212:
is applied for a short time (usually a few hundred milliseconds), followed by higher or lower potentials that are used for cleaning the electrode. The current is measured only while the working potential is applied, then sequential current measurements are processed by the detector to produce a smooth output. PAD is most often used for detection of carbohydrates after an anion exchange separation, but further development of related techniques show promise for amines, reduced sulfur species, and other electroactive compounds.
220:
In order to record vesicle fusion, a carbon fiber electrode is brought close to the cell. The electrode is held at a positive potential, and when the cargo from a fused vesicle is near the electrode, oxidation of the cargo transfers electrons to the electrode. This causes a spike, the size of which
211:
An extension of single-potential amperometry is pulsed amperometry, most commonly used for analytes that tend to foul electrodes. Analytes that foul electrodes reduce the signal with each analysis and necessitate cleaning of the electrode. In pulsed amperometric detection (PAD), a working potential
67:
Carbon is used as a working electrode which is coated with mediator and glucose oxidase. Ag/AgCl is used as the reference electrode. The enzyme oxidase catalyzes the reaction of glucose with oxygen. Hydrogen peroxide concentration is measured by oxidation which occurs at +0.6V.
98:
is low, complete conversion is inhibited. Hence mediator ferrocene is introduced. Now, current is directly proportional to the concentration of ferrocene which in turn is directly proportional to glucose concentration.
114:
was single-potential or DC amperometry, useful for certain electrochemically active ions such as cyanide, sulfite, and iodide. The development of pulsed amperometric detection (PAD) for analytes that fouled
199:, which are problematic by conductometric methods. Another, possibly more important advantage of amperometry over other detection methods for these and other ions, such as iodide, sulfite, and
191:. The measured current changes as an electroactive analyte is oxidized at the anode or reduced at the cathode. Single-potential amperometry has been used to detect weak acid anions, such as
64:
It is the electric current measured between a pair of electrodes. The measured current is directly proportional to the concentration of the analyte. Example: Blood glucose monitor
203:, is specificity. The applied potential can be adjusted to maximize the response for the analyte of interest while minimizing the response for interfering analytes
179:
Any analyte that can be oxidized or reduced is a candidate for amperometric detection. The simplest form of amperometric detection is single-potential, or
286:
Gonon F, Cespuglio R, Ponchon JL, et al. (April 1978). "In vivo continuous electrochemical determination of dopamine release in rat neostriatum".
123:. Another advancement, known as integrated amperometry, has increased the sensitivity for other electrochemically active species, such as
315:"Nicotinic receptor-mediated catecholamine secretion from individual chromaffin cells. Chemical evidence for exocytosis"
475:
221:
can be used to estimate the number of vesicles, and the frequency gives information about the release probability.
251:
Kissinger PT, Hart JB, Adams RN (May 1973). "Voltammetry in brain tissue--a new neurophysiological measurement".
356:"Temporally resolved catecholamine spikes correspond to single vesicle release from individual chromaffin cells"
119:
surfaces when detected eventually helped create a new category of ion chromatography for the determination of
367:
57:
of a vesicle cargo released into the medium. Another technique used to measure vesicle release is
451:
426:
Mosharov EV, Sulzer D (September 2005). "Analysis of exocytotic events recorded by amperometry".
151:
111:
26:
is the detection of ions in a solution based on electric current or changes in electric current.
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Leszczyszyn DJ, Jankowski JA, Viveros OH, Diliberto EJ, Near JA, Wightman RM (September 1990).
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but brought nearby of the cell. The measurements from the electrode originate from an
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390:
355:
264:
163:
120:
455:
38:
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from oxidizing neurotransmitters. One of the first measurements was made using an
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concentration this in turn is directly proportional to glucose concentration. If O
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42:
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Proceedings of the
National Academy of Sciences of the United States of America
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Wightman RM, Jankowski JA, Kennedy RT, et al. (December 1991).
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183:(DC), amperometry. A voltage (potential) is applied between two
49:
used for amperometry is not inserted into or attached to the
414:
Handbook of
Instrumental Techniques for Analytical Chemistry
207:
Pulsed amperometry (pulsed amperometric detection, PAD)
131:groups, that are sometimes weakly detected by PAD.
288:Comptes Rendus de l'Académie des Sciences, Série D
110:or amperometric detection as it was first used in
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142:detected by placing a carbon electrode into
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379:
330:
166:release from large dense core vesicles.
127:and many compounds that contain reduced
230:
86:Current is directly proportional to H
7:
319:The Journal of Biological Chemistry
158:of rats. Further work was done in
14:
237:D. C. Johnson and W.R. LaCourse,
154:carbon fiber electrode in the
1:
332:10.1016/S0021-9258(18)77173-1
265:10.1016/0006-8993(73)90503-9
175:Single-potential amperometry
492:
412:Settle, F. (Ed.). (1997).
187:positioned in the column
16:Electroanalytic technique
381:10.1073/pnas.88.23.10754
134:It was established that
416:(1 ed.). Prentice Hall.
37:release events using a
29:Amperometry is used in
39:carbon fiber electrode
241:, 62 (1990), 589A-97A
239:Analytical Chemistry
372:1991PNAS...8810754W
146:and recording the
112:ion chromatography
55:oxidizing reaction
476:Electrophysiology
170:Detection methods
140:electrochemically
136:neurotransmitters
31:electrophysiology
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440:10.1038/nmeth782
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160:chromaffin cells
45:techniques, the
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366:(23): 10754–8.
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325:(25): 14736–7.
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162:to investigate
108:Electrochemical
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5:
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428:Nature Methods
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294:(16): 1203–6.
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253:Brain Research
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181:direct current
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61:measurements.
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290:(in French).
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259:(1): 209–13.
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164:catecholamine
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121:carbohydrates
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434:(9): 651–8.
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156:neostriatum
83:+2H+ + 2e-
43:patch clamp
20:Amperometry
225:References
185:electrodes
59:capacitive
216:Principle
201:hydrazine
152:implanted
138:could be
117:electrode
47:electrode
41:. Unlike
33:to study
24:chemistry
470:Category
456:15489257
448:16118635
189:effluent
400:1961743
368:Bibcode
341:2394692
273:4145914
197:sulfide
193:cyanide
148:current
103:History
79:——>O
35:vesicle
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144:tissue
129:sulfur
125:amines
452:S2CID
391:53009
300:96981
444:PMID
396:PMID
337:PMID
296:PMID
269:PMID
195:and
51:cell
436:doi
386:PMC
376:doi
327:doi
323:265
292:286
261:doi
22:in
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96:2
92:2
90:O
88:2
81:2
77:2
75:O
73:2
71:H
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