Quantification of the Organic Acids in Hawthorn Wine: A Comparison of Two HPLC Methods

Hawthorn wine is rich in anthocyanins, polyphenols, flavonoids and other macromolecular substances, which results in difficulty to rapidly determine organic acids in the wine. An enzymatic method is accurate but expensive and not able to quantify all of the organic acids simultaneously. Therefore, in this study, two HPLC methods were applied to quantify the organic acids in the wine with the enzymatic method as a reference. Seven organic acids were found with the enzymatic method including citric, succinic, l-malic, acetic, lactic, pyruvic, and fumaric acids, in which citric and succinic acid accounted for more than 80% of the total acids. By an 87H column equipped with DAD (diode array) detector at 215 nm (HPLC method 1), only citric and lactic acids were quantified accurately and the elution period was shortened from 100 min to 20 min by removing the impurity in the sample with a LC-18 SPE(solid-phase extraction) tube. While citric, succinic, l-malic, acetic, pyruvic, and fumaric acids were quantified reliably by a dC18 column equipped with DAD detector at 210 nm (HPLC method 2), with the sample requires only dilution and filtration before injection. It was suggested that HPLC method 2 was an effective method to quantify the organic acids in hawthorn wine. The method provides a choice for accurate quantification of organic acids in hawthorn wine or other drinks, and would be helpful for controlling the quality of hawthorn wine.

Rapid and Simple Method for Isolation and Gas Chromatographic Determination of N-Nitrosodimethylamine in Dimethyldithiocarbamate Formulations

A rapid and simple method to isolate and determine JV-nitrosodimethylamine (NDMA) in formulations of ferbam or dibam has been developed. Depending on the type of formulation, the sample is extracted or diluted with water which is subsequently extracted with dichloromethane. NDMA is isolated by passing the organic fraction through a silica gel column and eluting the column with acetone. The acetone eluate is analyzed directly for NDMA by using a gas chromatograph connected to a thermal energy analyzer detector (GC/ TEA). The limit of detection (LOD) is 40 pg (0.04 ppm) and the limit of quantitation (LOQ) is 100 pg (0.1 ppm). The recovery range for this method is 85-112% for ferbam spiked at 0.33-0.75 ppm, and 91- 113% for dibam spiked at 0.32-1.09 ppm. Sixteen commercial samples of ferbam and 4 of dibam were analyzed; one ferbam sample contained 19.8 ppm NDMA while all others contained less than 1 ppm. Chem-Elut extraction tubes were found to generate trace quantities of nitrosamine from samples containing amine. If amine is absent, an extraction tube could be used in place of dichloromethane extraction to give similar values in recovery range, LOD, and LOQ.

Gas Chromatographic Determination of N-Nitrosodialkanolamines in Herbicide Di- or Trialkanolamine Formulations

A modified method is presented to determine trace quantities of N-nitrosodiethanolamine (NDE1A) and yV-nitrosodiisopropanolamine (NDiPlA) in the triisopropanolamine (TiPlA) formulation of a mixture of picloram and 2,4-D. Aqueous sample is extracted with dichloromethane to remove organic interferences, and then the aqueous layer is passed sequentially through chloride anion exchange column, hydrogen cation exchange column, and Clin-Elut extraction tube. The final eluate, 10% acetone in ethyl acetate, is concentrated. The isolated nitrosamines are converted to the corresponding trimethylsilyl (TMS) derivatives and determined by gas chromatography (GC) on a DB1 column coupled with a thermal energy analyzer (GC-TEA). Eight samples of commercial TiPlA formulations are analyzed. Maximum detected levels of NDE1A and NDiPlA were 0.6 and 0.9 ppm, respectively, expressed relative to total weight of active ingredients. Analysis of 13 samples of herbicide DEIA formulation using a previously established method and a DB225 column gave NDE1A results of 0.7-6.0 ppm. NDiPlA was not detected in those samples. Results are confirmed by GC-mass spectrometry (GC/MS) with oxygen negative chemical ionization (ONCI) detection. Dectection limits for both nitrosamines are 0.05 or 0.07 ng (0.1 or 0.17 ppm) for GC-TEA detection, depending on the analytical columns used, and 20 pg (0.04 ppm) for GC/MS detection. Recoveries of NDE1A are 87-109% for DEIA formulation spiked at 2.6 and 3.9 ppm and 90-115% for TiPlA formulation spiked at 0.2-0.3 ppm. Similarly, recoveries of NDiPlA are 95.7-100% for the DEIA formulation spiked at 0.24 and 0.48 ppm, and 82-118% for the TiPlA formulation spiked at 0.2-0.3 ppm.

Gas-Liquid Chromatographic Method for Determining 1,4-Dioxane in Cosmetics

A gas-liquid chromatographic procedure has been developed for the quantitation of 1,4-dioxane in various cosmetic products including lotions, cleansers, skin creams, make-ups, and shampoos. The impurity is extracted into an aqueous phase followed by column cleanup to remove nonpolar interferents. 1,4-Dioxane is partitioned into toluene, passed through an extraction tube to remove water and other polar compounds including organic dyes, concentrated by adsorption onto silica, further purified by washing with dichloromethane, and eluted with acetonitrile for injection into the gas chromatograph. The mean recovery of 1,4-dioxane from 51 cosmetic products, determined by spiking, was 63%. The limit of detectability is about 0.5 ppm and the minimum quantifiable level is about 2 ppm. The identity of 1,4-dioxane is confirmed by mass spectrometry.