δ15N of soil N and plants in a N‐saturated,subtropical forest of southern China

We investigated the δ¹⁵N profile of N (extractable NH, NO, and organic N (EON)) in the soil of a N‐saturated subtropical forest. The order of δ¹⁵N in the soil was EON > NH > NO. Although the δ¹⁵N of EON had been expected to be similar to that of bulk soil N, it was higher than that of bulk soil N by 5‰. The difference in δ¹⁵N between bulk soil N and EON (Δ¹⁵N_bulk‐EON) was correlated significantly with the soil C/N ratio. This correlation implies that carbon availability, which determines the balance between N assimilation and dissimilation of soil microbes, is responsible for the high δ¹⁵N of EON, as in the case of soil microbial biomass δ¹⁵N. A thorough δ¹⁵N survey of available N (NH, NO, and EON) in the soil profiles from the organic layer to 100 cm depth revealed that the δ¹⁵N of the available N forms did not fully overlap with the δ¹⁵N of plants. This mismatch in δ¹⁵N between that of available N and that of plants reflects apparent isotopic fractionation during N uptake by plants, emphasizing the high N availability in this N‐saturated forest. Copyright © 2010 John Wiley & Sons, Ltd.     

The natural abundance of 15N in plant and soil‐available N indicates a shift of main plant N resources to NO from NH along the N leaching gradient

To investigate which of ammonium (NH) or nitrate (NO) is used by plants at gradient sites with different nitrogen (N) availability, we measured the natural abundance of ¹⁵N in foliage and soil extractable N. Hinoki cypress (Chamaecyparis obtusa Endlicher) planted broadly in Japan was selected for use in this study. We estimated the source proportion of foliar N (NH vs. NO) quantitatively using mass balance equations. The results showed that C. obtusa used mainly NH in N‐limited forests, although the dependence of C. obtusa on NO was greater in other NO‐rich forests. We regarded dissolved organic N (DON) as a potential N source because a previous study demonstrated that C. obtusa can take up glycine. Thus we added DON to our mass balance equations and calculated the source proportion using an isotope‐mixing model (IsoSource model). The results still showed a positive correlation between the calculated plant N proportion of NO and the NO pool size in the soil, indicating that high NO availability increases the reliance of C. obtusa on NO. Our data suggest the shift of the N source for C. obtusa from NH to NO according to the relative availability of NO. They also show the potential of the foliar δ¹⁵N of C. obtusa as an indicator of the N status in forest ecosystems with the help of the δ¹⁵N values of soil inorganic and organic N. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of relative sensitivity factors during secondary ion sputtering of silicate glasses by Au+, Au and Au ions

In recent years, Au‐cluster ions have been successfully used for organic analysis in secondary ion mass spectrometry. Cluster ions, such as Au and Au, can produce secondary ion yield enhancements of up to a factor of 300 for high mass organic molecules with minimal sample damage. In this study, the potential for using Au⁺, Au and Au primary ions for the analysis of inorganic samples is investigated by analyzing a range of silicate glass standards. Practical secondary ion yields for both Au and Au ions are enhanced relative to those for Au⁺, consistent with their increased sputter rates. No elevation in ionization efficiency was found for the cluster primary ions. Relative sensitivity factors for major and trace elements in the standards showed no improvement in quantification with Au and Au ions over the use of Au⁺ ions. Higher achievable primary ion currents for Au⁺ ions than for Au and Au allow for more precise analyses of elemental abundances within inorganic samples, making them the preferred choice, in contrast to the choice of Au and Au for the analysis of organic samples. The use of delayed secondary ion extraction can also boost secondary ion signals, although there is a loss of overall sensitivity. Copyright © 2009 John Wiley & Sons, Ltd.     

A fragmentation study of dihydroquercetin using triple quadrupole mass spectrometry and its application for identification of dihydroflavonols in Citrus juices

A mass spectrometric method using electrospray ionization with triple quadrupole and quadrupole time‐of‐flight hybrid (Q‐Tof) mass spectrometry has been applied to the structural characterization of dihydroflavonols. This family of compounds has been studied by liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the first time in this work. A comprehensive study of the product ion MS spectra of the [M+H]⁺ ion of a commercially available standard has been performed. The most useful fragmentations in terms of structural identification are those that involve cleavage of the C‐ring, resulting in diagnostic ions of dihydroflavonol family: ^1,3A, ^1,2B, ^1,2B‐CO, ^0,2A, ^0,2A‐H₂O, ^0,2A‐CO, and ^0,2A‐H₂O‐CO, that allow the characterization of the substituents in the A‐ and B‐rings. In addition to those ions, other product ions due to losses of H₂O and CO molecules from the Y ion were observed. Their fragmentation mechanisms and ion structures have been proposed. The established fragmentation patterns have been used to successfully identity three dihydroflavonols found in tangerine juices for the first time. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples

BaSO₄ precipitated from mixed salt solutions by common techniques for SO isotopic analysis may contain quantities of H₂O and NO that introduce errors in O isotope measurements. Experiments with synthetic solutions indicate that δ¹⁸O values of CO produced by decomposition of precipitated BaSO₄ in a carbon reactor may be either too low or too high, depending on the relative concentrations of SO and NO and the δ¹⁸O values of the H₂O, NO, and SO. Typical δ¹⁸O errors are of the order of 0.5 to 1‰ in many sample types, and can be larger in samples containing atmospheric NO, which can cause similar errors in δ¹⁷O and Δ¹⁷O. These errors can be reduced by (1) ion chromatographic separation of SO from NO, (2) increasing the salinity of the solutions before precipitating BaSO₄ to minimize incorporation of H₂O, (3) heating BaSO₄ under vacuum to remove H₂O, (4) preparing isotopic reference materials as aqueous samples to mimic the conditions of the samples, and (5) adjusting measured δ¹⁸O values based on amounts and isotopic compositions of coexisting H₂O and NO. These procedures are demonstrated for SO isotopic reference materials, synthetic solutions with isotopically known reagents, atmospheric deposition from Shenandoah National Park, Virginia, USA, and sulfate salt deposits from the Atacama Desert, Chile, and Mojave Desert, California, USA. These results have implications for the calibration and use of O isotope data in studies of SO sources and reaction mechanisms. Published in 2008 by John Wiley & Sons, Ltd.     

Comparison of the silver nitrate and bacterial denitrification methods for the determination of nitrogen and oxygen isotope ratios of nitrate in surface water

Nitrogen (N) and oxygen (O) isotope ratios of NO are often used to trace dominant NO pollution sources in water. Both the silver nitrate (AgNO₃) method and the bacterial denitrification method are frequently used analytical techniques to determine δ¹⁵N‐ and δ¹⁸O‐NO in aqueous samples. The AgNO₃ method is applicable for freshwater and requires a concentration of 100–200 µmol of NO for isotope determination. The bacterial denitrification method is applicable for seawater and freshwater and for KCl extracts of soils with a NO concentration as low as 1 µmol. We have carried out a thorough method comparison using 42 real surface water samples having a wide range of δ¹⁵N‐ and δ¹⁸O‐NO values and NO concentrations. Various correction pairs using three international references and blanks were used to correct raw δ¹⁵N‐ and δ¹⁸O‐NO values. No significant difference between the corrected data was observed when using various correction pairs for each analytical method. Both methods also showed excellent repeatability with high intraclass correlation coefficients (ICC). The ICC of the AgNO₃ method was 0.992 for δ¹⁵N and 0.970 for δ¹⁸O. The ICC of the bacterial denitrification method was 0.995 for δ¹⁵N and 0.954 for δ¹⁸O. Moreover, a positive linear relationship with a high correlation coefficient (r ≥ 0.88) between the two methods was found for δ¹⁵N‐ and δ¹⁸O‐NO. The comparability of the methods was assessed by the Bland‐Altman technique using 95% limits of agreement. The average difference between results obtained by the bacterial denitrification and the AgNO₃ method for δ¹⁵N was ?1.5‰ with 95% limits of agreement ?3.6 and +0.5‰. For δ¹⁸O this was +2.0‰, with 95% limits of agreement ?3.3 and +7.3‰. We found that for δ¹⁵N and for δ¹⁸O, 97% of the differences fell within these 95% limits of agreement. In conclusion, the AgNO₃ and the bacterial denitrification methods are highly correlated and statistically interchangeable. Copyright © 2010 John Wiley & Sons, Ltd.     

Contribution of atmospheric nitrate to stream‐water nitrate in Japanese coniferous forests revealed by the oxygen isotope ratio of nitrate

Evaluation of the openness of the nitrogen (N) cycle in forest ecosystems is important in efforts to improve forest management because the N supply often limits primary production. The use of the oxygen isotope ratio (δ¹⁸O) of nitrate is a promising approach to determine how effectively atmospheric nitrate can be retained in a forest ecosystem. We investigated the δ¹⁸O of nitrate in stream water in order to estimate the contribution of atmospheric NO in stream‐water NO (f_atm) from 26 watersheds with different stand ages (1–87 years) in Japan. The stream‐water nitrate concentrations were high in young forests whereas, in contrast, old forests discharged low‐nitrate stream water. These results implied a low f_atm and a closed N cycle in older forests. However, the δ¹⁸O values of nitrate in stream water revealed that f_atm values were higher in older forests than in younger forests. These results indicated that even in old forests, where the discharged N loss was small, atmospheric nitrate was not retained effectively. The steep slopes of the studied watersheds (>40°) which hinder the capturing of atmospheric nitrate by plants and microbes might be responsible for the inefficient utilization of atmospheric nitrate. Moreover, the unprocessed fraction of atmospheric nitrate in the stream‐water nitrate in the forest (f_unprocessed) was high in the young forest (78%), although f_unprocessed was stable and low for other forests (5–13%). This high f_unprocessed of the young forest indicated that the young forest retained neither atmospheric NO nor soil NO effectively, engendering high stream‐water NO concentrations. Copyright © 2010 John Wiley & Sons, Ltd.     

The reactions of a series of terpenoids with H(3) O(+) , NO(+) and O 2+ studied using selected ion flow tube mass spectrometry

The reactions of H₃O⁺, NO⁺ and O with twelve terpenoids and one terpene, all of which occur naturally in plants and which possess important smell and flavourant properties, were characterized using Selected Ion Flow Tube Mass Spectrometry (SIFT‐MS). The H₃O⁺ reactions resulted primarily in the formation of the proton transfer product and occasionally in a water elimination product. The NO⁺ reactions instead generated the charge transfer product or NO⁺ adducts, and occasionally alkyl fragments, or resulted in hydride abstraction. Reaction with O caused a higher fragmentation of the terpenoids with the molecular ion being the minor product of most reactions. Identification and quantification of each compound in complex mixtures are probably possible in most cases using the H₃O⁺ and/or NO⁺ precursors while O may be useful for isomer discrimination. Our data suggests that SIFT‐MS may be a useful tool for the rapid analysis of these compounds in plants and derived foodstuffs. Copyright © 2010 John Wiley & Sons, Ltd.     

Experimental and theoretical investigation on binary anionic clusters of AlmBi

Al_mBi (m = 1–12; n = 1–4) binary cluster anions are generated by laser ablation of a sample composed of Al and Bi, and studied by reflectron time‐of‐flight mass spectrometry (RTOF‐MS) in the gas phase. Some clusters with magic numbers are present in the mass spectrum. The structures of Al_mBi (m + n ≤7) clusters are investigated with the density functional theory (DFT) method and the most likely structures are obtained. The calculations of the binding energy (BE), energy gain (Δ) and HOMO‐LUMO gaps confirm that the Al₂Bi cluster has a very stable structure, which agrees well with the experimental results. It is further established that Al₂Bi can be considered as a gas‐phase Zintl analogue that follows Wade's rules and is the analogue of Ga₂Bi and Sn Zintl ions. Copyright © 2009 John Wiley & Sons, Ltd.     

Laser ablation of ternary As‐S‐Se glasses and time‐of‐flight mass spectrometric study

Ternary chalcogenide As‐S‐Se glasses, important for optics, computers, material science and technological applications, are often made by pulsed laser deposition (PLD) technology but the plasma composition formed during the process is mostly unknown. Therefore, the formation of clusters in a plasma plume from different glasses was followed by laser desorption ionization (LDI) or laser ablation (LA) time‐of‐flight mass spectrometry (TOF MS) in positive and negative ion modes. The LA of glasses of different composition leads to the formation of a number of binary As_pS_q, As_pSe_r and ternary As_pS_qSe_r singly charged clusters. Series of clusters with the ratio As:chalcogen = 3:3 (As₃S, As₃S₂Se⁺, As₃SSe), 3:4 (As₃S, As₃S₃Se⁺, As₃S₂Se, As₃SSe, As₃Se), 3:1 (As₃S⁺, As₃Se⁺), and 3:2 (As₃S, As₃SSe⁺, As₃Se), formed from both bulk and PLD‐deposited nano‐layer glass, were detected. The stoichiometry of the As_pS_qSe_r clusters was determined via isotopic envelope analysis and computer modeling. The structure of the clusters is discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Adaptation of a proton transfer reaction mass spectrometer instrument to employ NO+ as reagent ion for the detection of 1,3‐butadiene in the ambient atmosphere

A proton transfer reaction mass spectrometer (PTR‐MS) instrument was adapted to employ NO⁺ as a chemical reagent ion without any hardware changes by switching the reagent ion source gas from water vapor to dry air. Ionization of dry air within the hollow cathode ion source generates a very intense source of NO⁺ with only a minor impurity of NO. The intensities of the primary NO⁺ reagent ion and the unwanted impurity NO are controllable and dependent on the operational conditions of the hollow cathode ion source. Ion source tuning parameters are described, which maintain an intense source of NO⁺ while keeping the impurity NO signal to less than 2% of the total reagent ion intensity. This method is applied to the detection of 1,3‐butadiene. NO⁺ reacts efficiently with 1,3‐butadiene via a charge exchange reaction to produce only the molecular ion, which is detected at m/z 54. Detection sensitivities of the order of 45 pptv for a 1‐s measurement of 1,3‐butadiene are demonstrated. We present the first real‐time on‐line sub parts per billion measurement of 1,3‐butadiene in the ambient atmosphere. The only likely interference is from 1,2‐butadiene. Concurrent measurements of benzene are provided and suggest that the vehicular emissions are the predominant source of 1,3‐butadiene in a suburban Boston area monitoring location. Copyright © 2009 John Wiley & Sons, Ltd.     

Evidence for the production of NO and N2O in two contrasting subsoils following the addition of synthetic cattle urine

Nitrogenous materials can be transferred out of the topsoil, either vertically to a greater depth, or in lateral pathways to surface waters, and they may also become transformed, with the potential of generating environmentally active agents. We measured the production of NO and N₂O in two contrasting subsoils (70 to 90 cm): one poorly drained and the other freely drained and compared this with the topsoil (0 to 20 cm) of the corresponding soils. The soils were incubated aerobically in jars with subtreatments of either synthetic cattle urine or deionised water and sampled at intervals up to 34 days. ¹⁵N‐NO was used to determine the processes responsible for NO and N₂O production. The headspace was analysed for the concentrations of N₂O, NO and CO₂ and ¹⁵N enrichment of N₂O. The soil samples were extracted and analysed for NO, NO and NH, and the ¹⁵N enrichment of the extracts was measured after conversion into N₂O and N₂. The study demonstrated the potential for NO, N₂O and NO to be generated from subsoils in laboratory incubations. Differences in these N dynamics occurred due to subsoil drainage class. In the freely drained subsoil the rates of NO and NO production were higher than those observed for the corresponding topsoil, with mean maximum production rates of 3.5 µg NO‐N g⁻¹ dry soil on day 16 and 0.12 µg NO‐N g⁻¹ dry soil on day 31. The calculated total losses of N₂O‐N as percentages of the applied synthetic urine N were 0.37% (freely drained subsoil), 0.24% (poorly drained subsoil), 0.43% (freely drained topsoil) and 2.09% (poorly drained topsoil). The calculated total losses of NO‐N as percentages of the applied synthetic urine N were 1.53% (freely drained subsoil), 0.02% (poorly drained subsoil), 0.25% (freely drained topsoil) and 0.08% (poorly drained topsoil). Copyright © 2010 John Wiley & Sons, Ltd.     

Charge stripping C

Measurements of the translational energy loss accompanying the charge-stripping reactions M⁺+N→M²⁺+N+e⁻ and M²⁺+N→M³⁺+N+e⁻ have been performed for C, C and C, C respectively. The energy nesessary to remove the second electron from Buckminsterfullerene was determined, Q=IE(C→C=12.25±0.5 eV.     

Laser ablation of AgSbS2 and cluster analysis by time‐of‐flight mass spectrometry

Thin films of AgSbS₂ are important for phase‐change memory applications. This solid is deposited by various techniques, such as metal organic chemical vapour deposition or laser ablation deposition, and the structure of AgSbS₂(s), as either amorphous or crystalline, is already well characterized. The pulsed laser ablation deposition (PLD) of solid AgSbS₂ is also used as a manufacturing process. However, the processes in plasma have not been well studied. We have studied the laser ablation of synthesized AgSbS₂(s) using a nitrogen laser of 337 nm and the clusters formed in the laser plume were identified. The ablation leads to the formation of various single charged ternary Ag_pSb_qS_r clusters. Negatively charged AgSbS, AgSb₂S, AgSb₂S, AgSb₂S and positively charged ternary AgSbS⁺, AgSb₂S⁺, AgSb₂S, AgSb₂S clusters were identified. The formation of several singly charged Ag⁺, Ag, Ag, Sb, Sb, S ions and binary Ag_pS_r clusters such as AgSb, Ag₃S^?, SbS (r = 1–5), Sb₂S^?, Sb₂S, Sb₃S (r = 1–4) and AgS, SbS⁺, SbS, Sb₂S⁺, Sb₂S, Sb₃S (r = 1–4), AgSb was also observed. The stoichiometry of the clusters was determined via isotopic envelope analysis and computer modeling. The relation of the composition of the clusters to the crystal structure of AgSbS₂ is discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

The 18O signature of biogenic nitrous oxide is determined by O exchange with water

To effectively mitigate emissions of the greenhouse gas nitrous oxide (N₂O) it is essential to understand the biochemical pathways by which it is produced. The ¹⁸O signature of N₂O is increasingly used to characterize these processes. However, assumptions on the origin of the O atom and resultant isotopic composition of N₂O that are based on reaction stoichiometry may be questioned. In particular, our deficient knowledge on O exchange between H₂O and nitrogen oxides during N₂O production complicates the interpretation of the ¹⁸O signature of N₂O. Here we studied O exchange during N₂O formation in soil, using a novel combination of ¹⁸O and ¹⁵N tracing. Twelve soils were studied, covering soil and land‐use variability across Europe. All soils demonstrated the significant presence of O exchange, as incorporation of O from ¹⁸O‐enriched H₂O into N₂O exceeded their maxima achievable through reaction stoichiometry. Based on the retention of the enrichment ratio of ¹⁸O and ¹⁵N of NO into N₂O, we quantified O exchange during denitrification. Up to 97% (median 85%) of the N₂O‐O originated from H₂O instead of from the denitrification substrate NO. We conclude that in soil, the main source of atmospheric N₂O, the ¹⁸O signature of N₂O is mainly determined by H₂O due to O exchange between nitrogen oxides and H₂O. This also challenges the assumption that the O of N₂O originates from O₂ and NO, in ratios reflecting reaction stoichiometry. Copyright © 2008 John Wiley & Sons, Ltd.     

Quantification of methane in humid air and exhaled breath using selected ion flow tube mass spectrometry

In selected ion flow tube mass spectrometry, SIFT‐MS, analyses of humid air and breath, it is essential to consider and account for the influence of water vapour in the media, which can be profound for the analysis of some compounds, including H₂CO, H₂S and notably CO₂. To date, the analysis of methane has not been considered, since it is known to be unreactive with H₃O⁺ and NO⁺, the most important precursor ions for SIFT‐MS analyses, and it reacts only slowly with the other available precursor ion, O. However, we have now experimentally investigated methane analysis and report that it can be quantified in both air and exhaled breath by exploiting the slow O/CH₄ reaction that produces CH₃O ions. We show that the ion chemistry is significantly influenced by the presence of water vapour in the sample, which must be quantified if accurate analyses are to be performed. Thus, we have carried out a study of the loss rate of the CH₃O analytical ion as a function of sample humidity and deduced an appropriate kinetics library entry that provides an accurate analysis of methane in air and breath by SIFT‐MS. However, the associated limit of detection is rather high, at 0.2 parts‐per‐million, ppm. We then measured the methane levels, together with acetone levels, in the exhaled breath of 75 volunteers, all within a period of 3 h, which shows the remarkable sample throughput rate possible with SIFT‐MS. The mean methane level in ambient air is seen to be 2 ppm with little spread and that in exhaled breath is 6 ppm, ranging from near‐ambient levels to 30 ppm, with no significant variation with age and gender. Methane can now be included in the wide ranging analyses of exhaled breath that are currently being carried out using SIFT‐MS. Copyright © 2010 John Wiley & Sons, Ltd.     

Laser desorption ionization time‐of‐flight mass spectrometric study of binary As‐Se glasses

Binary chalcogenide As‐Se glasses and their thin films are important for optics, computers, materials science and technological applications. To increase understanding of the properties of thin films fabricated by plasma deposition techniques, more information concerning the physics of plasma plume is needed. In this study the formation of clusters in plasma plume from different As‐Se glasses by laser desorption ionization (LDI) or laser ablation (LA) was studied by time‐of‐flight mass spectrometry (TOF MS) in positive and negative ion modes. Formation of a number of As_pSe_q singly charged clusters As₃Se (q = 1–5), AsSe (q = 1–3), As₂Se (q = 2–4), and As₃Se (q = 2–5) was found from As‐Se glasses with the molar ratio As:Se in the range from 1:2 to 7:3. The stoichiometry of the As_pSe_q clusters was determined via isotopic envelope analysis and computer modeling. The structure of the clusters is proposed and the relationship to the structure of the parent glasses, as also suggested by Raman scattering spectra, is discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Experimental and theoretical investigation on binary semiconductor clusters of B/Si and Al/Si

ASi (A = B and Al; n = 1–6) binary cluster anions were generated by laser ablation of samples composed of mixtures of Si and A (A = B and Al), and studied in the gas phase by tandem time‐of‐flight mass spectrometry. Some abundant ions are present in the mass spectrum, indicating that the clusters with these ions have stable structures. The structures of ASi clusters were investigated theoretically by the density functional theory (DFT) method and the energetically lowest‐lying structures were obtained. The binary clusters BSi and AlSi, with the same number of n, share different geometric structures except for ASi with n = 1 and 6, which have the same geometric structures in the ground state. For all the anionic clusters ASi, the lower spin state is lower in energy than the higher spin state in their optimized structures except for the linear ASi^? anions, for which the triplet state is lower in energy than the singlet. Calculations of the bonding energy (BE), energy gain (Δ) and HOMO‐LUMO energy gaps confirm that the cluster ASi has a very stable structure, which agrees well with the experimental results. Copyright © 2007 John Wiley & Sons, Ltd.     

Energy‐resolved depth profiling of metal‐polymer interfaces using dynamic quadrupole secondary ion mass spectrometry

Quadrupole secondary ion mass spectrometry (qSIMS) characterization of a metallized polypropylene film used in the manufacturing of capacitors has been performed. Ar⁺ primary ions were used to preserve the oxidation state of the surface. The sample exhibits an incomplete metallization that made it difficult to determine the exact location of the metal‐polymer interface due to the simultaneous contribution of ions with identical m/z values from the metallic and the polymer layers. Energy filtering by means of a 45° electrostatic analyzer allowed resolution of the metal‐polymer interface by selecting a suitable kinetic energy corresponding to the ions generated in the metallized layer but not from the polymer. Under these conditions, selective analyses of isobaric interferences such as ²⁷Al⁺ and ²⁷C₂H or ⁴³AlO⁺ and ⁴³C₃H have been successfully performed. Copyright © 2009 John Wiley & Sons, Ltd.     

Demonstration of high‐precision continuous measurements of water vapor isotopologues in laboratory and remote field deployments using wavelength‐scanned cavity ring‐down spectroscopy (WS‐CRDS) technology

This study demonstrates the application of Wavelength‐Scanned Cavity Ring‐Down Spectroscopy (WS‐CRDS) technology which is used to measure the stable isotopic composition of water. This isotopic water analyzer incorporates an evaporator system that allows liquid water as well as water vapor to be measured with high precision. The analyzer can measure HO, HO and HD¹⁶O content of the water sample simultaneously. The results of a laboratory test and two field trials with this analyzer are described. The results of these trials show that the isotopic water analyzer gives precise, accurate measurements with little or no instrument drift for the two most common isotopologues of water. In the laboratory the analyzer has a precision of 0.5 per mil for δD and 0.1 per mil for δ¹⁸O which is similar to the precision obtained by laboratory‐based isotope ratio mass spectrometers. In the field, when measuring vapor samples, the analyzer has a precision of 1.0 per mil for δD and 0.2 per mil for δ¹⁸O. These results demonstrate that the isotopic water analyzer is a powerful tool that is appropriate for use in a wide range of applications and environments. Copyright © 2009 John Wiley & Sons, Ltd.