Introduction

Triazines are a group of herbicides widely used to provide pre- and post-emergence of grasses, crops and many weeds in cereals (Wang et al. 2010). They are also employed for non-agricultural purposes including soil sterilization and road maintenance (Papadopoulos et al. 2012). However, it has been estimated that after their application, a large proportion remains in the environment, and due to their widespread use, persistence and mobility, fluxes of these compounds can reach the marine environment (Li et al. 2010). The cumulative effects of these compounds on the coastal environment are considerable (Camino-Sánchez et al. 2011).

The chemical contamination of the marine environment from herbicides is of great concern because of their high distribution in the aquatic system and their toxic properties; as an example, atrazine produces genotoxic damage in fish species (Santos and Martínez 2012). Triazines can be transformed in the environment by biotic and abiotic processes, and their degradation products can be even more toxic and persistent than parent compounds.

On the one hand, triazine herbicides are considered an important class of chemical pollutants; hence, they are included in the Endocrine Disruption Screening Program by the U.S. Environmental Protection Agency (2009). On the other hand, the European Union (EU) also included simazine and atrazine in the list of 33 priority substances in the EU Water Framework Directive (2000/60/EC) by way of Decision 2455/2001/EC. Moreover, the Directive 2008/105/EC sets the Environmental Quality Standards (EQS) for these compounds in surface water (2 and 4 μg L−1 for atrazine and simazine, respectively) and committees the Member States to set EQS for these compounds in sediments and/or biota at national level. Recently, the Directive 2013/39/EU, amending the Directives 2000/60/EC and 2008/105/EC, includes terbutryn to the list of priority substances and establishes a maximum permitted concentration for this compound in surface water (0.34 μg L−1). Although the EU Directive does not establish the maximum levels for the listed pollutants in sediments, the European Directive requires the Member States to monitor sediment at an adequate frequency to provide sufficient data of those priority substances that tend to accumulate in sediment.

Furthermore, Directive 2013/39/EU calls the attention on the important role of monitoring emerging pollutants that are not regularly considered in monitoring programs but can have toxicological effects. In this way, studies examining the concentration of triazines in surface waters have expanded the list of compounds including their main degradation products (hydroxy and dealkylated products) (Bottoni et al. 2013; Köck-Schulmeyer et al. 2012). Because of their mobility in the soil–water environment, the degradation products can reach marine environment more easily than triazines; thus, the impact of herbicides tends to be underestimated when only the triazines are analysed in samples. Therefore, the main degradation products should be included in current analytical methods to obtain a better knowledge of aquatic ecosystem quality regarding herbicides contamination (Masiá et al. 2013).

Different chromatographic techniques have been used to determine triazines and/or their degradation products. Amongst these techniques, the application of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has provided an increased selectivity and sensitivity (Beale et al. 2010; Dujakovic et al. 2010; García-Galán et al. 2010; Huff and Foster 2011; Kalogridi et al. 2014; Lissalde et al. 2001; Postigo et al. 2010; Zhang et al. 2014).

Regarding extraction procedure, solid phase extraction (SPE) is the preconcentration technique most commonly used for the determination of triazines and their degradation products in water samples. Nonpolar SPE sorbents are generally selected for extracting triazines from water samples. However, the degradation products, which contain polar functional groups, can be more efficiently extracted by using polar sorbents (Sabik et al. 2000). Different solid phases such as Oasis MCX cartridges (Li et al. 2013; Papadopoulos et al. 2007), PLRP-s (Hurtado-Sánchez et al. 2013; Postigo et al. 2010), Oasis HLB cartridges (Huff and Foster 2011; Hurtado-Sánchez et al. 2013), Amberlite XAD-4 resin (Akdogan et al. 2013) and Oasis MAX cartridges (Zhang et al. 2014) have been employed for triazines and their main degradation products. However, Oasis HLB has shown to have better ability to retain some degradation products (desethylatrazine, desisopropylatrazine, desethylterbuthylazine, 2-hydroxyatrazine and 2-hidroxyterbuthylazine) than other sorbents (Benvenuto et al. 2010; Gervais et al. 2008).

The most frequently used methodologies for the analysis of triazines in sediments employ solvent extraction procedures such as soxhlet (Galanopoulou et al. 2005), mechanical shaking (Li et al. 2010; Papadopoulos et al. 2012), sonication (Nödler et al. 2013), microwave-assisted extraction (MAE) (Fernández et al. 2013; Kalogridi et al. 2014) and pressurized liquid extraction (PLE) (Camino-Sánchez et al. 2011, Devault et al. 2010). In the last years, different innovation procedures have been developed and applied for the determination of pollutants in complex matrices with improved capabilities, reduced cleanup and concentration steps, the avoidance of toxic solvents and improved limits of detection. In this context, extraction techniques such as Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) (Brondi et al. 2011; Masiá et al. 2013) and matrix solid-phase dispersion (MSPD) (González-Mariño et al. 2010; Sánchez-Brunete et al. 2010) appear to be appropriate for the determination of emerging contaminants in sediments.

MSPD is an extraction procedure, which combines aspects of several analytical techniques allowing sample homogenization, disruption, extraction, fractionation and cleanup within a single process (Barker 2000). MSPD methods have been developed for extraction of contaminants from both vegetable and animal matrices. However, application of the MSPD methods to environmental solid samples such as soil or sediments is relatively minimal compared to solvent extraction techniques (Capriotti et al. 2013).

Therefore, it is necessary to have accurate, effective, simple and fast methods of analysis for these compounds. Their determination in environmental matrices enables to improve the knowledge and data available on sources of these priority substances and ways in which pollution occurs (Brondi et al. 2011).

The aim of this work was the development and validation of selective, sensitive and accurate analytical methodology for the quantification of 17 compounds (nine triazine herbicides as well as their main degradation products) in two compartments of the marine environment. The methods are based on SPE and MSPD using LC-ESI-MS/MS for simultaneous analyses of all compounds in seawater and marine sediment samples. Furthermore, the proposed methods were applied to the analysis of the target compounds in seawater and marine sediments samples from ten points susceptible to contamination by triazines from a coastline area of A Coruña (Galicia, NW of Spain).

Materials and methods

Chemicals and materials

All herbicides analytical standards were supplied by Sigma-Aldrich (Inc. St. Louis, MO, USA). The molecular structures of the target compounds are shown in Fig. 1. The individual stock standard solutions of 100 mg L−1 were prepared in methanol by exact weighing of high-purity substances and stored at −18 °C in the dark. Then, two working standard solutions (Mix I and II) of concentration 1 mg L−1 were prepared using methanol. Mix I contained the compounds having higher sensitivity (ametryn, atrazine, cyanazine, desethylterbuthylazine (DET), desethylatrazine (DEA), desisopropylatrazine (DIA), 2-hydroxyatrazine (HA), 2-hidroxyterbuthylazine (HT), prometryn, propazine, simazine, simetryn, terbuthylazine and terbutryn). Mix II contained desethyldesisopropylatrazine (DEDIA), desethyl-2-hydroxyatrazine (DEHA) and desisopropyl- 2-hydroxyatrazine (DIHA). All working solutions were freshly prepared every time by appropriate dilution of the mixed solution with methanol.

Fig. 1
figure 1

Structures of the target compounds (a) Triazines: (1) Ametryn, (2) Atrazine, (3) Cyanazine, (4) Prometryn, (5) Propazine, (6) Simazine, (7) Simetryn, (8) Terbuthylazine and (9) Terbutryn (b) Degradation products: (1) DEA, (2) DEDIA, (3) DET, (4) DIA, (5) HA, (6) HT, (7) DEHA and (8) DIHA

Full size image

Acetonitrile (HPLC grade) and ethyl acetate (PAR, solvents for analysis of pesticide residues by GC) for instrumental analysis were purchased from Panreac (Barcelona, Spain). Methanol of superpurity was obtained from Romil (Cambridge, UK). Acetic acid (LC grade) was purchased from Sigma-Aldrich (Inc. St Louis, MO, USA). Milli-Q water was freshly prepared and obtained from a purification system from Millipore (Billerica, MA).

Oasis HLB cartridges (6 mL, 200 mg) were supplied by Waters (Milford, MA, USA) and ENVI-Carb bulk packing was from Sigma-Aldrich (Inc. St Louis, MO, USA). Empty glass solid phase extraction syringes (6 mL capacity) and 20 μm polyethylene frits were purchased from Sigma-Aldrich (Inc. St Louis, MO, USA). Syringe polytetrafluoroethylene (PTFE) filters of 0.2 μm were obtained from Teknocroma (Barcelona, Spain).

A Visiprep® vacuum distribution manifold from Supelco (Bellefonte, PA, USA) was employed in the purification step. A Büchi R-3000 rotary-evaporator (Büchi Labortechnic AG, Flawil, Switzerland) was used in the evaporation step.

Sample collection

The area studied is located in the coastline of Galicia (NW of Spain). Seawater and marine sediment samples were collected from 10 potential polluted sites by triazines in estuary of A Coruña (see Fig. 2) during July of 2016. The mouth of Mero River forms the estuary, and it is also fed by many small rivers and brooks that traverse areas dedicated to agriculture. The sampling locations were selected by their proximity to one or more potential sources of contamination by triazine herbicides. The study area is illustrated in Fig. 2, and the 10 sampling points and the source in brackets are listed below: 1 (tram line), 2 (golf course), 3 (a railway line and vegetable gardens), 4 (vegetable gardens), 5 (mouth of a river flowing through a golf course and growing areas), 6 (mouth of the Mero river that traverses areas dedicated to agriculture), 7 and 8 (residential areas with gardens and parks), 9 (mouth of two rivers flowing through a campsite, vegetable gardens and residential areas with gardens) and 10 (lake with access to the sea which receives two rivers that cross growing areas, vegetable gardens and residential areas with gardens). At each sampling point, three samples were collected.

Fig. 2
figure 2

Location of sampling sites in estuary of A Coruña (Galicia, NW of Spain)

Full size image

Furthermore, triazine-free seawater samples from the Riazor beach at the city of A Coruña (Galicia, NW Spain) were used for the optimization and validation of the SPE procedure. Seawater samples were collected in amber glass containers and transported to the laboratory under cooled conditions (4 °C). Upon reception, samples were filtered through 0.6 μm glass fibre MN GF-6 filters from Macherey Nagel (Düren, Germany) to eliminate suspended solid matter. Due to the low stability of triazines, the samples were analysed the day of sampling.

Triazine-free marine sediments collected from the Ares estuary (A Coruña, NW Spain) were used for optimization and validation of MSPD procedure. After collection, samples were homogenized, frozen at −20 °C and freeze-dried. The samples were then pulverized by using a vibrating ball mill and sieved through a 0.5-mm mesh. Finally, the samples were stored in amber glass bottles with hermetic seals out of light exposure until analysis.

Liquid chromatography-tandem mass spectrometry

The LC-ESI-MS/MS analyses were performed using an Agilent HP-1200 Series LC system equipped with an autosampler, a binary solvent pump and a thermostated column oven. The LC system was coupled to a mass spectrometer with a triple quadrupole detector (API 3200, Applied Biosystem, Carlsbad, CA, USA) equipped with an ESI source.

The column was a stainless steel column (150 mm × 4.6 mm ID, particle size 5 μm) packed with Hypersil GOLD C18 chemical bonded phase from Thermo Scientific (Austin, TX, USA). Elution was performed under gradient mode using acetonitrile as mobile phase A and 0.3% acetic acid in water as mobile phase B. Separation was carried out using a flow rate of 1 mL min−1. The gradient elution was performed as follows: mobile phase A initial percentage of 30% (2 min) increased linearly to 50% in 13 min, after which the percentage was returned to the initial conditions in 8 min. The sample volume injected into the LC system was 20 μL. The optimized method allows the concurrent detection of 17 pesticides in a chromatographic run of 23 min.

The LC-ESI-MS/MS analysis of the herbicides was carried out in the positive ionization mode. Data acquisition was performed under multiple reaction monitoring (MRM) mode, recording the transition between the precursor ion and the two most abundant product ions for each target analyte. The optimization of MS/MS conditions, including the search for precursor and product ions, optimization of the sample cone voltage and collision energy, was performed using the Analyst 1.4.2 software. MRM conditions used for analysis of the pesticides are shown in Table 1.

Table 1 Retention time and MS/MS optimized parameters for the studied pesticides
Full size table

The ESI interface conditions were optimized for maximum intensity of the precursor ions as follows: capillary voltage 5 kV, source and desolvation temperature 600 °C. The nebulizer and desolvation gas flows were set at 850 and 50 L h−1, respectively. Nitrogen and air (35 psi) were used as nebulizer and desolvation gases. Nitrogen was used as collision gas at a pressure of 5 psi.

Extraction methods

In the case of seawater, an extraction method based on SPE using Oasis HLB cartridges was used. The extraction was performed by loading 10 mL of the sample solution at 10 mL min−1 through an OASIS® HLB cartridge previously conditioned with 10 mL of methanol and 10 mL of Milli-Q water. After sample loading, the cartridge was washed with 5 mL of Milli-Q water. Once the retention step was completed, the cartridge was totally dried using a nitrogen stream for 30 min. Retained compounds were eluted with 2.5 mL of methanol. Finally, the eluate was filtered through a 0.2-μm PTFE filter.

The extraction method for sediments was based on MSPD. The extraction procedure was performed as follows: 1.0000 g of freeze-dried sediment sample was homogenized with 1 g of ENVI-Carb in a glass mortar with a pestle for 5 min. The final mixture was transferred into a 6-mL glass syringe, and once packed, MSPD columns were connected to a Visiprep® vacuum distribution manifold. Elution was performed with 20 mL of ethyl acetate and 5 mL of acetonitrile. The obtained eluate was evaporated to a drop in rotary-evaporator and got to dryness by a gentle nitrogen stream. The residue was reconstituted in 1 mL methanol and the solution was filtered through of a 0.2-μm syringe filter of PTFE.

Results and discussion

LC-MS/MS development

The optimum cone voltage and collision energy for each pesticide were selected, with the aim of obtaining the precursor ion and the MRM transition with the highest sensitivity and the other product ion (Table 1). The most sensitive transition was chosen for quantification, and the other transition was used for confirmation. Optimization of MS/MS settings was performed by direct infusion of individual standard solutions (0.5–1 μg mL−1 in methanol). Negative or positive mode was studied for all analytes. The analyses of the compounds were performed in the positive mode. The suitable settings of the instrument for each pesticide are shown in Table 1.

The LC method was optimized to get a good peak separation. The optimization was performed using standard solutions of 1 μg mL−1 in methanol. Since degradation products are strongly dependent on pH, the use of a mobile phase with a buffer or a modifier is necessary. The most employed mobile phases using modifiers are acetonitrile–acetic acid solution (Gikas et al. 2012), acetonitrile–ammonium formate and acetonitrile–formic acid (Li et al. 2013). For this reason, these modifiers were studied, and the best chromatographic separation was obtained using acetonitrile-acetic acid solution.

Once the modifier is chosen, the concentration of acetic acid in the mobile phase B was assayed in order to achieve optimum separation. Three concentration of acetic acid (0.1, 0.3 and 0.5%) were evaluated. The best chromatographic separation was achieved with 0.3% of acetic acid, whereas a higher overlap was observed with 0.5% and four compounds were missing when employing 0.1%. Figure 3 shows a MS chromatogram employing acetonitrile–0.3% acetic acid as mobile phase. From the chromatogram, it is evident that some compounds remain overlapped. However, the use of tandem MS enabled an accurate analysis even of co-eluted compounds.

Fig. 3
figure 3

LC-MS chromatogram of standard mixture (1 μg mL−1 of each compound). Target compounds are numbered as follows: (1) DIHA, (2) DEHA, (3) HA, (4) DEDIA, (5) HT, (6) DEA, (7) DIA, (8) simetryn, (9) simazine, (10) cyanazine, (11) DET, (12) ametryn, (13) atrazine, (14) prometryn, (15) terbutryn, (16) propazine and (17) terbuthylazine

Full size image

Extraction methods

Extraction methods performance

Both extraction methods are based on procedures previously developed by the authors for the analysis of the nine target triazines in seawater and marine sediments using DAD as detection system (Rodríguez-González et al. 2013, 2016). For this reason, it was necessary to modify both methods since in this work, the analysis of their main degradation products was included and a MS/MS detector was employed.

Regarding SPE method, the sample volume was reduced from 25 to 10 mL due to the high sensitivity of mass detector. Furthermore, Milli-Q volume used for washing the loaded cartridge was decreased from 20 to 5 mL to avoid loss of the more polar degradation products.

On the other hand, in order to remove the concentration step of the eluate using rotary-evaporator and simplify the method, acetone was replaced by methanol (2.5 mL) as elution solvent. For this purpose, the results obtained by Beceiro-González et al. (2014) which have shown satisfactory recoveries using different elution solvents (acetonitrile, methanol and acetone) for the nine triazine studied was taken into account.

In the case of MSPD method, due to higher polarity of the degradation products, the eluent was slightly modified by adding 5 mL of acetonitrile to the eluent of the initial method (20 mL of ethyl acetate). This modification was based on a previous study for the determination of target triazines in seaweeds (Rodriguez-González et al. 2014). In this work, volume and type of elution solvent (ethyl acetate, acetonitrile and mixtures of both solvents) were optimized and the best results were obtained using sequential elution of 20 mL ethyl acetate and 5 mL acetonitrile.

Methods validation

Both methods were validated in terms of linearity, limits of detection and quantification, precision and accuracy. The limits of detection (LODs) were calculated as 3*Sy/x/b and the limits of quantification (LOQs) as 10*Sy/x/b, where Sy/x is the residual standard deviation and b is the slope of the matrix calibration curves. The precision of the overall analytical procedures, expressed as relative standard deviation (RSD), was evaluated as intra-day and inter-day precision. To study intra-day precision, RSDs were calculated by spiking samples at two levels of concentrations (one level close to LOQ of each compound and the other five times higher) measuring five replicates of spiked samples at each concentration level during the same day. The inter-day precision was studied at an intermediate level of concentration by measuring five replicates on three consecutive days. Finally, the accuracy of the methods was evaluated in terms of recovery.

SPE method: All quantitative results were calculated using 10 mL of triazine-free seawater sample spiked with a standard mixture of the compounds. Calibration curves were constructed using six calibration points, with three replicates for each calibration level, at the concentration range shown in Table 2. As it can be seen, very good linearity was obtained for all the compounds with coefficients of determination (R 2) higher than 0.996.

Table 2 Limits of detection and quantification of the LC-MS/MS methods
Full size table

LODs and LOQs were in the range of 0.02–0.03 and 0.05–0.10 μg L−1, respectively, for all compounds, except DEDIA, DEHA and DIHA (Table 2). These values were satisfactory because LOQs are lower than 30% of the more restrictive parametric value requested by the legislation for triazines in surface water (maximum permitted concentration of 0.34 μg L−1 for terbutryn). For DEDIA, DEHA and DIHA, the limits of detection and quantification (between 0.08–0.15 and 0.26–0.45 μg L−1, respectively) were adequate, being the LOQs <30% of the parametric value requested by the legislation for atrazine in surface water (Directive 2013/39/EU). LOQs obtained permit to ensure proper determination of the target compounds at the levels established by the Directive 2013/39/UE.

Moreover, the selectivity of the method was evaluated by analysing control blank samples. The absence of any signal at the same retention time of the selected compounds indicated there were no any matrix interferences or contamination that can give a false positive signal.

Regarding precision, the results are shown in Table 3. The values obtained for intra-day and inter-day precision were satisfactory for all compounds (RSDs lower than or equal to 1.41%), indicating that the developed method was reproducible.

Table 3 Precision and accuracy of the LC-MS/MS methods
Full size table

Accuracy of the proposed method was determined by spiking 10 mL of triazine-free seawater sample at two levels of concentration, depending on the compound (0.25 and 1.25 μg L−1 for DEDIA, DEHA and DIHA and 0.05 and 0.25 μg L−1 for the remaining compounds). Five replicates at each fortification level were used, and the analytical recoveries of the spiked samples were calculated. As it can be seen in Table 3, satisfactory recoveries at both levels of concentration for all compounds were achieved. Figure 4 shows the MS/MS chromatograms of the degradation products and four triazines for a seawater sample spiked at 0.05 and 0.25 μg L−1 depending on the compound.

Fig. 4
figure 4

LC-MS/MS chromatograms of the degradation products and four triazines from a seawater sample spiked with 0.25 μg L−1 for DEDIA, DEHA and DIHA and 0.05 μg L−1 for remaining compounds

Full size image

MSPD method: The matrix effect was evaluated since signal suppression or enhancement can severely compromise quantitative analysis of the compounds at trace levels. The matrix effect was studied by comparison of the slopes of the calibration curves in solvent and in extracts of a triazine-free sediment sample obtained after the MSPD procedure (employing six points). Both the solvent and the matrix calibration curves had good linearity, with determination coefficients higher than 0.999 for solvent calibration curves and 0.998 for matrix-matched ones. Most of compounds did not show matrix effect, except cyanazine and DEHA, which evidenced a light matrix effect and signal suppression.

The linearity was evaluated by spiking triazine-free sediment samples with different amounts of the target compounds and analysed with the proposed method. Calibration curves were constructed using six calibration points, with three replicates for each calibration level, at a concentration range shown in Table 2. As can be seen, good linearity was obtained for all compounds with coefficients of determination (R 2) higher than 0.997.

LODs and LOQs obtained for all compounds (between 0.08–1.40 and 0.23–4.26 μg kg−1, respectively) were adequate. Although there is not legislation for these compounds in sediments, the LOQs obtained (Table 2) were satisfactory because the values for all compounds (except DEDIA, DEHA and DIHA) were 20–40 times lower than the maximum limit of the most restrictive parametric value requested by the European legislation for triazines in edible seaweed (10 μg kg−1 for simazine) (Commision Regulation (EC) No 310/ 2011). For DEDIA, DEHA and DIHA, the LOQs obtained were 10–20 times lower than the maximum limit established by legislation for terbuthylazine in edible seaweed (50 μg kg−1) (Commision Regulation (EC) No 149/ 2008).

The values obtained for intra-day and inter-day precision are shown in Table 3. The RSD values were lower than 0.73% which indicate the developed method was reproducible.

Accuracy was determined by spiking 1.0000 g of triazine-free marine sediment samples at two concentration levels (0.5 and 2.5 μg kg−1 for ametryn, atrazine, cyanazine, DEA, DET, DIA, HA, HT, prometryn, propazine, simetryn, simazine, terbutryn and terbuthylazine and 5 and 25 μg kg−1 for DEDIA, DEHA and DIHA). To evaluate the accuracy, the analytical recoveries of spiked samples, using five replicates at each fortification level, were calculated using matrix-matched calibration standards. The analytical recoveries of the 17 analytes were acceptable for both levels of concentration (between 60.9 and 99.7%). Figure 5 shows the MS/MS chromatograms of a marine sediment spiked at 0.5 μg kg−1 level corresponding to atrazine, prometryn, propazine, terbutryn and terbuthylazine.

Fig. 5
figure 5

LC-MS/MS chromatograms of five triazines obtained after MSPD method was applied, from a marine sediment spiked with 0.5 μg kg−1 for each compound

Full size image

Application of methods to the analysis of seawater and marines sediments samples

The proposed methods were applied to analyse the target compounds in seawater and marine sediment samples from ten points of the coastline area of Galicia (NW of Spain). The sampling took place during July of 2016. The seawater samples registered concentrations of triazines and degradation products below the LODs. In the case of sediments, out of the 17 compounds analysed only terbuthylazine was detected in sample M4 (0.45 μg kg−1).

Conclusions

The analysis of triazines and their degradation products in the marine environment are of great interest in order to control the quality of the marine environment and to evaluate risks for human health. The presence of pesticides in seawater and sediments has been associated with a wide range of effects such as acute and chronic toxicity to aquatic organisms. These compounds as well as others emerging contaminants have been the goal of the development of methods in order to find viable determination procedures that could be applied to complex and diluted matrices.

The proposed methods based on SPE and MSPD coupled to LC-ESI-MS/MS have been demonstrated to be selective and sensitive for the simultaneous analysis of nine triazines herbicides and eight degradation products in seawater and marine sediments samples. An important difference of the proposed methods with previously described methodology for the analysis of triazines herbicides and their main degradation products is the determination of a greater number of degradation products simultaneously with triazines. It is noteworthy that methods based on solid-phase extraction combined with LC-MS/MS have been used to measure triazines and degradation products in river waters; however, there are not studies in seawater. Regarding sediments, to the best of our knowledge, studies using MSPD to extract these chemicals residues from sediments have not been published.

With the proposed analytical methodologies, satisfactory precision and accuracy were obtained for both methods. The limits of quantification achieved for seawater enable the determination of these pollutants at the levels required by European Union legislation (Directive 2013/39/EU). Although there is no legislation for these compounds in sediments, the LOQs obtained are much lower than the maximum limits legislated for triazines in edible seaweeds (Commision Regulation (EC) No 310/ 2011). Consequently, these methods can be an important tool to determine triazines and their degradation products at trace levels in marine environment.

Once the methodology is optimized, we applied both methods to determine the target compounds in ten different seawater and marine sediments samples from the coastline of A Coruña (NW, Spain). Only one of the compounds was detected in one of the marine sediment analysed.

It is worthy to note that both methods are simple, fast, with a lower consumption of solvents and energy requirements according to the principles of Green Chemistry.