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As a chemist, I would like to extract all the analytical methods used to characterize and analyze the 2-Nitropyridine in the following procedure and only the one used in this procedure.
At this step, I only need the name or type  of the analytical methods and not the analytical results and not the full description of the methods.

The response should follow the format:
Method 1: 
Method 2:  
Method 3 : 
Method 4 : 

At this step, I only need the name or type  of the analytical methods and not the analytical results and not the full description of the methods.

Could you help me ?

 
Procedure : 
Synthesis 2-Nitropyridine 

1.0 g (10.6 mmol) of 2-aminopyridine was dissolved in 10 mL of concentrated sulphuric acid and the resulting solution was cooled to 0°C using an ice bath. To this solution, a cooled (5°C) mixture of 30% aqueous hydrogen peroxide (15 mL) in 30 mL of concentrated sulphuric acid was added dropwise, thus maintaining the temperature below 15°C. The colour of the solution changed from yellow to green. It was kept stirring at room temperature overnight and then carefully basified with 3 M aqueous KOH. The resulting mixture was then filtered and extracted with ethyl acetate. The organic layer was washed with water and brine, then dried over anhydrous Na2SO4 and the solvent was evaporated. The residue was separated by MPLC using petroleum ether/ethyl acetate (50/50; v/v) as mobile phase at
a flow rate of 20 mL/min. 2-Nitropyridine was obtained as yellow solid (69%).
1H NMR (DMSO-D6, 400 MHz):
δ 9.07(1H, bdd, Japp = 0.91 & 4.5 Hz, H6), 8.69(1H, dd, J = 1.22 & 8.24 Hz, H3), 8.62 (1H, td, J = 1.53 & 7.02 Hz, H4), 8.3(1H, ddd, J = 1.53 & 3.05 & 7.1 Hz, H5).
13CNMR (DMSO-D6, 100 MHz):
δ 158(C-2), 150(C-6), 141(C-4), 130(C-5), 118.5(C-3).
MS-FAB (70 eV) m/z:
124(10%) [M]+, 94.1(18%)[M-NO]+, 78.1(100%)[M-NO2]+.
m.p.: 73°C.
Rf: (PE/EtAc 1:1):0.45.

gpt
--- Reasoning ---
1. Is the question multiple-choice question?
No
2. Is it implied multiple-choice question?
No
3. If two experts were independently asked the question, will the final answer be exactly the same?
Yes

--- Answer ---
grounded