grade and were used without further purification; yttrium nitrate
hexahydrate (Y(NO3)3·6H2O, 99.89%),
gadolinium nitrate hexahydrate (Gd(NO3)3·6H2O, 99.89%), and terbium nitrate hexahydrate (Tb(NO3)3·6H2O, 99.89%), PEI (with Mw = 25 000 and Mn =
10 000), TNP, 2,4-DNT, 2,6-DNT, 2,4-DNP, RDX, phenylalanine,
cysteine, isoleucine, tryptophan, glutamic acid, aspartic acid, lysine,
histidine, and glutamine were purchased from Sigma-Aldrich Inc. TNT
and RDX were purchased from HEMRL, Pune. NaCl, Na2HPO4, NaH2PO4, Na2CO3, NaHCO3, and NaOH were received from Thomas Baker. NH4F was received from Merck. Dextrose, glucose, sucrose, fructose,
lactose, and maltose were received from Himedia laboratories Pvt.
Ltd. 1,3-DNB, 4-NP, 2,4-DNB, NM, 4-NT, NB, copper oxychloride, cypermethrin,
malathion, fenvelerate, carbendazim, and chloropyrifos were purchased
from a local company and used as received. Ethanol was obtained from
Hayman Ltd. Deionized water was used throughout the experiments.