In this work the development of a comprehensive 2-D GC flame ionization detection (GC x GC FID) method for biodiesel fuels is reported. This method is used for the analysis of fatty acid methyl esters (FAMEs) in both biodiesel (B100) and biodiesel blend (B5) samples. The separation of FAME was based on component boiling point in the first dimension and polarity in the second dimension by using a BPX5/BP20 column set to provide a measure of 'orthogonality' in the 2-D space. Here the columns are coupled with a cryogenic modulator operating in a novel temperature programmed mode (T(M)) whereby the cryotrap is progressively incremented in temperature as the oven temperature is increased. The final method employs eight cryotrap temperature settings. The developed GC x GC method is able to successfully characterize and identify both B100 and B5 FAME components, which are produced from a variety of vegetable oils, animal fats and waste cooking oils, with high precision. The method is capable of analysing FAME with carbon numbers C4-C24, and is particularly suitable to characterize various types of biodiesel, making it possible to differentiate the origin and type of FAME used in the biodiesel samples.

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This work describes development of a new spectrophotometric flow analysis technique suitable for monitoring of ethanol content in gasohol fuel. In this technique, the concept of membraneless gas-diffusion (MBL-GD) was applied with one-step aqueous extraction of gasohol (1:2 gasohol:water). Segments of aqueous extract and color developing reagent were allowed to flow into two separate channels in the MBL-GD device. Inside the device, ethanol vapor can diffuse across a small headspace between the two channels (donor and acceptor). Introduction of an air-segment behind the zone of acceptor reagent to stop dispersion of the colored zone has greatly improved the rapidity of analysis using this MBL-GD technique. Two methods were developed for quality control of gasohol by measuring ethanol content. Method I is suitable for direct calibration of E5 and E10. Method II is recommended for E20. These methods have high accuracy with good precision (% RSD: 1 to 4.9, n=45) and have a sample throughput of 26 samples h -1 . E10 samples were compared with analysis using a standard GC method.

BackgroundThe aim of this study was to compare the intraosseous concentrations and the inhibitory effects on the growth of Staphylococcus aureus of 1 g versus 2 g of intravenous (IV) prophylactic cefazolin in total knee arthroplasty (TKA).Materials and methodsEighteen patients (21 knees) with primary knee osteoarthritis were divided into two groups receiving 1 g (12 patients: 14 knees) versus 2 g (six patients: seven knees) IV prophylactic cefazolin prior to the incision in TKA. Subchondral bone samples (proximal tibia, distal femur) were taken during the operation. These samples were analyzed for intraosseous concentration of cefazolin and their inhibitory effects on the growth of S. aureus, using high-performance liquid chromatography (HPLC) and agar disc diffusion bioassays.ResultsThe mean intraosseous concentration in the 2 g dose group was significantly higher than in the 1 g dose group in the proximal tibia (p = 0.007) and distal femur (p = 0.016). There were no significant differences between the two groups in terms of mean inhibitory effects in the proximal tibia or distal femur (p > 0.05). No significant correlations were found between the intraosseous concentrations and inhibitory effects in the proximal tibia (r = 0.18, p = 0.52) and distal femur (r = −0.29, p = 0.30).ConclusionIV cefazolin at a dose of 2 g produced greater intraosseous concentrations overall than a dose of 1 g. However, the higher intraosseous concentrations did not correlate with higher inhibitory effects.Level of evidenceLevel III.

A low-cost and user-friendly microfluidic paper-based analytical device (μPAD) was developed for identification of bullet hole from gunshot residue (GSR) on cotton fabric target. The device (25 × 82 mm) is made of filter paper with a printed pattern consisting of a circular sample loading reservoir (6 mm i.d.), a circular waste reservoir (4 mm i.d.) and a straight flow channel (3 mm wide and 60 mm long). A sticker with a ruler scale in millimeters was mounted alongside the channel. The straight channel is first impregnated with rhodizonate and dried at ambient temperature. Tartrate extract of the target fabric is loaded on the sample reservoir. If Pb(II) ions are present in the extract, pink streak of Pb(II)-rhodizonate precipitate is formed as the sample solution flows from the reservoir along the channel. The length of the pink strip is employed to estimate the firing distance.