. 2022 Feb 26;27(5):1563. doi: 10.3390/molecules27051563

Table 1.

Examples of kinetic discrimination in flow analysis.

Analyte(s)	Sample	Reaction	Sampling Rate (h⁻¹)	CV (%)	Remarks	Ref.
Acetaminophen or isoxsuprine, isoniazid	Pharmaceuticals	Reaction with 1-fluoro-2,4-dinitrobenzene releasing fluoride	40	1.8–3.6	Detection by a fluoride ion-selective electrode	[92]
Ascorbic acid, cysteine	Dietary supplements	Reduction of 8-molybdodiphosphate	―	1.3–3.2	Novel approach for data treatment (mean centering of ratio kinetic profiles method)	[93]
Bromate, chlorite	Treated water	Analytes oxide bromide reagent to bromine, which reacts with o-dianisidine	―	8.5–8.8	Sample splitting, reaction at different temperatures	[77]
Bromide	Brine	Bromide oxidation by chloramine T, reaction with phenol red	60	<1.0	Slower reaction with chloride minimising its interference	[94]
Carbofuran, propoxur, metolcarb, fenobucarb	Water, fruits	Hydrolysis/diazotization with p-nitroaniline in alkaline medium	18	0.8–3.3	Data processing by back-propagation/artificial neural network	[95]
Cathecol, resorcinol	Synthetic mixtures	Oxidation by H₂O₂ under peroxidase catalysis	60	3.4	Flow stopping associated to multiple linear regression	[82]
Chlorpyrifos, carbaryl	Pesticide formulations	Oxidation by H₂O₂ under alkaline medium	80	4.0–6.0	Exploitation of different analytes degradation rates	[83]
Cobalt, nickel	Synthetic mixtures	Complexation with HBAT	―	―	Different strategies to modify the sample residence times	[84]
Cobalt, nickel	Metal alloys	Complexation with PAR from citrate complexes	40	<1.0	Relocatable reactor to achieve two sample residence times	[80]
Copper, nickel	Plant materials	Complexation with Br-PADAP	20	2.0	Relocation of the flow cell for detection at two sample residence times	[81]
Free and total SO₂	Wines	p-rosaniline method	55	<3.1	Dual flow stopping, measurements before and after alkaline hydrolysis	[85]
Furfural, vanillin	Synthetic mixtures	Reactions with p-aminophenol, yielding Shiff bases	30	0.2–1.9	Zone splitting to achieve two sample residence times	[78]
Gallium, aluminum	Synthetic mixtures	Complexation with PAR	―	0.8–1.6	Flow stopping, principal component regression	[86]
Glucose, fructose	Synthetic mixtures	Analytes oxidation by periodate	―	2.0	Remaning periodate detected by reaction with pyrogallol	[87]
3-Hydroxybutyrate, 3-hydroxyvalerate	Biodegraded polymers	3-hydroxybutyrate dehydrogenase-catalysed reaction with coenzyme NAD⁺	20	0.8–1.5	Exploitation of differential enzimatic reactions with two enzyme reactors and fluorimetric/spectrophotometric detectors placed in series	[79]
Iron, copper	Wastewater, pharmaceuticals	Hydroxylamine oxidation yielding nitrite, determined by Griess method	32–39	1.3–1.6	Microchip with two reaction coils at different temperatures	[88]
Iron, vanadium	Metal alloys	Iodide oxidation by Cr(VI)	50	0.5–3.0	Differential catalitic effect, data treatment by PLS	[23]
Levodopa, benserazide	Pharmaceutical formulations	Analytes oxidation by periodate	20	2.5–4.0	Flow stopping, multiway PLS	[89]
Molybdate, tungstate	Steels	Iodide oxidation by H₂O₂	―	1.6–3.4	Mathematical algorithm to compensate the synergistic analytes catalytic effects	[90]
Phosphate, silicate	Waters	Oxidation of thiamine to thiochrome by the molybdate heteropoly acids	60	0.25–0.7	Exploitation of different rates of the molybdate heteropoly acids formation	[91]

Br-PADAP: 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol; HBAT: 2-hydroxybenzaldehyde thiosemicarbazone; NAD⁺: Nicotinamide adenine dinucleotide; PAR: 4-(2-pyridylazo) resorcinol; PLS: Partial least squares regression.