With internal standard, our FA extraction efficiency was 87.5% (data now shown).
All samples were processed in the presence of internal standards to monitor extraction efficiency and verify measurement accuracy.
We have now provided the quantification of anthocyanins but were unable to do this for the lignins for technical reasons, i.e., insufficient amounts of material and lack of internal standards for the extraction efficiency.
We have now quantified anthocyanins but were unable to do this for the lignins for technical reasons, i.e., insufficient amounts of material and lack of internal standards for the extraction efficiency.
To investigate the effect of the sample matrix on extraction efficiency, standard curves were prepared for DCP and ECH in ethyl acetate, water, and blood.
However, because the inclusion of the C13 internal standard to correct for FAME extraction efficiency, the accuracy of FAME quantification in algal biomass with multiple or single hexane extractions did not change significantly (data not shown).
In each instance, a deuterium-labeled internal standard was included to correct for extraction efficiency and to facilitate quantification.
DNA was extracted using standard extraction kits following the manufacturer's protocol (Blood and Tissue DNA extraction, Qiagen).
Laboratory validations were done using parallelism and recovery checks (extraction efficiency) of the cortisol standard against pooled Koala faecal extracts.
Steroid extraction efficiency (mean percentage ± standard deviation = SD of recoveries) was included (Methods subsection "Reproductive stages"): Testo: 70.9 ± 2.7, DHT: 73.7 ±4.3, E2: 59.9 ±4.0, P4: 55.9 ±11.0.
We verified the extraction efficiency by recovery of standard toxins added to seawater samples and processed as described above.
