Accepted Manuscript

Fragmentation patterns involving ammonium adduct fragment

ions: A comparison of the determination of metaldehyde in human
blood by HPLC-QqQ-MS/MS and UHPLC-Q-TOF-MS

Paweł Szpot, Grzegorz Buszewicz, Tomasz Jurek, Grzegorz

Teresiński

PII: S1570-0232(17)31708-7
DOI: doi:10.1016/j.jchromb.2018.03.011
Reference: CHROMB 21077
To appear in:
Received date: 1 October 2017
Revised date: 4 March 2018
Accepted date: 8 March 2018

Please cite this article as: Paweł Szpot, Grzegorz Buszewicz, Tomasz Jurek, Grzegorz
Teresiński , Fragmentation patterns involving ammonium adduct fragment ions: A
comparison of the determination of metaldehyde in human blood by HPLC-QqQ-MS/
MS and UHPLC-Q-TOF-MS. The address for the corresponding author was captured
as affiliation for all authors. Please check if appropriate. Chromb(2017), doi:10.1016/
j.jchromb.2018.03.011

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 ACCEPTED MANUSCRIPT

Fragmentation patterns involving ammonium adduct fragment ions: a comparison of the determination of
metaldehyde in human blood by HPLC-QqQ-MS/MS and UHPLC-Q-TOF-MS

Paweł Szpot,1,* Grzegorz Buszewicz2, Tomasz Jurek1, Grzegorz Teresiński2

1
Chair and Department of Forensic Medicine, Wroclaw Medical University, ul. Jana Mikulicza-Radeckiego 4,,
50-345 Wrocław, Poland
2
Chair and Department of Forensic Medicine, Medical University of Lublin, ul. Jaczewskiego 8b, 20-090 Lublin,
Poland

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*corresponding author: phone: +48 071 784 14 60, fax: +48 071 784 00 95, email: pawel.szpot@umed.wroc.pl

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Abstract:

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This paper presents a rapid, sensitive and precise method for the determination of metaldehyde in human
blood, using ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass
spectrometry and high-performance liquid chromatography coupled with triple quadrupole tandem mass
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spectrometry. Separation was performed with a Poroshell 120 EC-C18 column; 2.7 μm atrazine-d5 (IS) and 200
mg NaCl were added to the blood sample. Proteins in human blood were precipitated using acetonitrile; the
supernatant was then analyzed with the UHPLC-Q-TOF-MS or HPLC-QqQ-MS/MS system. The results of
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selectivity, linearity, accuracy, precision, limits of quantification, recovery, and matrix effects were sufficient to
enable the measurement of metaldehyde in human blood samples. In addition, we proposed a fragmentation
pathway involving ammonium adduct fragment ions for metaldehyde.
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Keywords: metaldehyde, ammonium adducts, fragmentation pattern, QqQ, Q-TOF, comparison

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1. Introduction
Metaldehyde is a cyclic tetramer of acetaldehyde with the formula (CH3CHO)4. This compound, like iron
phosphate, is used as a pesticide against slugs and snails [1]. Although the toxicity of metaldehyde is relatively
low, some cases of poisoning have been reported [2‒8], some of them fatal. Shih et al. described a fatal case of
human poisoning following the ingestion of 12 g (258.6 mg/kg) of metaldehyde [6]. However, metaldehyde
poisoning occurs more frequently in pets [9]. Most cases of exposure to molluscicides with metaldehyde as the
suspected poisoning agent have involved dogs [10].
Metaldehyde can be detected by various methods such as gas chromatography [11], gas chromatography with
mass spectrometry (GC-MS) [2,3], liquid chromatography with mass spectrometry (LC-MS) [12,13,14] and

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reactive paper spray mass spectrometry [15]. It has been identified in water [10,14,15], human serum [2,7],
stomach contents [3], cabbage, and soil [13].

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To our knowledge, no study on the determination of metaldehyde using ultra-performance liquid
chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF-MS) has

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been published to date.
Recently, more often adducts are used to determine hardly ionizing substances in LC-MS analysis [16-22].
The aim of this study is the development of a method based on ammonium adducts analysis for determining
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metaldehyde in human blood using UHPLC-Q-TOF-MS and UHPLC-QqQ-MS/MS.

2. Experimental
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2.1. Chemicals and reagents

Water, methanol, acetonitrile (CHROMASOLV® LC-MS, Fluka, Germany), metaldehyde, atrazine-d5
(PESTANAL®, Fluka, Germany), sodium chloride (Sigma-Aldrich, Germany), formic acid (Fluka, Germany),
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ammonium formate (J. T. Baker, USA).

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2.2. HPLC-QqQ-MS/MS analysis

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Chromatographic analysis was performed using a high-performance liquid chromatograph (Agilent 1260
HPLC system, Agilent Technologies, Germany).
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Detection of the investigated compounds was achieved using a triple quadrupole mass spectrometer (Agilent
6460 QqQ system, Agilent Technologies, USA) equipped with an atmospheric pressure chemical ionization ion
source (APCI).
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Separation was done using a Poroshell 120 EC-C18 column, 3.0 × 50 mm; 2.7 μm (Agilent Technologies,
USA), with the thermostat at 35 °C. A mixture of 0.1% formic acid in water (A) and acetonitrile (B) was used as
a mobile phase. The injection volume was 10 μl. A flow rate of 0.5 ml/min was used. Gradient elution was as
follows: 0 min., 5 % (B); 2 min., 95 % (B); 6 min., 95 % (B). The column was re-equilibrated for 2.5 min. after
the gradient separation.
Quantitative analysis was carried out in a dynamic multiple reaction monitoring (dynamic-MRM) mode. The
following MS parameters were fixed: gas temperature: 300 °C; gas flow: 4 l/min.; vaporizer: 325 °C; nebulizer:
20 psig; capillary voltage: 4500 V; corona current: 4 µA; cell accelerator voltage: 7 V, positive ionization. A
summary of precursor and product ions, collision energies, fragmentor voltage and retention time for each
compound is presented in Table 1.

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Table 1. MRM conditions applied in the HPLC/APCI-MS/MS analysis of metaldehyde and atrazine-d5

2.3. UHPLC-Q-TOF-MS analysis

UPLC-Q-TOF-MS was carried out using an Agilent 1290 UPLC system (Agilent Technologies, USA)
equipped with an hybrid quadrupole coupled with a time-of-flight analyzer (Q-TOF-MS 6540, Agilent
Technologies, USA). The Q-TOF detector was equipped with an electrospray (ESI) ion source. Separation was
done employing a Poroshell 120 EC-C18 column 3.0 × 100 mm; 2.7 μm (Agilent Technologies, USA) with a
thermostat at 30°C. An isocratic elution mobile phase consisting of 0.25 mM ammonium formate

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solution/methanol (15:85, v/v) was used. The flow rate was 0.2 ml/min for 10 min. The post time was performed
at 1 min. The injection volume was 10 μl.

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The optimized operating spectrometer was fixed at: gas temp.: 100 °C; drying gas: 10 l/min.; nebulizer: 35
psig (N2), sheath gas temp.: 250°C, sheath gas flow: 12 l/min., capillary voltage: 5000 V; fragmentor: 80 V,

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skimmer: 45 V, octopole 1 RF voltage: 750 V, positive ionization, mass range: 50–1000 m/z. The spectrometer
operating mode was extended dynamic range (2 GHz). Optimization of selected parameters of the spectrometer
was performed. Detector response was a factor enabled us to compare the parameters. Determination of optimal
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spectrometer parameters were performed for: Gas Temp. in the range: 100 - 300˚C, Sheat Gas Temp.: 200 – 400˚C,
VCap.: 2000 – 5000V, Fragmentor: 60 – 140V, Skimmer: 25 – 90V and OCT 1RF 450 – 750V.
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2.4. Standard solutions and calibration standards

Standard solutions of metaldehyde were prepared in acetonitrile. Standard solutions of atrazine-d5 (IS) were
diluted in methanol. Working solutions of metaldehyde of 10, 25, 50, 100, 1000 and 10000 µg/ml were freshly
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prepared in acetonitrile. The calibration curve was freshly prepared by mixing 20 μl IS and 20 μl of the appropriate
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metaldehyde working solution with a 200-μl blank sample of human blood to yield final concentrations of 1, 2.5,
5, 10, 100 and 1000 μg/ml.
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Blank samples of human blood were screened prior to spiking in order to ensure that they were free from
metaldehyde. All solutions were stored at ‒20 °C.
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2.5. Sample preparation

200 μl of human blood was transferred to 2-ml Eppendorf tubes with the addition of 20 μl of internal standard
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(1 μg/ml) and 200 mg sodium chloride. During the process of vortex mixing for 0.5 min., 300 μl of cold (‒20 °C)
acetonitrile was added dropwise and centrifuged for 10 min. at 20,627 g at 5 °C. The supernatant was transferred
to the insert and analyzed by HPLC-QqQ-MS/MS or UHPLC-Q-TOF-MS.

2.6. Validation
Selectivity: the selectivity of the method was evaluated by analyzing blank samples of human blood and blank
samples spiked with metaldehyde and internal standard.
Linearity: calibration curves were prepared by spiking the treated blood with working solutions of appropriate
volume ratios to yield concentrations of 1, 2.5, 5, 10, 100 and 1000 µg/ml. The coefficient of determination (R 2)
was determined.

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Precision and accuracy: four repeats of metaldehyde-spiked blank samples of human blood at 10 µg/ml were
analyzed with calibration samples in one batch. The relative standard deviation (RSD) and accuracy in terms of
relative error (RE) were calculated.
Limit of quantitation (LOQ): the LOQ was defined as the lowest measurable concentration which could be
determined with a RSD below 20 %.
Recovery: each recovery of the analyte was evaluated at a concentration of 10 μg/ml. The recovery of
metaldehyde was determined using the ratio of analytical signal from five repeats of metaldehyde extract
concentration to that of non-extracted acetonitrile standard of equal concentrations.
Matrix effects were calculated using the equation described by Chambers et al. [23]:

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𝑅𝑒𝑠𝑝𝑜𝑛𝑠𝑒 𝑒𝑥𝑡𝑟𝑎𝑐𝑡𝑒𝑑 𝑠𝑎𝑚𝑝𝑙𝑒
% Matrix effects = ( − 1) ∗ 100
𝑅𝑒𝑠𝑝𝑜𝑛𝑠𝑒 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑

A negative result indicates suppression, while a positive result indicates enhancement of the analyte signal.

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3. Results and discussion

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3.1. Sample preparation
We noted that maintaining a low temperature (cold ACN, centrifuge at 5 °C, thermostatted autosampler at
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5 °C) for sample preparation enhances recovery of the analyte.

3.2. HPLC-QqQ-MS/MS analysis

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In order to ascertain the optimal ion mode and identify the precursor ions of metaldehyde, APCI-QqQ-MS
was performed in full-scan mode by recording the mass spectra from m/z 50 to 500 in both positive and negative
modes. The protonated molecular ion [M+H]+ of metaldehyde was acquired in positive ion mode, whereas the
deprotonated molecular ion [M−H]− was recorded in negative ion mode. No protonated or deprotonated molecular
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ions for metaldehyde were observed. A chromatogram in positive ion mode was dominated by ion 194.1. This, it
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was concluded, was a pseudomolecular (ammonium adduct) ion [M+NH4]+ of metaldehyde. This ion was chosen
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as the precursor ion for further MS/MS transition analysis in MRM mode. Collision energy and fragmentor voltage
were optimized. Retention times of metaldehyde and IS were 3.12 and 3.73 min., respectively. Fig. 1 shows MRM
chromatograms of blood samples spiked with metaldehyde and IS.
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Despite the fact that in some papers the authors managed to observe the protonated molecular ion [M+H] + of
metaldehyde [15], in our conditions it was not possible to do so. It will probably be possible using different
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operating conditions of the spectrometer, other type of mobile phase or different ion source. Maher et al. used, for
example, reactive paper spray mass spectrometry [15], while Li et al. [12] they used a different mobile phase. Li
et al. was found that the order of the abundance of precursor ions was [M + NH4] + > [M + Na]+ > [M + H]+ when
methanol/20mM ammonium acetate solution as the tuning solutions. In addition, the order of the abundance of
precursor ions was [M + Na]+ > [M + NH4]+ > [M + H]+ when methanol/0.1% formic acid solution as the tuning
solutions [12].
The biological material contains aminotransferases and amino acids from which ammonium ions can be
released during extraction. Ammonium adducts of metaldehyde can therefore be formed in blood. The authors
realize that the limitation of this method is lack of the use of a deuterated internal standard. A deuterated internal
standard would guarantee that the adduct conditions were sufficient to detect the metaldehyde in the blood.

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Fig. 1. Total ion chromatogram (TIC) of blood sample spiked with 100 µg/ml of metaldehyde and IS (A); MRM
chromatograms of blood sample spiked with metaldehyde (B,C) and IS (D)

3.3. UHPLC-Q-TOF-MS analysis

The retention time for metaldehyde was 2.54 min. The quantification of metaldehyde was performed in a scan
mode. The quantitative ion was 194.13868 [M+NH4]+ for metaldehyde and 221.13243 [M+H:35Cl]+ for atrazine-
d5. The qualitative ion was 223.12948 [M+H:37Cl]+ for atrazine-d5 and 62.06004 [M+NH4]+ and 106.08626
[M+NH4]+ for metaldehyde. During the analysis with Q-TOF-MS, ions of sodium and potassium adducts were
observed (it is visible at the bottom of Figure 2: (+) ESI-Q-TOF high-resolution mass spectrum of metaldehyde:

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199.09463 m/z and 215.06745) while under no conditions did we notice the [M+H] + ion. During the optimization
of the ion source, it was observed that the reduction of gases temperature resulted in higher intensity of ammonium

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adduct ions in relation to sodium adduct ions. Most likely, ammonium ions made the most effective methaldehyde
adducts in applied conditions.

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3.4. Validation
The validation parameter results of the method described in this paper are presented in Table 2.
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Table 2. Results of validation of the method
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Precision and accuracy were very similar for both applied techniques. The obtained values of recovery and LOQ
were higher for the triple quadrupole method than for the Q-TOF mass spectrometer. The triple quadrupole method
was also characterized by a wider range of linearity.
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Table 3. Comparison of methods for determination of metaldehyde in biological samples.

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It can be seen from the above table, that previously only gas chromatography has been used for determination of
metaldehyde in biological material, which is worth emphasizing. Booze et al. [11] and Jones and Charlton [3]
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obtained similar limits of quantification to our method, but they needed much more biological material for this
purpose, which is limiting in the forensic toxicology. Only Saito et al. [2] presented a complicated HS-SPME-GC-
MS method, which allows to determine much lower concentrations than those observed in our work, however, the
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recovery they achieved with the developed method was very low. Despite all the mentioned drawbacks of other
methods, all the methods described above allow the determination of metaldehyde in the biological material form
people poisoned with metaldehyde, because its concentrations usually exceed 10 μg/ml. Saito et al. [2] described
a case in which A 21-year-old healthy female had attempted suicide by ingesting an unknown volume of
molluscicide (3% metaldehyde and 3% Carbaryl). In the serum of this patient there was metaldehyde in
concentration of 21 µg/ml. Moody and Inglis [7] reported that the peak metaldehyde concentration detected in the
coma patient’s serum was 125 µg/ml. Keller et al.[8] reported that metaldehyde concentration at 16 h postingestion
is 10 µg/ml, which is shown by coma patients and those with seizures.

3.5. Fragmentation pattern

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The study of the fragmentation pattern of metaldehyde ammonium adduct was carried out by triple quadrupole
and quadrupole time-of-flight detectors. Fig. 2 shows the most abundant fragments of metaldehyde ammonium
adduct. The adduct formation, while not unusual for intact precursor ions, is uncommon for fragment ions.
However, we can make this assumption based on the obtained high-resolution mass spectrum of metaldehyde;
moreover, similar findings had been reported previously by Li et al. [12]. However, the authors did not have
accurate masses of fragments and did not propose structural formulas for them. By using milder ionization, in
contrast to Saito et al. [2] and Jones and Charlton [3], who used the GC-MS-EI method, we observed not only the
fragments but also the precursor ion (m/z 194.13846).

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Fig. 2. Product ion spectra of [M+NH4]+= 194.1 m/z ions from metaldehyde ammonium adduct obtained in (+)
APCI-QqQ (A) and (+) ESI-Q-TOF high-resolution mass spectrum of metaldehyde ammonium adduct (B).

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The experimental mass for major fragments of metaldehyde ammonium adduct, error in ppm, and proposed

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elemental composition is shown in Table 4.

Table 4. Observed m/z values for the [M+NH4]+ ions and major fragments of metaldehyde ammonium adduct
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Using the obtained MS spectrum and the defined accurate masses, we proposed the metaldehyde ammonium
adduct fragmentation pathway (Fig. 3).
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Fig. 3. Proposed fragmentation pattern of metaldehyde ammonium adduct

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The molecular ion peak of metaldehyde (194.13846) fragmented in MS 2 into two ions of m/z 106.08626 and
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62.06004. The proposed fragmentation mechanism is based on the hydrolysis of amide and of the 8-membered
ring of metaldehyde. The fragmentation of metaldehyde results in the formation of either ethyl acetate or 2,4-
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dimethyl-1,3-oxetane. As far as we know, it is impossible to determine exactly which of those ions is formed, as
they are structural isomers and have identical molecular weights. However, given that during the formation of
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ethyl acetate one oxygen atom is oxidized, it is more likely that the fragment with a molecular weight of 88.05243
is 2,4-dimethyl-1,3-oxetane. The last stage in metaldehyde ammonium adduct fragmentation is the formation of
acetaldehyde.
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Our proposed fragmentation pathway is highly probable, as the determined masses are characterized by a
small error. The error of mass determination for 62.06004 m/z and 106.08626 m/z was higher, since effective mass
correction ranged from 121.0509 to 922.0098 m/z. The mass of the second fragment is closer to the mass correction
range and is characterized by a level of error similar to that of the mass error for metaldehyde.

4. Conclusion
The presented method for identifying metaldehyde using UHPLC-Q-TOF-MS is very simple, quick and
precise. As a result of the high accuracy of the determination of masses, it is possible to gain more information
about the structure of the compound and to determine the pathway of metaldehyde ammonium adduct

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fragmentation. The achieved LOQ, recovery, accuracy, and precision were satisfactory for the purpose of
identifying metaldehyde in human blood.

5. References
[1] National Pesticide Information Center: http://npic.orst.edu/pest/slugsnail.html
[2] T. Saito, S. Morita, M. Motojyuku, K. Akieda, H. Otsuka, I. Yamamoto, S. Inokuchi, Determination of
metaldehyde in human serum by headspace solid-phase microextraction and gas chromatography–mass
spectrometry, J. Chromatogr. B 875 (2008) 573–576.
[3] A. Jones, A. Charlton, Determination of Metaldehyde in Suspected Cases of Animal Poisoning Using Gas

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Chromatography-Ion Trap Mass Spectrometry, J. Agric. Food Chem., 47 (1999) 4675–4677.
[4] C. Bleakley, E. Ferrie, N. Collum, L. Burke, Self-poisoning with metaldehyde, Emerg. Med. J., 25 (2008) 381-

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382.
[5] E. Yas-Natan, G. Segev, I. Aroch, Clinical, neurological and clinicopathological signs, treatment and outcome

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of metaldehyde intoxication in 18 dogs, J. Small Anim. Pract. 48 (2007) 438–443.
[6] C.C. Shih, S.S. Chang, Y.L. Chan, J.C. Chen, M.W. Chang, M.S. Tung, J.F. Deng, C.C. Yang, Acute
metaldehyde poisoning in Taiwan, Vet. Hum. Toxicol. 46 (2004), 140-143.
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[7] J.P. Moody, F.G. Inglis, Persistence of metaldehyde during acute molluscicide poisoning, Hum. Exp.
Toxicol. 11 (1992) 361-362.

[8] K.H. Keller, G. Shimizu, F.G. Walter et al. Acetaldehyde analysis in severe metaldehyde poisoning, Vet.
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Hum. Toxicol. 33 (1991) 374.

[9] A.De Roma, G. Miletti, N. D’Alessio, C. Rossini, L. Vangone, G. Galiero, M. Esposito, Metaldehyde poisoning
of companion animals: a three-year retrospective study, J. Vet. Res. 61 (2017) 307–311.
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[10] F. Caloni, C. Cortinovis, M. Rivolta, F. Davanzo: Suspected poisoning of domestic animals by pesticides.
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Sci. Total. Environ. 539 (2016) 331–336.

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[11] T.F. Booze, F.W. Oehme, Gas chromatographic analysis of metaldehyde in urine and plasma, J. Anal.
Toxicol., 9 (1985) 172-173.
[12] C. Li, Y.-L. Wu, T. Yang, Y. Zhang, Determination of metaldehyde in water by SPE and UPLC-MS-MS,
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Chromatographia, 72 (2010) 987-991.

[13] H.-yan Zhang, C. Wang, H.-ze Lu, W.-bi Guan, Y.-qiang Ma, Residues and dissipation dynamics of
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molluscicide metaldehyde in cabbage and soil, Ecotox. Environ. Safe., 74 (2011) 1653–1658.
[14] M. Schumacher, G. Castle, A. Gravell, G.A. Mills, G.R. Fones, An improved method for measuring
metaldehyde in surface water using liquid chromatography tandem mass spectrometry, MethodsX 10 (2016) 188-
194.
[15] S. Maher, F.P.M. Jjunju, D.E. Damon, H. Gorton, Y.S. Maher, S.U. Syed, R.M.A. Heeren, I.S. Young, S.
Taylor, A.K. Badu-Tawiah, Direct analysis and quantification of metaldehyde in water using reactive paper spray
mass spectrometry, Scientific Reports 6, (2016) 1-10.
[16] M. Dziadosz, Influence of buffer concentration on electrospray ionisation of γ-hydroxybutyrate adducts with
the components of the mobile phase used in liquid chromatography-tandem mass spectrometry, J. Chromatogr. B
1008 (2016) 240-241.
[17] M. Dziadosz, Influence of sodium addition on taurine adduct formation generated in acetic acid/acetate

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buffer applied in LC-MS/MS analysis, J. Iran. Chem. Soc. 13 (2016) 1283-1287.

[18] M. Dziadosz, The application of multiple analyte adduct formation in the LC-MS3 analysis of valproic acid
in human serum, J. Chromatogr. B 1040 (2017) 159-161.
[19] M. Dziadosz, J.P. Weller, M. Klintschar, J. Teske, Adduct supported analysis of γ-hydroxybutyrate in human
serum with LC-MS/MS, Anal. Bioanal. Chem. 405 (2013) 6595-6597.
[20] M. Dziadosz, M. Klintschar, J. Teske, Drug detection by tandem mass spectrometry on the basis of adduct
formation, J. Chromatogr. B 955-956 (2014) 108-109.
[21] M. Dziadosz, M. Klintschar, J. Teske, Small molecule adduct formation with the components of the mobile
phase as a way to analyse valproic acid in human serum with liquid chromatography-tandem mass spectrometry,

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J. Chromatogr. B 959 (2014) 36-41.
[22] M. Dziadosz, Applicability of adduct detection in liquid chromatography-tandem mass spectrometry, J. Liq.

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Chromatogr. Rel. Tech. 38 (2015) 1671-1674.
[23] E. Chambers, D.M. Wagrowski-Diehl, Z. Lu, J.R. Mazzeo, Systematic and comprehensive strategy for

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reducing matrix effects in LC/MS/MS analyses, J. Chromatogr. B 852 (2007) 22-34.
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Table 1. MRM conditions applied in the HPLC/APCI-MS/MS analysis of metaldehyde and atrazine-d5
Precursor Product ion Collision Retention time
Compound Fragmentor [V]
ion [m/z] [m/z] energy [V] [min.]
106.1 2
Metaldehyde 194.1 5 3.12
62.2* 2
Atrazine-d5 221.1 179.1 16 104 3.73
*The underlined product ion was used for quantification

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Table 2. Results of validation of the method

Type of mass spectrometer
QqQ Q-TOF
Mean concentration [µg/ml] 9.20 10.66
SD 0.31 0.34
RSD [%] 3.32 3.22
RE [%] ‒8 7
Recovery [%] 95.73 87.5
Matrix effect [%] ‒4.27 ‒12.46
LOQ [µg/ml] 1 2.5
Equation of calibration curve y=5.092916E-004x‒0.001146 y=0.001497x+0.023085
R2 >0.999 >0.999
LOL [µg/ml] 1–1000 2.5–1000

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LOL – limit of linearity

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Table 3. Comparison of methods for determination of metaldehyde in biological samples.

Sample LOD
Matrix Method Recovery/IS References
preparation [ng mL‒1]

human 0.01% and

solid-phase HS–SPME–
serum 0.13%/ 2,4- 0.25 µg/ml [2]
microextraction GC–MS
(0.2 ml) dimethylphenol

stomach

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contents LLE - chloroform GC-ITMS 74% and 94%/- 3 µg/g [3]
(2 g)

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Urine

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and 1 µg/ml and 2
LLE - chloroform GC-FID 95.8% - 101.2/- [11]
Plasma µg/ml
(1 ml)
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HPLC-QqQ-
Human Precipitation – MR/MS 87.5% and
1 µg/ml and
blood acetonitrile and 95.73/atrazine- This article
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UHPLC-Q-TOF- 2.5 µg/ml

(0.2 ml) NaCl d5
MS
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Table 4. Observed m/z values for the [M+NH4]+ ions and major fragments of metaldehyde ammonium adduct
Proposed elemental Theoretical Error
Mass Observed m/z
composition m/z (ppm)
Metaldehyde
176.10486 194.13846 194.13841 ‒0.26
(C8H16O4)
C4H8O2 88.05243 106.0863 106.0864 1.32
C2H4O 44.02621 62.06004 62.0603 4.03

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Figure 1
Figure 2
Figure 3