In order to have lower limits of quantification and in an
attempt to reduce the solvent volume that was employed, lower
volumes of acetonitrile were tested. When 1 mL acetonitrile was
used for pesticide elution, the recoveries were lower than when
5 and 10 mL were used (data is not shown). One mL may not be
enough to elute all the compounds retained in the sorbent. Higher
recoveries were reached when 5 and 10 mL acetonitrile were
employed. Five mL was chosen because it presented no significant
differences from 10 mL when a statistical test was carried out
(t test, P40.05) and it is cheaper, safer and environmentally
friendlier than 10 mL.
After these experiments, a modification during the elution step
was performed [28]. After blending the sample (0.5 g) with 1 g
reused C18 sorbent in a mortar, the mixture was poured into a 15 mL
polypropylene centrifuge tube and 5 mL acetonitrile was added. The
tube content was thoroughly mixed for 1 min in a vortex. Then, the
tubes were placed into a centrifuge at 4000 rpm for 10 min. This
procedure (vortex-assisted) was compared to the traditional MSPD
with elution in a vacuum manifold. Results are shown in Fig. 3
In order to have lower limits of quantification and in an
attempt to reduce the solvent volume that was employed, lower
volumes of acetonitrile were tested. When 1 mL acetonitrile was
used for pesticide elution, the recoveries were lower than when
5 and 10 mL were used (data is not shown). One mL may not be
enough to elute all the compounds retained in the sorbent. Higher
recoveries were reached when 5 and 10 mL acetonitrile were
employed. Five mL was chosen because it presented no significant
differences from 10 mL when a statistical test was carried out
(t test, P40.05) and it is cheaper, safer and environmentally
friendlier than 10 mL.
After these experiments, a modification during the elution step
was performed [28]. After blending the sample (0.5 g) with 1 g
reused C18 sorbent in a mortar, the mixture was poured into a 15 mL
polypropylene centrifuge tube and 5 mL acetonitrile was added. The
tube content was thoroughly mixed for 1 min in a vortex. Then, the
tubes were placed into a centrifuge at 4000 rpm for 10 min. This
procedure (vortex-assisted) was compared to the traditional MSPD
with elution in a vacuum manifold. Results are shown in Fig. 3
การแปล กรุณารอสักครู่..
