Efficient optimization and development of two methods for the determination of acrylamide in deep-frying oil by liquid chromatography-tandem mass spectrometry: Application of multifactor analysis assessment strategy.

A new multifactor analysis assessment strategy was developed for evaluating, optimizing, and comparing analytical techniques for acrylamide in frying oils. Based on five indices (absolute recovery, absolute matrix effect, the intensity of the full ion scan, and the precursor ion scan to m/z 184 and m/z 241), the proposed strategy was performed with radar analysis, relative contribution analysis, and the entropy-weighted technique for order performance by similarity to ideal solution analysis. Two novel methods based on quick, easy, cheap, effective, rugged, and safe extraction methodology and gel permeation chromatography-liquid-liquid extraction followed by liquid chromatography-tandem mass spectrometry have been developed for the analysis of acrylamide in frying oils. Two methods were suitable for rapid and sensitive analysis of acrylamide in oils in different laboratories, with a limit of quantitation at 2 µg/kg, and the average recovery ranging from 92.5% to 107.8%, with relative standard deviations below 10%. When considering automation efficiency and matrix effects, gel permeation chromatography is the most efficient method, whereas the other method has an advantage when analyzing large samples. The developed methods were used in a pilot study to analyze frying oils with acrylamide content below 9.82 µg/kg, showing that the repeated frying process did not produce significant content of acrylamide in oils.

[Determination of diazepam in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry with pass-through solid phase extraction].

A method was developed for the determination of diazepam in aquatic products by pass-through solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analyte was extracted with acetonitrile directly and purified on a Prime HLB solid phase extraction column (60 mg/3 mL). The separation was performed on an Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 µm)using methanol-0.1% (v/v) formic acid aqueous solution as the mobile phase in gradient elution mode. Qualitative analysis was performed in the multiple reaction monitoring (MRM) mode. The analyte was quantified by matrix-matched external standard curves. The results showed good linear relationship in the range of 0.1-10 ng/mL, and the correlation coefficient (r2) was greater than 0.99. The spiked recoveries of diazepam were 88.2%-101.1% at the spiked levels of 1.5, 3.0 and 15.0 µg/kg, and both the intra-and inter-day precisions were less than 10%. The developed method is simple, rapid and accurate, and it can meet the requirements for diazepam determination in aquatic product samples.

[Determination of vitamin K1 and vitamin K2 in modulation milk powder by post-column reduction-high performance liquid chromatography].

A method for the determination of vitamin K1 and vitamin K2 in modulation milk powder was developed by high performance liquid chromatography (HPLC) coupled with post-column reduction. The samples were dissolved in water, lipase hydrolyzed, saponified with 2.5 mol/L sodium hydroxide solution and ethanol solution, extracted with n-hexane, and dissolved in methanol after concentration. The vitamin K were first separated on an Xbridge C18 column and then on a zinc powder reduction column, and detected using a fluorescence detector. The excitation and emission wavelengths were 326 nm and 432 nm, respectively. An external standard method was used for quantification. The results showed that the linearities of vitamin K1 and vitamin K2 was in the ranges of 0.0025-2.0 µg/mL and 0.01-2.0 µg/mL, respectively, with correlation coefficients both greater than 0.999. The spiked recoveries were 80.39%-94.39% and the precisions were 0.85%-3.98%. The limits of detection of vitamin K1 and vitamin K2 were 0.07 µg/100 g and 0.2 µg/100 g, respectively. The limits of quantification of vitamin K1 and vitamin K2 were 0.2 µg/100 g and 0.8 µg/100 g, respectively. The method has high sensitivity and good repeatability, and gives accurate results. It is suitable for the analysis and determination of the vitamin K1 and vitamin K2 in formula milk powder.

A sensitive flow injection chemiluminescence method for the determination of progesterone.

A sensitive flow injection (FI) chemiluminescence (CL) method was developed for the determination of trace amounts of progesterone. This method was based on the luminescent properties of the tris(1,10-phenanthroline) ruthenium(II) - potassium permanganate (KMnO4 ) - progesterone in acidic medium sensitized by Na2 SO3 . With the peak height as a quantitative parameter applying optimum conditions, the relative CL intensity was linear with progesterone concentration in the range of 1.0 × 10(-10) ∼ 6.0 × 10(-9) g·ml(-1) and 6.0 × 10(-9) ∼ 4.0 × 10(-8) g·ml(-1) with a detection limit of 7.1 × 10(-11) g·ml(-1) . The relative standard deviation (RSD) was 2.79% for 1.0 × 10(-8) g·ml(-1) progesterone (n = 11). The proposed method held low detection limit and was successfully applied to determination of progesterone in pharmaceutical preparations. The possible CL reaction mechanism was also discussed.

Determination of phenol by flow-injection with chemiluminescence detection based on the hemin-catalysed luminol-hydrogen peroxide reaction.

This study established a novel flow injection (FI) methodology for the determination of phenol in aqueous samples based on luminol chemiluminescence (CL) detection. The method was based on the inhibition that phenol caused on the hemin-catalysed chemiluminescence reaction between luminol and hydrogen peroxide in alkaline solution. Optimum conditions and possible mechanisms have been investigated. The linear range was 2.0×10(-9) to 4.0×10(-7)gmL(-1) for phenol. The proposed method is sensitive with a detection limit of 4.0×10(-10)gmL(-1). The relative standard deviation for 11 measurements was 2.3% for 1.0×10(-7)gmL(-1) phenol. The method was applied for the determination of phenol in waste water samples. The results obtained compared well with those by an official method.