The uptake of O3 on a salt film coating of MgCl2·6H2O at T = 254 and 295 K is studied in the range ([O3] = 2.5 × 1013–1.6 × 1014 cm–3) using a flow reactor with a movable insert and mass spectrometric recording. The time dependence of the uptake coefficient of the ozone at different O3 concentrations is obtained in the relative humidity range from zero to 24

This work is devoted to the analysis of the results obtained during the separation of the mass spectra of apamin and its complex after the deutero-hydrogen substitution of these molecules when leaving the electrospray ion source. The goal of the work was to determine the origin of the structural components identified in apamin and its complex. The separation method assumes that the substitution of labile hydrogen atoms with deuterium ones occurs independently, while charge carriers are retained independently too by various amino acid residues of a polypeptide with a specific structural form. This method also includes an indirect assessment of the contribution of natural isotopes to the measured data, without requiring knowledge of the elemental composition or other structural features of the biomolecule under study. Previously, we performed similar calculations by directly accounting for the contribution of natural isotopes. For apamin electrosprayed ions, after introducing a gas flow of ND3 into the molecular ion reactor of the mass spectrometer, three main components were identified, with contributions of approximately 57, 39, and 5

Using a flow reactor with a movable insert and mass-spectrometric control of the gas composition, methane soot samples are treated with O 3 and NO 2 reagents until the surface is completely poisoned. A solution of the initial methane soot in acetonitrile and solid products of its reaction with oxidizing reagents O 3 and NO 2 is analyzed using high-resolution mass spectrometry with an electrospray ion source and gas chromatography (GC)–mass spectrometry (MS) with electron ionization. It is established that the original soot contains a number of aromatic compounds, including polycyclic compounds, which are completely consumed in the reaction with these oxidizing agents. Compounds from the paraffin class remain inert with respect to NO 2 and O 3 . The products of the ozonization of prenitrated soot are the same as those of simple ozonation. The number of ozonation products is much higher than similar nitration products. This is the reason for the reactivity of nitrated soot with respect to the ozone uptake.

The uptake of N 2 O 5 on a methane soot coating at T = 255 and 298 K in the range of [N 2 O 5 ] = 1.3 × 10 12 –3.3 × 10 13 cm −3 is studied using a flow reactor with a movable insert and mass spectrometric detection. A series of dependences of the uptake coefficient on the exposure time of the coating to the reagent gas at the given concentrations are obtained. A multistage uptake mechanism is proposed in the framework of the Langmuir conception of adsorption, which explains the complex time dependence of the uptake coefficient and the shape of its dependence on the concentration. Based on the proposed mechanism, a number of elementary parameters are obtained from an analytical description of the experimental data, which make it possible to model the uptake coefficient at arbitrary N 2 O 5 concentrations and temperatures.

С использованием проточного реактора с подвижной вставкой и масс-спектрометрическим контролем газового состава была проведена обработка образцов метановой сажи реагентами O 3 и NO 2 до момента полного прекращения их захвата поверхностью. Анализ растворов исходной метановой сажи и твердых продуктов ее реакции с окисляющими реагентами O 3 и NO 2 в ацетонитриле проводился с использованием масс-спектрометрии высокого разрешения с электроспрейным ионным источником и газовой хроматографии–масс-спектрометрии с электронной ионизацией. Установлено, что исходная сажа содержит ряд ароматических соединений, включая и полициклические, которые полностью расходуются в реакции с этими окислителями. Соединения из класса парафинов остаются инертными по отношению к NO 2 и О 3 . В качественном отношении продукты нитрования и озонирования одинаковы как по своему составу, так и по содержанию основных функциональных групп. Количество продуктов озонирования значительно больше аналогичных продуктов нитрования. Это является причиной высокой реакционной способности нитрованной сажи по отношению к захвату озона.

The uptake of O3 (1 × 1012–5× 1013 cm−3) on a methane soot coating preliminarily exposed to N2O5, is studied using a flow reactor with a movable insert. Based on the dependence of the ozone uptake coefficient on the exposure time and O3 concentration, the uptake mechanism is established and a number of elementary parameters are obtained that describe the uptake process at arbitrary O3 concentrations. Based on the Langmuir representation of adsorption, a model description of the uptake on soot under conditions of the competitive adsorption of O3/NOx, where NOx = NO2 and N2O5, taking into account the multistage uptake process, is proposed. Based on the developed model and elementary parameters describing the uptake of O3, NO2, and N2O5 on a fresh soot surface, as well as the uptake of ozone on a surface pretreated with NO2 and N2O5, numerical estimates were made of the additional contributions to the ozone uptake for two real scenarios of the O3/NOx ratio. For an industrial region in winter, when the ozone concentration is minimal (10 ppb O3, 17 ppb NO2, and 4 ppb N2O5), the additional integral contribution to the uptake of O3 on the reaction products of NO2 with soot is 68

Исследован захват О 3 (1 · 10 12 –5 · 10 13 см −3 ) на покрытии из метановой сажи, предварительно обработанном N 2 O 5 , с использованием проточного реактора с подвижной вставкой. Исходя из зависимости коэффициента захвата озона от времени экспозиции и от концентрации [O 3 ], установлен механизм захвата и получен ряд элементарных параметров, описывающих процесс захвата при произвольных концентрациях О 3 . На базе ленгмюровского представления адсорбции предложено модельное описание захвата на покрытии из сажи в условиях конкурентной адсорбции O 3 /NO x , где NO x = NO 2 и N 2 O 5 , с учетом многостадийности процесса захвата. На основании разработанной модели и элементарных параметров, описывающих захват О 3 , NO 2 и N 2 O 5 на свежем сажевом покрытии, а также захват озона на поверхности, предварительно обработанной NO 2 и N 2 O 5 , проведены численные оценки дополнительных каналов захвата озона для двух реальных сценариев соотношения концентраций O 3 /NO 2 и O 3 /N 2 O 5 . Для промышленно развитого региона в зимнее время, когда концентрация озона минимальна (10 ppb O 3 , 17 ppb NO 2 и 4 ppb N 2 O 5 ), дополнительный интегральный вклад в захват O 3 на продуктах реакции NO 2 с сажей составляет 68%, а в случае N 2 O 5 – 3.6%. Для того же региона летом при максимальной концентрации озона (36 ppb O 3 , 17 ppb NO 2 и 4 ppb N 2 O 5 ) аналогичные вклады будут составлять 20% и 1% соответственно. Причины такого различия обсуждаются.

A laser plasma ion source was used to ionize volatile organic compounds in a gas sample. The plasma was generated on a metal target in the intermediate vacuum region of ~0.3 Torr using a pulsed Nd:YAG laser with a wavelength of 1 μm. The resulting ions mass spectra were acquired using orthogonal time-of-flight mass spectrometer (O-TOF MS). When using a copper target, the ions formed are simple complexes (CuM+ ) of copper ions with organic molecules. The possibility of online identification of trace amounts of alkanes in nitrogen and air, with a detection limit of ~10 ppb, was demonstrated. The ionization efficiency of volatile organic compounds through the formation of clusters with metal ions is 10-4 in terms of the quasimolecular complex ions. The rate constants of ion-molecular reactions of copper ions with octane and water molecules in nitrogen and air are estimated.

Using a flow tube reactor with a movable insert and mass spectrometric recording, the uptake of O3 is established and investigated (6.6 × 1012–4.3 × 1013 cm–3) on a methane soot coating preexposed to the NO2 flux until the complete cessation of its uptake. Based on the dependence of the uptake coefficient on the exposure time and concentration of O3, an analytical representation of the uptake coefficient γ(t) = γ (t = 0) exp(–krθt), γ (t = 0) = γ0/(1 + KL[O3]), expressed in terms of elementary parameters, such as the amplitude value of the uptake coefficient γ0, Langmuir coefficient KL, and rate constant kr of monomolecular decay, is proposed. Analytical dependences are obtained under the assumption of an uptake mechanism that occurs through a reaction on the surface with an adsorbed particle. Based on these parameters, as well as the parameters for the uptake of NO2 and O3 on a fresh surface of methane soot, a model of the uptake of O3 and NO2 under the conditions of their competitive adsorption is discussed. The influence of the additional sink channel О3 on solid products of the uptake of NO2 on the value of the uptake coefficients and the characteristic soot processing time at the typical surface air concentrations of these reagent gases is estimated.

The uptake of ozone on methane flame soot has been studied in a flow reactor with a mobile insert coupled to a beam-sampling mass spectrometer at T = 256 and 295 K in the range of [O3] = 1.1 × 1012–4.1 × 1013 cm–3. The uptake was found to be multistage. Both the fast and slow stages of the uptake occur by the reaction mechanism on the surface with an adsorbed particle. Based on the Langmuir concept of adsorption, the uptake coefficient can be represented as γ = γ0/(1 + KL[O3]) with the γ0 and KL parameters for the first stage of the uptake γ0(295 K) = (6.6 ± 0.4) × 10–4 and γ0(256 K) = (8.1 ± 2.6) × 10–4, KL(295 K) = (7 ± 1) × 10–14 and KL(256 K) = (22 ± 9) × 10–14 cm3. The same parameters for the second stage are γ0(295 K) = (1.3 ± 0.2) × 10–4 and γ0(256 K) = (1.2 ± 0.5) × 10–4, KL(295 K) = (11 ± 2) × 10–14 and KL(256 K) = (28 ± 13) × 10–14 cm3. The rate constant of the unimolecular decomposition of the surface complex with the adsorbed ozone molecule was evaluated from the dependence of γ on the exposure time of the soot coating to the О3 flow: kr(295 K) = (0.39 ± 0.01) s–1, kr(256 K) = (0.15 ± 0.01) × 10–2 s–1 for the fast stage and kr(295 K) = (2.8 ± 0.1) × 10–2 s–1, kr(256 K) = (1 ± 0.04) × 10–2 s–1 for the slow stage. In the limit of low concentrations, γ depends only weakly on [O3] and T due to the relation γ0 ∼ kr/kd and close values of the activation energy of the reaction rate constant kr and the heat of adsorption of the desorption rate constant kd.

We report the results of a study of the effect of a supersonic gas jet on the formation and extraction of analyzed ions from a liquid supplied through a capillary to an RF quadrupole connected to a time-of-flight mass spectrometer with orthogonal ion injection. The supersonic gas jet is formed inside a cylindrical channel and passes through an electron ionization ion source. The results confirm the prospects of using a supersonic jet to creating a high-performance ion source from a liquid supplied to the vacuum region under the pressure of ~10–4 Torr.

The article describes the results of a study of the effect of a supersonic gas jet on the formation and extraction of deuterium-substituted ions from a liquid supplied through a capillary into a radio-frequency quadrupole coupled to a time-of-flight mass spectrometer with orthogonal ion injection. The supersonic gas jet is formed inside a cylindrical channel and passes through an electron ionization ion source. With an increase in the flow rate of the a solution, there was no steady trend in the relative contributions of deuterated ions from the liquid phase. The results confirm the prospects of using a supersonic jet to create a high-performance source of deuterium-substituted ions from a liquid supplied into a vacuum region under residual pressure of 10–4 Torr without using strong electric fields.

В статье описываются результаты исследования воздействия сверхзвуковой газовой струи, сформированной внутри цилиндрического канала и пропущенной через источник электронной ионизации, на выход дейтерозамещённых ионов из жидкости, подаваемой через капилляр внутрь радиочастотного квадруполя, сопряжённого с времяпролётным масс-спектрометром с ортогональным вводом ионов. При увеличении потока анализируемого раствора не наблюдалось явной зависимости изменения относительных вкладов дейтерированных ионов в жидкой фазе от скорости подачи образца. Полученные результаты подтверждают перспективность использования сверхзвуковой струи для создания высокоэффективного источника дейтерозамещённых ионов из растворов при остаточном давлении на уровне 10-4 Торр и в отсутствие сильных электрических полей. The article describes the results of a study of the effect of a supersonic gas jet on the formation and extraction of the deuterosubstituted ions from a liquid supplied through a capillary into a radio-frequency quadrupole coupled to a time-of-flight mass spectrometer with orthogonal ion injection the supersonic gas jet being formed inside a cylindrical channel and passed through the ion source with electron ionization. With an increase in the flow of the analyzed solution, there was no steady trend in the relative contributions of deuterated ions from liquid phase. The results confirm the prospects of using a supersonic jet to create a high-performance source of deuterosubstituted ions from a liquid supplied into a vacuum region under conditions of 10-4 Torr residiual pressure and absence of strong electric fields.

В статье описываются результаты исследования воздействия сверхзвуковой газовой струи, сформированной внутри цилиндрического канала и пропущенной через источник электронной ионизации, на образование и экстракцию анализируемых ионов из жидкости, подаваемой через капилляр внутрь радиочастотного квадруполя, который сопряжён с времяпролётным масс-спектрометром с ортогональным вводом ионов. Полученные результаты подтверждают перспективность использования сверхзвуковой струи для создания высокоэффективного источника ионов из жидкости, подаваемой в область вакуума 10-4 Торр.

A soot coating was treated with NO3 radicals using a flow reactor having a movable insert and coupled to a mass spectrometer for kinetic studies; the treatment was performed until the surface completely stopped to trap the radicals. The chromatographic and mass spectrometry analyses of the composition of the original methane soot and the solid products of its reaction with the gas-phase NO3 oxidant showed that the main products of this heterogeneous reaction were phthalic acid derivatives, paraffins, and acetophenones. The untreated soot contained arenes (up to four-membered aromatic molecules). The nitro compounds were not detected in the original soot and the products of its treatment with NO3 radicals.