Ion chromatographic determination of perchlorate in foods by on-line enrichment and suppressed conductivity detection

Occurrence of perchlorate, chlorate and polar herbicides in different baby food commodities

The incidence of endocrine disruptors, both possible (glyphosate and glufosinate), and demonstrated (perchlorate and chlorate), was estimated in baby food commodities (meat, fish, cheese, vegetable and fruit). Ion-chromatography coupled to high resolution mass spectrometry analysis of the 105 samples did not show traces of glyphosate, glufosinate or their metabolites, while in 10.5% of the samples a quantifiable amount of perchlorate was found. Some samples based on fruit and vegetables revealed a substantial amount of chlorate, especially the preparations that contained carrots and potatoes: five samples were in a concentration range of 40-120 μg kg^-1, while one homogenized pear sample reached 372.2 μg kg^-1. The pure meat samples revealed occasional chlorate appearance, with less than 10 μg kg^-1. This is the first report of chlorate evaluated in various types of baby food and may serve as symptomatic data regarding its occurrence in infant/toddler diets. Therefore, effective monitoring programs and subsequent strict regulations are strongly required.

Rapid determination of polar pesticides and plant growth regulators in fruits and vegetables by liquid chromatography/tandem mass spectrometry

A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) multiresidue analysis method was developed for the simultaneous determination of polar pesticides, plant growth regulators and other polar compounds. These included amitrole, chlormequat, mepiquat, cyromazine, ETU, PTU, perchlorate, and daminozide using a mixed-mode column. A 10 g test portion was shaken with acidified methanol for 10 min. After centrifugation, the sample extract was injected and analyzed within 11 min by LC-MS-MS. This column eliminated the need for derivatization or the use of ion paring reagent. Two MS-MS transitions were monitored in the method for each target compound to achieve true positive identification. Eight isotopically-labeled internal standards corresponding to each analyte were used to correct for matrix suppression effect and/or instrument signal drift. The average recovery for all analytes at 20, 40, and 250 ng/g (n = 6) ranged from 73-136%, with a relative standard deviation of ≤ 20%.

Determination of iodide and thiocyanate in powdered milk and infant formula by on-line enrichment ion chromatography with photodiode array detection

Thiocyanate ranks after perchlorate as a potent inhibitor of iodide uptake by the thyroid but may be more concentrated in some food items such as milk products as to supersede perchlorate as the goitrogen of concern. A column-switching anion-exchange chromatographic method with UV spectral detection was developed to measure and confirm iodide and thiocyanate in powders of dry milk and infant formula. An aqueous solution was subjected to centrifugal ultrafiltration, the ultrafiltrate was cleaned up on a carbon solid-phase extraction column, and an aliquot was transferred to a precolumn for enrichment and subsequent injection onto an analytical column. In infant formula samples, thiocyanate was found at 2.0-5.1 mg/kg in five of seven milk-based products and was not found in the other two nor in three soy-based products tested (0.2 mg/kg LOQ); iodide was found at 0.3-1.3mg/kg (0.04 mg/kg LOQ). In 13 dry milk samples, thiocyanate was found at 27-38 mg/kg (1 mg/kg LOQ), and iodide was found at 1.8-3.2 mg/kg (0.2 mg/kg LOQ).