Spectrophotometric determination of ammonia using ninhydrin assay and kinetic studies

Abstract

A spectrophotometric method for the determination of ammonia in aqueous media was investigated. This newly developed method for the reaction of ammonia with ninhydrin found to be simple, accurate and precise. A deep red color product was formed in the presence of sodium hydroxide at wavelength of 508 nm. The effects of variables such as temperature, time, acidity and reagents concentration have been evaluated to select the appropriate conditions for this reaction. Beer's law is obeyed; the calibration curve is linear over the range of 2×10 -4 -1.4×10 -3 M of ammonia with regression coefficient (r 2 ) of 0.994 (n = 7). The calculated molar absorptivity and Sandell's sensitivity values are 1.069×10 3 L/mol.cm and 0.015 μg/cm 2 , respectively. The limits of detection (LOD) and quantification (LOQ) are calculated to be 1.2×10 -5 and 3.6×10 -5 M, respectively. The intra-day accuracy expressed as relative error was less than 0.5% with precision (RSD) ranging from 0.49 to 1.55%. The interday accuracy ranged (RSD) from 0.49 to 1.90 % with a relative error was less than 1.50 %. The stoichiometry of this reaction was determined to be of 1:2 between ammonia and ninhydrin with first order reaction.

Optical System Based on Nafion Membrane for the Detection of Ammonia in Blood Serum Samples

“…The limit of detection was 0.029 µmol/mL, similar to the LOD retrieved for PBS. Moreover, the LOD of the sensor result was satisfactory with respect to other methods present in the literature [ 21 , 22 , 23 , 26 ], as the reported LOD values were in a range between 0.004 µmol/mL and 0.088 µmol/mL. Therefore, the proposed method results were capable of detecting the ammonia present in more complex solutions, emulating thee blood-based samples, with a performance in the linear range similar to the ideal case.…”

Spectrophotometric method for determination of ranitidine hydrochloride in bulk and in pharmaceutical preparation using ninhydrin

“…The accuracy for this analytical method is investigated; the %relative error (%RE) for each analysis (Intra-and Interday accuracy) was calculated as shown in Table 2. The small values of %RE indicate that the reference amount and the found amount are close to each other [18]. Statistical analysis was done for the Intraday and interday using F-test and the results are 2.7 and 4.4, respectively, these values indicate that there is no bias between the reference concentration and the actual concentration for ranitidine hydrochloride at 95% confidence level.…”

“…The spectrophotometric method takes a unique position because of its sensitivity, accuracy, rapidity, and simplicity. The kinetic spectrophotometer methods such as initial rate and fixed time methods have a great attention because of selectivity and because there are no interferences due to other chemical reagents during measurement the colored complex in the aqueous media for which we used the two kinetic methods in this research [17][18][19].…”

“…The experimental K values in Table 4 were used to plot the linear curve; log K versus log C. The linear regression equation is: Log K = 0.9884x+2.224, (r 2 = 0.9774), the slope value which is n is 0.9884 (≈1) this confirming that the order of the reaction is the first one. The data analysis was performed at 95% confidence level, the standard error of the slope is ±0.106 and the standard error of the intercept is ±0.179 [18,21].…”

Sustainable agro-waste pellets as granular slow-release fertilizer carrier systems for ammonium sulfate

“…Aliquots of diluted ammonium solution were added to 0.25 mL 0.128 M NaOH with 0.04 M ninhydrin solution (1 mL). 37 A stable colour was developed after ca. 45–60 min and measured via UV-vis (Thermo Fisher Scientific Spectronic 200E) spectrophotometry at a fixed wavelength (508 nm).…”