Determination of Lisinopril in Pure and Tablet form by Using 2-Hydroxynaphthaldehyde as Derivatizing Reagent

An easy, sensitive and accurate spectrophotometric method has been developed for the determination of Lisinopril (LNP) in pure and tablet formulations based on derivatization reaction with 2-hydroxynaphthaldehyde (2HNA). The derivatization reaction was carried out in methanol solvent at pH-5.5 at 95±2C for 15 min. The linear calibration curve was obtained that obeyed the Beer’s law within the concentration range 5-50 μgmL-1 of LNP at 433 nm with a coefficient of determination R²=0.996. The recovery was in the range from 98.25-101.82 with molar absorptivity of drug 9×103 mole-1cm-1. The method was accurate and precise (intra-day variation 0.05-0.97% and inter-day 0.07-1.6%), with limit of detection (LOD) and limit of quantification (LOQ) 0.264 μgmL-1 and 0.8 μgmL-1, respectively. No interferences from the excipients were detected. The method was applied for the rapid analysis of LNP in pharmaceutical products.

NQS-Doped PDMS Solid Sensor: From Water Matrix to Urine Enzymatic Application

The development of in situ analytical devices has gained outstanding scientific interest. A solid sensing membrane composed of 1,2-naphthoquinone-4-sulfonate (NQS) derivatizing reagent embedded into a polymeric polydimethylsiloxane (PDMS) composite was proposed for in situ ammonium (NH4+) and urea (NH2CONH2) analysis in water and urine samples, respectively. Satisfactory strategies were also applied for urease-catalyzed hydrolysis of urea, either in solution or glass-supported urease immobilization. Using diffuse reflectance measurements combined with digital image processing of color intensity (RGB coordinates), qualitative and quantitative analyte detection was assessed after the colorimetric reaction took place inside the sensing membrane. A suitable linear relationship was found between the sensor response and analyte concentration, and the results were validated by a thymol-PDMS-based sensor based on the Berthelot reaction. The suggested sensing device offers advantages such as rapidity, versatility, portability, and employment of non-toxic reagents that facilitate in situ analysis in an energy-efficient manner.

Exploration of 1, 2-naphthoquinone-4-sulfonate derivatizing reagent for determination of chlorthalidone in tablets: a spectrophotometric investigation

Background Chlorthalidone is a diuretic medicinal agent used to treat hypertension. Lowering hypertension results in the prevention of strokes, heart attacks and kidney-related problems. Results In this work, the spectrophotometric investigation was employed to examine the reaction between chlorthalidone and 1, 2-naphthoquinone-4-sulfonate. A reaction is performed at the alkaline environment (pH 9.2) and heated at a moderate temperature of 60 ± 1 °C using a water bath. The red colour product was produced, and it displayed a maximum absorbance at 440.50 nm. Further, the advancement of response conditions was explored by UV/visible spectrophotometer. The stoichiometric of the reaction was considered by using Job’s plot and the reaction mechanism of the proposed work was drawn. The established approach obeyed the calibration curve in the concentration range of 2–12 μg/mL with a regression coefficient superior to 0.994. The accuracy of the method, assessed by employing the % recovery, was in the range of 99.06–99.60% with the % relative standard deviation being less than 2%. The limit of detection and limit of quantification were 0.58 μg/mL and 1.72 μg/mL, respectively. Conclusion A UV/visible spectrophotometric investigation for the analysis of the chlorthalidone in the tablet matrix was successfully established and validated. The established investigation was found to be simple and accurate, and because of its ease of use, the proposed strategy could be applied for quality control investigation of chlorthalidone in pharmaceutical matrices.

Determination of biogenic amines in alcoholic beverages using a novel fluorogenic compound as derivatizing reagent

A novel fluorescent turn-on probe was synthesized and served as a pre-column derivatizing reagent for quantitative analysis of biogenic amines, then a method was established and used in their quantification in several alcoholic beverages.

The Importance of Derivatizing Reagent in Chromatography Applications for Biogenic Amine Detection in Food and Beverages

Biogenic amines (BA) are chemical compounds formed in foods that contain protein, allowing the foods to undergo a bacterial degradation process. Biogenic amines are labeled as toxic food because its consumption exceeding the FDA regulation (50 mg/kg) can be harmful to humans. Some countries also have regulations that prohibit the consumption of biogenic amines in high concentrations, especially histamine. The chromatography methods generally applied by researchers are liquid chromatography (LC) and gas chromatography (GC), where the use of a derivatization reagent is necessary to increase their sensitivity. This review is based on past and present studies about biogenic amine detection related to food samples. The rationale of this study is also to provide data on the comparison of the analytical approaches between LC and GC methods. Furthermore, the various approaches of biogenic amine determination and the most applied analytical methods have been reviewed.

LC-MS Quantification of Malondialdehyde-Dansylhydrazine Derivatives in Urine and Serum Samples

We developed a robust analytical method for quantification of malondialdehyde (MDA) in urine and serum samples using dansylhydrazine (DH) as a derivatizing reagent. The derivatization procedure was partially carried out using an autosampler injection program to minimize errors associated with the low-volume addition of reagents and was optimized to yield a stable hydrazone derivative of MDA and its labeled d2-MDA analogue. The target MDA-DH derivatives were separated on an Agilent Zorbax Eclipse Plus Phenyl-Hexyl (3.0 × 100 mm, 3.5 μm) column. The mass-to-charge ratios of the target derivatives [(M+H)+ of 302 and 304 for MDA-DH and d2-MDA-DH, respectively] were analyzed in single ion monitoring mode using a single quadrupole mass spectrometer operated under positive electrospray ionization. The method limits of quantification were 5.63 nM (or 0.405 ng/mL) for urine analysis and 5.68 nM (or 0.409 ng/mL) for serum analysis. The quantification range for urine analysis was 5.63–500 nM (0.405–36.0 ng/mL) while the quantification range for serum analysis was 5.68–341 nM (0.409–24.6 ng/mL). The method showed good relative recoveries (98–103%), good accuracies (92–98%), and acceptable precisions (relative standard deviations 1.8–7.3% for inter-day precision; 1.8–6.1% for intra-day precision) as observed from the repeat analysis of quality control samples prepared at different concentrations. The method was used to measure MDA in individual urine samples (n = 287) and de-identified archived serum samples (n = 22) to assess the overall performance of the method. The results demonstrated that our method is capable of measuring urinary and serum levels of MDA, allowing its future application in epidemiologic investigations.

Measurement of α-dicarbonyl compounds in human saliva by pre-column derivatization HPLC

Background α-Dicarbonyl compounds (α-DCs) have been detected in body fluids including plasma and urine and elevation of this sort of compounds in vivo has been associated with the development of many kinds of chronic diseases. However whether α-DCs are present in human saliva, and if their presence/absence can be related with various chronic diseases is yet to be determined. Methods In this study, a pre-column derivatization HPLC-UV method was developed to measure 3-deoxyglucosone (3-DG), glyoxal (GO), methylglyoxal (MGO), diacetyl (DA), and pentane-2,3-dione (PD) in human saliva employing 4-(2,3-dimethyl-6-quinoxalinyl)-1,2-benzenediamine (DQB) as a derivatizing reagent. The derivatization of the α-DCs is fast and the conditions are facile. The method was evaluated and the results show that it is suitable for the quantification of α-DCs in human saliva. Results In the measurements of these α-DCs in the saliva of 15 healthy subjects and 23 type 2 diabetes mellitus (T2DM) patients, we found that the concentrations of GO and MGO in the saliva of the diabetic patients were significantly higher than those in healthy subjects. As far as we know, this is the first time that salivary α-DC concentrations have been determined and associated with T2DM. Conclusions The developed method would be useful for the measurement of the salivary α-DC levels and the data acquired could be informative in the early screening for diabetes.