Interference in determination of ammonia with the hypochlorite-alkaline phenol method of Berthelot

Ngo, T. T.; Phan, Alvin; Yam, C.F.; Lenhoff, Howard M.

doi:10.1021/ac00238a015

Cited by 148 publications

(79 citation statements)

References 27 publications

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“…Samples were centrifuged (1700 X g, < 5 min) and NH4+ analysed in the supernatants. Absorbance units were read in suitably diluted samples (> 10-fold), to prevent inhibition of colour development (Ngo et al 1982, Laima 1991. Blank absorbance5 were low, with optical density typically within the range 0.011 f 0.005.…”

Section: Methodsmentioning

confidence: 99%

Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

Laima¹

1992

Mar. Ecol. Prog. Ser.

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Seasonal variations in pools of porewater NH,' and exchangeable NH,+ desorbed by l-step [easily desorbed NH,') and multiple KC1 extractions (tightly bound NH,') were investigated in sediments from 3 stations in Danish coastal waters. One-step KC1 extractions gave higher yields in winter and lower yields in periods of increased sediment activity and temperature. The exchangeable NH,' pool obtained by l-step extraction was always less than the total pool removed by the multiextraction technique, independent of sediment type. The multi-extraction technique proved the existence of sediment NH,' pools with different exchange capacities. There was evidence to indicate that the tightly bound pool changed seasonally and entered the normal N cycle. The size and dynamic nature of this pool have not previously been recognized: maximum and minimum integrated values for Aarhus Bay, Norsminde Fjord and Randers Fjord sedirnents were 32, 36, 25 and 4, 9 and 6 mm01 m-2, respectively. A lack of correlation between pool sizes of easily desorbed NH,' and porewater NH,' was not compatible with literature values of the NH,' adsorption coefficient (K-value). K-values varied with station, depth and season (means of all values 3.7 and 11.7 by l-step and multiple extractions, respectively), and were in general higher than the literature values.

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Section: Methodsmentioning

confidence: 99%

Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

Laima¹

1992

Mar. Ecol. Prog. Ser.

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“…This assay utilises the Berthelot reaction [11]. Unless otherwise stated, 100 µL of ammonia chloride standards (25 to 200 μM) were prepared using a provided calibrator stock of 1 mM ammonia.…”

Section: Spectrophotometric Measurement Of Ammoniamentioning

confidence: 99%

An electrochemical sensor device for measuring blood ammonia at the point of care

Brannelly

Killard

2017

Talanta

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“…The Berthelot reaction had an elevated lower detection limit in milk and apple juice compared to that of the standards in buffer and was completely inhibited in orange juice, infant formula, and yogurt ( Table 1). The Berthelot reaction is established chemistry that is used in standard analytical methods but is subject to many know interferences (25,26), including ascorbic acid, which was present in many of the samples. In contrast, the indole assay was found to function in all of the test matrices and was therefore chosen for further development.…”

Section: Resultsmentioning

confidence: 99%

Rapid Method Using Two Microbial Enzymes for Detection of l -Abrine in Food as a Marker for the Toxic Protein Abrin

Dodge

Carrasquillo

Rivera

et al. 2015

Appl Environ Microbiol

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Abrin is a toxic protein produced by the ornamental plant Abrus precatorius, and it is of concern as a biothreat agent. The small coextracting molecule N-methyl-L-tryptophan (L-abrine) is specific to members of the genus Abrus and thus can be used as a marker for the presence or ingestion of abrin. Current methods for the detection of abrin or L-abrine in foods and other matrices require complex sample preparation and expensive instrumentation. To develop a fast and portable method for the detection of L-abrine in beverages and foods, the Escherichia coli proteins N-methyltryptophan oxidase (MTOX) and tryptophanase were expressed and purified. The two enzymes jointly degraded L-abrine to products that included ammonia and indole, and colorimetric assays for the detection of those analytes in beverage and food samples were evaluated. An indole assay using a modified version of Ehrlich's/Kovac's reagent was more sensitive and less subject to negative interferences from components in the samples than the Berthelot ammonia assay. The two enzymes were added into food and beverage samples spiked with L-abrine, and indole was detected as a degradation product, with the visual lower detection limit being 2.5 to 10.0 M (ϳ0.6 to 2.2 ppm) L-abrine in the samples tested. Results could be obtained in as little as 15 min. Sample preparation was limited to pH adjustment of some samples. Visual detection was found to be about as sensitive as detection with a spectrophotometer, especially in milkbased matrices. R ecent ricin poisoning attempts by individuals have validated concerns about the availability of highly toxic materials that are produced by widely cultivated plants (1). Ricin is isolated from seeds of the castor bean plant (Ricinus communis), which is grown ornamentally throughout the world and is cultivated in large scale for oil production, primarily in Asia and South America (2). The taxonomically unrelated legume Abrus precatorius, also known as China doll eyes, the rosary pea, or jequirity bean plant, produces the protein toxin abrin, which is similar to ricin in structure and mode of action (inactivation of ribosomes) and has a level of toxicity equal to or greater than that of ricin (3). Abrus precatorius is likely native to Southeast Asia but has been introduced as an ornamental plant to other tropical and subtropical areas around the world, where it has spread and naturalized (2). Its seeds have long been used as ornamental jewelry and toy doll eyes, and accidental poisonings have resulted from the ingestion of seeds used for those purposes (2, 3).Direct and indirect methods for the detection of abrin or ricin are typically based on immunoassays, mass spectrometry (MS), or PCR (2, 4, 5), all of which require sample preparation and/or specialized instrumentation. Indirect detection can be done by using PCR amplification of DNA targeted to the source plants or through liquid chromatography-MS identification of small molecules that coextract from plant material with the toxic proteins and therefore can serve as m...

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Interference in determination of ammonia with the hypochlorite-alkaline phenol method of Berthelot

Cited by 148 publications

References 27 publications

Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

An electrochemical sensor device for measuring blood ammonia at the point of care

Rapid Method Using Two Microbial Enzymes for Detection of l -Abrine in Food as a Marker for the Toxic Protein Abrin

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