Sensing Heavy Metals Using Mesoporous-Based Optical Chemical Sensors

Table 4

Properties of OCSs for selected heavy metal ions.

Analyte	Indicator dye	Material	Detection principle	Working range (M)	LOD (M)	𝑡𝑅	Ref.
Cu^2+	P2	SBA-15	Fluorescence quenching	1.6×10^−9--1.1×10^−8	1.6×10^−9	Not given	[35]
Cu^2+	DZ	HOM-11	Absorption (colour change)	1.57×10^−8--7.86×10^−6	3.1×10^−8	60 s	[36]
		MCM-41		7.86×10^−8--7.86×10^−6	12.5×10^−8	80 s
Cu^2+	SGAAn	Type not defined	Fluorescence quenching	5×10^−8--10^−4	2×10^−8	4-5 s	[37]
Cu^2+	PAR	HMS	Absorption (colour change)	6.3×10^−7--6.3×10^−6	1.3×10^−8	60 s	[38]
Zn^2+	QTEPA	MCM-41	Fluorescence enhancement	0.1×10^−6--30×10^−6	0.1×10^−6	Not given	[39]
Zn^2+	8-AQ	Type not defined	Fluorescence enhancement	5×10^−8--2×10^−5	2×10^−8	Not given	[40]
Zn^2+	SSD	Type not defined	Fluorescence enhancement	Not given	70×10^−9	Not given	[41]
Zn^2+	8-HQ	MCM-41	Fluorescence enhancement	Not given	1.2×10^−6	30 s	[42]
Cd^2+					1.9×10^−9	30 s
Co^2+	Azo dye	HOM-2	Absorption (colour change)	1.7×10^−8--17×10^−6	~15×10^−9	15 min	[43]
Bi^3+	DZ	HOM-11 (3.2 nm pore size)	Absorption (colour change)	2.3×10^−9--9.6×10^−6	6.5×10^−10	20 s	[44]
		MCM-41		2.39×10^−8--9.6×10^−6	8.1×10^−9	40 s
Cr^3+	R6G	SBA-15	Fluorescence enhancement	1×10^−6--6×10^−6	1×10^−6	Not given	[45]
Cr^6+	DPC	HOM-10	Absorption (colour change)	13.3×10^−10--3.8×10^−6	8.1×10^−10	60 s	[46]
Pd^2+	TPPS			9.4×10^−9--9.4×10^−6	2.3×10^−9	80 s
Co^2+	PR			8.4×10^−9--1.7×10^−5	2×10^−9	45 s
Pb^2+	DZ			2.4×10^−10--4.8×10^−6	2.7×10^−11	60 s
Pb^2+	DTAR	HOM-13	Absorption (colour change)	4.8×10^−8--4.83×10^−7	13×10^−9	12.5–17.5 min	[46]
		HOM-9		2.4×10^−8--7.2×10^−7	9×10^−9	5–7 min
Pb^2+	PMBA	SBA-15	Fluorescence quenching	2×10^−6--50×10^−6	0.5×10^−9	Immediate response	[48]