Precise thermal ionization mass spectrometric measurements of 142Nd/144Nd and 143Nd/144Nd isotopic ratios of Nd separated from geological standards by chromatographic methods

A chromatographic separation technique for ¹⁴²Nd/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd isotope ratio measurements is established and applied to the analyses of geological standards of basaltic compositions (BCR-2, BIR-1) using Isoprobe-T TIMS. The instrument was tested for reliability and reproducibility to measure Nd isotope composition using the synthetic standard JNdi-1. The techniques were also applied to a carbonatite lava sample, OL-6, Oldoinyo Lengai, to check the validity of method for carbonatite matrix. The isotope ratios of ¹⁴³Nd/¹⁴⁴Nd for synthetic Nd standard JNdi-1, geological standards BCR-2, BIR-1, and carbonatite lava sample OL-6 obtained by these methods are in good agreement with previously published data. The ¹⁴³Nd/¹⁴⁴Nd values for JNdi-1 and BCR-2 have an external precision of ±13 ppm and ±15 ppm (2σ), respectively. The JNdi-1 and BCR-2 data for ¹⁴²Nd/¹⁴⁴Nd has an external precision of ±12 ppm and ±8 ppm (2σ), respectively. The ¹⁴²Nd/¹⁴⁴Nd composition of the two geological standards BCR-2 and BIR-1 are indistinguishable from synthetic mono-element standard JNdi-1, and they all fall within the 12 ppm (2σ) envelope of external precision. The external reproducibility is sufficient to distinguish and resolve 20 ppm anomalies in ¹⁴²Nd/¹⁴⁴Nd values.     

Rapid and precise determination of Sr and Nd isotopic ratios in geological samples from the same filament loading by thermal ionization mass spectrometry employing a single-step separation scheme

Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr + REEs fractions were dissolved and loaded onto the same Re filament using 1 μL of 2 M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method.     

An evaluation of a single-step extraction chromatography separation method for Sm-Nd isotope analysis of micro-samples of silicate rocks by high-sensitivity thermal ionization mass spectrometry

A single-step separation scheme is presented for Sm–Nd radiogenic isotope system on very small samples (1–3 mg) of silicate rock. This method is based on Eichrom^® LN Spec chromatographic material and affords a straightforward separation of Sm–Nd from complex matrix with good purity and satisfactory blank levels, suitable for thermal ionization mass spectrometry (TIMS).This technique, characterized by high efficiency (single-step Sm–Nd separation) and high sensitivity (TIMS on NdO⁺ ion beam), is able to process rapidly (3–4 h), with low procedure blanks (<10 pg) and very small sample (1–3 mg). Replicate measurements by TIMS on ¹⁴³Nd/¹⁴⁴Nd ratios and Sm–Nd concentrations are presented for eleven international silicate rock reference materials, spanning a wide range of Sm–Nd contents and bulk compositions. The analytical results show a good agreement with recommended values within ±0.004% for the ¹⁴³Nd/¹⁴⁴Nd isotopic ratio and ±2% for Sm–Nd quantification at the 95% confidence level. It is noted that the uncertainty of this method is about 3 times larger than typical precision achievable with two-stage full separation followed by state-of-the-art conventional TIMS using Nd⁺ ion beams which require much larger amounts of Nd. Hence, our single-step separation followed by NdO⁺ ion beam technique is preferred to the analysis for microsamples.     

Isomeric yield ratios of 148Pm from the natSm(γ, x) and the natNd(p,xn) reactions

The independent isomeric yield ratios of ¹⁴⁸Pm from the ^natSm(γ, x) reaction at the end-point bremsstrahlung energy of 45–64 MeV have been determined using an off-line γ-ray spectrometric technique at the 100 MeV electron linac of Pohang accelerator laboratory, Pohang, Korea. We also have determined the isomeric yield ratios of ¹⁴⁸Pm from the ^natNd(p,xn) reactions in the proton energy of 5.08–44.72 MeV by a stacked-foil activation and an off-line γ-ray spectrometric techniques at the MC-50 cyclotron of the Korean Institute of Radiological and Medical Sciences, Korea. The determined isomeric yield ratios of ¹⁴⁸Pm were compared with literature data and theoretical values estimated by the TALYS 1.4. The present data along with the similar data from literature at other energies shows that the isomeric yield ratio of ¹⁴⁸Pm increases with the excitation energy both in the ^natSm(γ, x) and the ^natNd(p, xn) reactions. The isomeric yield ratios of ¹⁴⁸Pm from the ^natNd(p, xn) reactions are always higher than those from the ^natSm(γ, x) reactions at the same excitation energy, which indicate the role of input angular momentum besides excitation energy.     

Rapid analysis of trinitite with nuclear forensic applications for post-detonation material analyses

Analysis of post-nuclear detonation materials provides information on the type of device and its origin. Compositional analysis of trinitite glass, fused silicate material produced from the above ground plasma during the detonation of the Trinity nuclear bomb, reveals gross scale chemical and isotopic heterogeneities indicative of limited convective re-homogenization during accumulation into a melt pool at ground zero. Regions rich in weapons grade Pu have also been identified on the surface of the trinitite sample. The absolute and relative abundances of the lanthanoids in the glass are comparable to that of average upper crust composition, whereas the isotopic abundances of key lanthanoids are distinctly non-normal. The trinitite glass has a non-normal Nd isotope composition, with deviations of ?1.75 ± 0.60 ε (differences in parts in 10⁴) in ¹⁴²Nd/¹⁴⁴Nd, +2.24 ± 0.75 ε in ¹⁴⁵Nd/¹⁴⁴Nd, and +1.01 ± 0.38 ε in ¹⁴⁸Nd/¹⁴⁴Nd (all errors cited at 2σ) relative to reference materials: BHVO-2 and Nd-Ames metal. Greater isotopic deviations are found in Gd, with enrichments of +4 ± 1 ε in ¹⁵⁵Gd/¹⁶⁰Gd, +4.19 ± 0.75 ε in ¹⁵⁶Gd/¹⁶⁰Gd, and +3.48 ± 0.52 ε in ¹⁵⁸Gd/¹⁶⁰Gd compared to BHVO-2. The isotopic deviations are consistent with a ²³⁹Pu based fission device with additional ²³⁵U fission contribution and a thermal neutron fluence between 1.4 and 0.97 × 10¹⁵ neutrons/cm².     

A new method for calibrating the current gain of 1013 Ω amplifiers in thermal ionization mass spectrometry

We report a new method for calibrating the current gain of 10¹³ Ω amplifiers in both positive and negative mode used in thermal ionisation mass spectrometry (TIMS). This method uses any isotopic standard or sample to calibrate the gain factor as long as it can produce a stable current signal. It is simpler and more flexible than that recommended by Thermo‐Fisher (the manufacture of the TIMS). In these analyses, the gains of five 10¹³ Ω amplifiers were assessed. The precision of gain factors was better than 100 ppm (2 RSD) in a day, and the long‐term reproducibility was better than 300 ppm (2 RSD) within 2 to 8 months. After a gain was calibrated, the ratio accuracy and precision in the positive mode for ⁸⁷Sr/⁸⁸Sr of NIST 987 Sr and ¹⁴³Nd/¹⁴⁴Nd of La Jolla Nd were 0.710242 ± 60 (2 SD, n = 14) and 0.511842 ± 10 (2 SD, n = 22), respectively, at intensities of ⁸⁸Sr 0.3 V and ¹⁴²Nd 0.4 V, while in the negative mode for ¹⁸⁷Os/¹⁸⁸Os of Merck Os was 0.120229 ± 34 (2 SD, n = 23) at an intensity of ¹⁸⁷OsO₃ 0.01 mV. In addition, a difference in the gain factors between the negative mode TIMS (NTIMS) and positive mode TIMS (PTIMS) has been recognized. The values of the gain factor for NTIMS and PTIMS show a deviation of 0.54% on the Triton and 0.31% on the Triton Plus TIMS in this study; therefore, gain calibration should be carried out on both NTIMS and PTIMS. Moreover, a bias of ~ 1.5 × 10⁻⁵ between H and L Faraday cups for the same 10¹³ Ω amplifier has been detected, hinting that the efficiency of different Faraday cups may affect the gain factors, which can be eliminated through the new method of “cross‐calibration” discribed in this study.     

Novel Sorbent Extraction Technique Using a Chelating Agent Impregnated Porous PTFE Filter Tube: Preconcentration of Rare Earth Elements (REEs) with Bis(2‐Ethyl‐Hexyl)Hydrogen Phosphate (HDEHP) Loaded Porous PTFE Filter Tube Prior to Determination by ICP‐MS

Abstract

Sorbent extraction and elution of rare earth elements (REEs) by using bis(2‐ethyl‐hexyl)hydrogen phosphate (HDEHP) impregnated porous PTFE filter tube were studied. A 100 ng amount of each REEs was quantitatively extracted by filtering 1000 mL of matrix‐free solution under pH 2.0–3.2. For a synthetic seawater sample, extractability of lighter REEs (La–Sm) was lowered; optimum pH range to simultaneously extract all REEs was shifted to 2.9–3.2, and limit of sample volume for quantitative extraction was decreased to 100 mL for La–Sm [although heavier REEs (Eu–Lu) were quantitatively extracted from 1000 mL]. Extracted REEs were quantitatively eluted by filtering through 5 mL of 10 mol/L^?1 hydrochloric acid to the tube. Hence, maximum preconcentration factors were of 200‐ and 20‐fold for Nd–Lu and La–Sm, respectively. Total recovery of 0.5–10 ng of REEs spiked to 300 mL of natural sea salt solution was tested; quantitative recovery (95.9% for Gd–102% for Eu) were obtained for all REEs except La (54.9%). The REEs in the natural sea salt solution were also determined by ICP‐MS after preconcentration with the present method [RSD=16% (La)–1.1% (Yb), n=3].     

热电离质谱法超高精度测定~(142)Nd/~(144)Nd同位素比

142Nd/144Nd比值的超高精度测定技术对于研究太阳系早期演化及月球-地球早期硅酸盐分异具有重要应用价值.本实验利用热电离质谱(TIMS)开展142Nd/144Nd比值的超高精度测试研究,并对比了动态多接收和静态多接收两种测量方式.结果表明,动态模式具有更高的准确度和精密度.讨论了影响测试精度的各种因素,在此基础上通过优化测试条件,对国际标准(Jndi-1)的142Nd/144Nd测试结果为1.1418348,外部精度优于5×10-6(2SD), 完全满足146Sm-142Nd体系研究的技术要求.     

Term isotope shift of high lying odd and even energy levels of Nd II

The isotope shifts of the odd and even parity energy levels of singly-ionised neodymium (Nd II) have been evaluated using the measurements carried out in more than 300 spectral lines of Nd II in the region 3290–5820 Å. Term shift, ΔT (¹⁴⁴Nd-¹⁵⁰Nd), is being reported for 23 low even and 15 high lying even parity levels of Nd II. ΔT for a level of 4f ³6s6p configuration and 8 even levels between 36892 and 43212 cm^-1 are being reported for the first time. ΔT values of 151 high lying odd parity levels are being reported and compared with some of the available earlier reported values. ΔT values of 47 odd parity levels are being reported for the first time, most of which are based on our isotope shift studies in UV region. The electronic configuration assignments to energy levels of Nd II by earlier workers are discussed on the basis of present ΔT values. Electronic configurations to some of the unclassified high lying odd levels have been suggested; the levels with ΔT (144–150) between 300mK and 380mK are assigned to 4f ³5d6s configuration whereas a level with ΔT value of 60mK to 4f46p configuration.     

Quantitative analysis of trivalent uranium and lanthanides in a molten chloride by absorption spectrophotometry

As an analytical application for pyrochemical reprocessing using molten salts, quantitative analysis of uranium and lanthanides by UV/Vis/NIR absorption spectrophotometry was performed. Electronic absorption spectra of LiCl–KCl eutectic at 773 K including trivalent uranium and eight rare earth elements (Y, La, Ce, Pr, Nd, Sm, Eu, and Gd as fission product elements) were measured in the wavenumber region of 4,500–33,000 cm^?1. The composition of the solutes was simulated for a reductive extraction condition in a pyroreprocessing process for spent nuclear fuels, that is, about 2 wt% U and 0.1–2 wt% rare earth elements. Since U(III) possesses strong absorption bands due to f–d transitions, an optical quartz cell with short light path length of 1 mm was adopted in the analysis. The quantitative analysis of trivalent U, Nd, Pr, and Sm was possible with their f–f transition intensities in the NIR region. The analytical results agree with the prepared concentrations within 2σ experimental uncertainties.     

Effects of retrograde-zoning of garnet on Sm-Nd isotopic dating of eclogite and oxygen isotopic disequilibrium between eclogitic minerals

The compositional zoning of the garnet in a strongly deformed eclogite from Raobazhai foliated peridotite has been recognized. The CaO concentrations of the garnet are decreased from the core to the rim, while its MnO concentrations are increased, suggesting the retrograde origin of such CaO—MnO zoning. The tie line of garnet + omphacite from this eclogite gives a Sm-Nd age of (187 ± 5) Ma, which is less significant than the Sm-Nd ages of (221±5)—(228 ± 3) Ma and (210 ± 6)—(214 ± 6) Ma for ultrahigh-pressure eclogites in the southern Dabie zone and in the northern Dabie zone, respectively. This younger Sm-Nd age could result from the¹⁴³Nd/¹⁴⁴ Nd ratio decrease of the retrograde zone in the garnet. The δ¹⁸O values of the garnet and omphacite show that their fractionation values are less than the equilibrium fractionation value between the garnet and omphacite at 500—900°C, which suggests an oxygen isotopic disequilibrium between them.     

Analysis of high burnup spent nuclear fuel by ICP-MS

Summary We have used inductively coupled plasma mass spectrometry (ICP-MS) as the primary tool for determining concentrations of a suite of nuclides in samples excised from high-burnup spent nuclear fuel rods taken from light water nuclear reactors. The complete analysis included the determination of ⁹⁵Mo, ⁹⁹Tc, ¹⁰¹Ru, ¹⁰³Rh, ¹⁰⁹Ag, ¹³⁷Cs, ¹⁴³Nd, ¹⁴⁵Nd,148Nd,147Sm, ¹⁴⁹Sm, ¹⁵⁰Sm, ¹⁵¹Sm, ¹⁵²Sm, ¹⁵¹Eu, ¹⁵³Eu, ¹⁵⁵Eu, ¹⁵⁵Gd, ²³⁷Np, ²³⁴U, ²³⁵U, ²³⁶U, ²³⁸U, ²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu, ²⁴²Pu, ²⁴¹Am, ^242mAm, and ²⁴³Am. The isotopic composition of fissiogenic lanthanide elements was determined using high-performance liquid chromatography (HPLC) with ICP-MS detection. These analytical results allow the determination of fuel burn-up based on ¹⁴⁸Nd, Pu, and U content, as well as provide input for storage and disposal criticality calculations. Results show that ICP-MS along with HPLC-ICP-MS are suitable of performing routine determinations of most of these nuclides, with an uncertainty of ±10% at the 95% confidence level.     

Synthesis and luminescence properties of the Pr(III), Sm(III), Eu(III), Nd(III), and Yb(III) complexes with propane-1,3-dione derivatives

The luminescence method, mass spectrometry, and elemental analysis are used to reveal that under optimal conditions (pH 5–8) Ln³⁺ ions (Ln = Pr, Sm, Eu, Nd, and Yb) with 1-(2-hydroxy-4-methylphenyl)-3-(5-methyl-1-phenyl-¹ H-1,2,3-triazol-4-yl)propane-1,3-dione form complexes with the mole ratio Ln: ligand = 2: 3. According to the IR spectral data, Ln³⁺ ions coordinate three oxygen atoms of two carbonyl groups and one hydroxyl group. In the IR spectra of the complexes, an intense band at 628.7 cm^?1 is assigned to the Ln-O bond vibrations. The X-ray diffraction patterns of the complexes contain no lines corresponding to the ligand. The luminescence intensity of the complexes in the visible spectral range changes in the series Eu(III) > Sm(III) > Pr(III), whereas in the IR region the order is Yb(III) > Nd(III). In all cases, luminescence of the solid complexes is considerably more intense than that of their solutions.     

Rapid and Sensitive LC−MS–MS Method for the Determination of Sarpogrelate in Human Plasma

A rapid and sensitive liquid chromatographic–tandem mass spectrometric method has been developed and validated for the estimation of sarpogrelate in human plasma. Sarpogrelate was extracted from human plasma by solid-phase extraction. Temocapril was used as the internal standard. Heated electron spray ionization mass spectrometry was performed on a TSQ Quantum Ultra MS system. The LC column was a Hypurity C₁₈ and the mobile phase was 2 mM ammonium formate (pH 3.00 ± 0.05):acetonitrile (30:70 v/v). A flow rate of 0.250 mL min^?1 was used. The quantitative analyses were carried out in the positive ion and full scan mode over the mass range m/z 60–500. The capillary, vaporiser temperatures were 325 and 200 °C respectively. The sheath gas pressure, spray voltage, collision energy and tube lense were 40, 3,500 V, 19 V, 198 V, respectively, and the mass spectra of the drugs were recorded by total ion monitoring. Retention times and characteristic mass fragments were recorded and the chosen diagnostic mass fragments were monitored in the mass chromatography mode. Signal intensities of each of the mass fragments: m/z 477 [M + H]⁺ for temocapril, m/z 430 [M + H]⁺ for sarpogrelate, were used for quantification. The calibration curves (the ratio between the peak areas as signal intensities of the drug analyzed and that of the internal standard (temocapril: m/z 477 [M + H]⁺) vs. the concentration of drug) exhibited linearity over the concentration range 5.00–2,500.00 ng mL^?1 human plasma. The recovery and the accuracy were calculated by comparing the peak areas as the signal intensities of each mass fragment for the drug in spiked samples after solid-phase extraction from human plasma to the peak area as the signal intensity of the mass fragment of internal standard sample. The method involves a rapid solid phase extraction from plasma, simple isocratic chromatography conditions and mass spectrometric detection that enables detection up to picogram levels with a total run time of 3.0 min only. The method was validated over the range of 5.0–2,500.0 ng mL^?1. The absolute recoveries for sarpogrelate (93.72%) and IS (91.42%) achieved from spiked plasma samples were consistent and reproducible.     

Chromatographic separation of neodymium isotopes by using chemical exchange process

The neodymium isotope effects were investigated in Nd–malate ligand exchange system using the highly porous cation exchange resin SQS-6. The temperature of the chromatographic columns was kept constant at 50 °C by temperature controlled water passed through the columns jackets. The separation coefficient of neodymium isotopes, ?’s, was calculated from the isotopic ratios precisely measured by means of an ICP mass spectrometer equipped with nine collectors as ion detectors. The separation coefficient, ? × 10⁵, were calculated and found to be 1.4, 4.8, 5.4, 10.6, 16.8 and 20.2 for ¹⁴³Nd, ¹⁴⁴Nd, ¹⁴⁵Nd, ¹⁴⁶Nd, ¹⁴⁸Nd and ¹⁵⁰Nd, respectively.     

Chemical study on the separation and purification of promethium-147

A chemical process for the separation of¹⁴⁷Nd/¹⁴⁷Pm from fission products of synthetic radioactive waste solution has been developed. The process includes: (1) denitration, (2) removal of high concentration of uranium by 30% TBP/kerosene extraction, (3) removal of⁹⁵Nb,¹⁰³Ru,¹³⁷Cs and part of⁹⁰Sr by 50% TBP/dodecane extraction, (4) separation of¹⁴⁷Nd/¹⁴⁷Pm from part of⁹⁰Sr and⁹⁵Zr by oxalic acid precipitation, and (5) removal of¹⁴⁴Ce by mixture of 0.4M D2EHPA and 0.2M TBP extraction. Experimental results indicate that the recovery of¹⁴⁷Nd/¹⁴⁷Pm in the final separated solution is about 90%. The purification of¹⁴⁷Nd and¹⁴⁷Pm from some other rare earth elements, viz.¹⁵³Sm,¹⁵⁴Eu and¹⁴⁴Ce was further investigated by using a Dowex 50W×8 ion-exchanger. Parameters of flow rate, eluent concentration and pH were examined. The results show that the recovery and radionuclide purity of¹⁴⁷Nd plus¹⁴⁷Pm under the present separation conditions are 77.8% and 98.6% for diethylenetriaminepentaacetic acid (DTPA) and 87.3% and 99.5% for nitrilotriacetic acid (NTA), respectively.     

A validated method for measurement of serum total,serum free,and salivary cortisol,using high-performance liquid chromatography coupled with high-resolutionESI-TOF mass spectrometry

Blood cortisol level is routinely analysed in laboratory medicine, but the immunoassays in widespread use have the disadvantage of cross-reactivity with some commonly used steroid drugs. Mass spectrometry has become a method of increasing importance for cortisol estimation. However, current methods do not offer the option of accurate mass identification. Our objective was to develop a mass spectrometry method to analyse salivary, serum total, and serum free cortisol via accurate mass identification. The analysis was performed on a Bruker micrOTOF high-resolution mass spectrometer. Sample preparation involved protein precipitation, serum ultrafiltration, and solid-phase extraction. Limit of quantification was 12.5 nmol L^?1 for total cortisol, 440 pmol L^?1 for serum ultrafiltrate, and 600 pmol L^?1 for saliva. Average intra-assay variation was 4.7 %, and inter-assay variation was 6.6 %. Mass accuracy was <2.5 ppm. Serum total cortisol levels were in the range 35.6–1088 nmol L^?1, and serum free cortisol levels were in the range 0.5–12.4 nmol L^?1. Salivary cortisol levels were in the range 0.7–10.4 nmol L^?1. Mass accuracy was equal to or below 2.5 ppm, resulting in a mass error less than 1 mDa and thus providing high specificity. We did not observe any interference with routinely used steroidal drugs. The method is capable of specific cortisol quantification in different matrices on the basis of accurate mass identification.     

Orthorhombic HP‐REOF (RE = Pr,Nd, Sm – Gd) – High‐Pressure Syntheses and Single‐Crystal Structures (RE = Nd,Sm, Eu)

High‐pressure modifications of the rare earth oxide fluorides REOF (RE = Pr, Nd, Sm – Gd) were successfully synthesized under conditions of 11 GPa and 1200 °C applying the multianvil high‐pressure/high‐temperature technique. Single crystals of HP‐REOF (RE = Nd, Sm, Eu) were obtained making it possible to analyze the products by means of single‐crystal X‐ray diffraction. The compounds HP‐REOF (RE = Nd, Sm, Eu) crystallize in the orthorhombic α‐PbCl₂‐type structure (space group Pnma, No. 62, Z = 4) with the parameters a = 632.45(3), b = 381.87(2), c = 699.21(3) pm, V = 0.16887(2) nm³, R₁ = 0.0156, and wR₂ = 0.0382 for HP‐NdOF, a = 624.38(3), b = 376.87(2), c = 689.53(4) pm, V = 0.16225(2) nm³, R₁ = 0.0141, and wR₂ = 0.0323 for HP‐SmOF, and a = 620.02(4), b = 374.24(3), c = 686.82(5) pm, V = 0.15937(2) nm³, R₁ = 0.0177, and wR₂ = 0.0288 for HP‐EuOF. Calculations of the bond valence sums clearly showed that the oxygen atoms occupy the tetrahedrally coordinated position, whereas the fluorine atoms are fivefold coordinated in form of distorted square‐pyramids. The crystal structures and properties of HP‐REOF (RE = Nd, Sm, Eu) are discussed and compared to the isostructural phases and the normal‐pressure modifications of REOF (RE = Nd, Sm, Eu). Furthermore, results of investigations by EDX and Raman measurements including quantum mechanical calculations are presented.     

Identification and quantification of domoic acid by UHPLC/QTOF tandem mass spectrometry,with simultaneous identification of non-target photodegradation products

Amnesic shellfish poisoning is a potentially lethal human toxic syndrome which is caused by domoic acid (DA), a neurotoxin produced by marine phytoplankton, principally from Pseudonitzschia genus. In this report, a method to identify and quantify the DA toxin, with simultaneous identification of its photodegradation products, has been developed. It uses an ultra high performance liquid chromatography coupled to a quadrupole-time-of-flight tandem mass spectrometer (UHPLC–QTOF) after solid-phase extraction (SPE). An unambiguous identification of DA was carried out by considering both the retention time of DA in UHPLC and the exact mass of protonated DA molecule ([M + H]⁺ = 312.1447 m/z) and of the most intense fragment ion (m/z 266.1391). The quantification was conducted using protonated DA molecule with protonated Glafenin as internal standard, obtaining a limits of detection of 0.75 µg L^?1. Large screening with UHPLC–QTOF could also give structural information about degradation products of DA present in samples after UV-irradiation. This method was applied for the determination of DA in complex liquid samples after SPE and is applicable for environmental monitoring of this toxic substance in the aquatic environment.