Automated Regularized Deconvolution for Eliminating Extra-Column Effects in Fast High-Efficiency Separations.

With the introduction of ultrahigh efficiency columns and fast separations, the need to eliminate peak deformation contributed by the instrument must be effectively solved. Herein, we develop a robust framework to automate deconvolution and minimize its artifacts, such as negative dips, wild noise oscillations, and ringing, by combining regularized deconvolution and Perona-Malik (PM) anisotropic diffusion methods. A asymmetric generalized normal (AGN) function is proposed to model the instrumental response for the first time. With no-column data at various flow rates, the interior point optimization algorithm extracts the parameters describing instrumental distortion. The column-only chromatogram was reconstructed using the Tikhonov regularization technique with minimal instrumental distortion. For illustration, four different chromatography systems are used in fast chiral and achiral separations with 2.1 and 4.6 mm i.d. columns. Ordinary HPLC data can approach highly optimized UHPLC data. Similarly, in fast HPLC-circular dichroism (CD) detection, 8000 plates were gained for a fast chiral separation. Moment analysis of deconvolved peaks confirms correction of the center of mass, variance, skew, and kurtosis. This approach can be easily integrated and used with virtually any separation and detection system to provide enhanced analytical data.

Symmetrization of Peaks in Chiral Chromatography with an Area-Invariant Resolution Enhancement Method.

A majority of enantiomeric separations show some degree of peak asymmetry, which is detrimental to quantitative and semiquantitative chiral analysis. This paper presents a simple and rapid peak symmetrization algorithm for the correction or reduction of peak tailing or fronting in exponentially modified Gaussians. Raw chromatographic data can be symmetrized by adding a correct fraction of the first derivative to the chromatogram. The area remains invariant since the area under the first derivative is zero for a pure Gaussian and numerically close to zero for asymmetric peaks. A method of easily extracting the distortion parameter is provided, as well as insight into how pre-smoothing the data with the "perfect smoother" algorithm can suppress high frequencies effectively. The central difference method is also used to compute the first derivative, reducing root-mean-square noise by up to 28% compared to the standard forward difference method. A survey of 40 chiral separations is presented, demonstrating the range of asymmetry observed in chiral separations. Examples of symmetrization of the peaks from enantiomers in comparable and disproportionate concentrations are also provided. Artifacts of deconvolution are discussed, along with methods to mitigate such artifacts.

Direct Construction of Peaks from Free Induction Decay Curves for Gas Chromatography-Molecular Rotational Resonance Spectroscopy without Fourier Transforms.

The concept of coupling gas chromatography with molecular rotational resonance spectroscopy (GC-MRR) was introduced in 2020, combining the separation capabilities of GC with the unparalleled specificity of MRR. In this study, we address the challenge of the high data throughput of MRR spectrometers, as GC-MRR spectrometers can generate thousands to millions of data points per second. In the previous GC-MRR studies, a free induction decay (FID) measurement was Fourier transformed to generate each point on the chromatogram. Such extensive calculations limit the performance, sensitivity, and speed of GC-MRR. A direct approach is proposed here to extract peak intensity from FID using the Gram-Schmidt vector orthogonalization method. First, analyte-free FIDs are used to construct a basis set representing the instrument's background noise, and then the remaining FIDs are orthogonalized to this fixed basis set. Each FID yields a single intensity value after Gram-Schmidt orthogonalization. The magnitude of the orthogonalized analyte FID is the signal intensity plotted in the chromatogram. This approach is computationally much faster (up to 10 times) than the conventional Fourier transform algorithm, is at least as sensitive as the FT algorithm, and maintains or improves the chromatographic peak shape. We compare the sensitivity, linearity, and chromatographic peak shapes for the Fourier transform and Gram-Schmidt approaches using both synthetically generated FIDs and instrumental data. This approach would allow the summed peak intensity to be displayed essentially in real-time, following which identified peaks can be further investigated to identify and quantify the species associated with each.

Insights into enantioselective separations of ionic metal complexes by sub/supercritical fluid chromatography.

Sub/supercritical fluid chromatography (SFC) is a green separation technique that has been used to separate a wide variety of compounds and is proven to be immensely useful for chiral separations. However, SFC is currently not thought to be applicable for ionic compounds due to their low solubility in CO2, even with additives and organic modifiers. Recently, a large amount of research has been centered on octahedral complexes of Ru(II) and Os(II) with bidentate polypyridyl ligands due to their ability to serve in cancer treatment and other biological activities. These compounds exist as the delta (Δ) and lambda (Λ) enantiomers. Previously, similar compounds have been enantiomerically separated using HPLC and capillary electrophoresis, but never with SFC. Cyclofructan-6 (CF6) derivatized with (R)-naphthyl ethyl (RN) groups has been proven to be an effective chiral stationary phase for these separations in HPLC. This column chemistry was expanded to SFC to provide the first chiral separation of a wide variety (23 complexes in total) of ionic octahedral polypyridyl complexes. Unexpected behavior for mixing methanol and acetonitrile as the organic modifier will be discussed, along with the effects of additives. Enantioselectivity on CF6-RN chemistry is shown to be dependent on the conjugation level and rigidity of the metal complexes. Mass transfer kinetic behavior is also shown, and high-efficiency baseline resolved rapid separations are shown for fast screening or quantitation of representative coordination complexes.

An examination of the effects of water on normal phase enantioseparations.

Superficially porous silica bonded with macrocyclic glycopeptides can separate enantiomers in various chromatographic formats, including normal phase liquid chromatography (NPLC). The conventional wisdom in NPLC is to avoid intentionally adding water in the eluents. Herein we examine the effects of small quantities of water as an additive on chiral separations in NPLC with the n-hexane-ethanol system. A phase diagram (n-hexane-ethanol-water) is used to analyze the physicochemical properties of the mobile phase. The relative polarity change of solvents upon adding water was determined by using bathochromic shifts of dissolved Nile Red dye. The effectiveness of chiral NPLC with water traces is demonstrated for various pharmaceutically relevant enantiomeric compounds. It is postulated that water molecules weaken stationary phase-solute interactions, resulting in lower retention times for both enantiomers in addition to significantly higher efficiencies. Gibbs free energy changes provided an understanding of the different enantioselectivity shifts caused by water addition. Some interesting kinetic effects also were observed. Classical van Deemter curves are not observed on macrocyclic glycopeptide stationary phases due to slow mass transfer kinetics and thermal effects at high flow rates. The most significant advantage of adding water in NPLC is reducing mass transfer kinetics and altering the mass overloading properties which is highly beneficial on macrocyclic glycopeptide phases. By overloading a 10 × 0.46-cm column with up to 0.6 mg alprenolol, it was found that the relative adsorption isotherm of the first eluting enantiomer was switched from Langmuir to anti-Langmuir type by water addition. The peak shape tuning effect demonstrated the strong influence of water on specific interaction sites of the chiral stationary phases. Water addition effects were most beneficial for enantiomeric and preparative separations in NP mode.

Enhancing Sensitivity for High-Selectivity Gas Chromatography-Molecular Rotational Resonance Spectroscopy.

A next-generation gas chromatograph-molecular rotational resonance (MRR) spectrometer (GC-MRR) with instrumental improvements and higher sensitivity is described. MRR serves as a structural information-rich detector for GC with extremely narrow linewidths and capabilities surpassing 1H nuclear magnetic resonance/Fourier transform infrared spectroscopy/mass spectrometry (MS) while offering unparalleled specificity in regard to a molecule's three-dimensional structure. With a Fabry-Pérot cavity and a supersonic jet incorporated into a GC-MRR, dramatic improvements in sensitivity for molecules up to 244 Da were achieved in the microwave region compared to the only prior work, which demonstrated the GC-MRR idea for the first time with millimeter waves. The supersonic jet cools the analytes to ∼2 K, resulting in a limited number of molecular rotational and vibrational levels and enabling us to obtain stronger GC-MRR signals. This has allowed the limits of detection of the GC-MRR to be comparable to a GC thermal conductivity detector with an optimized choice of gases. The performance of this GC-MRR system is reported for a range of molecules with permanent dipole moments, including alcohols, nitrogen heterocyclics, halogenated compounds, dioxins, and nitro compounds in the molecular mass range of 46-244 Da. The lowest amount of any substance yet detected by MRR in terms of mass is reported in this work. A theoretically unexpected finding is reported for the first time about the effect of the GC carrier gas (He, Ne, and N2) on the sensitivity of the analysis in the presence of the gas driving the supersonic jet (He, Ne, and N2) in the GC-MRR. Finally, the idea of total molecule monitoring in the GC-MRR analogous to selected ion monitoring in GC-MS is illustrated. Structural isomers and isotopologues of bromobutanes and bromonitrobenzenes are used to demonstrate this concept.

High efficiency functionalized hydrophilic cyclofructans as stationary phases in sub/supercritical fluid chromatography.

Packed column SFC has become very popular for preparative and analytical separations due to the low cost of CO2, its accessible critical temperature, and pressure, with the additional benefit of a low environmental burden. Currently, there is a shortage of new polar stationary phase chemistries for SFC. In this work, two new functionalized cyclofructan columns are introduced and evaluated for their performance in achiral SFC separations for the first time. Cyclofructan (CF6), a macrocyclic oligosaccharide, was covalently linked with benzoic acid (BCF6) and propyl sulfonic acid (SCF6) groups by ether bonds. Superficially porous particles (2.7 µm) bonded with modified CF6 showed markedly different selectivity than native CF6. In SFC, peak shapes of amines and basic compounds are often compromised. We show that small quantities (~5.7% v/v) of water added to the methanol modifier in CO2 improves peak symmetries of primary, secondary, and tertiary amines. Efficiencies as high as 200,000 plates/m (reduced plate height ~ 1.8) were observed for benzamide and amitriptyline on the BCF6 column. The relative standard deviations (RSDs) of retention times on BCF6 were about 1.4%, and on SCF6 were less than 1%. Amines on the SCF6 column showed plate counts as high as 170,000 plates/m. Tetramethylammonium acetate is examined as an alternative to water in MeOH. A run time of 36 min with methanol, trifluoroacetic acid, triethylamine mobile phase was reduced to <5 min with complete baseline resolution for a set of amines. The new stationary phases allow greener approaches towards solving separation problems.

The theory and practice of ultrafast liquid chromatography: A tutorial.

Modern high-throughput experimentation and challenging analytical problems of academic/industrial research have put the responsibility on separation scientists to develop new fast separation approaches. With the availability of high-pressure pumps, small particles with hydrolytically stable surface chemistries, reduced extra-column band broadening, and low volume detectors with fast signal processing, it is now feasible to do sub-minute to sub-second chromatography. Herein, the fundamental theoretical principles of ultrafast chromatography, along with practical solutions, are reviewed. Approaches for rapid separations in packed beds, narrow open tubular columns, and monoliths are demonstrated, along with the challenges that were faced. The instrumentation requirements (pumps, injection systems, detectors, column packing process) for using short columns ranging from 0.5 to 5 cm are examined, followed by real applications. One of the main problems in ultrafast chromatography is partial or complete peak overlap. As per Gidding's statistical overlap theory, peak overlap cannot be avoided for a completely random sample for a column with a given peak capacity. Signal processing techniques based on Fourier transform deconvolution of band broadening, power laws, derivatives, and iterative curve fitting are explained to help improve the chromatographic resolution. An example of ten peaks separated in under a second is shown and discussed. Other ultrafast separations in supercritical fluid chromatography or capillary electrophoresis are briefly mentioned to provide a complete understanding of this emerging field.

Facile Solutions to the Problems Associated with Chemical Information and Mathematical Symbolism While Using Machine Translation Tools.

Advances in computer-aided translation technology have made tremendous progress in accuracy in the past few years. Chemical Abstracts Service of the American Chemical Society summarizes scientific works from more than 50 languages and allows the users to search papers in nine selected languages. Currently, only the abstracts are rendered into English by human experts or by machine translation because full text translation of millions of articles is beyond the human capacity today. An English translation of a research paper, scientific book, or patent is often required for research, data mining, and for historical purposes from various foreign languages. Many fundamental papers in chemistry, quantum chemistry, physics, and mathematics contain a significant number of chemical or mathematical equations. One of the major known problems in machine translation of such symbolically dense texts is incorrect or meaningless output. This article describes how to optimize the existing machine translation tools to read foreign language papers embedded with chemical/mathematical equations. German and French languages have been selected for illustrative purposes for English translation. Direct upload of text with extensive symbolism is possible with certain services, but this also occasionally produces erroneous rendition into English. A facile solution to the associated problems with embedded equations and mathematical formulas is replacing the equations and notations with "dummy" variables. The placeholder or dummy symbols can be removed after translation, and the original equations are substituted again. This approach, which can be automated in future, relies on the idea that chemical formulas and mathematical notations are universal. Following the guidelines in the article, excellent translations can be produced from a text having interspersed equations and chemical symbols.

Enhancing supercritical fluid chromatographic efficiency: Predicting effects of small aqueous additives.

Supercritical fluid chromatography is becoming more prevalent, particularly in industry. This is due to the inexpensive, and more importantly, environmentally benign carbon dioxide that is used as the major component of the mobile phase. Water is minimally miscible with carbon dioxide at temperatures and pressures commonly used in SFC. However, the introduction of a polar alcohol modifier component increases the solubility of water in carbon dioxide. Previously, the addition of small amounts of water in the mobile phase was shown to provide significant gains in efficiency in chiral supercritical fluid chromatography, especially with polar stationary phases. In this work, we report the effect of the addition of small amounts of water on efficiency and retention factor with four different SFC stationary phases used for achiral analysis namely FructoShell-N (native cyclofructan-6), SilicaShell (bare silica), PoroShell 120 EC C18 (octadecyl silica) and Xselect C18 SB. This is the first reported use of FructoShell-N, a cyclofructan derivatized phase for SFC applications. We devised a predictive test to determine which analytes show an increase in efficiency using their known chemical constants (logKow, pKa, PSA and Hsum). We also use discriminant analysis to elucidate the most important analyte parameters that contribute to "water enhanced" efficiency gains.

Improving peak capacities over 100 in less than 60 seconds: operating above normal peak capacity limits with signal processing.

A primary focus in liquid chromatography analysis of complex samples is high peak capacity separations. Using advanced instrumentation and optimal small, high-efficiency columns, complex multicomponent mixtures can now be analyzed in relatively short times. Despite these advances, chromatographic peak overlap is still observed. Recently, attention has shifted from improvements in chromatographic efficiency and selectivity to enhancing data processing after collection. Curve fitting methods can be used to trace underlying peaks, but do not directly enhance chromatographic resolution. Methods based on the properties of derivatives and power transform were recently shown to enhance chromatographic peak resolution while maintaining critical peak information (peak areas and retention times). These protocols have been extensively investigated for their fundamental properties, advantages, and limitations, but they have not been evaluated with complex chromatograms. Herein, we evaluate the use of deconvolution via Fourier transform (FT), even-derivative peak sharpening, and power law with the fast separation (< 60 s) of a 101-component mixture using ultra-high-pressure liquid chromatography. High noise and peak overlap are present in this gradient separation, which is representative of fast chromatography. Chromatographic resolution enhancement is demonstrated and described. Further, accurate quantitation is maintained and shown with representative examples. Enhancements in peak capacity and peak-to-peak resolutions are discussed. Finally, the statistical theory of overlap is used for 101 peaks and predictions are made for the number of singlet, doublet, and multiplets analyte peaks. The effect of increasing peak capacity by FT even derivative sharpening and power laws leads to a decrease in the number of peak overlaps and an increase in total peak number. Graphical abstract.

Enhancing the selectivity of polar hydrophilic analytes with a low concentration of barium ions in the mobile phase using geopolymers and silica supports.

Charged analytes such as organic sulfonic acids, sulfates, carboxylates, and phosphates are often analyzed by hydrophilic interaction liquid chromatography (HILIC). In many cases, these analytes do not show any selectivity and elute near the dead time using the conventional acetonitrile-ammonium acetate buffers. In this work, we introduce a powerful selectivity enhancing technique by using a trace amount of Ba2+ ion in the mobile phase as a general approach for HILIC with UV-Vis detection. Silica and a newly developed material called geopolymers are used as stationary phases. Geopolymers are X-ray amorphous aluminosilicate inorganic polymers with cation exchange properties. Barium exchanged geopolymers (Ba-NM-GP) are synthesized from metakaolin based geopolymer. Thorough characterization of Ba-NM-GP is reported using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area analyzer and laser diffraction particle size distribution analyzer for the determination of their shape, size, porosity, surface area and particle size distribution respectively. It is demonstrated that in the absence of Ba2+, baseline separations of sulfonates, carboxylates, and phosphates is not possible, whereas, in the presence of Ba2+ in the mobile phase, these analytes are easily separated. Barium perchlorate is suggested as an additive for it is UV transparent, and it has practically an unlimited solubility in acetonitrile.

A Gas Chromatography-Molecular Rotational Resonance Spectroscopy Based System of Singular Specificity.

We designed and demonstrated the unique abilities of the first gas chromatography-molecular rotational resonance spectrometer (GC-MRR). While broadly and routinely applicable, its capabilities can exceed those of high-resolution MS and NMR spectroscopy in terms of selectivity, resolution, and compound identification. A series of 24 isotopologues and isotopomers of five organic compounds are separated, identified, and quantified in a single run. Natural isotopic abundances of mixtures of compounds containing chlorine, bromine, and sulfur heteroatoms are easily determined. MRR detection provides the added high specificity for these selective gas-phase separations. GC-MRR is shown to be ideal for compound-specific isotope analysis (CSIA). Different bacterial cultures and groundwater were shown to have contrasting isotopic selectivities for common organic compounds. The ease of such GC-MRR measurements may initiate a new era in biosynthetic/degradation and geochemical isotopic compound studies.

Extending the power transform approach for recovering areas of overlapping peaks.

Power functions, p n ( x ) = [ f ( x ) ] n , are embedded in some modern chromatography detectors and software which not only alter the linear dynamic range of such detectors but also improve the cosmetic aspects of the chromatograms. These aspects include a reduction in baseline noise, improved peak symmetry, and better resolution. However, after raising the electronic output of a detector to a selected power (n > 1), the original peak area information is lost as are very small peaks. Recent advances in the peak processing protocol allow us to recover peak areas from overlapping peak areas, even in noisy environments using power functions. One of the primary protocol requirements of this approach was to have resolution factors ≥0.9. An increasing positive bias in the recovered area was observed as the resolution factors decreased below 0.9. In this work, we extend the capabilities of power function to lower resolution values. This bias is addressed by considering the increasing contributions in peak height coming from adjacent peaks. It is shown that the power function can now be used as long as the peak maxima are visible, making R s  = 0.5, the lower treatable resolution factor for two peaks of similar areas.

Ramifications and Insights on the Role of Water in Chiral Sub/Supercritical Fluid Chromatography.

More than 40 cosolvents have been used with carbon dioxide to alter its solvation strength. Among the most interesting systems is the subcritical/supercritical CO2/alkanol eluents. Using small amounts of water in CO2/MeOH is known to be beneficial in chiral subcritical/supercritical chromatography. However, the ramifications of introducing water as a cosolvent component is not entirely understood. In this work, we demonstrate important aspects of the CO2/MeOH/H2O system on nine chiral stationary phases with very different surface chemistries, encompassing derivatized polysaccharides, macrocyclic glycopeptides, iso-butylmercaptoquinine, isopropyl macrocyclic oligosaccharides, and π-electron acceptor/π-electron donor phases. A hydrophilicity scale has been shown to be useful in predicting if a given chiral column chemistry would show a significant enhancement in separation efficiency in the presence of water in the CO2/MeOH system. We demonstrate up to 8-fold enhancements in plate counts of chiral separations with a concomitant decrease in retention times, as predicted by the qualitative test. The same chiral analysis can now be completed in almost a third of the time with the addition of small amounts of water, thereby decreasing organic solvent consumption by a considerable amount. Hydrophobic stationary phases show a minimal increase in efficiency and decrease in analysis times and optimized separations show much larger reduced plate heights, compared to more hydrophilic stationary phases. Furthermore, the presence of water can alter the nature of the adsorption isotherm under nonlinear conditions. Small amounts of water can be used to tune nonlinear tailing peaks into fronting ones, significantly improving preparative enantiomeric separations.

Synthetic aluminosilicate based geopolymers - Second generation geopolymer HPLC stationary phases.

A survey of existing stationary phases classified by the United States Pharmacopeia reveals that 120 groups of chromatographic supports mostly utilize silica-silane chemistry, polymeric materials along with some niche metal oxides. In this work, the synthesis and characterization of transition-metal free geopolymers as a new class of stationary phases for hydrophilic interaction liquid chromatography and normal phase separations is reported. The geopolymers were synthesized by reaction of synthetic aluminosilicate with potassium silicate (fumed silica dissolved in KOH) in a water-in-oil emulsion. For comparative purposes of peak shapes, a geopolymer from natural metakaolin was also synthesized. The geopolymers were examined by X-ray diffraction, energy dispersive spectroscopy, laser diffraction, and N2-adsorption isotherms. This two-step approach gives spherical microparticles with surface area and pore size comparable to silica phases (150 m2/g and 120 Šrespectively). Both synthetic aluminosilicates based and natural metakaolin based geopolymers occupy a unique "spot" in the HILIC selectivity chart when compared to 35 HILIC phases. An additional promising feature of geopolymers is high pH and temperature stability which are used to tune selectivity for small polar analytes. High pH separations are shown with carboxylic acids. Geopolymers also show mixed mode behavior in retention with ion-exchange properties in purely aqueous mobile phases. The separation of derivatized sugars is demonstrated and compared with porous graphitic carbon (Hypercarb™) as another pH-stable stationary phase.

The utility of statistical moments in chromatography using trapezoidal and Simpson's rules of peak integration.

Modern chromatographic data acquisition softwares often behave as black boxes where the researchers have little control over the raw data processing. One of the significant interests of separation scientists is to extract physico-chemical information from chromatographic experiments and peak parameters. In addition, column developers need the total peak shape analysis to characterize the flow profile in chromatographic beds. Statistical moments offer a robust approach for providing detailed information for peaks in terms of area, its center of gravity, variance, resolution, and its skew without assuming any peak model or shape. Despite their utility and theoretical significance, statistical moments are rarely incorporated as they often provide underestimated or overestimated results because of inappropriate choice of the integration method and selection of integration limits. The Gaussian model is universally used in most chromatography softwares to assess efficiency, resolution, and peak position. Herein we present a user-friendly, and accessible approach for calculating the zeroth, first, second, and third moments through more accurate numerical integration techniques (Trapezoidal and Simpson's rule) which provide an accurate estimate of peak parameters as compared to rectangular integration. An Excel template is also provided which can calculate the four moments in three steps with or without baseline correction.

Increasing chromatographic resolution of analytical signals using derivative enhancement approach.

A few decades ago, Giddings made a bleak statistical prediction stating that when using a chromatographic column with a peak capacity of n, one "has no real hope" of separating n compounds because of peak overlap. This statement holds true for today's far more complex separations including chiral, achiral or isotopic separations. Co-eluting chiral and isotopically labeled positional isomers pose a mass spectrometric challenge as isobaric analytes. Several advanced mathematical approaches exist to resolve and extract areas from overlapping data, such as Fourier self-deconvolution, wavelets, multivariate curve resolution, and iterative curve fitting. In this work, we develop a very straightforward approach to mathematically enhance signal resolution using the properties of derivatives while conserving peak area and its position. This technique is based on the fact that the area under a derivative of a distribution is equal to zero. Consequently, by alternately subtracting and adding multiples of even-derivatives (second, fourth, sixth, and so on) from the original peak, the area under a peak is conserved, and the bandwidth is reduced. Unlike multivariate curve resolution and iterative curve fitting approaches, this protocol does not require prior knowledge of the number of peaks. The concept is theoretically discussed for Gaussian and Lorentzian peaks. Several challenging chromatographic applications using deuterated benzenes, chiral separations, and biological applications are shown using twin-column recycling and conventional chromatography. The proposed protocol for a pair of overlapping peaks is currently limited to a Rs of 0.7 or greater with error < 1% under ideal conditions. Furthermore, tuning of peak shape by the first derivative is also described which can remove the exponential convolution of tailing peaks.

Mass spectrometry detection of basic drugs in fast chiral analyses with vancomycin stationary phases.

Current trends in chiral analysis of pharmaceutical drugs are focused on faster separations and higher separation efficiencies. Core-shell or superficially porous particles (SPP) based chiral stationary phases (CSPs) provide reduced analysis times while maintaining high column efficiencies and sensitivity. In this study, mobile phase conditions suitable for chiral analyses with electrospray ionization LC-MS were systematically investigated using vancomycin as a representative CSP. The performance of a 2.7 µm SPP based vancomycin CSP (SPP-V) 10 cm × 0.21 cm column was compared to that of a corresponding 5 µm fully porous particles based analogue column. The results demonstrated that the SPP-V column provides higher efficiencies, 2-5 time greater sensitivity and shorter analysis time for a set of 22 basic pharmaceutical drugs. The SPP-V was successfully applied for the analysis of the degradation products of racemic citalopram whose enantiomers could be selectively identified by MS.

Is Machine Translation a Reliable Tool for Reading German Scientific Databases and Research Articles?

A significant number of published databases and research papers exist in foreign languages and remain untranslated to date. Important sources of primary scientific information in German are Beilstein Handbuch der Organischen Chemie, Gmelin Handbuch der Anorganischen Chemie, Landolt-Börnstein Zahlenwerte und Funktionen, Houben-Weyl Methoden der Organischen Chemie, fundamental research papers, and patents. Although Reaxys has acquired Beilstein and Gmelin, many original references are still in German since 1770s, and the information presented in printed and online versions is often not duplicated. To read these resources, either costly professional translation services are needed or a reading knowledge of German has to be acquired. A convenient approach is to utilize machine translation for reading German texts; however, there is a question of translation reliability. In this work, several different platforms that employ neural network for machine translation (NMT) were tested for translation capability of scientific German. From a preliminary survey, Google Translate and DeepL were finalized for further studies (German to English). Excerpts from German documents spanning more than a century have been carefully chosen from standard works. DeepL Translator and Google Translate were found to be reliable for converting German scientific literature into English for a wide variety of technical passages. As a benchmark, human and machine translations are compared for complex sentences from old literature and a recent publication. Care and intuition should be used before relying on machine translation of methods and directions in general. Reagent addition (to or from) may be inverted in some synthetic procedures using machine translations.