Environmental Analysis 25
Figure 5: Overlay HPLC – FLD chromatograms of the spiked soil sample containing: 1. Nap 2. Acy 3. Ace 4. Flu 5. Phe 6. Ant 7. Fln 8. Pyr 9. BaA 10. Chr 11. BeP 12. BeA 13. BkF 14. DahA 15. BghiP 16. InP. The spiking level for this sample was a level 1 (see Table 3). The blue portion of the chromatogram used the following excitation/emission wavelengths: 260-nm/352-nm; the red portion: 260-nm/420-nm and the light blue portion: 260-nm/440-nm. However, due to lack of a fluorophore, UV detection at 230 nm was employed for acenaphthylene. Chromatographic conditions are shown in Table 1.
QuEChERS extraction
The use of CH3CN as an extracting solvent in a salting-out condition, without the need to add co-solvents, attained high extraction yields as shown by the
recoveries in Table 4. In addition, the CH3CN solvent is compatible with the HPLC – FLD procedure in this application note. Therefore, no evaporation or reconstitution solvent was required. This is particularly important for the PAHs since some of these compounds (naphthalene, acenaphthene and fluorene) are extremely volatile and may be lost during an evaporation step [7].
Linearity, Limit of Detection (LOD) and Limit of Quantification (LOQ) Linearity
The linear calibration curves were obtained by plotting the peak area for each analyte versus its concentration. Curves were generated by spiking the sample blanks at a concentration range of 0 – 300 ng/g.
Limits of Detection and Quantification The limits of detection and quantification were evaluated from the PAH Naphthalene *Acenaphthylene
Acenaphthene Fluorene
Phenanthrene Anthracene Fluoranthene Pyrene 1,2-Benzanthracene Chrysene Benzo[e]pyrene Benz[e]acenaphthylene Benzo[k]fluoranthene
Dibenzo[a,h]anthracene Benzo[g,h,i]perylene Indeno[1,2,3-cd]pyrene
* UV detection at 230 nm Table 2: Linearity, LOD and LOQ for the Sixteen Polycyclic Aromatic Hydrocarbons Regression equation Y = 0.0266x + 0.1568 Y = 0.0580x – 0.1323
Y = 0.0176 x + 0.0122 Y = 0.0358x – 0.1701
Y = 0.1097x - 0.4277 Y = 0.0884x – 0.096 Y = 0.0273x – 0.0069 Y = 0.0284x – 0.1041 Y = 0.0120x – 0.0249 Y = 0.0067x + 0.0165
Y = 0.017x – 0.0252 Y = 0.1304x + 0.0727
Y = 0.052x + 0.0165
Y = 0.062x – 0.0346 Y = 0.0599x + 0.0779 Y = 0.0352x – 0.1588
R2 0.9992 0.9991
0.9995 0.9991
0.9994 0.9993 0.9997 0.9993 0.9994 0.9992
0.9995 0.9993
0.9993
0.9994 0.9995 0.9992
concentration of sulfonamides required to give a signal-to-noise ratio of 3 and 10 respectively. Table 2 shows the regression equation, correlation coefficients, and very limits of detection and quantification.
Recovery and Reproducibility
The recovery and reproducibility (RSD) were evaluated on spiked samples at three different levels as shown in Table 3. The analysis was performed in replicates of six (n = 6) at each level. Table 4 shows the recoveries and RSD values for the sixteen polycyclic aromatic hydrocarbons.
Conclusions
A simple and fast multiresidue method based on SampliQ QuEChERS AOAC and HPLC-FLD has been developed for the simultaneous determination of sixteen polycyclic aromatic hydrocarbons at parts-per-billion levels in soil. High recoveries with excellent RSD were attained, therefore it is concluded that the method is applicable for quality control PAHs in real samples.
LOD 0.48 0.06
0.12 0.24
0.07 0.18 0.07 0.005 0.78 0.007
0.008 0.03
0.06
0.18 0.18 0.05
LOQ 1.6 0.20
0.41 0.79
0.22 0.60 0.24 0.02 0.26 0.02
0.03 0.11
0.21 0.6
0.81 0.59
August/September 2010 AET
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