Table 2.

Analytical parameters of reviewed research papers about the speciation and determination of mercury by spectrophotometer and spectrofluorometer.

S. number	Analyte	Analytical instrument used for the detection	Method	Limit of detection (LOD)#	Linearity range	Analyzed samples	Interference study	Supporting media	Reference
1	Hg(II)	Fluorescence spectrophotometer	Fluorescence	4.0 × 10−9 M	6.0–450 nM	Water samples	10-fold of Pb2+, Cu2+, and Ag+ shows <7% influence on the determination of Hg2+ compared to reported ones	CdTe quantum dots	[80]
2	Hg(II)	Spectrophotometer	Colorimetric	23 × 10−9 M	0.00–0.31 μM	River water	Selective in presence of Ag+, Cd2+, Cu2+, Co2+, Ni2+, and Pb2+	Carbon nanodots	[81]
3	Hg(II)	Spectrophotometer	Colorimetric	2.6 × 10−9 M	0.001–1 μM	Water samples	Selective in presence of 20 μM of Al3+, Ca2+, Co2+, Cu2+, Cd2+, Fe3+, Mn2+, Ni2+, Pb2+, and Zn2+	Gold nanoparticles	[82]
4	Hg(II)	Spectrophotometer	Colorimetric	—	0.83–8.6 μg mL−1	Water samples	The tolerance limit of Cu2+, V5+, Ag+, Pd2+, Pt4+, Au3+, Fe2+, Ni2+, Cd2+, Pb2+, and Cr6+ is in the range of 0.11–041 μg mL−1in the determination of 1.91 μg mL−1 of Hg2+	5-Methylthiophene-2-carboxaldehyde ethylenediamine	[83]
5	Hg(II)	Spectrofluorometer	Fluorescence	1.73 × 10−9 M	2.0 nM–60 μM	—	Interference of major cations studied	ONPCRs1	[84]
6	Hg(II)	Spectrophotometer	Colorimetric	50 × 10−9 M2	0–1000 nM	Water samplers	Selective in presence of Ni2+, Co2+, Ca2+, Cu2+, Na+, K+, As3+, Mg2+, Cd2+, and Fe2+	Silver nanoparticles	[85]
7	Hg(II)	UV-Vis spectrophotometer	Colorimetric	1.35 × 10−6 M	—	Drinking water	Cd2+, Pb2+, Fe3+, and Ba2+ do not interfere in the determination of Hg2+ but Mg2+, Ca2+, and Mn2+ interfere slightly	Gold nanoparticles	[86]
8	Hg(II)	Spectrofluorometer and UV-spectrometer	Colorimetric and fluorescent sensor	2.7 × 10−8 M	0–1.0 × 10−6 M	Water samples and living cells	The fluorescent signal for Hg(II) is not influenced by the major metal ions including Fe(III), Cu(II), and Al(III)	2,4-Dichloroquinazoline	[87]
9	Hg(II)	Spectrophotometer	Colorimetric	5.3 × 10−13 M	1.0 × 10−12–8.6 × 10−4 M	Water samples and SRM	Selective in presence of Mn2+, Fe2+, Fe3+, Ni2+, Co2+, Cd2+, and Pb2+	Chromoionophore V	[88]
10	Hg(II)	Spectrofluorometer	Fluorescent and colorimetric	1.0 × 10−9 M	—	Spiked water samples	Na+, Mg2+, K+, Cr3+, Mn2+, Co2+, Ni2+, Fe3+, Cu2+, Zn2+, Ag+, Cd2+, and Pb2+ did not interfere	Rhodamine B	[89]
11	Hg(II)	Spectrofluorometer	Fluorescence	14.2 × 10−9 M	0–5 × 10−7 M	Aqueous solutions	Cd2+, Cu2+, and Ag+ do not interfere	Thioether-appended dipeptide	[90]
12	Hg(II)	Spectrofluorometer	Fluorescence	0.5 × 10−9 M	0.0005–0.01 μM	Lake water samples	Zn2+, Pb2+, Ni2+, Ca2+, Mg2+, Cu2+, Co2+, Cd2+, Fe3+, and Mn2+ did not interfere	Carbon nanotubes	[91]
13	Hg(II)	Spectrofluorometer	Fluorescent	1.74–3.83 × 10−6 M	—	Living cells	Minor interference from Ag+, Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, Rb+, and Zn2+	Pyrene	[92]
14	Hg(II)	Spectrophotometer	Colorimetric	0.4 × 10−6 M	0.1–4.2 μg mL−1	Water, biological, plant leaves, and soil samples	Tolerance limit of the Cd2+, Zn2+, Ce3+, Ce4+, In3+, Cr3+, La3+, Yb3+, and Eu3+ is 300 μg mL−1 and the tolerance limit of the Co2+, Cu2+, Fe3+, Ti4+, Pb2+, Ni2+, and Ag+ is 100 μg mL−1 and at Hg(II) is 2.0 μg mL−1	2,4,7-Triamino-6-phenylpteridine	[93]
15	Hg(II)	Spectrofluorophotometer	Fluorescent	1.0 × 10−7 M	2.0 × 10−7–3.0 × 10−5 M	Water samples	Selective in presence of Na+, K+, NH4 +, Ba2+, Zn2+, Cd2+, Mg2+, Ca2+, and Ni2+	Conjugated polymer multilayer films	[94]
16	Hg(II)	Spectrophotometer	TGFRET3	0.49–0.87 × 10−9 M	1.0 × 10−9–1.0 × 10−8 M	Water samples	Selective in presence of Mn2+, Ba2+, Ni2+, Cu2+, Ca2+, Cr2+, Co2+, Cd2+, Mg2+, Zn2+, Al3+, Fe3+, and Pb2+	Gold nanoparticles	[95]
17	Hg(II)	Spectrofluorometer	Fluorescent	1 × 10−9 M	0.01–0.12 μM	Water samples	Selective in presence of Zn2+, Pb2+, Ni2+, Co2+, Ca2+, Cu2+, Mg2+, Cd2+, Fe3+, and Mn2+	Carbon nanodots	[96]
18	Hg(II)	Spectrofluorometer	Fluorescent	0.012 × 10−6 M	0-1 μM	Tap and river water samples	Selective in presence of Ag+, Pb2+, Na+, K+, Cr3+, Cd2+, Ba2+, Zn2+, Mg2+, Cu2+, Ni2+, Ca2+, Al3+, and Fe3+	Rhodamine	[97]
19	Hg(II)	Spectrofluorometer	Fluorescence	2.24 × 10−9 M	5.0–100 nM	Drinking water	20-fold of Ca2+, Mg2+, Zn2+, Cr3+, Pb2+, Cr6+, Mn2+, Cd2+, Fe3+, Al3+, and Ni2+, 10-fold of Fe2+, and Co2+, 5-fold of Cu2+, and the same concentration of Ag+ caused almost no interference	Gold nanoparticles	[98]
20	Hg(II)	Spectrophotometer	Optical chemical sensor	0.18 × 10−12 M	7.2 × 10−13–4.7 × 10−4 M	Tap water, river water, and canned tuna fish	Interference of Cu(II) eliminated with the addition of L-histidine as a masking agent	Synthesized ionophore	[99]
21	Hg(II)	UV-Vis spectrophotometer	Colorimetric sensor	5.0 × 10−6 M (visual), 1.0 × 10−7 M (UV-Vis)	—	Aqueous solutions	Mg2+, Ca2+, Zn2+, Cu2+, Cr3+, Fe3+, Pb2+, Ni2+, Co2+, and Ag+ did not interfere	Dimethyl sulphoxide	[100]
22	Hg(II)	Fluorescence spectrophotometer	Fluorescence probe	16 × 10−9 M	0.02–1.0 μM	Aqueous solutions	Selective in the determination of Hg2+ over other metal ions such as Fe3+, Ca2+, Mg2+, Mn2+, Cr3+, Ni2+, Cu2+, Co2+, and Pb2+	Gold nanoparticles	[101]
23	Hg(II)	—	Colorimetric	1.2 × 10−9 M	2–30 nM	Water samples	Na+ (2 mM), K+ (2 mM), Fe3+, Zn2+ and Mg2+ (0.1 mM), Ni2+, Co2+, Cd2+, Pb2+ and Cu2+ (50 μM), and Ag+ (3.5 μM) did not interfere with the detection of Hg2+ (25 nM) in the mentioned amounts	Rhodamine B thiolactone	[102]

^#For the conversion of limit of detection values into moles per liter (M) the atomic weight of Hg is taken as 200.59 g, MeHg as 215.59 g, EtHg as 229.59 g, and PhHg as 277.59 g.

¹ONPCRs: oxygen-doped nitrogen-rich photoluminescent polymer carbon nanoribbons; ²Limit of quantification; ³TGFRET: time-gated fluorescence resonance energy transfer.