A Review on GC-MS Hyphenated Technique

The hyphenated technique is developed from the coupling of a separation technique and an on-line spectroscopic detection technology, GCMS, LC-MS, LC-FTIR, LC-NMR, and CE-MS. Gas chromatography combined with mass spectrometry is an important technique for identification and quantification of analytes in multifactor systems. GC-MS is highly effective and versatile analytical techniques with numerous scientific applications to cater the field of applied Sciences and Technology. This review elaborates the significant uses of this technique. It includes a brief discussion of the instrumental set-up and theory for the comprehensive GC × GC hyphenated with different detection techniques. It is fast and sensitive, provides a high peak capacity, and allows determination of thermally stable and volatile compounds.

Polyacrylamide co-N,N'-methylene bisacrylamide monoliths for high peak capacity HILIC-HRMS of intact proteins at low trifluoroacetic acid content

In this study, we optimized a polymerization mixture to synthesize polyacrylamide-co-N,N-methylene bisacrylamide monolithic stationary phases for hydrophilic-interaction chromatography (HILIC) of intact proteins. Thermal polymerization was performed, and the effects of varying the amount of crosslinker and the porogen composition on the separation performance of the resulting columns were studied. The homogeneity of the structure and the different porosities were examined through scanning electron microscopy. Further characterization of the monolithic structure revealed a permeable (K_f between 2.5 × 10-15 and 1.40 × 10-13 m2) and polar stationary phase suitable for HILIC. The HILIC separation performance of the different columns was assessed using gradient separation of a sample containing four intact proteins, with the best performing stationary phase exhibiting a peak capacity of 51 in a gradient of 25 min. Polyacrylamide-based materials were compared with a silica-based particulate amide phase (2.7 μm core-shell particles). The monolith has no residual silanol sites and, therefore, fewer sites for ion-exchange interactions with proteins. Thus, it required lower concentrations of ion-pair reagent in HILIC of intact proteins. When using 0.1% of trifluoroacetic acid (TFA) the peak capacities of the two columns were similar (31 and 36 for the monolithic and packed column, respectively). However, when decreasing the concentration of TFA to 0.005%, the monolithic column maintained its separation performance and selectivity (peak capacity 26), whereas the packed column showed greatly reduced performance (peak capacity 7), lower selectivity, and inability to elute all four reference proteins. Finally, using a mobile phase containing 0.1% formic acid and 0.005% TFA the HILIC separation on the monolithic column was successfully hyphenated with high-resolution mass spectrometry. Detection sensitivity for protein and glycoproteins was increased and the amount of adducts formed was decreased in comparison with separations performed at 0.1% TFA.

Strategies towards simpler configuration and higher peak capacity with comprehensive multidimensional gas chromatography

Experimental and data analysis approaches in MDGC comprising comprehensive H/C and GC × GC were developed with an example application illustrated for analysis of a technical glycol precursor sample.

Reduced Mortality During Holidays and the COVID-19 Pandemic in Israel

Evidence suggests varied trends in mortality surrounding the holiday period. Most studies support an association between increased mortality rates and holidays. We compare the effect of the number of holiday days per week on the overall mortality rate in the Israeli population. Between 2000-2020, we see significantly reduced mortality rates in weeks containing national holidays. We observed the same trend in all-cause mortality during the 3-weeks COVID-19 pandemic lockdown. As the Israeli health care system, and hospitals especially, function near peak capacity year-round, we propose that reduced medical service utilization during holidays and the COVID-19 lockdown period might underlie the lower mortality rates.

Predicting the Future Capacity and Dimensions of Container Ships

Since the introduction of the container ship, there has been an impressive increase in its use to take advantage of economies of scale. In the last two decades, the capacity of vessels has trebled. Currently, vessels of 23,000 TEU (20-ft equivalent unit) sail the seas. With the exponential growth experienced in this sector, the question arises if it is possible to reach a peak capacity, as has occurred with bulk cargo vessels and, recently, aircraft. This paper aims to predict the possible size and dimensions of a new generation of mega container ships. Based on economies of scale, port infrastructure, demand, environmental trends, and naval design criteria, the limit to ship size has been estimated. The results suggest that additional increases in ship size are still possible. The aim of this study is to help port authorities to understand the needs of the shipping container industry and to calculate the expansion and investment necessary.