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A detailed MS(n) study on an ion trap instrument of the quaternary ammonium pesticides paraquat, diquat, difenzoquat, mepiquat and chlormequat reveals a number of ions not reported previously, and has allowed examination of the fragmentation pathways. A number of transitions that are highly specific to each quat have been identified. Optimal ion trap operating conditions determined using Simplex optimisation can promote either detection of a particular fragmentation transition or a range of MS/MS product ions with a high overall signal response. Thus, fragmentation conditions were optimised to enhance the specificity or sensitivity of MS/MS methods.

Optimisation of the activation parameters for ion trap mass spectrometric analysis of the chlormequat cation using simplex optimisation enabled the product ion (m/z 58) response to be improved 1000-fold. A comparison of the sensitivity of the optimised ion trap mass spectrometer with that of a triple quadrupole mass spectrometer for liquid chromatography/tandem mass spectrometry (LC/MS/MS) showed that similar limits of detection (LODs) could be achieved. For the MS/MS transition of the (35)Cl precursor to the most abundant product, LODs were 0.8 ng cation mL(-1) (0.004 mg cation kg(-1) pear equivalent) and 1.0 ng cation mL(-1) (0.005 mg cation kg(-1) pear equivalent) on the triple quadrupole and ion trap instrument, respectively.

A UK survey of plasticizer levels in retail foods (73 samples) wrapped in plasticized films or materials with plasticized coatings has been carried out. A wide range of different food-types packaged in vinylidene chloride copolymers (PVDC), nitrocellulose-coated regenerated cellulose film (RCF) and cellulose acetate were purchased from retail and 'take-away' outlets. Plasticizers found in these films were dibutyl sebacate (DBS) and acetyl tributyl citrate (ATBC) in PVDC, dibutyl phthalate (DBP), dicyclohexyl phthalate (DCHP), butylbenzyl phthalate (BBP), and diphenyl 2-ethylhexyl phosphate (DPOP) in RCF coatings, and diethyl phthlate (DEP) in cellulose acetate. Foodstuffs analysed included cheese, pate, chocolate and confectionery products, meat pies, cake, quiches and sandwiches. Analysis was by stable isotope dilution GC/MS for DBP, DCHP and DEP, GC/MS (selected ion monitoring) for BBP and DPOP, and GC with flame ionization detection for DBS and ATBC, but with mass spectrometric confirmation. Levels of plasticizers found in foods were in the following ranges: ATBC in cheese, 2-8 mg/kg; DBS in processed cheese and cooked meats, 76-137 mg/kg; 76-137 mg/kg; DBP, DCHP, BBP, and DPOP found individually or in combination in confectionery, meat pies, cake and sandwiches, total levels from 0.5 to 53 mg/kg; and DEP in quiches, 2-4 mg/kg.

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A high performance liquid chromatographic/atmospheric pressure chemical ionization-mass spectrometric (HPLC/APCI-MS) method has been developed for the determination of the pesticides diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea) and clofentezine (3,6-bis(2-chlorophenyl)-1,2,4,5-tetrazine) in plums, strawberries and blackcurrant-based fruit drinks. Samples were homogenized with acetone, extracted into dichloromethane + cyclohexane and cleaned-up by high performance gel permeation chromatography. HPLC was performed on an ODS column with methanol + water at 1 mL/min. Detection was by negative-ion selected-ion monitoring APCI-MS. Comparison of response with solvent and matrix-matched standards showed some enhancement of response for the latter, and these standards were consequently used for quantification. The calibration was linear over the range 0.05-0.50 ng/microL in all three matrices. The mean overall recovery of diflubenzuron and clofentezine from spiked extracts (0.086 mg/kg) in all three matrices was 76% and 70% respectively with relative standard deviations of 15% and 12% respectively (n = 12). The limit of detection was both compound and commodity dependent and ranged from 0.01-0.05 ng/microL, equivalent to 0.003-0.014 mg/kg in the crop.

A method was developed for the determination in honey of the Ragwort (Senecio jacobaea) derived pyrrolizidine alkaloids jacoline, jacozine, jacobine, seneciphylline and senecionine, combining solid-phase extraction with high performance liquid chromatography and atmospheric pressure chemical ionization mass spectrometric detection. The method allowed determination of individual alkaloids and offered a considerable improvement in terms of speed, sensitivity and specificity over previous approaches, but was not suitable for determination of jaconine, a minor alkaloid in Ragwort. Instrument calibrations were linear over the range 0.005 to 100 micrograms/ml, equivalent to approximately 0.001 to 2.0 mg/kg in honey with the extraction method used and allowing for observed recoveries. Detection limits in honey were 0.002 mg/kg. Recoveries for most of the alkaloids were between 57 and 70%. The alkaloids have been determined in a number of samples of honey selected after pollen identification and counting. The alkaloids were not detectable in samples containing two grains or less of Ragwort pollen per gram of honey. Samples collected in late July and August contained Ragwort pollen at 15-21 grains/g and total alkaloid concentrations of 0.011-0.056 mg/kg. Similar contributions to the total were made by jacozine, seneciophylline and senecionine, with jacobine making a larger and jacoline a smaller contribution. Two samples of honey containing Ragwort pollen at 24 and 16 grains/g had total alkaloid concentrations of 0.42 and 1.48 mg/kg respectively (not corrected for recovery). The alkaloid profile in these samples was dominated by seneciphylline and senecionine which together comprised 90-95% of the total. Alkaloids were not detected in retail honeys.

Food, especially meat, milk, and fish, is the immediate source of almost all polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxinlike compounds in the general population. To estimate intake of these highly toxic compounds, we performed congener-specific dioxin analyses for the first time on U.S. food for 18 dairy meat, and fish samples from a supermarket in upstate New York. 2,3,7,8 Tetrachlorodibenzo-p-dioxin (TCDD, "dioxin") toxic equivalents (TEqs) on a wet weight basis for the dairy products ranged for 0.04 to 0.7 ppt, meat TEqs ranged from 0.03 to 1.5 ppt, and fish TEqs ranged from 0.02 to 0.13 ppt. Previous human breast milk and infant formula analyses were used with the current preliminary food data to estimate a range of dioxin intake for Americans. Average daily food intake of TEqs for an adult weighing 65 kg was estimated to be between 0.3 and 3.0 pg/kg body weight, for a total of 18-192 pg TEq, using 1986 American consumption rates. Due to the relatively high level of PCDDs and PCDFs commonly found in human breast milk from American women and from women in other industrial countries, a nursing infant may consume an average of 35-53 pg TEq/kg body weight/day in its first year of life. This may be compared with the current U.S. EPA virtually safe dose of 0.006 pg TCDD/kg body weight per day over a 70-year lifetime based on an upper limit cancer risk of 10(-6), or the 10 pg/kg/day used by some European government agencies.