Multiresidue analysis of 59 nonallowed substances and other contaminants in cosmetics.

A method was developed for the determination of 59 glucocorticoids, sex hormones, nonsteroidal anti-inflammatory drugs, antibiotics, and other contaminants in cosmetics simultaneously by ultra high performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Acetonitrile was used to extract the sample, and the mixed sorbents were dispersed for purification. With the optimal conditions, the optimized pretreatment processes led to no significant interference on analysis from an extremely complicated sample matrix, and the linear ranges of 59 analytes were 0-480.0 µg/kg with the correlation coefficients above 0.99 and the limits of quantification (S/N≥10) were 5-40 µg/kg. Statistical evaluation revealed that the average recoveries were in the range of 61.2-131.2%, and relative standard deviations were in the range of 2.0-22.8%, meanwhile the interday precision ranged from 3.8 to 21.8%. This method is simple, fast, and credible, and it can be applied to simultaneous screening and determination of various classes of substances under investigations illegally presented in cosmetic products, covering a wide diversity of polarities, and pKa values.

Development of an automated on-line pre-column derivatization procedure for sensitive determination of histamine in food with high-performance liquid chromatography-fluorescence detection.

An improved sensitive method was developed and validated for the determination of histamine in food samples by using automated on-line pre-column derivatization coupled with high performance liquid chromatography and fluorescence detection (HPLC-FLD). o-Phthaldialdehyde (OPA) was adopted as derivatization reagent, and a "sandwich" (OPA+histamine+OPA) aspiration mode for the automated on-line pre-column derivatization was found to efficiently enhance the method sensitivity and precision. Histamine in food samples was efficiently extracted with a methanol-phosphate buffer solution (50:50, v/v) at 60 degrees C for 30 min, and purified with Waters Oasis MCX solid-phase extraction (SPE) cartridge. The limit of quantification for this method is 0.2 mg/kg, which is very sensitive for histamine determination. With the "sandwich" injection program, 3.7% of relative standard deviation (RSD) was achieved by five replicative determinations of a sample blank spiked with 0.25 mg/kg histamine standard. Histamine in food samples such as fumitory skipjack and mackerel was analyzed with relative recoveries over 95% at spiking level of 150 mg/kg, as well as canned tuna fish and cheese with relative recoveries up to 98% at spiking levels of 0.50 and 5.0 mg/kg, respectively. The proposed method was validated with a sample from the Food Analysis Performance Assessment Scheme (FAPAS) as a standard certified material; and the results (140+/-6 mg/kg) agreed well with the assigned value (139 mg/kg).

Multi-class method for determination of veterinary drug residues and other contaminants in infant formula by ultra performance liquid chromatography-tandem mass spectrometry.

A rapid, simple and generic analytical method which was able to simultaneously determine 220 undesirable chemical residues in infant formula had been developed. The method comprised of extraction with acetonitrile, clean-up by low temperature and water precipitation, and analysis by ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS-MS) using multiple reaction monitoring (MRM) mode. Most fat materials in acetonitrile extract were eliminated by low temperature clean-up. The water precipitation, providing a necessary and supplementary cleanup, could avoid losses of hydrophobic analytes (avermectins, ionophores). Average recoveries for spiked infant formula were in the range from 57% to 147% with associated RSD values between 1% and 28%. For over 80% of the analytes, the recoveries were between 70% and 120% with RSD values in the range of 1-15%. The limits of quantification (LOQs) were from 0.01 to 5 µg/kg, which were usually sufficient to verify the compliance of products with legal tolerances. Application of this method in routine monitoring programs would imply a drastic reduction of both effort and time.

Comprehensive screening for multi-class veterinary drug residues and other contaminants in muscle using column-switching UPLC-MS/MS.

A quantitative multi-class analytical method covering more than 226 veterinary drugs and other contaminants in muscle, belonging to different drug families, was developed. The method is based on liquid-liquid extraction, purification by low-temperature clean-up and dispersive solid-phase extraction (D-SPE), and analysis was conducted in two analytical runs by column-switching UPLC coupled with electrospray ionisation and tandem mass spectrometry (UPLC-ESI-MS/MS). For most of the target analytes, the optimised pre-treatment processes led to no significant interference from the sample matrix. The limit of quantification varied from 0.05 to 10 µg kg(-1). Statistical evaluation indicated that average recoveries spiked into pork were in the range from 62.4% to 138.8%, and the relative standard deviations were in the range from 2.8% to 26.6% (intra-day precision). The availability of this method will contribute to a better safety assurance of meat with a significant reduction of both effort and time.