Precise and Sensitive Ambient Temperature Based Analytical Colorimetric Method for Pregabalin

Abstract Pregabalin, a GABA analogue is used to treat epilepsy and neuropathic pain. The drug poses problems in analytical quantification when estimated at a shorter UV wavelength. The expensive and non-repetitive reported analytical methods necessitate the utility and development of an accurate, precise, repetitive, simple and highly sensitive colorimetric method for pregabalin in solution as well as sustained release mini matrices. Pregabalin (having primary amino group) was derivatized at alkaline pH of mixture with optimized ninhydrin solution at ambient temperature (25oC). The ninhydrin-pregabalin derivatized complex (Ruhemann's Purple) was analyzed for drug concentration at absorption maximum (λmax) of 570nm. The linearity was observed in the concentration range of 5-150 µg/mL with coefficient of correlation, 0.998. The developed analytical method was validated according to ICH guidelines and proved to be highly sensitive (LOD 0.917µg/mL, LOQ 3.055µg/mL), with good inter-day as well as intra-day accuracy and precision as 4.65% and 3.75%, respectively. The proposed method was proved to be a simple, sensitive, precise and accurate for the estimation of the minute concentrations of pregabalin in pure form and the developed formulations. Results verified that the proposed method could determine pregabalin at the ambient temperature without requiring high temperatures used in the existing methods. It was concluded that developed method was easier and more suitable for analysis of pregabalin in quality control of commercial preparations

Comparative application of biological and ninhydrin- derivatized spectrophotometric assays in the evaluation and validation of amikacin sulfate injection

Abstract Instrumental techniques are preferred over bioassay methods for antibiotic quantification mainly due to speed and ability to quantify metabolites in biological samples; however, the potency and biological activity of these drugs cannot be assessed. Two methods - agar well diffusion (bio-assay) and spectrophotometric methods were used to evaluate amikacin sulfate injection. Agar plates were inoculated with S. aureus inoculum; zones of inhibition from its susceptibility to amikacin were obtained, while spectrophotometric absorption at 650 nm of ninhydrin- derivatized amikacin in phosphate buffer (pH 8) was measured. Methods performance showed linearity from 1 - 16 µgmL-1 (bioassay, r = 0.9994) and 10-50 µgmL-1 (spectrophotometric, r = 0.9998). Molar absorptivity was 2.595 x 104 Lmol-1cm-1. Limits of detection and quantification were 1.07 and 3.24 µgmL-1 respectively for bioassay method, while corresponding values for spectrophotometric method were 0.98 and 2.97 µg mL-1. Relative standard deviations were ≤ 2.0% for both methods, with recoveries from 95.93 - 100.25%. Amikacin in brands ranged from 97.53 ± 2.68 to 100.84 ± 1.82%, student's t-test was ≤ 2.78 (n = 4) with respect to label claim for both methods. Experimental paired t-test (t = 2.07; n = 4) and F-test (F = 3.94; n = 4) values indicated no significant difference between both methods, hence comparable and can jointly be used in quality control assessment of antibiotics

Criteria for identification of Schistosoma mansoni eggs in faecal sediments prepared with the Helmintex method and stained by ninhydrin

Helmintex is a sensitive method used for detecting Schistosoma mansoni eggs. Here, we describe the observed frequency of six proposed criteria associated with the identification of S. mansoni eggs prepared with the Helmintex method and stained with ninhydrin. The efficacy of these criteria in classifying S. mansoni eggs when applied in various combinations was also examined. Nine observers registered the presence or absence of 6 different criteria in 100 eggs using a microscope at 100x magnification. Ninhydrin purple, which was frequently observed, was the criterion associated with the lowest inter-observer variability. At least three criteria were associated with a significantly better performance in egg identification. In conclusion, ninhydrin staining and a combination of criteria are recommended for microscope examination of faecal sediments.

Comparação entre três métodos analíticos para determinação de soro em leite cru refrigerado / Comparison of three analytical methods to determine serum in refrigerated raw milk

O objetivo deste experimento foi comparar três métodos analíticos para determinação de soro em leite cru refrigerado: cromatografia líquida de alta eficiência, ninidrina ácida e colorimétrico adaptado. Foram coletadas 100 amostras de leite cru refrigerado de tanques de expansão. Estas, quando submetidas à análise pelo método da ninidrina ácida, apresentaram 10 (14,7%) amostras negativas e 58 (85,3%) positivas. O teor médio de ácido siálico encontrado na técnica da ninidrina foi de 5,58(g/mL, com valor mais frequente de 2,70(g/mL. Das 68 amostras negativas pela cromatografia líquida de alta eficiência, duas foram positivas (2,94%) e 66 (97,06%) negativas, quando analisadas pelo método colorimétrico. A frequência relativa de amostras positivas foi de 32%, com a CLAE apresentando a maior média de soro (14,37%), seguida do método colorimétrico (5,28%) e o da ninidrina ácida (3,12%). A técnica de cromatografia líquida de alta eficiência diferiu dos métodos de ninidrina ácida e colorimétrico, enquanto os métodos da ninidrina e colorimétrico não diferiram entre si, podendo ambos serem utilizados como metodologias de triagem. Entre as três técnicas, a cromatografia líquida de alta eficiência foi a metodologia mais sensível na detecção e quantificação do soro em leite cru refrigerado.(AU)

The objective of this study was to compare three analytical methods to determine serum in refrigerated raw milk. High-performance liquid chromatography (HPLC), acidic and colorimetric ninhydrin methods were applied. A collection of 100 samples of raw milk from cooled expansion tanks took place. The results showed that 10 samples (14.7%) were negative and 58 (85.3%) were positive for the acidic ninhydrin method. The mean sialic acid content found in the ninhydrin technique was 5.58µg/mL, with a more frequent value of 2.70µg/mL. From all 68 HPLC negative samples, two were positive (2.94%) and 66 (97.06%) negative to the colorimetric method. The relative frequency of positive samples was 32%, HPLC had the highest mean serum levels (14.37%), followed by the colorimetric method (5.28%) and acid ninhydrin (3.12%). The high-performance liquid chromatography method was different from the acid and colorimetric ninhydrin methods. The ninhydrin and colorimetric methods were not different from each other, both of which could be used as screening methodologies. Among the three techniques, HPLC was the most sensitive methodology for the detection and quantification of serum in refrigerated raw milk.(AU)

Revealing Weapon Impacts on Clothes Using Reaction Reagents for Amino Acids / 대한법의학회지

If we analogize any external physical force applied to victims of crimes involving violence, it would be possible to not only presume the mutual action between victims and suspects but also deduce more facts related to the cases. Therefore, in this study, defining the phenomenon of amino acid compounds in sweat spreading into clothes as impact marks, experiments using ninhydrin, 1,8-dizafluoren-9-one (DFO), 1,2-indanedione-zinc (1,2-IND-Zn) were conducted to determine developmental variations through change over time, which was not performed in previous studies. A 5-week period was set up including first damage as a variation factor, and materials in each action were developed using certain reagents. The level of specimen development depending on the change over time was identified. Thus, no changes were observed at each initial level of development.

A Comparative Study on Mechanical and Biochemical Properties of Bovine Pericardium After Single or Double Crosslinking Treatment

BACKGROUND AND OBJECTIVES: Glutaraldehyde (GA) has been used as a representative method of tissue preservation in cardiovascular surgery. However, GA has showed limited durability including calcification, mechanical failure and toxicity. To overcome those unsolved problems, we analyzed the crosslinking differences of primary amines, GA and genipin in their mechanical and biochemical properties with a single or double crosslinking agent for clinical application. MATERIALS AND METHODS: Samples were divided into 3 groups; control, single crosslinking fixation and double crosslinking fixation after decellurarization using bovine pericardium. For analysis of the biochemical and mechanical properties of each crosslinking method, tensile strength, percentage strain, thermal stability, resistance to pronase, nynhydrin and cytotoxicity test were studied. RESULTS: Combined hexamethylene diamine and suberic acid in the carbodiimide hydrochloride/N-hydroxysucinimide solution (EDC/NHS) after decellurarization, tensile strength and strain percentage were not statistically significant compared to the single crosslinking treated groups (p>0.05). Tissue crosslinking stability was weak in single treatment of diphenylphosphoryl azide, suberic acid, low concentration of EDC, hexamethylene diamine and procyanidin groups, but thermal stability and resistance to the pronase and ninhydrin were markedly increased in concentrated EDC/NHS or after combined double treatment with low concentration of GA or genipin (p<0.001). CONCLUSION: Single or double crosslinking with low concentration of carbodiimide, diphenylphosphonyl azide, procyanidin, suberic acid and hexane diamine were not as effective in mechanical, biochemical, cytotoxic and crosslinking properties compared to GA or genipin fixation, but their mechanical and chemical properties were much improved when combined with low concentrations of GA or genipin in the double crosslinking process.

Ninhydrin sweat test in leprosy.

Loss of sensation is an important feature of leprosy. Loss of sweating over the affected site due to loss of autonomic function occurs in leprosy. We have studied a simple, non-invasive, rapid method, using 1% ninhydrin in acetone, to detect loss of sweat function. The test was effective in detecting and grading the sweat function in 84 cases of different types of leprosy. We were able to detect normal sweating in 16 patients with hypopigmented lesion due to causes other than Hansen's disease.

Usefulness of a Disk Method for Detection of Hippurate Hydrolysis by Campylobacter jejuni / 대한임상미생물학회지

BACKGROUND: The test for hippurate hydrolysis is critical for differentiation of C. jejuni and other thermophilic Campylobacter species. So, we evaluated the disk method for detection of hippurate hydrolysis by C. jejuni. METHODS: Twenty-eight Campylobacter species isolated from stool culture were simultaneously tested with disk method for detection of hippurate hydrolysis and polymerase chain reaction (PCR) for hippuricase specific gene. Disk method was tested with difference in incubation time (2 hours vs. 4 hours), hippurate concentration (1%, 2%, and 4%), amount of ninhydrin (50 microliter vs. 100 microliter), and inoculation method (colony vs. suspension of organism adjusted by turbidity), finally, 24 types of disk methods were performed. RESULTS: By using hippuricase PCR method as the reference for the detection of hippurate hydrolysis, the disk method showed a sensitivity of 91.7% and a specificity of 100% when two kinds of disk methods were simultaneously performed. CONCLUSIONS: The disk method for detection of hippurate hydrolysis is simple to use and require fewer cells than the tube method do, and should be useful as a routine diagnostic test in clinical laboratory for rapid identification of C. jejuni.

Effect of temperature, medium, metals and ligand structure on the stability of metal complexes of certain schiff base ligands derived frome ninhydrin and isatin with some substituted hyrazines

Stability constants of Ni2+, Co2+, Cd2+, and Mn2+ complexes with some Schiff base ligands of isatin-semi and thiosemicarbazones, isatin S-methylhydrazine carbodithioate and ninhydrinsemi and thiosemi- carbazones have been determined potentiometrically in different media containing ratios of aquo-organic solvents [ethanol, acetone, dioxane, tetrahydrofuran, dimethyl formamide] at ionic strength u=0.04 mol. dm-3 KCl at different temperatures. The acid dissociation constants of the ligands have been also determined under identical conditions. The results obtained are discussed in terms of the molecular structure of the ligands. The solvent characteristics as well as the nature of central metal ion. It has been found that the stability constant values increase with increasing the organic solvent in the reaction medium and decrease at higher temperatures. Thermodynamic functions [delta G, delta H, delta S] were evaluated and discussed

Synthesis and characterization study on some metal complexes of schiff base derived from ninhydrin with S-methylhydrazine carbodithioate

Synthesis and characterization of Schiff base ligand of ninhydrin with S-methylhydrazinecarbodithioate and its Cr [III], Mn [II], Fe [III], Co [II], Ni [II], Cu [II], Zn [II] and Cd [II] complexes were reported. Elemental analysis, molar conductivity, magnetic moment, spectral 1H NMR, UV/Visible and IR data have been used to characterize these complexes. It has been found that the ligand behaves as mononegative ONS tridentate towards divalent metal ions forming 1:2 [metal:ligand] stoichiometry and as mononegative NS bidentate towards trivalent metal ions forming 1:3 [metal: ligand] stoichiometry. For all complexes, a non-electrolytic nature was observed. Some available spectral parameters were calculated. Octahedral and distorted octahedral geometries were proposed for the complexes on the basis of magnetic and spectral measurements

Estudio preliminar de la composición química de la toxina de paederus irritans chapin, 1926 (coleopera, staphylinidae) / Preliminar study of the chemical composition of the toxin of paederus irritans chapin, 1926 (coleoptera, staphylinidae)

Se hace un estudio preliminar de la composición química de la toxina de Paederus irritans, Chapin, 1926 (Coleoptera, Staphylinidae), agente causal de lesiones cutáneas de lenta cicatrización en los pobladores de la zona norte del Perú. Con el test de ninhidrina y los métodos de diálisis y Sickevitz encontramos en la toxina un alto contenido de aminoácidos de elevado peso molecular, termoestables.