Evaluation of matrix effects in analysis of estrogen using liquid chromatography–tandem mass spectrometry

Matrix effects of different biological samples, including phosphate‐buffered saline–bovine serum albumin (PBS‐BSA), gelded horse serum, mouse serum, and mouse brain, were investigated for the determination of 17α‐ and β‐estradiol using derivatization with dansyl chloride prior to LC‐MS/MS. Matrix effects were evaluated based on the slopes of regression lines plotted from results obtained in biological matrices versus pure standard solutions. Such plots indicate the enhancement or suppression of signal based on the presence of a particular biological fluid for a particular method. The matrix effects from PBS‐BSA were similar to those of mouse serum. In contrast, analyses performed from horse serum and mouse brain yielded significant ion suppression, especially for 17β‐estradiol. Precipitation during derivatization was observed when pre‐concentrated samples were processed with ethyl acetate as an extraction solvent. This was overcome with the use of methyl tert‐butyl ether; however, matrix effects from this preparation were still present, evidenced by signal suppression and poor linearity in the standard curve. This work affirms that caution should be taken in the transfer of methods for use with different biological matrices, especially in the case where surrogate matrices are necessary for calibration purposes.     

Kerr Lens Mode-locked Operation of Yb∶KYW Laser

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　Ｒｅｃｅｎｔｌｙ ,ｌａｓｅｒ ｐｅｒｆｏｒｍａｎｃｅｏｆｎｅｗＹｂ3 ∶ＫＹ (ＷＯ4) 2 ｃｒｙｓｔａｌ (Ｙｂ3 ∶ＫＹＷ )ｈａｓｂｅｅｎｏｂｔａｉｎｅｄａｔ 1 0 2 5ｎｍ[1] .ＴｈｅＹｂ3 ∶ＫＹＷｃｒｙｓｔａｌｉｓａ ｐｒｏｍｉｓｉｎｇｍａｔｅｒｉａｌｆｏｒｍｉｃｒｏｃｈｉｐａｎｄ ｐａｓｓｉｖｅｍｏｄｅ ｌｏｃｋｅｄｌａｓｅｒｓｔｕｎａｂｌｅｉｎｔｈｅｒａｎｇｅｏｆ 1 0 2 0～ 1 0 6 0ｎｍ .ＩｔｉｓｋｎｏｗｎｔｈａｔＫｅｒｒ ｌｅｎｓｍｏｄｅ ｌｏｃｋｉｎｇｔｅｃｈｎｉｑ…     

Kerr Lens Mode-locked Operation of Yb:KYW Laser

Using a modified ABCD-matrix approach accounting for nonlinear refraction in active medium,the ranges of cavity parameters that provide a mode-locking of Yb∶KYW-laser in usual z-fold cavity configuration are determined.Taking the cavity parameters that provide a most efficient mode locking and based on fluctuation model,a numerical simulation of laser operation is performed.In the calculations the side-band pump power of 6W at 982 nm is used in 1 cm length KYW crystal with 1 cm×0.005 cm beam cross section.Calculations show that self-starting operation is possible with these parameters and dispersion compensation allows for bandwidth-limited ultrashort pulse generation.The shortest pulse duration was determined to be about 200 fs with self-starting buid-up time of 130 μs.Such a built-up time is comparable and even shorter than that one for the lasers with semiconductor saturable absorbers.The region of negative dispersion provided by prism pair for a stable ultrashort pulse generation was determined to be (-17000～-42000)fs2.     

Impedimetric biosensor based on bimetallic AgPt nanoparticle-decorated carbon nanotubes as highly conductive film surface

Journal of Solid State Electrochemistry - In the present study, an ultrasensitive impedimetric aptasensor for the quantitative detection of diclofenac (DCF) was fabricated based on a novel signal...