Application of ion chromatography to the determination of inorganic anions in foodstuffs.

A review on the applications of ion chromatography (IC) to the determination of inorganic anions in foodstuffs is presented. The anions were commonly determined in food, i.e., SO3(2-), NO3- and NO2-, and to a lesser extent Cl-, Br-, I-, SO4(2-), IO3-, BrO3- and phosphate, are considered. In comparison with standard methods for the determination of anions in food products, chromatographic methods are rapid, sensitive and precise. They also have the advantage of determining several ions simultaneously. The separation may be achieved by conventional IC, by ion interaction chromatography or by ion exclusion chromatography. IC has also been applied to the determination of Br, I, N and S in foods after oxidation or combustion of samples and conversion into anionic forms.     

沉淀滴定计算分析法同时测定溴酸根与碘酸根

以银电极为指示电极，Ag^ 标准溶液为滴定剂，对BrO3^-,IO3^-的混合离子进行了测定。结果表明：BrO3^-或IO3^-单种离子，测定误差小于1％；BrO3^-与IO3^-混合离子，IO3^-的测定误差约为1％，但BrO3^-的测定误差较大，此外，对BrO3^-,IO3^-与Ag^ 沉淀反应的动力学为进行了研究，并对产生误差的原因进行了讨论。     

Determination of iodine and bromine compounds by ion chromatography/dynamic reaction cell inductively coupled plasma mass spectrometry.

An inductively coupled plasma mass spectrometer (ICP-MS) was used as an ion chromatographic detector for the speciation of iodine and bromine. Gradient elution using NH4NO3 at pH 10 allowed the chromatographic separation of ionic iodine (I- and IO3-) and bromine (Br- and BrO3-) species in less than 8 min. Effluents from the ion-exchange column were delivered to the nebulization system of ICP-MS for the determination of I and Br. The potentially interfering 38Ar40ArH+ and 40Ar40ArH+ at the bromine masses m/z 79 and 81 were significantly reduced in intensity (by approximately two orders of magnitude) by using 0.6 mL min(-1) O2 as a reactive cell gas in the dynamic reaction cell (DRC). Moreover, the signal-to-background ratio at iodine mass m/z 127 increased significantly when O2 was used as the reaction gas. The detection limits were in the range of 0.001-0.002 and 0.03-0.04 ng mL(-1) for various I and Br compounds, respectively, based on the peak height. The relative standard deviation of the peak areas for five injections of a 2 ng mL(-1) I-, IO3- and 20 ng mL(-1) Br-, BrO3- mixture was in the range of 3-4%. The concentrations of I and Br compounds have been determined in selected water and urine samples. The spike recoveries were in the range of 94-102% for all of the determinations. This method has also been applied to determine various I and Br compounds in an NIST RM 8435 whole-milk powder reference material and a seaweed sample obtained locally. A microwave-assisted extraction method was used to extract these compounds, which were quantitatively leached with a 10% mass/volume (m/v) tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 6 min. The major components of I and Br in milk powder and seaweed were I- and Br-.     

Determination of iodine and bromine compounds in foodstuffs by CE-inductively coupled plasma MS

A CE-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for iodine and bromine speciation analysis is described. Samples containing ionic iodine (I(-) and IO(3)(-)) and bromine (Br(-) and BrO(3)(-)) species are subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100). The separation has been achieved in a 50 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used is 10 mmol/L Tris (pH 8.0), while the applied voltage is set at -8 kV. Detection limits are 1 and 20-50 ng/mL for various I and Br compounds, respectively, based on peak height. The RSD of the peak areas for seven injections of 0.1 microg/mL I(-), IO(3)(-) and 1 microg/mL Br(-), BrO(3)(-) mixture is in the range of 3-5%. This method has been applied to determine various iodine and bromine species in NIST SRM 1573a Tomato Leaves reference material and a salt and seaweed samples obtained locally. A microwave-assisted extraction method is used for the extraction of these compounds. Over 87% of the total iodine and 83% of the total bromine are extracted using a 10% m/v tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 10 min. The spike recoveries are in the range of 94-105% for all the determinations. The major species of iodine and bromine in tomato leaves, salt, and seaweed are Br(-), IO(3)(-), I(-), and Br(-), respectively.     

结晶紫与卤素或卤酸根离子共吸附的近红外表面增强喇曼散射

采用近红外激光（１０６４ｎｍ）激发和扫描式双光栅单色仪研究了卤素、卤酸根离子及吡啶对结晶紫近红外表面增强喇曼散射光谱（ＮＩＲ－ＳＥＲＳ）的影响．揭示了这些离子（或分子）与结晶紫及银表面的相互作用．Ｃｌ－、Ｂｒ－、Ｉ－、ＢｒＯ－３离子及吡啶均能引起结晶紫ＮＩＲ－ＳＥＲＳ的明显增强，而ＣｌＯ－３和ＩＯ－３离子则不能．观察到ＮＩＲ－ＳＥＲＳ中化学增强的直接证据，并估算了化学增强因子．Ｃｌ－、Ｂｒ－、Ｉ－和ＢｒＯ－３离子引起结晶紫ＮＩＲ－ＳＥＲＳ的化学增强因子分别约为４９、７７、１５和３６．     

Polarographic microdetermination of halogens in organic compounds after oxygen flask combustion

A method for the microdetermination of organic compounds containing halogens, by a polarographic finish, is reported. After the combustion of the organic sample in the oxygen flask, the products are absorbed in a suitable absorbent and chemically treated to produce Cl(-), Br(-), BrO(3)(-) or IO(3)(-) ions in solution before the polarography. The method is applicable to partially, highly, and fully halogenated aromatic and aliphatic compounds, whether solid or liquid. The results are generally within the acceptable limits of error.     

Kinetic studies on the temperature dependence of the BrO + BrO reaction using laser flash photolysis

The BrO self-reaction, BrO + BrO → products (1), has been studied using laser flash photolysis coupled with UV absorption spectroscopy over the temperature range T = 266.5-321.6 K, under atmospheric pressure. BrO radicals were generated via laser photolysis of Br(2) in the presence of excess ozone. Both BrO and O(3) were monitored via UV absorption spectroscopy using charge-coupled device (CCD) detection. Simultaneous fitting to both temporal concentration traces allowed determination of the rate constant of the two channels of , BrO + BrO → 2Br + O(2) (1a); BrO + BrO → Br(2) + O(2) (1b), hence the calculation of the overall rate of and the branching ratio, α: k(1a)/cm(3) molecule(-1) s(-1) = (1.92 ± 1.54) × 10(-12) exp[(126 ± 214)/T], k(1b)/cm(3) molecule(-1) s(-1) = (3.4 ± 0.8) × 10(-13) exp[(181 ± 70)/T], k(1)/cm(3) molecule(-1) s(-1) = (2.3 ± 1.5) × 10(-12) exp(134 ± 185 /T) and α = k(1a)/k(1) = (0.84 ± 0.09) exp[(-7 ± 32)/T]. Errors are 1σ, statistical only. Results from this work show a weaker temperature dependence of the branching ratio for channel (1a) than that found in previous work, leading to values of α at temperatures typical of the Polar Boundary Layer higher than those reported by previous studies. This implies a shift of the partitioning between the two channels of the BrO self-reaction towards the bromine atom and hence directly ozone-depleting channel (1a).     

Generation of pH-oscillations in closed chemical systems: method and applications

All pH-oscillators reported to date function only under open (flow reactor) conditions. We describe an approach to generating pH-oscillations in a closed system by starting from an open system pH-oscillator, finding semibatch conditions under which it oscillates with an inflow of a single reactant to an otherwise closed reactor containing the remaining components, and replacing this inflow with a layer of silica gel impregnated with the key reactant. We present data showing the successful application of this technique to the BrO(3)(-)-Mn(2+)-SO(3)(2-), IO(3)(-)-Fe(CN)(6)(4-)-SO(3)(2-), and BrO(3)(-)-Fe(CN)(6)(4-)-SO(3)(2-) systems. In all three cases, sulfite ion is the species that is replenished via dissolution from the gel layer.     

Photoelectron spectroscopy of higher bromine and iodine oxide anions: electron affinities and electronic structures of BrO(2,3) and IO(2-4) radicals

This report details a photoelectron spectroscopy (PES) and theoretical investigation of electron affinities (EAs) and electronic structures of several atmospherically relevant higher bromine and iodine oxide molecules in the gas phase. PES spectra of BrO(2)(-) and IO(2)(-) were recorded at 12 K and four photon energies--355 nm/3.496 eV, 266 nm/4.661 eV, 193 nm/6.424 eV, and 157 nm/7.867 eV--while BrO(3)(-), IO(3)(-), and IO(4)(-) were only studied at 193 and 157 nm due to their expected high electron binding energies. Spectral features corresponding to transitions from the anionic ground state to the ground and excited states of the neutral are unraveled and resolved for each species. The EAs of these bromine and iodine oxides are experimentally determined for the first time (except for IO(2)) to be 2.515 ± 0.010 (BrO(2)), 2.575 ± 0.010 (IO(2)), 4.60 ± 0.05 (BrO(3)), 4.70 ± 0.05 (IO(3)), and 6.05 ± 0.05 eV (IO(4)). Three low-lying excited states along with their respective excitation energies are obtained for BrO(2) [1.69 (A (2)B(2)), 1.79 (B (2)A(1)), 1.99 eV (C (2)A(2))], BrO(3) [0.7 (A (2)A(2)), 1.6 (B (2)E), 3.1 eV (C (2)E)], and IO(3) [0.60 (A (2)A(2)), 1.20 (B (2)E), ～3.0 eV (C (2)E)], whereas six excited states of IO(2) are determined along with their respective excitation energies of 1.63 (A (2)B(2)), 1.73 (B (2)A(1)), 1.83 (C (2)A(2)), 4.23 (D (2)A(1)), 4.63 (E (2)B(2)), and 5.23 eV (F (2)B(1)). Periodate (IO(4)(-)) possesses a very high electron binding energy. Only one excited state feature with 0.95 eV excitation energy is shown in the 157 nm spectrum. Accompanying theoretical calculations reveal structural changes from the anions to the neutrals, and the calculated EAs are in good agreement with experimentally determined values. Franck-Condon factors simulations nicely reproduce the observed vibrational progressions for BrO(2) and IO(2). The low-lying excited state information is compared with theoretical calculations and discussed with their atmospheric implications.     

Long-chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion-exchange chromatography

Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.     

Zur kristallchemischen Ähnlichkeit von Aurid- und Halogenid-Ionen

On the Crystal Chemical Similarity of Auride and Halide Anions The crystallographic properties of the aurides M₃AuO and the alkalimetal halide oxides M₃XO (M = K, Rb, Cs; × = Br, I) are compared. Rb₃BrO, Rb₃IO, Cs₃BrO, and Cs₃IO have been prepared and characterized for the first time: Rb₃BrO (a = 5.465(1) Å) crystallizes as a cubic anti perovskite, Cs₃BrO (a = 7.800(6), c = 7.122(6) Å) and Cs₃IO (a = 8.056(3), c = 7.168(3) Å) as hexagonal anti perovskites, Rb₃IO (a = 7.889(1), c = 19.640(1) Å) as a hexagonal anti BaTiO₃ type. The analysis of bond lengths, molar volumes and the systematic of the crystal structures leeds to the conclusion, that the crystallographic properties of auride- and bromide anions are similar. The radius of the Au^? has been found to be 2.2 Å (KZ 12).     

Kinetics and mechanisms of the ozone/bromite and ozone/chlorite reactions

Ozone reactions with XO(2)(-) (X = Cl or Br) are studied by stopped-flow spectroscopy under pseudo-first-order conditions with excess XO(2)(-). The O(3)/XO(2)(-) reactions are first-order in [O(3)] and [XO(2)(-)], with rate constants k(1)(Cl) = 8.2(4) x 10(6) M(-1) s(-1) and k(1)(Br) = 8.9(3) x 10(4) M(-1) s(-1) at 25.0 degrees C and mu = 1.0 M. The proposed rate-determining step is an electron transfer from XO(2)(-) to O(3) to form XO(2) and O(3)(-). Subsequent rapid reactions of O(3)(-) with general acids produce O(2) and OH. The OH radical reacts rapidly with XO(2)(-) to form a second XO(2) and OH(-). In the O(3)/ClO(2)(-) reaction, ClO(2) and ClO(3)(-) are the final products due to competition between the OH/ClO(2)(-) reaction to form ClO(2) and the OH/ClO(2) reaction to form ClO(3)(-). Unlike ClO(2), BrO(2) is not a stable product due to its rapid disproportionation to form BrO(2)(-) and BrO(3)(-). However, kinetic spectra show that small but observable concentrations of BrO(2) form within the dead time of the stopped-flow instrument. Bromine dioxide is a transitory intermediate, and its observed rate of decay is equal to half the rate of the O(3)/BrO(2)(-) reaction. Ion chromatographic analysis shows that O(3) and BrO(2)(-) react in a 1/1 ratio to form BrO(3)(-) as the final product. Variation of k(1)(X) values with temperature gives Delta H(++)(Cl) = 29(2) kJ mol(-1), DeltaS(++)(Cl) = -14.6(7) J mol(-1) K(-1), Delta H(++)(Br) = 54.9(8) kJ mol(-1), and Delta S(++)(Br) = 34(3) J mol(-1) K(-1). The positive Delta S(++)(Br) value is attributed to the loss of coordinated H(2)O from BrO(2)(-) upon formation of an [O(3)BrO(2)(-)](++) activated complex.     

Spectrophotometric Method for the Determination of Oxidative IonsWith Decoloring Reaction Using HCPCF

HCPCF is a color reagent for the determination of vanadium, zinc and magnesium, etc. To the best of our knowledge, no work on the decoloring reaction for analytical use of HCPCF for the determination of oxidative anions has been report. In this work, we found that some oxidative anions can oxidize HCPCF in acid medium, forming a colorless product. In addition, surfactant was used in this work, because of the low solubility of HCPCF in aqueous solutions. The purpose of this work is to establish a new, rapid and simple spectrophotometric method for the determination of NO2-, BrO3-,IO3-, IO4-and Cr2O7-based on the reaction between HCPCF and analytes in the presence of emulsion OP.     

Kinetic studies of the reactions of IO,BrO, and ClO with dimethylsulfide

The kinetics of the reactions of IO, BrO, and ClO with DMS have been investigated at 298 K and total pressures of 0.5–6.8 mbar He using the discharge flow-mass spectrometry technique to monitor the halogen oxide radicals. Rate coefficients of (8.8 ± 2.1) × 10^?15, (2.7 ? 0.5) × 10^?13 and (9.5 ± 2.0) × 10^?15 cm³ molecule^?1 s^?1 have been obtained for the reactions of IO, BrO, and ClO with DMS, respectively. The result for IO with DMS is in good agreement with two other recent studies on this reaction but is nearly three orders of magnitude slower than two earlier studies, one of which was from this laboratory. The earlier studies are now thought to be in error because of heterogeneous and secondary chemistry occurring in the systems investigated. The rate coefficient for BrO with DMS is in excellent agreement with a previously reported preliminary value from this laboratory. However, the rate coefficient for ClO with DMS is a factor of 4 lower than our previously determined value. The new data are considered more reliable in view of the much improved experimental technique in the present study. DMSO was detected as a product in all of these reactions. A semi-quantitative determination of the DMSO yield was only possible in the case of the reaction of IO with DMS where a yield of 84 ± 40% was found.     

离子色谱法测定纯净水中F~-,BrO_3~-等6种阴离子

建立阴离子分离柱离子色谱法测定纯净水中F~-,BrO_3~-,Cl~-,NO_2~-,Br~-,NO_3~- 6种微量阴离子的方法。以SH-AC-1型阴离子柱为分离柱,柱箱温度为35℃,以1.0 mmol/L Na_2CO_3为淋洗液,流量为1.5 mL/min。F~-,BrO_3~-,Cl~-,NO_2~-,Br~-,NO_3~-的线性范围分别为20~320,40~800,40~640,10~200,50~1 000,50~1 000μg/L,线性相关系数均大于0.999,检出限为0.7~7.5μg/L,加标回收率在95.0%~106.3%之间,测定结果的相对标准偏差为1.41%~4.27%(n=5)。该方法测定结果准确、可靠,操作简便、快速,适用于纯净水中BrO_3~-,F~-,Cl~-,NO_2~-,Br~-,NO_3~- 6种阴离子的测定。     

离子色谱法测定瓶(桶)装纯净水中痕量溴酸盐和亚硝酸盐的含量

采用离子色谱法同时测定瓶(桶)装纯净水中溴酸盐和亚硝酸盐的含量。水样经AG19-4mm保护柱及DIONEX AS19色谱柱分离,以不同浓度的氢氧化钾溶液为淋洗液,溴酸盐和亚硝酸盐得到很好的分离。BrO3-和NO2-分别在5.00～100.00μg.L-1和1.00～50.00μg.L-1范围内呈线性,检出限(3s/k)分别为0.08,0.14μg.L-1。方法用于瓶(桶)装水中溴酸盐和亚硝酸盐的测定,加标回收率在92.7%～98.4%之间,相对标准偏差(n=5)均小于5.0%。     

Separation and determination of selenium in rocks, marine sediments and plankton by direct evolution with the bromide-condensed phosphoric acid reagent

A new method is presented for the quantitative separation and determination of selenium by direct evolution with the bromide-condensed phosphoric acid reagent (Br(-)-CPA) from rocks, marine sediments and plankton. In the reaction with the Br(-1)-CPA, selenium(IV) and (VI) in the solid samples are evolved as selenium tetrabromide, and can be collected in an absorbing solution of 0.3M hydrochloric acid and 06M perchloric add (1:1), and then determined spectrophotometrically with 4-substituted o-phenylenediamines followed by the extraction of the resulting 5-substituted piazselenol into toluene. Elemental selenium and selenide do not react with the Br(-)-CPA, but can be determined after oxidation to selenite with potassium iodate. Therefore, successive distillations, the first with Br(-)-CPA and the second with IO(3)(-)-Br(-)-CPA, give a satisfactory means of diflerential determination of selenium(IV) and (VI), and elemental selenium and selenide. This method can be successfully applied for the separation of selenium in the neutron-activation analysis of standard rock samples, marine sediments and plankton, giving good and reliable results.     

On the spectroscopic and thermochemical properties of ClO, BrO, IO, and their anions

A coupled cluster composite approach has been used to accurately determine the spectroscopic constants, bond dissociation energies, and heats of formation for the X1(2)II(3/2) states of the halogen oxides ClO, BrO, and IO, as well as their negative ions ClO-, BrO-, and IO-. After determining the frozen core, complete basis set (CBS) limit CCSD(T) values, corrections were added for core-valence correlation, relativistic effects (scalar and spin-orbit), the pseudopotential approximation (BrO and IO), iterative connected triple excitations (CCSDT), and iterative quadruples (CCSDTQ). The final ab initio equilibrium bond lengths and harmonic frequencies for ClO and BrO differ from their accurate experimental values by an average of just 0.0005 A and 0.8 cm-1, respectively. The bond length of IO is overestimated by 0.0047 A, presumably due to an underestimation of molecular spin-orbit coupling effects. Spectroscopic constants for the spin-orbit excited X2(2)III(1/2) states are also reported for each species. The predicted bond lengths and harmonic frequencies for the closed-shell anions are expected to be accurate to within about 0.001 A and 2 cm-1, respectively. The dissociation energies of the radicals have been determined by both direct calculation and through use of negative ion thermochemical cycles, which made use of a small amount of accurate experimental data. The resulting values of D0, 63.5, 55.8, and 54.2 kcal/mol for ClO, BrO, and IO, respectively, are the most accurate ab initio values to date, and those for ClO and BrO differ from their experimental values by just 0.1 kcal/mol. These dissociation energies lead to heats of formation, DeltaH(f) (298 K), of 24.2 +/- 0.3, 29.6 +/- 0.4, and 29.9 +/- 0.6 kcal/mol for ClO, BrO, and IO, respectively. Also, the final calculated electron affinities are all within 0.2 kcal/mol of their experimental values. Improved pseudopotential parameters for the iodine atom are also reported, together with revised correlation consistent basis sets for this atom.     

New spot-test for silver(I) based on double iodide formation with bismuth(III)

The formation of an intense brownish-maroon or maroon-red product by the interaction of silver(I) and bismuth(III) solution in the presence of iodide forms the basis of a new and specific spot-test procedure for silver. The test is conducted on a spot plate with 2 or 3 drops of 2% potassium iodide solution, 1 drop of 1% bismuth(III) nitrate solution, and 1 drop of test solution. Limit of detection is 0.01 mug; limit of dilution is 1:5 x 10(6). Most cations and anions do not interfere. Only Tl(I), Cs, S(2)O(2-)(3), EDTA, pyridine, excess of thiourea, oxidizing ions (NO(-)(2), IO(-)(3), IO(-)(4), MnO(-)(4), BrO(-)(3), and S(2)O(2-)(8)) and ions such as Cl(-), Br(-), I(-), SCN(-), and N(-)(3) which cause precipitation of silver, interfere. The product formed is most probably Ag(2)BiI(5).     

离子色谱法测定饮用水中痕量溴酸盐

建立了一种利用离子色谱法测定饮用水中痕量溴酸盐(BrO<,3><'->)的方法.色谱条件为:IonPac AS19(250mm x4 mm)色谱柱分离,KOH 梯度淋洗,流速1.0 mL/min,抑制电导检测,外标法定量.BrO<,3><'->浓度在2.0～100μg/L范围内有良好的线性,检出限为0.3 ng/mL,...