Analytical in-house method validation for determination of permethrin (trans & cis isomers), methyl paraben, propyl paraben and BHT

Butyl paraben and propyl paraben modulate bisphenol A and estradiol concentrations in female and male mice.

People are routinely exposed to the antimicrobial preservatives butyl paraben (BP) and propyl paraben (PP), as well as the monomer of polycarbonate plastics, bisphenol A (BPA). These chemicals are reliably detected in human urine and potentially interact. We investigated whether BP or PP exposure can modulate the concentrations of 14C-BPA and 17β-estradiol (E2). Female and male CF1 mice were ea...

The Paraben Debate

This toxicology update reviews research over the past four years since publication in 2004 of the 1⁄4rst measurement of intact esters of p-hydroxybenzoic acid (parabens) in human breast cancer tissues, and the suggestion that their presence in the human body might originate from topical application of bodycare cosmetics. The presence of intact paraben esters in human body tissues has now been c...

STUDY PROTOCOL APMP.QM-S8 Supplementary Comparison and APMP.QM-P28 Pilot Study Determination of Mass Fraction of Benzoic Acid, Methyl Paraben and n-Butyl Paraben in Soy Sauce

Preservatives such as benzoic acid and parabens are being tested on a regular basis by regulatory authorities and food testing laboratories as they are widely found in condiments and beverages such as fruit juices, sports drinks and soft drinks. The consumption of excessive amount of preservatives can lead to adverse health effects such as allergy. Also, the levels of these preservatives in foo...

Hplc Method for Simultaneous Determination of Ketoprofen and Preservatives in Gel Formulation

Objective: The aim of presented study was to develop a high-performance liquid chromatography (HPLC) method with UV detection for simultaneous determination of ketoprofen, methyl paraben and propyl paraben in a gel formulation. Methods: The chromatography was carried out on a C18 Results: Under these chromatographic conditions, the obtained retention times were approximately 2.41 min for methyl...

Evaluation of Selected Cosmetic Preparations for the Presence of Formaldehyde and Methyl Paraben by Novel Analytical Methods

Cis-trans Isomers of Vitamin

We have recently described the synthesis of rhodopsin in a solution containing four components: vitamin A, the precursor of the rhodopsin chromophore; opsin, the protein of rhodopsin; and liver alcohol dehydrogenase and cozymase, the enzyme and coenzyme which oxidize vitamin A to retinene (Hubbard and Wald, 1951). 1 This experiment was first performed with a fish liver 0il concentrate as the so...