Table 1.

Atomic spectrophotometric and UV–Vis spectrophotometric techniques coupled with hollow fiber based extraction techniques for heavy metals determination.

Instrumental techniques	Metal/Analyte	Preconcentratio/Separation method	Complexing agent/Carrier	SLM composition	Real applications	LODa	EF/PFb	LRc	Instrumental technique mode	Ref.
Atomic spectroscopic techniques	Pb	HFSLPME	TiO2	TiO2 + Caprylic acid	Rice, milk, water	0.2 μg/L	790	0.6–3000 μg/mL	FAAS	[51]
	As	HFLPME	APDC	Triton X-100	Environmental water samples	0.08 ng/mL	280	0.4–12 ng/mL	FAAS	[52]
	Cr (VI)	IEME	—	1-octanol	Environmental water samples	3 ng/mL	23	10–600 ng/mL	FAAS	[53]
	Pb	HFLPME	Kronenether	Kronenether + oleic acid	Blood, urine samples	0.001–0.002 ng/mL	18.7–21.3	1–50 ng/mL	GFAAS	[54]
	Hg	EME	DEHP	DEHP + 1-octanol	Tap water	0.5 μg/L	102–108	0.5–10 μg/L	GFAAS	[55]
	Cr(VI)	EME	PANI	PANI + 1-octanol	Spring, sea and distilled water	0.02 ng/mL	106	0.02–2.0 ng/mL	ETAAS	[56]
	Cr(VI)	HFLPME	Methyltrialkylammonium chloride	Methyltrialkylammonium chloride + 1-octanol	Drinking, mineral and tap water	3 μg/L	—	10–90 μg/L	RGB/ ICP-AES	[57]
	Pb	CM-HFLPME	CTAB	CTAB + 1-octanol	Blood samples	0.1 ng/mL	33	1–200 ng/mL	ETAAS	[58]
	Cr (VI)	μEME	Tetra alkyl ammonium chloride	Tetra alkyl ammonium chloride+ 1-octanol	Wastewater samples	0.06 ng/mL	9.1	0.5–14 ng/mL	ETAAS	[59]
	Hg	HFLPME	DDTC	DDTC + toluene	Water and freshwater fish	0.143	103	0.5–7.5	ETAAS	[60]
UV–visible spectrometry	Cr (VI)	EME	1,5-diphenylcarbazide	NPOE	Environmental water samples	2.3–7 μg/L	80	10–80 μg/L	UV–vis spectrometry	[61]
	Cr (VI)	EME	Calix[4]arene	NPOE + calix[4]arene	Industrial water	—	—	—	UV–vis spectrometry	[62]
	Hg	EME	DEHP	1-octanol	River, tap water and fish sample	0.7–12 μg/kg	130–176	2.3–950 μg/L for water and 40–9500 μg/kg for fish sample	UV–vis spectrometry	[63]
	Au	EME	PAN	1-octanol	Tap, river and ground water	4.5 μg/L	200	20–2000 μg/L	UV–vis spectrometry	[64]
	Bi +3	EME	DEHP	DEHP + 1-octanol	Plasma, water	1.47 μg/L	151	4.9–800 μg/L	UV–vis spectrometry	[65]

EME: Electro-membrane extraction, HFLPME: Hollow fiber liquid phase microextraction, IEME: In-tube electro-membrane extraction, CM-HFLPME: carrier-mediated hollow fiber liquid phase microextraction, DEHP: bis(2-ethylhexyl) phosphate, CTAB: N,N,N-cetyltrimethyl ammonium bromide, APDC: Ammonium pyrroldinedithiocarbamate, PANI: Polyanniline, DDTC: Diethyldithiocarbamate, PAN: 1-(2-pyridylazo)-2-naphthol), NPOE: 2-nitrophenyl octyl ether, FAAS: Flame atomic absorption spectroscopy, GFAAS: Graphite furnace atomic absorption spectrometry, ETV-ICP-OES: Electrothermal vaporization inductive couple plasma optical emission spectroscopy, RGB/ ICP-AES: Red Green Blue Analysis/ inductive couple plasma atomic emission spectroscopy.

^aLimit of detection.

^bEnrichment factor/Pre-concentration factor.

^cLinear range.