Pietro Mazzeo

Simultaneous determination of losartan and hydrochlorothiazide in tablets by high-performance liquid chromatography.

A method for the simultaneous determination of losartan potassium and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 3.0-7.0 microg ml(-1) for losartan and 0.5-2.0 microg ml(-1) for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 0.08 microg ml(-1) for losartan and 0.05 microg ml(-1) for hydrochlorothiazide.

Exposure to Di(2-ethylhexyl)phthalate in Humans during Pregnancy

Background: Di(2-ethylhexyl)phthalate (DEHP), the most commonly used plasticizer, is a widespread ubiquitous environmental contaminant. The potential health hazards from exposure to DEHP and its main metabolite, mono(2-ethylhexyl)phthalate (MEHP), have been well documented. Exposure to DEHP and MEHP in humans at risk, such as pregnant women and human fetuses, has not been tested. Methods: Plasma DEHP and MEHP concentrations were measured in a total of 24 consecutive mother-infant pairs by high performance liquid chromatography. Associations between DEHP/MEHP and infant characteristics were tested using Fisher’s exact test, unpaired t tests and univariate linear regression analysis. Results: Measurable DEHP and MEHP concentrations were found in 17/24 (70.8%) and 18/24 (75%) maternal plasmas, respectively, and in 11/25 (44%) and 18/25 (72.0%) cord samples, respectively. Either DEHP or MEHP were detectable in 21/24 (87.5%) maternal plasmas and 19/25 (76%) cord samples. The mean DEHP concentrations in maternal and cord plasmas were 1.15 ± 0.81 and 2.05 ± 1.47 µg/ml, respectively. The mean MEHP concentrations were 0.68 ± 0.85 and 0.68 ± 1.03 µg/ml, respectively. No significant correlations were found between maternal and cord blood DEHP, maternal and cord blood MEHP, maternal DEHP and cord blood MEHP, or maternal MEHP and cord blood DEHP plasma concentrations. Conclusion: Although the effects of perinatal exposure to phthalates need further research, our findings: (i) confirm the high frequency of DEHP and/or MEHP exposure in human pregnancies; (ii) indicate that the exposure to these environmental contaminants begins during intrauterine life, and (iii) suggest that fetal exposure is closely related to the maternal exposure.

Comparison of different sorbents for multiresidue solid-phase extraction of 16 pesticides from groundwater coupled with high-performance liquid chromatography

A procedure based on solid-phase extraction (SPE) followed by high-performance liquid chromatography (HPLC) with diode array detection has been developed for the simultaneous analysis of 16 widely used pesticides in groundwater samples. The compounds analysed were: aldicarb, atrazine, desethylatrazine, desysopropylatrazine, carbofuran, 2,4-D, dicloran, fenitrothion, iprodione, linuron, metalaxyl, metazachlor, phenmedipham, procymidone, simazine and vinclozolin. Five different SPE sorbents, C(18) bonded silica (Isolute SPE C18 (EC)), graphitised carbon black (Superclean Envi-Carb), highly cross-linked polystyrene-divinylbenzene (Lichrolut EN), divinylbenzene-N-vinylpyrrolidone (Oasis HLB) and surface modified styrene-divinylbenzene (Strata X), were compared. HPLC separation and quantification of the selected pesticides was carried out under isocratic conditions by means of a new reversed-phase column (Gemini from Phenomenex) based on C(18) bonded to organic-silica particles. Oasis HLB and Strata X provided the best results in the preconcentration of 1-l samples, yielding average recoveries higher than 70%, except for phenmedipham that rapidly degrades in groundwater. Detection limits of the target pesticides provided by the proposed SPE-HPLC procedure were between 0.003 and 0.04microg l(-1).

Determination of losartan and hydrochlorothiazide in tablets by CE and CEC.

Capillary Electrophoresis (CE) and Capillary Electrochromatography (CEC) have been used to determine losartan and hydrochlorothiazide. The CE separation was carried out in an uncoated capillary filled with a 100 mM sodium borate pH 9 solution containing trimethyl-beta-cyclodextrins. CEC was performed using a capillary packed with a RP-18 stationary phase. The mobile phase was a mixture of 50 mM ammonium acetate pH 7, water, acetonitrile (1/1.5/7.5). By CE and CEC suitable methods to determine simultaneously losartan and hydrochlorothiazide in working standard mixture or pharmaceutical form were obtained. The proposed methods are very simple and both gave accurate and precise results.

Simultaneous determination of enalapril maleate and hydrochlorothiazide in tablets by derivative UV spectrophotometry and high-performance liquid chromatography

Abstract A method for the simultaneous determination of enalapril maleate and hydrochlorothiazide in pharmaceutical formulations (tablets) is described. The procedure is based on the use of the high-performance liquid chromatography (HPLC), and of the second-derivative ultraviolet spectra, by utilizing the linear relationship between substances concentration and derivative peak amplitude. The minimum concentration detectable by derivative spectrophotometry was 1 μg ml−1 for both drugs, and by HPLC 50 ng ml−1 for hydrochlorothiazide and 100 ng ml−1 for enalapril maleate. The relative standard deviations observed were approx. 2% for derivative spectrophotometry, and 1.5% for HPLC. The proposed methods, which give thoroughly comparable data, are simple and rapid, and allow precise and accurate results.

Simultaneous determination of valsartan and hydrochlorothiazide in tablets by high-performance liquid chromatography

ABSTRACT A method for the simultaneous determination of valsartan and hydrochlorothiazide in tablets is described. The procedure, based on the use of reversed-phase high-performance liquid chromatography, is linear in the concentration range 5.0-10.0 μg ml−1 for valsartan and 0.5-2.0 μg ml−1 for hydrochlorothiazide, is simple and rapid and allows accurate and precise results. The limit of detection was 1.0 μg ml−1 for valsartan and 0.05 μg ml−1 for hydrochlorothiazide.

Simultaneous determination of 5-aminosalicylic acid, acetyl-5-aminosalicylic acid and 2,5-dihydroxybenzoic acid in endoscopie intestinal biopsy samples in humans by high-performance liquid chromatography with electrochemical detection

A high-performance liquid chromatographic method for the simultaneous determination of 5-aminosalicylic acid (5-ASA), acetyl-5-aminosalicylic acid (Ac-5-ASA) and 2,5-dihydroxybenzoic acid (5-HSA) in human endoscopic intestinal biopsy with electrochemical detection has been developed and validated. A liquid-liquid extraction procedure was used to isolate these drugs from the biological material prior to analysis. The compounds were separated on an Erbasil S reversed-phase column using methanol-critic acid-sodium hydrogenphosphate-heptane-sulfonic acid-disodium ethylenediaminetetraacetate (pH 3) as mobile phase. The method was linear from 1.0 to 300 ng ml-1 for 5-ASA, from 10 to 1000 ng ml-1 for Ac-5ASA and from 0.1 to 10 ng m-1 for 5-HSA. The limit of detection for 5-ASA and for Ac-5-ASA was 1 ng ml-1 and that for 5-HSA was 0.1 ng ml-1. This procedure is suitable for pharmacological and clinical studies of 5-ASA.

Low serum concentrations of di-(2-ethylhexyl)phthalate in women with uterine fibromatosis

Di-(2-ethylhexyl)phthalate (DEHP) is the most commonly used plasticizer in flexible polyvinylchloride formulations, and is a widespread ubiquitous environmental contaminant. A potential role of exposure to DEHP and its primary metabolite, monoethylhexylphthalate (MEHP), on womens reproductive function is suggested in the current study. The aim of the study was to test serum concentrations of DEHP and/or MEHP in women with uterine fibromatosis. Two groups of women were enrolled in the study: (i) women with uterine fibromatosis undergoing surgical menopause (n = 15) and (ii) healthy women (n = 20). Serum DEHP and MEHP concentrations were measured by high-performance liquid chromatography. Serum MEHP distribution was found to be non-Gaussian (p = 0.001) while serum DEHP distribution was compatible with a normal curve (p = 0.141). Patients with uterine fibromatosis showed significantly lower serum MEHP concentrations (median [interquartile range]: 0 [0–0] μg/ml, range: 0–0.57 μg/ml) than controls (0.42 [0–0.51] μg/ml, range: 0–1.20 μg/ml, z = −2.93, p = 0.0034). Likewise, serum DEHP concentrations in women with fibromatosis were found to be significantly lower than in controls (patients: 0.27 ± 0.096 μg/ml (mean ± standard deviation (SD)), range: 0.14–0.59 μg/ml vs. controls: 0.30 ± 0.14 μg/ml (mean ± SD), range: 0–0.63 μg/ml; t = 3.212, df = 33, difference: −0.325 (95% confidence interval: −0.5309, −0.1191), p = 0.0029). In conclusion, the present findings indicate for the first time that serum DEHP and MEHP concentration are lower in women with uterine fibromatosis, suggesting a possible correlation between phthalate esters and fibromatosis pathology.

Determination of tenoxicam in human plasma using solid-phase extraction and high-performance liquid chromatography with ultraviolet detection

Abstract A sensitive, specific and rapid liquid chromatographic procedure to selectively monitor tenoxicam in human plasma was developed and validated. Plasma samples were acidified and extracted using solid-phase exctration column. The procedure was linear from 0.1 to 10 μ.g/ml with a detection limit of 0.05μg/ml. The coefficient of variation for the procedure is 6.2% and 2.0% for the range of concentrations examinated. This method is suitable for pharmacological, toxicological and pharmacokinetic studies of tenoxicam.

Liquid chromatographic method for the analysis of tocopherols in malt sprouts with supercritical fluid extraction

A simple, specific and sensitive high-performance liquid chromatographic method has been developed for the determination of tocopherols in malt sprouts. A supercritical fluid extraction (SFE) procedure was used to isolate tocopherols from the vegetal matrix before quantitative analysis. The analytes were separated on a Zorbax reversed-phase column using methanol-water as mobile phase and quantified by measuring its fluorescence at lambda(em)=328 nm after excitation of the analytes at lambda(exc)=303 nm. The limits of detection for alpha-, gamma- and delta-tocopherols were 0.04, 0.05, and 0.05 microg/ml, respectively. The calibration graphs of the method were linear from 0.1 to 1.5, 0.2 to 2.5, and 0.2 to 2.0 microg/ml, for alpha-, gamma- and delta-tocopherols, respectively. This SFE and HPLC procedure is simple, precise and accurate for the determination of tocopherols in malt sprouts.