A comparative study of the analytical methods for the determination of polycyclic aromatic hydrocarbons in seafood by high-performance liquid chromatography with fluorescence detection

Authors


Summary

This study was performed to establish a rapid analytical method to determine the presence of fourteen polycyclic aromatic hydrocarbons (PAHs) in seafoods by high-performance liquid chromatography with fluorescence detection (HPLC/FLD). The samples were prepared using two methods: the Quick, Easy, Cheap, Effective, Rugged, Safe (QuEChERS) method and the alkali digestion method. The QuEChERS method involved a convenient and effective solid–liquid extraction and a simple purification. The alkali digestion method was comprised of a liquid–liquid extraction after saponification with potassium hydroxide followed by purification. The limits of detection (LODs) and limits of quantification (LOQs) of the QuEChERS method ranged from 0.05 to 1.60 μg kg−1, and those of the alkali digestion method ranged from 0.28 to 5.18 μg kg−1. The repeatability for all target analytes was similar for the two methods, that is, 0.66–4.24% and 0.26–5.75% for the QuEChERS and alkali digestion methods, respectively. At analyte concentrations of 2.5–50 μg kg−1, the recovery of the QuEChERS method ranged from 86.87% to 115.67% and that of the alkali digestion method ranged from 69.22% to 100.21%.

Introduction

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants that may originate from a variety of incomplete combustion and pyrolysis processes from anthropogenic and natural sources (Lee & Shim, 2007; Varlet et al., 2007). A high amount of PAHs is emitted from processing coal and during the incomplete combustion of organic matter, such as fuel oils (Kishikawa et al., 2003). PAHs and their substituted derivatives are a large class of organic compounds containing two or more aromatic fused rings. Those compounds containing five or more aromatic rings are known as heavy PAHs, whereas those containing fewer than five rings are light PAHs. Many of these compounds, namely benzo[a]pyrene, benzo[a]anthracene, dibenzo[a,h]anthracene and chrysene, have been reported to possess carcinogenic and genotoxic properties (Poster et al., 2006). Other PAHs that are not defined as carcinogenic may act as synergists (Wenzl et al., 2006).

It is well documented that causes of PAHs in food sources include contamination by air pollutants, uptake from the soil and carbonisation of carbohydrates, fats and proteins during food processing, such as smoking or high-temperature cooking (European Commission, 2002). PAHs can accumulate on the waxy surfaces of many vegetables and fruits. The presence of PAHs in uncooked food, such as vegetables, seeds and grains, has been demonstrated with certainty. Food authorities from different countries worldwide have recommended different maximum residue limits. Most of these limits have been related to the sum of the heavy (five- and six-nuclear) PAHs and benzo[a]anthracene. In Spain, Italy and Canada, a limit of 3–5 ppb has been recommended (García Falcon et al., 1999). In Germany, the recommended limits are 5 ppb for the sum of heavy PAHs and 1 ppb for benzo[a]pyrene (BaP) (Šimko, 2002). Many researchers have determined the PAH content of various foods, including alcoholic drinks, instant coffee, plant foods, oils and seafood (García Falcon & Simal Gándara, 2005b; García Falcon et al., 2005a; Rey Salgueiro et al., 2008; Fernández González et al., 2012). The PAH contents are good indicators of the risk presented by these contaminants (Rey Salgueiro et al., 2009a). Therefore, seafood is an interesting example of the various routes by which human food sources may become contaminated by PAHs. PAHs enter the marine environment from a variety of sources, including petroleum pollution, fallout from air pollution, effluents from industries and sewage treatment plants and creosoted wharves. Bivalve molluscs, such as clams, oysters and mussels, more readily accumulate PAHs from contaminated waters relative to vertebrate fish. The most likely explanation for this difference is that although fish readily metabolise PAHs to water-soluble derivatives that are then excreted, seafood lacks any appreciable ability to metabolise these compounds (Lee et al., 1972; Payne, 1977; Dunn & Fee, 1979; Gratz et al., 2011).

The determination of multiple residues of PAHs in samples consists of extraction, purification and instrumental analysis. In the past, Soxhlet extraction was commonly employed (Malawska et al., 2002). However, this technique has an inherent disadvantage, which involves multistep processes that always risk the loss of some analytes. Therefore, ultrasound-assisted solvent extraction (UASE), shaking and pressurised liquid extraction (PLE) have been developed as alternative techniques to replace classical extraction methods (Wilcke et al., 1999; Aamot et al., 1996). Comparison of the three methods has shown that USAE and shaking do not require sophisticated equipment but long extraction time, while PLE involves sophisticated equipment but it lacks repeatability (Rey Salgueiro et al., 2009b). The general sample preparation methods are based on the conventional liquid–liquid extraction (LLE), microwave-assisted treatment followed by a purification step, such as solid-phase extraction (SPE) (García Falcon et al., 2000; Frenich et al., 2005; Tahboub et al., 2005). These sample preparation methods are complicated and require large amount of solvent. To address these problems, the QuEChERS method was first established by using dispersive SPE (Anastassiades et al., 2003). After these sample preparation procedures, the analytes have been analysed by gas or liquid chromatography mass spectrometry (Norman et al., 2011). The QuEChERS procedure is being successfully applied for multiple residue analysis of PAHs in fatty and nonfatty food matrices such as egg (Lehotay et al., 2005), milk (Lehotay et al., 2005), olive oil and olives (Cunha et al., 2007), rice (Nguyen et al., 2008a), several fruits and vegetables (Nguyen et al., 2008b; Schenck et al., 2008; Cunha et al., 2009). Saponification has predominantly been used to determine PAHs in marine organisms (Mostafa, 2002; Perugini et al., 2007). QuEChERS method has not been tested yet for PAH analysis in seafoods, such as manila clam (Ruditapes philippinarum), oyster (Crassostrea gigas), hard clam (Mercenaria mercenaria) and cockle (Tegillarca granosa), using high-performance liquid chromatography with fluorescence detection (HPLC/FLD). Accordingly, to prevent the consumption of contaminated seafood and minimise the impact on the seafood industry, quick and simple method is required to analyse PAH compounds from seafoods.

In this study, we established and validated QuEChERS method for the determination of fourteen PAHs in seafood using HPLC/FLD. In addition, we compared quick and simple QuEChERS and typical method named alkali digestion sample preparation methods to confirm the contents of fourteen PAHs in seafood using HPLC/FLD. Using this method, the fourteen PAHs except benzo[c]fluorene (BcL) and pyrene (PYR) were measured in seafood samples obtained from the south coast of Korea and the Yellow sea which had been previously polluted with an oil spill.

Materials and methods

Standards

The individual PAH standard solutions in acetonitrile were obtained from Dr. Ehrenstorfer (Augsburg, Germany): benzo[a]anthracene (BaA), chrysene (CHR), 5-methylchrysene (5-MC), benzo[j]fluoranthene (BjF), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), dibenzo[a,l]pyrene (DlP), benzo[g,h,i]perylene (BgP), indenol[1,2,3-cd]pyrene (IcP), dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP) and dibenzo[a,h]pyrene (DhP). The stock standard solutions in acetonitrile were prepared at concentrations of 0.5–50 μg kg−1. The working PAH mixtures were prepared by diluting the above stock standard solutions with acetonitrile according to their sensitivities of fluorescence detection. These solutions were stored in glass bottles at 4 °C in dark vials sealed with PTFE caps.

Materials and reagents

High-performance liquid chromatography-grade n-hexane and acetonitrile (Aldrich, Steinheim, Germany) were used as solvents. Water was purified through a Milli-Q system (Millipore, Bedford, MA, USA) for all sample preparations and for use as the mobile phase. All other chemicals and solvents used were of HPLC grade. In June 2010, seafoods such as manila clams (Ruditapes philippinarum), hard clams (Mercenaria mercenaria), oysters (Crassostrea gigas) and cockles (Tegillarca granosa) were obtained from the local market from Taean County and Namhae County, Korea. The raw seafood had matured on the coast of the Yellow Sea of Taean County, which incurred an oil spill on December 2007, and the south coast of Korea in Namhae County.

Analysis of polycyclic aromatic hydrocarbons

Sample preparation for the QuEChERS method

The QuEChERS method was modified according to the Wong's procedure (Wong et al., 2010). For the sample extraction step, a 2.0 g sample of manila clams homogenate was placed into a 50-mL centrifuge tube containing 2.0 g of anhydrous MgSO4 and 0.5 g of NaCl. Then, 5 mL of acetonitrile was added to the tube, and the sample was vortexed for 2 min to achieve a homogeneous sample. After vortexing the samples, the tubes were sonicated for 10 min to enhance the extraction efficiency and centrifuged for 5 min at 2300 g to produce a clear supernatant layer. The extraction process was then repeated as described. The supernatants were combined with those from the first extraction. For the sample purification step, 1.5 mL of the extract was transferred to a centrifuge tube containing 50 mg of PSA sorbents and 150 mg of anhydrous MgSO4. The sample tube was shaken vigorously for 1 min and centrifuged at 2300 g for 2 min. A 1-mL aliquot of the extract was filtered using a 0.2-μm nonsterile syringe filter, and then, 500 μL of the cleaned extract was placed in an autosampler vial for the HPLC/FLD analysis.

Sample preparation for the alkali digestion method

To analyse the PAHs from seafood using the alkali digestion method, the shell from manila clams was removed before being homogenised in a blender. A 2.0 g manila clams sample was then saponified with 10 mL of 1 m KOH in an ethanol solution for 30 min at 80 °C. Then, 5 mL of water and 5 mL of n-hexane were added, and the samples were mixed by a shaker seven times in 5-min intervals. All of the hexane fractions were collected. The fractions were transferred into a 50-mL tube containing 1 g of Na2SO4 and 1 g of silica gel to remove the water and then shaken for 10 min. The extract was filtered through filter paper and gently concentrated under a nitrogen gas stream to approximately 1 mL (Visciano et al., 2008). The 1-mL volume of the concentrated extract was filtrated through a 0.20-μm syringe filter into an Eppendorf tube for the HPLC injection.

Instruments

The SHISEIDO SP^LC chromatographic system was equipped with a SP3201 pump, an SP3023 autosampler system and a programmable SP3213 fluorescence detector (Shiseido, Tokyo, Japan). The chromatographic separations were carried out using a SUPELCOSIL LC_PAH (250 × 3.0 mm, 5 μm, Supelco, Bellefonte, PA, USA) with acetonitrile and water as the mobile phase. The analysis was performed at 30 °C, and the excitation and emission wavelength pairs were programmed to change during the analytical run to optimise the detection of each component. The conditions used for excitation and emission wavelengths are summarised in Table 1. The mobile phase consisted of water (A) and acetonitrile (B), with the following gradient programme: 25% A (0 min), 25% A (8 min), 0% A (23 min) and 0% A (40 min). The injection volume was 10 μL.

Table 1. The fourteen polycyclic aromatic hydrocarbons in this study
Time (min)λex (nm)λem (nm)Compounds
0270390Benzo[a]anthracene (BaA), chrysene (CHR), 5-methylchrysene (5-MC)
12310548Benzo[j]fluoranthene (BjF)
13290430Benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), dibenzo[a,l]pyrene (DlP)
19.1290460Benzo[g,h,i]perylene (BgP), indenol[1,2,3-cd]pyrene (IcP)
20.8290430Dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP), dibenzo[a,h]pyrene (DhP)

Method validation

The method was performed according to the International Conference on Harmonization to validate the analytical procedures (ICH, 1995, 1997).

Results and discussion

Optimisation of sample preparation

The method was developed and validated by using different sample preparation methods for seafoods. The sample preparation method was optimised by the QuEChERS and alkali digestion methods based on previous studies. The QuEChERS method was optimised using 2.0 g of sample, 2.0 g of anhydrous MgSO4 and 0.5 g of NaCl with 5 mL of acetonitrile twice to enhance the yield recovery at an extraction time of 10 min. The extract was purified using an SPE column made up of 50 mg of PSA sorbents and 150 mg of anhydrous MgSO4 to remove the matrix effect. The modified QuEChERS method was used to extract fourteen PAHs from seafoods. As a result, the experiments showed that the recovery of fourteen PAHs from the seafood samples was more than 91%, suggesting that the modified QuEChERS method is a reliable method for the sample preparation of seafoods. The Wong's QuEChERS method showed lower recovery than the modified QuEChERS method (data not shown). The alkali digestion method combined 2.0 g of sample with 10 mL of 1 m KOH in an ethanol solution with 5 mL of the 7th subfraction of n-hexane. The extract was purified by an SPE column made up of 1 g of Na2SO4 and 1 g of silica gel to remove the water. As shown in Fig. 1 and Table 3, the recovery of fourteen PAHs from the seafood samples was more than 82%. When comparing the two methods, the recovery level was higher in the QuEChERS method than in the alkali digestion method. The sample preparation method that has been previously reported for the determination of PAHs is the Soxhlet extraction due to its good separation in food samples (Mailer & Alfhelm, 1982; Lopez-Avila et al., 1993). However, the recoveries of fourteen PAHs from foods using Soxhlet extraction were not optimal (<60%). Richter and David (David & Seiber, 1996; Richter et al., 1996) developed a sample preparation method, accelerated solvent extraction (ASE), for PAH compounds to improve the average recovery. However, this method was difficult to apply to juicy foods because of its lower recovery rate. The sample preparation for the analytical method is very important for developing and implementing an official method to determine all PAH levels in seafood samples.

Figure 1.

Typical high-performance liquid chromatography with fluorescence detection chromatograms of the fourteen polycyclic aromatic hydrocarbons (PAHs): (a) a standard mixture of the selected PAHs prepared by the QuEChERS method, (b) an unspiked manila clams sample prepared by the QuEChERS method and (c) a spiked manila clams sample containing 2.5–12.5 ng g−1 of PAHs prepared by the QuEChERS method.

Method validation

The method validation protocol for all fourteen PAHs was used to compare the study of the QuEChERS and alkali digestion methods for the determination of PAHs in seafood. Figure 1 shows the chromatogram for a standard mix of fourteen PAHs found in seafood using HPLC/FLD. Peak identifications were made based on the injections of individual standards. The standard mix contains the fourteen PAHs: benzo[a]anthracene (BaA), CHR, 5-methylchrysene (5-MC), benzo[j]fluoranthene (BjF), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), dibenzo[a,h]anthracene (DhA), dibenzo[a,l]pyrene (DlP), benzo[g,h,i]perylene (BgP), indenol[1,2,3-cd]pyrene (IcP), dibenzo[a,e]pyrene (DeP), dibenzo[a,i]pyrene (DiP) and dibenzo[a,h]pyrene (DhP).

The linearity was examined using a calibration curve obtained by using working standard solutions with seven different concentrations for all fourteen PAHs in the range of 0.5–50 μg kg−1. The calibration curves of the fourteen PAHs were obtained by determining the linear relationship between the concentration of the standard compounds and their corresponding peak areas. As per the results, the correlation coefficient (r) of the calibration curve obtained from the fourteen PAH standards with the QuEChERS and alkali digestion method was 0.9869 and 0.9987, respectively, as shown in Table 2. These results showed a satisfactory linearity within the working range investigated for both developed sample preparation methods. The LODs and LOQs of the proposed methods were calculated on the basis of 3.3 and 10 σ S−1, respectively (σ is the standard deviation of the y-intercepts of the regression analysis and S is the slope of the calibration curve). In the case of the QuEChERS method, the LODs and LOQs for the fourteen PAHs were 0.0500–0.5270 and 0.1515–1.5971 μg kg−1, respectively. For the alkali digestion method, the LODs and LOQs were 0.2829–1.7096 μg kg−1 and 0.8573–5.1805 μg kg−1, respectively. The LODs and LOQs were approximately three times lower with the QuEChERS method compared with the alkali digestion method. These results were related to the matrix effect, as shown in Figs 1 and 2.

Table 2. The linearity and sensitivity data of the QuEChERS and alkali digestion methods for the determination of polycyclic aromatic hydrocarbons in spiked manila clams
AnalytesLinear range (μg kg−1)Alkali digestion methodQuEChERS method
Correlation coefficient (r)LOD (μg kg−1)LOQ (μg kg−1)Correlation coefficient (r)LOD (μg kg−1)LOQ (μg kg−1)
  1. BaA, benzo[a]anthracene; CHR, chrysene; 5-MC, 5-methylchrysene; BjF, benzo[j]fluoranthene; BbF, benzo[b]fluoranthene; BkF, benzo[k]fluoranthene; BaP, benzo[a]pyrene; DhA, dibenzo[a,h]anthracene; DlP, dibenzo[a,l]pyrene; BgP, benzo[g,h,i]perylene; IcP, indenol[1,2,3-cd]pyrene; DeP, dibenzo[a,e]pyrene; DiP, dibenzo[a,i]pyrene; DhP, dibenzo[a,h]pyrene; LOD, limit of detection; LOQ, limit of quantification.

BaA1.0–200.99920.55561.68350.99980.19430.5889
CHR1.0–200.99900.59291.79620.99980.24940.7557
5-MC1.0–200.99920.51691.56640.99980.24950.7560
BjF2.5–500.99931.28393.89050.99800.46781.4176
BbF1.5–300.99930.80842.44980.99990.24760.7503
BkF0.5–100.99940.28290.85730.98740.05000.1515
BaP0.5–100.99930.29580.89650.98690.07170.2172
DhA1.5–300.99930.82292.49370.99990.22460.6806
DlP1.5–300.99940.80902.45160.99990.22030.6676
BgP2.5–500.99921.51504.59100.99830.41711.2640
IcP2.5–500.99871.70965.18050.99900.52701.5971
DeP2.5–500.99951.27763.87160.99900.45421.3764
DiP1.5–300.99910.84622.56410.99970.36901.1183
DhP2.5–500.99941.33974.05980.99660.34281.0389
Figure 2.

Typical high-performance liquid chromatography with fluorescence detection chromatograms of fourteen polycyclic aromatic hydrocarbons (PAHs): (a) a standard mixture of the selected PAHs prepared by the alkali digestion method, (b) an unspiked manila clams sample prepared by the alkali digestion method and (c) a spiked seafood manila clams sample containing 2.5–12.5 ng g−1 of PAHs prepared by the alkali digestion method.

The accuracy and precision of the developed sample preparation methods were evaluated by spiking the manila clam with known amounts of standards of all of the PAHs. The method exhibited excellent precision, as shown in Table 3. The precision of the method was evaluated in terms of the intermediate precision (i.e. intraday and interday). The intraday data (CV%) conducted on three replicates of a sample in 1 day (n = 3) of all analytes were approximately 0.49–5.13% with the QuEChERS method, but were 0.26–6.20% with the alkali digestion method. The interday precision (CV%) was determined with a single analysis for a sample on three different days (n = 9) and was approximately 0.66–4.98% with the QuEChERS method and 1.45–5.79% with the alkali digestion method. The recovery experiments (n = 3) were performed by adding three different concentrations of each compound to the sample. The data for these experiments are shown in Table 3. The recovery of all analytes ranged from 86.87% to 115.67% with the QuEChERS method and from 69.22% to 100.21% with the alkali digestion method. This study evaluated the effectiveness and utility of the modified QuEChERS method. Compared to the alkali digestion method, the modified QuEChERS method substantially improved the average recovery of all fourteen PAHs by approximately 12%. Therefore, the precision and accuracy obtained by the QuEChERS method are considered acceptable for the analysis of the fourteen PAHs found in seafood. Additionally, the proposed QuEChERS method shows good potential for use in the determination of the selected PAHs in seafood.

Table 3. The intraday (n = 3) and interday (n = 3) precision and accuracy data for the determination of polycyclic aromatic hydrocarbons in spiked manila clams
AnalytesAdded amount (μg kg−1)Alkali digestion methodQuEChERS method
Intraday (CV%)*Interday (CV%)Recovery (%)Intraday (CV%)Interday (CV%)Recovery (%)
  1. CV%*, coefficient of variation in percentage; CHR, chrysene.

BaA52.344.5591.411.381.9293.54
102.262.1685.071.824.0295.52
201.953.3183.881.772.1093.14
CHR51.675.7590.913.102.1693.85
101.942.0682.152.824.2494.50
202.043.5782.362.081.6291.13
5-MC50.262.6091.032.322.3493.88
102.192.2687.792.104.2095.76
201.872.3386.221.941.8892.21
BjF12.52.544.3292.402.573.9791.29
252.143.1588.602.513.98113.66
502.224.4688.361.000.66115.67
BbF7.50.412.7586.171.023.0091.87
151.712.3986.281.353.9594.11
301.502.6184.791.562.7594.44
BkF2.50.673.1588.731.652.8292.29
51.291.8883.591.443.8694.67
101.531.5384.441.222.6593.13
BaP2.50.955.3190.421.562.9792.78
51.381.7982.471.694.1796.65
101.432.4085.221.472.9595.47
DhA7.52.414.4487.441.542.8391.92
151.682.0884.021.924.0192.39
301.172.7684.031.612.0992.78
DlP30.871.8386.601.173.0592.89
151.711.4585.651.904.6891.73
300.822.6085.681.903.2092.98
BgP2.55.885.7978.654.834.9894.69
12.51.483.2486.831.214.0190.59
501.151.9884.081.282.63112.16
IcP52.724.1595.492.712.73105.36
12.52.692.94100.211.403.4793.86
503.112.1388.971.051.60113.85
DeP2.56.205.0891.675.132.30111.74
54.484.2696.960.493.43112.57
12.50.752.5284.924.524.1092.55
DiP7.50.692.8684.801.415.1286.87
152.414.2086.541.544.5688.85
302.672.0583.031.002.5488.88
DhP2.53.312.7169.224.507.64105.48
54.204.9785.702.734.81113.34
12.50.204.9680.842.024.5892.91

Application of proposed methods –analysis of real seafood samples

The established analytical methods were applied to determine the amount of fourteen PAHs in different seafood samples collected from the Yellow Sea, which was contaminated by oil, and from the south coast of Korea. The contents of fourteen PAH compounds in the seafood were quantified, and the results are shown in Tables 4 and 5. Among the compounds analysed using the QuEChERS method and the alkali digestion method, CHR was the dominant compound, with concentrations ranging from 0.499 to 3.734 μg kg−1 at south coast of Korea and from 0.705 to 3.642 μg kg−1 in the Yellow Sea. Hu et al. suggested that CHR was detected from 3.51 μg kg−1 in cooked shellfish collected from south coast of Korea using HPLC/FLD (Hu et al., 2009). But Johnson reported that CHR was detected from 1.17 ppb in finfish collected from USA using HPLC/FLD (Johnson, 2012). In contrast, BaA, BbF and BkF were detected only in small amounts in the seafood samples using the QuEChERS and alkali digestion methods, with concentrations of 0.106–0.998 μg kg−1 at the south coast of Korea and 0.103–1.157 μg kg−1 at the Yellow Sea. The most carcinogenic compound, BaP, was found at a concentration of 0.117 μg kg−1 at the south coast of Korea using only the QuEChERS method in hard clams, whereas it was found at a concentration of 0.085 μg kg−1 at the Yellow Sea using only the QuEChERS method in oysters. Therefore, this result was determined by the aforementioned recovery data from the QuEChERS and alkali digestion methods. Also, Norman et al. reported that BaP was found at a concentration of 0.143 μg g−1 using QuEChERS method in oyster (Norman et al., 2011). Moreover, the value of BaP was considered to be in the acceptable range in the analysis of the fourteen PAHs in seafood according to the EU regulatory control value for BaP (10 μg kg−1) in seafood (EC, 2002). The concentrations below the LODs were considered to be not detected (ND).

Table 4. The determination of polycyclic aromatic hydrocarbons in various seafoods from the south coast of Korea
AnalytesManila clam (μg kg−1)Oyster (μg kg−1)Hard clam (μg kg−1)Cockle (μg kg−1)
Method 1Method 2Method 1Method 2Method 1Method 2Method 1Method 2
  1. ND, not detected; LOD, limit of detection; Method 1, alkali digestion; Method 2, QuEChERS; CHR, chrysene.

BaA<LOD<LOD0.6610.7610.7130.744<LOD<LOD
CHR0.6110.7223.7343.5271.2641.244<LOD0.499
5-MC<LOD0.2970.8810.785<LOD<LODND<LOD
BjFNDNDNDNDNDNDNDND
BbF<LOD<LOD0.9980.899<LOD0.429<LOD<LOD
BkF<LOD<LOD0.5370.531<LOD0.106<LOD0.183
BaP<LOD<LOD<LOD<LOD<LOD0.117<LOD<LOD
DhANDNDNDNDNDNDNDND
DlPNDNDNDNDNDNDNDND
BgPNDNDNDND<LODND<LODND
IcPNDNDNDNDNDNDNDND
DePNDNDNDNDNDNDNDND
DiPNDNDNDNDNDNDNDND
DhPNDNDNDNDNDNDNDND
Table 5. The determination of polycyclic aromatic hydrocarbons in various seafoods from the Yellow Sea
AnalytesManila clam (μg kg−1)Oyster (μg kg−1)Hard clam (μg kg−1)Cockle (μg kg−1)
Method 1Method 2Method 1Method 2Method 1Method 2Method 1Method 2
  1. ND, not detected; LOD, limit of detection; Method 1, alkali digestion; Method 2, QuEChERS; CHR, chrysene.

BaA0.8470.6951.1570.519<LOD0.343<LOD0.388
CHR2.1221.9163.6422.5710.7820.9310.7100.705
5-MCNDNDNDNDNDNDNDND
BjFNDNDNDNDNDNDNDND
BbF<LOD<LOD1.1470.788<LOD<LOD<LOD<LOD
BkF<LOD0.1380.3230.971<LOD0.103<LOD0.189
BaP<LOD<LOD<LOD0.085<LOD<LOD<LOD<LOD
DhANDNDNDNDNDNDNDND
DlPNDNDNDNDNDNDNDND
BgPNDNDNDNDNDND<LODND
IcPNDNDNDNDNDNDNDND
DePNDNDNDNDNDNDNDND
DiPNDNDNDNDNDNDNDND
DhPNDNDNDNDNDNDNDND

Conclusions

In this study, two efficient, quick and easy sample preparation procedures for the simultaneous determination of fourteen PAHs in seafood were developed and validated using HPLC/FLD. The proposed methods showed good linearity, precision and accuracy. However, the QuEChERS method showed a higher separation efficiency than the alkali digestion method for the determination of the fourteen PAHs in seafood when using the HPLC/FLD as described herein. The results of this study show that the proposed QuEChERS method was suitable for the evaluation of quality of selected PAHs in seafood. According to the results from the application of the QuEChERS method, this method is amenable to determining the levels of fourteen PAHs simultaneously in seafood. Therefore, the proposed QuEChERS method will be valuable for the further use in the determination of the selected PAHs in seafood.

Ancillary