Q2. How long did the chromatographic run take?
The determination of target compounds was performed in positive/negative voltage switching mode in a single chromatographic run of only 10 min.
Q3. What is the frequently detected compound in the sample?
used for the treatment of epilepsy and bipolar disorder, was the compound most frequently detected, appearing in all samples analyzed.
Q4. What is the goal of the present paper?
The goal of the present paper is to develop fast and sensitive analytical methodology combining the advantages of UHPLC-MS/MS with last-generation triple quadrupole and large-volume direct sample injection.
Q5. What was used for the preparation of the aqueous calibration standards?
Mixed working solutions containing all analytes were prepared daily from intermediate solutions by appropriate dilution with water, and were used for preparation of the aqueous calibration standards and for spiking samples in the validation study.
Q6. How many transitions were acquired in the confirmation process?
Although the acquisition of two SRM transitions per compound together with the accordance in the retention time are normally considered sufficient for a reliable confirmation of the compound identity, in this work three transitions were acquired in order to increase the confidence of the confirmation process [40].
Q7. What is the common method for analyzing pharmaceuticals in aquatic samples?
Current analytical methods developed for quantifying low concentration of pharmaceuticals [2,8–10] and illicit drugs [11,12] in aquatic samples, usually include pre-concentration steps, the most common being those based on solid-phase extraction (SPE).
Q8. What were the two internal standards used to correct possible deviations?
Regarding quantification parameters, two internal standards were used to correct possible deviations: diclofenac-13C6 forpharmaceuticals and cocaine-d3 for drugs of abuse.
Q9. How can one minimize the possibility of false negatives when one of the transitions seems to be?
Using three transitions, one can minimize the possibilities of reporting false negatives when the ion ratio is not accomplished, in those cases where one of the transitions seems to be interfered.
Q10. What was the method used for the UPLC analysis?
UHPLC analysis were carried out with a Waters Acquity ultra-performance liquid chromatography (UPLC) system (Waters, Milford, MA, USA), equipped with a binary solvent manager and a sample manager.
Q11. What type of water samples were used for the validation of the method?
Analytical characteristics of the method were evaluated in two types of water samples: five surface water and five effluent wastewater samples, spiked at three concentration levels each (10, 100 and 1000 ng/L).
Q12. How many compounds were found in the on-line method?
Six compounds (cocaine, benzoylecgonine, diclofenac, naproxen, sulfamethoxazole and venlafaxine) were found in EWW samples, less than in the direct injection methodology (32 compounds).
Q13. How many compounds could be corrected with their own ILIS?
Fourteen compounds could be corrected with their own ILIS, as they were available to their laboratory, obtaining satisfactory figures after correction, as expected.
Q14. How many compounds were quantified using an analogue IS?
14 compounds were quantified using their corresponding labelled analyte as internal standard and 5 compounds were quantified using an analogue IS (see Table 2).
Q15. How many compounds were detected in 10 samples?
The application of this method to 10 effluent wastewater and 10 surface samples, allowed the detection of 32 and 26 compounds, respectively.
Q16. What is the preferred method for removing or compensating for the matrix effects?
Among the different approaches proposed in the literature to remove or compensate for the matrix effects, the use of isotopically-labeled internal standards (if available) was considered the preferred option.