![Fig. 2. ESI(−) mass spectra of -KgCN (A) and -KgCN-d4 (B) with identification of the abundant ions. (A) The -KgCN ion at 172.0 m/z corresponds to [M−H]− and the ion at 144.7 m/z corresponds to [ -Kg-H]− , the precursor to -KgCN. (B) The -KgCN-d4 ion at 176.1 m/z corresponds to [M−H]− and the ion at 149.1 m/z corresponds to [ -Kg-d4-H]− . Insets: Structures of -KgCN (A) and -KgCN-d4 (B) with abundant fragments indicated.](/figures/fig-2-esi-mass-spectra-of-kgcn-a-and-kgcn-d4-b-with-23p69i1t.webp)
Q2. What have the authors stated for future works in "Quantification of α-ketoglutarate cyanohydrin in swine plasma by ultra-high performance liquid chromatography tandem mass spectrometry" ?
Future work will include the application of the method to analyze -KgCN from the plasma of cyanide-exposed swine and investigations pertaining to the low recovery of -KgCN from swine plasma.
Q3. What side reactions remove cyanide from the swine plasma?
cyanide may undergo various side reactions that remove it from the swine plasma such as protein binding [3,14], ATCA formation [7,32], or evaporation of HCN [4,33].
Q4. How was the plasma shipped to South Dakota State University?
The plasma was shipped overnight on dry ice to South Dakota State University, where it was immediately frozen upon arrival and stored at −80 ◦C until needed.
Q5. How long did the QC standards stand at room temperature?
For bench-top stability, the QC standards were allowed to stand at room temperature for 0, 2, 4, 8, 12 and 24 h prior to analysis.
Q6. What was the flow rate for the nebulizer and heater?
The ion source was operated at −4500 V and a temperature of 750 ◦C with a flow rate of 90.0 psi for both the nebulizer (GS1) and heater (GS2) gasses.
Q7. How much recovery is -KgCN in swine plasma?
Heating the swine plasma to precipitate proteins and cooling back to room temperature before spiking in -KgCN actually decreased the recovery (7%, 4%, and 4% for low, medium, and high QC standards, respectively).
Q8. What are the limitations of cyanide analysis?
The direct analysis of cyanide to confirm exposure has serious limitations, due to cyanide’s volatility, reactivity, and short half-life in biological fluids [4–6].
Q9. What is the main advantage of using -KgCN as a biomarker?
The method allows -KgCN to serve as a biological marker for cyanide exposure and should aid in studies of therapeutic treatment of cyanide exposure with -Kg.
Q10. What was the resulting linear dynamic range of -KgCN in swine?
Calibration standards at 0.2, 100, and 300 M were found to be outside the LLOQ or ULOQ, resulting in a linear dynamic range from 0.3 to 50 M as described by a weighted (1/x2) curve validated over 3 separate days of analysis (within 9 calendar days).
Q11. How many days did the LOD of -KgCN in swine plasma?
The LOD was found to be 200 nM -KgCN in swine plasma validated over a 7-day period with 3 separate days of analysis (n = 7 for each day).
Q12. What is the reaction between cyanide and ketoglutarate?
In biological systems, cyanide is converted to -ketoglutarate cyanohydrin ( -KgCN) through an equilibrium reaction with -ketoglutarate ( -Kg) (Fig. 1) [6].
Q13. What is the m/z ratio of -KgCN?
The -KgCN elutes at approximately 1.6 min with some degree of tailing, which is most likely caused by the interaction of exposed silica support with -KgCN.
Q14. What was the effect of thiocyanate on the recovery of whole blood?
Ballantyne reported that thiocyanate concentrations fluctuated during various sample storage conditions and recovery of thiocyanate from whole blood was low [8].
Q15. What is the stability of -KgCN in swine plasma?
the bench-top stability of -KgCN was poor with -KgCN concentrations falling significantly below 85% of the control within 2 h, showing that -KgCN is quickly eliminated from swine plasma at room temperature.