Al and Cu, respectively. The trace elements Al, Ca, Cr, Cu, Fe, Mn, Ni, Si, Ti and Zr could be determined in the standard reference material and their concentrations determined by DC-arc AES were found to be between 89 and 116% of the accepted values. Fe and Ti were determined by DC-arc AES in the three boron carbide samples as well as in Al₂O₃, BN, SiC, coal fly ash, graphite and obsidian rock. The correlation coefficients of the plots of the net intensities versus the accepted values over the concentration ranges from 18 to 1750 and from 6 to 8000???g?g^?1 are 0.999 and 0.990 for Fe and Ti, respectively.

Single robust RP-HPLC analytical method for quantification of curcuminoids in commercial turmeric products,Ayurvedic medicines,and nanovesicular systems

A single robust reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated as per International Conference on Harmonization guidelines for the accurate quantification of curcuminoids in commercial turmeric products, Ayurvedic medicines, and nanovesicular systems. The proposed chromatographic method was found to be specific, linear (r²?≥?0.999), precise at intra- and inter-day levels (percentage relative standard deviation <2.0%), accurate (percentage recovery 99.14–102.29%), and robust. The limits of detection and quantification were found to be 7.40 and 24.70?ng?mL^?1 for curcumin, 9.24 and 30.80?ng?mL^?1 for demethoxycurcumin, and 6.48 and 21.61?ng?mL^?1 for bisdemethoxycurcumin, respectively. Among different commercial turmeric products and Ayurvedic medicines tested, the contents of curcumin (3.54?±?0.06–25.8?±?0.08?mg?g^?1), demethoxycurcumin (1.28?±?0.02–9.97?±?0.03?mg?g^?1), and bisdemethoxycurcumin (0.50?±?0.01–5.97?±?0.01?mg?g^?1) varied significantly. The developed method was effectively applied to the determination of encapsulation efficiency of curcuminoids (ranged between 84.33?±?3.50 and 96.59?±?2.53%) in the nanovesicular systems. In conclusion, the reported method is suitable for the analysis of curcuminoids in a wide variety of turmeric products and used for the quality control of products that contain curcuminoids.     

Absorption,fluorescence and phosphorescence spectra of the singlet and triplet states of s-tetrazine in the crystal and in mixed crystals at low temperatures

The electronic absorption, fluorescence and phosphorescence spectra of s-tetrazine at low temperatures (4.2-1.5 K) are reported and analyzed in the neat crystal and in several mixed crystals. The ³B_3u-¹A_g (nπ^*) origin is at 18414 ± 5 cm^?1 for neat tetrazine. In the mixed crystal several sites identified. The lowest energy origin is at 17453 cm^?1 for tetrazine in pyrazine; 17 701 cm^?1 in pyrimidine; and 17 676 cm^?1 in pyridazine. The ^eB_3u-¹A_g (nπ^*) origin is at 14 096 ± 2 cm^?1 for the neat crystal. The phosphorescence lifetime of neat tetrazine is measured to be 96.8 ± 2.1 μs at 4.2 and 1.8 K. All the spectra are predominately composed of members of progressions in a single totally symmetric mode (ν_6a) built upon site origins and vibrational fundamentals. The ν_6a interval is: 743 (¹A_g), 715 (³B_3u), and 709 cm^?1 (¹B_3u) in the neat tetrazine crystal; 732 (¹A_g) and 705 cm^?1 (¹B_3u in pyrazine host, 737 (¹A_g) and 701 cm^?1 (¹B_3u) in pyrimidine host, and 732 (¹A_g) and 703 cm^?1 (¹B_3u) in pyridazine host mixed crystals. All emission spectra may be analyzed by Oi → (ν″_6a)^o_n (i), i indicating the observed s     

Metal-metabolomics of microalga Chlorella sorokiniana growing in selenium- and iodine-enriched media

The microalga Chlorella sorokiniana has been used to accumulate selenium and iodine from culture media enriched with these elements as a first stage in the production of supplemented foods. The microalgal colony was grown in a conventional culture medium containing iodine (KI) at concentrations in the range of 150?C4000 ??g mL^?1. Similar experiments were performed with selenium (SeO ₄ ^2? ) at concentrations in the range of 20?C500 ??g mL^?1. The concentration of iodine and selenium in the culture medium was analytically monitored daily and the viability of the colony was checked by biomass concentration measurement and by evaluation of the total content of chlorophyll and carotenoids. In addition, photosynthetic activity and the number of cells were also monitored. Iodine accumulation in the algal biomass increased rapidly with time and reached a steady state after 4 h of exposure. With Se exposure the colony viability decreased, although the culture grew well with concentrations of the element of 50 ??g mL^?1 in the culture medium; this experiment produced Se-enrichment in the alga (3 ??g g^?1) within 100 h. Sequential extraction of an algal pellet was performed in order to separate Se compounds according to their affinity with the following solvents: hot water to recover low molecular mass Se species, enzymatic extraction with driselase for species associated with the cell wall, sodium dodecyl sulphate (SDS) for water insoluble selenoproteins and, finally, enzymolysis with lipase and pronase that release and fragment residual selenoproteinsproducing compounds with low molecular mass. Size-exclusion chromatography (SEC) coupled with an ICP-MS detector showed the preponderance of Se-containing molecules with low molecular mass, possibly seleno-amino acids. Only a peak of low intensity located at 10 min was observed in the SDS extract that could be associated with a protein with molecular mass of 67 kDa. Finally, analysis of the aqueous extract of alga by reverse-phase chromatography with inductively-coupled plasma mass-spectrometry (RPC-ICP-MS) detection revealed the presence of selenocysteine (SeCys₂), selenomethylselenocysteine (SeMetSeCys), selenomethionine (SeMet), and Se(VI), particularly the last two species.     

Spectrophotometric determination of oxyhalides with N,N-diethylaniline

We have developed procedures for the spectrophotometric determination of ClO^?, BrO ₃ ^? , and IO ₃ ^? in waters of different origin. The procedures are based on the oxidation of N,N-diethylaniline in acidic media and their detection limits (by 3s criterion) are 0.04, 0.18, and 0.53 ??g/mL, respectively. The calibration curves are linear in the concentration ranges 0.1?C2.0, 0.4?C12.5, and 1.6?C40 ??g/mL, respectively. The procedures provide simple and rapid determination of these analytes.     

Determination of deoxynivalenol, T-2 and HT-2 toxins in a bread model food by liquid chromatography-high resolution-Orbitrap-mass spectrometry equipped with a high-energy collision dissociation cell

A sensitive and accurate method employing a single stage high resolution mass spectrometer equipped with a high-energy collision-dissociation cell (HCD) for the simultaneous determination of deoxynivalenol (DON), T-2 toxin (T-2) and HT-2 toxin (HT-2) in a processed bread model food has been developed. Two sample pre-treatment routes for the extraction of these mycotoxins were investigated, based on Mycosep^® column clean up or QuEChERS-like procedure, respectively. The former approach suffered less from matrix effects and allowed to achieve in bread samples LODs of 7, 12 and 17 ng/g for T-2, HT-2 and DON, respectively, with 0.5 ppm mass accuracy. Two acquisition modes, full scan MS and all ion fragmentation, exploiting the fragmentation features offered by an HCD chamber and integrated within the Orbitrap analyser, were compared for quantitative purposes. The method was applied to investigate the degradation of these mycotoxins during bread processing using a bread model food. Most T-2 hydrolyzed to HT-2 during dough preparation, and about 20–30% of HT-2 and DON was degraded during bread baking.     

Reactivity of selected volatile organic compounds (VOCs) toward the sulfate radical (SO4−)

Rate constants for a series of alcohols, ethers, and esters toward the sulfate radical (SO₄^?) have been directly determined using a laser photolysis set‐up in which the radical was produced by the photodissociation of peroxodisulfate anions. The sulfate radical concentration was monitored by following its optical absorption by means of time resolved spectroscopy techniques. At room temperature the following rate constants were derived: methanol ((1.6 ± 0.2) × 10⁷ M^?1 s^?1); ethanol ((7.8 ± 1.2) × 10⁷ M^?1 s^?1); tert‐butanol ((8.9 ± 0.3) × 10⁵ M^?1 s^?1); diethyl ether ((1.8 ± 0.1) × 10⁸ M^?1 s^?1); MTBE ((3.13 ± 0.02) × 10⁷ M^?1 s^?1); tetrahydrofuran (THF) ((2.3 ± 0.2) × 10⁸ M^?1 s^?1); hydrated formaldehyde ((1.4 ± 0.2) × 10⁷ M^?1 s^?1); hydrated glyoxal ((2.4 ± 0.2) × 10⁷ M^?1 s^?1); dimethyl malonate (CH₃OC(O)CH₂C(O)OCH₃) ((1.28 ± 0.02) × 10⁶ M^?1 s^?1); and dimethyl succinate (CH₃OC(O)CH₂CH₂C(O)OCH₃) ((1.37 ± 0.08) × 10⁶ M^?1 s^?1) where the errors represent 2σ. For the two latter species, we also measured the temperature dependence of the corresponding rate constants. A correlation of these kinetics with the bond dissociation energy is also presented and discussed. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 539–547, 2001