Advances in capillary electrophoresis-mass spectrometry for cell analysis

Synergistic enantioseparation system based on a novel nanomaterial synthesized by chiral metal-organic framework and chiral molecularly imprinted polymer in capillary electrochromatography

A capillary electrochromatography (CEC) synergistic enantioseparation system based on a novel nanomaterial synthesized by chiral molecularly imprinted polymers (CMIPs) and chiral metal organic frameworks (CMOFs) was developed. Compared with CMIPs and CMOFs alone, the enantioseparation performance of ofloxacin (OFL) of the CEC with the novel nanomaterial as stationary phases was greatly improved. CMOFs with chiral recognition ability have synergize with CMIPs to greatly improve the chiral selectivity of the novel stationary phases in CEC. As a proof-of-concept demonstration, a coated capillary column was prepared by a sol-gel method using S-OFL (template), iron-based cyclodextrin MOF (Fe-CD-MOF, a CMOF), 3-aminopropyltriethoxysilane (functional monomer), and tetraethyl orthosilicate (cross-linking agent). Then, the newly constructed CEC system has excellent enantioseparation performance of OFL with a resolution of 3.92. Finally, computerized molecular docking revealed that the difference in the binding ability of Fe-CD-MOF to ofloxacin enantiomers was an important mechanism for CEC chiral separation. This innovative development of synergistic chiral stationary phases based on CMOFs and CMIPs creates a highly efficient potential direction for enantiomer separation.

Study of molecular interactions by nonequilibrium capillary electrophoresis of equilibrium mixtures: Originations, developments, and applications

Molecular interactions play a vital role in regulating various physiological and biochemical processes in vivo. Kinetic capillary electrophoresis (KCE) is an analytical platform that offers significant advantages in studying the thermodynamic and kinetic parameters of molecular interactions. It enables the simultaneous analysis of these parameters within an interaction pattern and facilitates the screening of binding ligands with predetermined kinetic parameters. Nonequilibrium capillary electrophoresis of equilibrium mixtures (NECEEM) was the first proposed KCE method, and it has found widespread use in studying molecular interactions involving proteins/aptamers, proteins/small molecules, and peptides/small molecules. The successful applications of NECEEM have demonstrated its promising potential for further development and broader application. However, there has been a dearth of recent reviews on NECEEM. To address this gap, our study provides a comprehensive description of NECEEM, encompassing its origins, development, and applications from 2015 to 2022. The primary focus of the applications section is on aptamer selection and screening of small-molecule ligands. Furthermore, we discuss important considerations in NECEEM experimental design, such as buffer suitability, detector selection, and protein adsorption. By offering this thorough review, we aim to contribute to the understanding, advancement, and wider utilization of NECEEM as a valuable tool for studying molecular interactions and facilitating the identification of potential ligands and targets.

Determination of Pathogens by Electrophoretic and Spectrometric Techniques

In modern medical diagnostics, where analytical chemistry plays a key role, fast and accurate identification of pathogens is becoming increasingly important. Infectious diseases pose a growing threat to public health due to population growth, international air travel, bacterial resistance to antibiotics, and other factors. For instance, the detection of SARS-CoV-2 in patient samples is a key tool to monitor the spread of the disease. While there are several techniques for identifying pathogens by their genetic code, most of these methods are too expensive or slow to effectively analyze clinical and environmental samples that may contain hundreds or even thousands of different microbes. Standard approaches (e.g., culture media and biochemical assays) are known to be very time- and labor-intensive. The purpose of this review paper is to highlight the problems associated with the analysis and identification of pathogens that cause many serious infections. Special attention was paid to the description of mechanisms and the explanation of the phenomena and processes occurring on the surface of pathogens as biocolloids (charge distribution). This review also highlights the importance of electromigration techniques and demonstrates their potential for pathogen pre-separation and fractionation and demonstrates the use of spectrometric methods, such as MALDI-TOF MS, for their detection and identification.

Technological advances for analyzing the content of organ-on-a-chip by mass spectrometry

Three-dimensional (3D) cell cultures, including organ-on-a-chip (OOC) devices, offer the possibility to mimic human physiology conditions better than 2D models. The organ-on-a-chip devices have a wide range of applications, including mechanical studies, functional validation, and toxicology investigations. Despite many advances in this field, the major challenge with the use of organ-on-a-chips relies on the lack of online analysis methods preventing the real-time observation of cultured cells. Mass spectrometry is a promising analytical technique for real-time analysis of cell excretes from organ-on-a-chip models. This is due to its high sensitivity, selectivity, and ability to tentatively identify a large variety of unknown compounds, ranging from metabolites, lipids, and peptides to proteins. However, the hyphenation of organ-on-a-chip with MS is largely hampered by the nature of the media used, and the presence of nonvolatile buffers. This in turn stalls the straightforward and online connection of organ-on-a-chip outlet to MS. To overcome this challenge, multiple advances have been made to pre-treat samples right after organ-on-a-chip and just before MS. In this review, we summarised these technological advances and exhaustively evaluated their benefits and shortcomings for successful hyphenation of organ-on-a-chip with MS.

High-Throughput and Rapid Screening of Drugs of Abuse in Saliva by Multi-Segment Injection Using Solid-Phase Microextraction-Automated Microfluidic Open Interface-Mass Spectrometry

There is great demand for analytical methods capable of providing high-throughput and rapid screening, especially for anti-doping and clinical point-of-care applications. In this work, automated microfluidic open interface-mass spectrometry (MOI-MS) was used for coupling with high-throughput, automated solid-phase microextraction (SPME) to achieve this objective. The design of the MOI-MS interface provides a continuous and stable electrospray fluid flow to the MS without introducing any bubble, a feature that we exploit to introduce the concept of multi-segment injection for the determination of multiple samples in a single MS run. By eliminating the need to start a new MS run between sample assays, the developed approach provides significantly simplified protocols controlled by programmed software and increased reproducibility. Furthermore, the biocompatible SPME device, which utilizes coating consisting of hydrophilic-lipophilic balanced particles embedded in a polyacrylonitrile (PAN) binder, can be directly used for biological sample analysis, as the PAN acts as both a binder and a matrix-compatible barrier, thus enabling the enrichment of small molecules while eliminating interferences associated with the presence of interfering macromolecules. The above design was employed to develop a fast, quantitative method capable of analyzing drugs of abuse in saliva samples in as little as 75 s per sample. The findings indicate that the developed method provides good analytical performance, with limits of detection ranging between 0.05 and 5 ng/mL for analysis of 16 drugs of abuse, good calibration linear correlation coefficients (R2 ≥ 0.9957), accuracy between 81 and 120%, and excellent precision (RSD% < 13%). Finally, a proof-of-concept experiment was performed to demonstrate the method's suitability for real-time analysis in anti-doping applications.

Comparison of different approaches for direct coupling of solid-phase microextraction to mass spectrometry for drugs of abuse analysis in plasma

The direct coupling of solid-phase microextraction (SPME) to mass spectrometry (MS) (SPME-MS) has proven to be an effective method for the fast screening and quantitative analysis of compounds in complex matrices such as blood and plasma. In recent years, our lab has developed three novel SPME-MS techniques: SPME-microfluidic open interface-MS (SPME-MOI-MS), coated blade spray-MS (CBS-MS), and SPME-probe electrospray ionization-MS (SPME-PESI-MS). The fast and high-throughput nature of these SPME-MS technologies makes them attractive options for point-of-care analysis and anti-doping testing. However, all these three techniques utilize different SPME geometries and were tested with different MS instruments. Lack of comparative data makes it difficult to determine which of these methodologies is the best option for any given application. This work fills this gap by making a comprehensive comparison of these three technologies with different SPME devices including SPME fibers, CBS blades, and SPME-PESI probes and SPME-liquid chromatography-MS (SPME-LC-MS) for the analysis of drugs of abuse using the same MS instrument. Furthermore, for the first time, we developed different desorption chambers for MOI-MS for coupling with SPME fibers, CBS blades, and SPME-PESI probes, thus illustrating the universality of this approach. In total, eight analytical methods were developed, with the experimental data showing that all the SPME-based methods provided good analytical performance with R ² of linearities larger than 0.9925, accuracies between 81% and 118%, and good precision with an RSD% ≤ 13%.

Direct coupling in-tube solid-phase microextraction with mass spectrometry using polymer coated open-tubular column for rapid analysis of antiepileptic drugs in biofluids

Development of high-throughput and rapid screening analytical method is in high demand for anti-doping and clinical point-of-care (POC) analysis. Solid-phase microextraction and mass spectrometry direct coupling (SPME-MS) has been proved as a rapid and effective way for target analysis in complex sample matrixes. An online direct coupling of in-tube SPME (IT-SPME) with MS using polymer coated open-tubular column has been developed in this work. A sharp stainless-steel needle was attached at the end of the SPME column, which enables the direct ionization of the analytes after elution from the IT-SPME column. Itaconic acid-benzene co-polymer was in-situ grown on the inner surface of the fused silica capillary and used as extraction phase. This column has low backpressure and provides both hydrophobic and weak cationic exchange interaction with the target analytes due to the chemical properties. The developed online IT-SPME-MS method showed good extraction performance towards various target analytes and good reusability at least for 60 times. As a proof-of-concept application, the above method was applied for the analysis of antiepileptic drugs (AEDs) in both plasma and urine samples with linear range (1 ng/mL-200 ng/mL), good linearity (R² ≥ 0.99), and good reproducibility (intra-day RSDs less than 4.36%, inter-day RSDs less than 6.55%). The method exhibited high enrichment factors between 187 and 204 for the two AEDs and high sensitivity for the analysis of human plasma samples and urine samples.

Aptamer affinity-based microextraction in-line coupled to capillary electrophoresis mass spectrometry using a porous layer/nanoparticle -modified open tubular column

An aptamer affinity based microextraction column is developed to be directly in-line coupled to capillary electrophoresis-mass spectrometry (CE-MS) for analyzing mycotoxins in food samples. Single-stranded DNA aptamers for selective recognition of aflatoxin B1 (AFB1) and ochratoxin A (OTA) targets are co-immobilized via covalent bonds on the surface of the inlet end of a capillary, which is pre-modified with three-dimensional porous layer and gold nanoparticles to enhance the specific surface area and loading capacity. The outlet of the capillary is designed as a porous tip to serve as the spray source for injection to the mass spectrometry. All the necessary processes for pretreatment and analysis of a sample are accomplished in one injection, including aptamer affinity-based microextraction, CE separation and MS detection of analytes. AFB1 and OTA are simultaneously determined in a wide linear range with sample consumption of only 1 μL and the limit-of-detection as low as 1 pg/mL. The microextraction column exhibits excellent repeatability and stability, which can be used over 45 runs within a month with CE separation efficiency and only MS intensity slightly decreased. Mycotoxins in three kinds of cereal based infant foods are accurately analyzed using the proposed method. The study provides a robust and universal approach that would have potential applications in a variety of analytical fields based on selective molecular recognition coupling to CE-MS analysis.

Separation methods in single-cell proteomics: RPLC or CE?

Cellular heterogeneity is commonly investigated using single-cell genomics and transcriptomics to investigate biological questions such as disease mechanism, therapeutic screening, and genomic and transcriptomic diversity between cellular populations and subpopulations at the cellular level. Single-cell mass spectrometry (MS)-based proteomics enables the high-throughput examination of protein expression at the single-cell level with wide applicability, and with spatial and temporal resolution, applicable to the study of cellular development, disease, effect of treatment, etc. The study of single-cell proteomics has lagged behind genomics and transcriptomics largely because proteins from single-cell samples cannot be amplified as DNA and RNA can using well established techniques such as PCR. Therefore, analytical methods must be robust, reproducible, and sensitive enough to detect the very small amount of protein within a single cell. To this end, nearly every step of the proteomics process has been extensively altered and improved to facilitate the proteomics analysis of single cells including cell counting and sorting, lysis, protein digestion, sample cleanup, separation, MS data acquisition, and data analysis. Here, we have reviewed recent advances in single-cell protein separation using nano reversed phase liquid chromatography (nRPLC) and capillary electrophoresis (CE) to inform application driven selection of separation techniques in the laboratory setting.

Review of Recent Modern Analytical Technology Combined with Chemometrics Approach Researches on Mushroom Discrimination and Evaluation

Mushroom is a macrofungus with precious fruiting body, as a food, a tonic, and a medicine, human have discovered and used mushrooms for thousands of years. Nowadays, mushroom is also a "super food" recommended by the World Health Organization (WHO) and Food and Agriculture Organization (FAO), and favored by consumers. Discrimination of mushroom including species, geographic origin, storage time, etc., is an important prerequisite to ensure their edible safety and commodity quality. Moreover, the effective evaluation of its chemical composition can help us better understand the nutritional properties of mushrooms. Modern analytical technologies such as chromatography, spectroscopy and mass spectrometry, etc., are widely used in the discrimination and evaluation researches of mushrooms, and chemometrics is an effective means of scientifically processing the multidimensional information hidden in these analytical technologies. This review will outline the latest applications of modern analytical technology combined with chemometrics in qualitative and quantitative analysis and quality control of mushrooms in recent years. Briefly describe the basic principles of these technologies, and the analytical processes of common chemometrics in mushroom researches will be summarized. Finally, the limitations and application prospects of chromatography, spectroscopy and mass spectrometry technology are discussed in mushroom quality control and evaluation.

Single-Cell Metabolomics in Hematopoiesis and Hematological Malignancies

Aberrant metabolism contributes to tumor initiation, progression, metastasis, and drug resistance. Metabolic dysregulation has emerged as a hallmark of several hematologic malignancies. Decoding the molecular mechanism underlying metabolic rewiring in hematological malignancies would provide promising avenues for novel therapeutic interventions. Single-cell metabolic analysis can directly offer a meaningful readout of the cellular phenotype, allowing us to comprehensively dissect cellular states and access biological information unobtainable from bulk analysis. In this review, we first highlight the unique metabolic properties of hematologic malignancies and underscore potential metabolic vulnerabilities. We then emphasize the emerging single-cell metabolomics techniques, aiming to provide a guide to interrogating metabolism at single-cell resolution. Furthermore, we summarize recent studies demonstrating the power of single-cell metabolomics to uncover the roles of metabolic rewiring in tumor biology, cellular heterogeneity, immunometabolism, and therapeutic resistance. Meanwhile, we describe a practical view of the potential applications of single-cell metabolomics in hematopoiesis and hematological malignancies. Finally, we present the challenges and perspectives of single-cell metabolomics development.

Open Tubular Capillary Electrochromatography-Mass Spectrometry for Analysis of Underivatized Amino Acid Enantiomers with a Porous Layer-Gold Nanoparticle-Modified Chiral Column

By developing a novel chiral column, we integrate open tubular capillary electrochromatography into sheathless mass spectrometry (MS) for efficient analysis of underivatized amino acid enantiomers. The chiral column is easily fabricated by modifying the inner surface of a capillary with a three-dimensional porous layer (PL, thickness ∼ 90 nm, pore size ∼ 30 nm) and gold nanoparticles and by introducing a chiral selector, thiol β-cyclodextrin (SH-β-CD), onto the modified surface via Au-S bonds. This approach greatly enhances the specific surface area and thus the ratio of the stationary phase to mobile phase and interaction between the stationary phase and analytes. The proposed PLOT@Au@CD column is coupled to the sheathless CE-ESI-MS system for chiral analysis of amino acid enantiomers. No derivatization of amino acids is required for chiral analysis, and baseline separation of a total of 15 pairs of amino acid enantiomers is achieved within 17 min with high column efficiencies of 5.60 × 10⁴ to 1.82 × 10⁶ N/m, high resolutions of 1.51-10.0, and low limits of detection between 0.02 and 0.09 μg/mL. The separation efficiency and MS intensity are only slightly decreased over 60 runs or after usage for 15 days, showing excellent repeatability and stability of the PLOT@Au@CD column. The proposed method is successfully applied to the determination of amino acid enantiomers in vinegar samples with satisfactory accuracy. Our study provides a new approach for developing a chiral stationary phase in the chromatographic separation technique, which can be easily coupled to sensitive MS detection, thus it would be of value for various applications in the fields of chiral analysis.

Hydrogen/Deuterium Exchange Aiding Metabolite Identification in Single-Cell Nanospray High-Resolution Mass Spectrometry Analysis

The identification of metabolites in single-cell or small-volume tissue samples using single-cell mass spectrometry (MS) is challenging. In this study, hydrogen/deuterium (H/D) exchange was combined with microsampling nanospray high-resolution mass spectrometry (HRMS) to improve the efficiency and confidence level of metabolite identification in a single cell using commercial software. A nanospray ion source showed an improved reaction depth of 8% for H/D exchange compared with an electrospray ion source. In total, 273 metabolites were identified in Allium cepa L. single cells by searching commercial databases. Generally, more than one candidate is given for a precursor ion by MS or tandem MS (MS²) databases such as ChemSpider, MetDNA, MassBank, and mzCloud. With the help of the H/D exchange technique, the number of candidates decreased and reduction of the search space by a factor of 8 was achieved. In addition, two enzymolysis products of isoalliin, the transient intermediate and its isomer, were tracked at the single-cell level using the proposed method.

Titanium dioxide-coated core-shell silica microspheres-based solid-phase extraction combined with sheathless capillary electrophoresis-mass spectrometry for analysis of glyphosate, glufosinate and their metabolites in baby foods

Because of their extremely low amount in complex samples, it is quite challenging to accurate determine residues of phosphorus-containing amino-acid-like herbicides (PAAHs) in food products. Here we develop novel core-shell mesoporous silica (CSMS) microspheres coated by titanium dioxide (CSMS@TiO2) for extraction and enrichment of PAAHs in baby foods. After the dispersive solid phase extraction (d-SPE), sheathless capillary electrophoresis-mass spectrometry (sheathless CE-MS) is utilized to achieve efficient separation and sensitive detection. The synthesized CSMS@TiO2 composites are characterized by various spectroscopic techniques, proving TiO2 is uniformly distributed onto the channel surface of CSMS. The composites have essential features that are favorable for adsorption of the analytes on the material for d-SPE, including uniform diameter (1.0 μm with a shell thickness of 133 nm), large perpendicular mesopores (15.6 nm), high surface area (101.1 m2/g) and large pore volume (0.4 cm3/g). Taking glyphosate, glufosinate and their main metabolites (aminomethylphosphonic acid and 3-methylphosphinicopropionic acid) as analytes, selective and efficient enrichment is achieved by CSMS@TiO2-based d-SPE through the affinity interaction between titanium dioxide and phosphate groups. Sensitive detection of target compounds is achieved with low limits of quantitation (LOQs) between 0.3-1.6 ng/mL and excellent inter/intra-day repeatability. The compounds in nine different commercial baby foods from local markets are analyzed using the proposed method. Good recoveries of 82.3-102.6% are achieved with low RSDs (n = 5) of 2.1-8.3%. Our study indicates that the proposed CSMS@TiO2-based d-SPE combined with sheathless CE-MS is an accurate and reliable approach for sensitive determination of trace-amount PAAHs and their metabolites in complex samples.

Recent developments in capillary and microchip electroseparations of peptides (2019-mid 2021)

The review provides a comprehensive overview of developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) for analysis, microscale isolation, and physicochemical characterization of peptides from 2019 up to approximately the middle of 2021. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis, such as sample preparation, sorption suppression, EOF control, and detection, are presented. New developments in the individual CE and CEC methods are demonstrated and several types of their applications are shown. They include qualitative and quantitative analysis, determination in complex biomatrices, monitoring of chemical and enzymatic reactions and physicochemical changes, amino acid, sequence, and chiral analyses, and peptide mapping of proteins. In addition, micropreparative separations and determination of significant physicochemical parameters of peptides by CE and CEC methods are described.

Porous layer open-tubular column with styrene and itaconic acid-copolymerized polymer as stationary phase for capillary electrochromatography-mass spectrometry

Enhancing the specific surface area of stationary phase is important in chromatographic science, especially in open-tubular column in which the coating only exists on the inner surface. In this work, a porous layer open-tubular (PLOT) column with stationary phase of styrene and itaconic acid-copolymerized polymer was developed. Thermal-initiated polymerization method with strategies like controlling the ratio of reaction reagents to solvents and reaction time, confinement by the narrow inner diameter of capillary were used for preparing the stationary phase with uniform structure and relatively thick layer. Due to the high separation efficiency and capacity, the PLOT column was used for capillary electrochromatography (CEC) separation of multiple groups of analytes like alkylbenzenes, phenyl amines, phenols, vanillins, and sulfonamides with theoretical plates (N) up to 1,54,845 N/m. In addition, due to high permeability of the CEC column and large electroosmotic flow mobility generated by abundant carboxyl groups in the coating material, the PLOT-CEC column was successfully coupled with mass spectrometry (MS) through a sheath flow interface. The developed PLOT-CEC-MS method was used for the analysis of antiseptics like parabens and herbicides like pyridines.

Towards high throughput and high information coverage: advanced single-cell mass spectrometric techniques

Mass spectrometry (MS) is attractive for single-cell analysis because of its high sensitivity, rich information, and large dynamic ranges, especially for the single-cell metabolome and proteome analysis. Efforts have been made to deal with the throughput and information coverage problems in typical manual single-cell MS techniques. In this review, advanced techniques to improve the automation and throughput for single-cell sampling and single-cell metabolome and proteome MS detection have been discussed. Furthermore, representative MS-based strategies that can increase the in-depth cellular information coverage and achieve the more comprehensive single-cell multiomics information during high throughput detection have been highlighted, providing an ongoing perspective of the MS performance for the single-cell research.

In-situ growth of a spherical vinyl-functionalized covalent organic framework as stationary phase for capillary electrochromatography-mass spectrometry analysis

Column technology is an important part in capillary electrochromatographic science. Developing novel stationary phase with high separation efficiency and high loading capacity is an essential work. In this work, a novel spherical vinyl-functionalized covalent-organic framework (COF-V) was synthesized at room temperature and firstly employed as stationary phase for CEC-MS analysis. The COF-V based CEC column was characterized by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The results proved the successful modification of COF-V. The COF-V based column possesses the advantages like strong electroosmotic flow, high separation efficiency and high loading capacity. The CEC column showed powerful separation selectivity to several kinds of compounds, and the highest column efficiency (theoretical plates, N) was over 1.4 × 10⁵ plates·m^-1 for methylbenzene. Besides, the COF-V modified column exhibited excellent repeatability and stability. The relative standard deviations (RSDs) of retention times for intra-day (n = 5), inter-day (n = 3) runs and column-to-column (n = 3) were all less than 2.1%. Hence, the COF-V modified column was successfully applied in CEC-MS for determination of antiepileptic drug, triazine herbicides and active ingredients in traditional Chinese medicine.

Past, present, and future developments in enantioselective analysis using capillary electromigration techniques

Enantioseparation of chiral products has become increasingly important in a large diversity of academic and industrial applications. The separation of chiral compounds is inherently challenging and thus requires a suitable analytical technique that can achieve high resolution and sensitivity. In this context, CE has shown remarkable results so far. Chiral CE offers an orthogonal enantioselectivity and is typically considered less costly than chromatographic techniques, since only minute amounts of chiral selectors are needed. Several CE approaches have been developed for chiral analysis, including chiral EKC and chiral CEC. Enantioseparations by EKC benefit from the wide variety of possible pseudostationary phases that can be employed. Chiral CEC, on the other hand, combines chromatographic separation principles with the bulk fluid movement of CE, benefitting from reduced band broadening as compared to pressure-driven systems. Although UV detection is conventionally used for these approaches, MS can also be considered. CE-MS represents a promising alternative due to the increased sensitivity and selectivity, enabling the chiral analysis of complex samples. The potential contamination of the MS ion source in EKC-MS can be overcome using partial-filling and counter-migration techniques. However, chiral analysis using monolithic and open-tubular CEC-MS awaits additional method validation and a dedicated commercial interface. Further efforts in chiral CE are expected toward the improvement of existing techniques, the development of novel pseudostationary phases, and establishing the use of chiral ionic liquids, molecular imprinted polymers, and metal-organic frameworks. These developments will certainly foster the adoption of CE(-MS) as a well-established technique in routine chiral analysis.

Smart Classification Paradigms for Protein Samples from 1-D Electrophoresis Gel

Electrophoresis allows us to identify the types of proteins present in food, DNA, tissues and more. With the help of the molecular marker their weight is known, these markers are applied within the one-dimensional gel, and their protein value is known by means of marks. In this research, the molecular marker is obtained and the wavelet transform (WT) is obtained, generating approximation coefficients, which were taken to determine a molecular weight using three classification paradigms. The first paradigm is an approach in content-based image retrieval (CBIR) which makes a detection of the molecular weight in electrophoresis samples. The second approach is a neural network, thus two models are employed: self-organization maps (SOM) and back propagation in a supervised and unsupervised way, respectively. The third approach is based in a J48 decision tree. A comparison is made between the three paradigms for molecular weight computation. Neural networks obtained an improvement in the precision compared versus the CBIR-WT. Five parametric statistics were generated from the wavelet approximation coefficients. The CBIR-WT, SOM, back propagation and J48 were decisive for the classification and calculation of the molecular weight of each protein stain in the one-dimensional electrophoresis gel.