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This paper presents a novel method of fabricating an enzymatic biosensor for breath analysis using chromatography paper as enzyme supporting layer and a liquid phase layer on top of screen printed carbon electrodes. We evaluated the performance with ethanol vapor being one of the breathing ingredients. The experimental results show that our sensor is able to measure the concentration of ethanol vapor within the range of 50 to 500 ppm. These results suggest the ability of detecting breath ethanol, and it can possibly be applied as a generic vapor biosensor to a wide range of diseases.

A detection method of gold nanoparticles in chromatography paper has been developed for a simple, cost-effective and reliable quantitation of immunochromatographic strip test. The time courses of the solution resistance in chromatography paper with the gold nanoparticles solution are electrochemically measured by chrono-impedimetry. The dependence of the solution resistance on the concentration of gold nanoparticles has been successfully observed. The main factor to increase the solution resistance may be obstruction of the ion transport due to the presence of gold nanoparticles. The existence of gold nanoparticles with 1.92 × 10(9) particles/mL in an indistinctly-colored chromatography paper is also identified by a solution resistance measurement. This indicates that the solution resistance assay has the potential to lower the detection limit of the conventional qualitative assay.

Detection of mycotoxins by conventional methods such as ELISA or LC-MS can be expensive and time-consuming. Therefore, paper-based biosensors can be effectively used for on-site analysis, due to their low cost and easy detection procedures. Nevertheless, even when the application of colorimetric methods on paper enhance the simplicity and affordability of multiple determinations, the signal intensity and final readout can be affected by a limited color uniformity. In this work, Ellman’s method for the quantification of aflatoxin B1 was utilized as a model colorimetric assay on paper, in which the test zones were modified with chitosan-immobilized enzyme (AChE). A comparison of the cross-linking effect of genipin on two chitosans of varying molar mass and degree of acetylation, exhibited a greater signal enhancement from the sample with a higher degree of acetylation and molecular weight.

Anemia affects a quarter of the world's population, and a lack of appropriate diagnostic tools often prevents treatment in low-resource settings. Though the HemoCue 201+ is an appropriate device for diagnosing anemia in low-resource settings, the high cost of disposables ($0.99 per test in Malawi) limits its availability. We investigated using spectrophotometric measurement of blood spotted on chromatography paper as a low-cost ($0.01 per test) alternative to HemoCue cuvettes. For this evaluation, donor blood was diluted with plasma to simulate anemia, a micropipette spotted blood on paper, and a bench-top spectrophotometer validated the approach before the development of a low-cost reader. We optimized impregnating paper with chemicals to lyse red blood cells, paper type, drying time, wavelengths measured, and sensitivity to variations in volume of blood, and we validated our approach using patient samples. Lysing the blood cells with sodium deoxycholate dried in Whatman Chr4 chromatography paper gave repeatable results, and the absorbance difference between 528 nm and 656 nm was stable over time in measurements taken up to 10 min after sample preparation. The method was insensitive to the amount of blood spotted on the paper over the range of 5 μL to 25 μL. We created a low-cost, handheld reader to measure the transmission of paper cuvettes at these optimal wavelengths. Training and validating our method with patient samples on both the spectrometer and the handheld reader showed that both devices are accurate to within 2 g dL(-1) of the HemoCue device for 98% and 95% of samples, respectively.

Background: Fingertip prick whole blood collection on chromatography paper is amenable to high-throughput fatty acid (FA) profiling for large clinical and field studies. However, sample storage is problematic because highly unsaturated FAs (HUFAs) in erythrocytes rapidly degrade in samples stored at 220C. Objective: The aim of the current study was to determine the mechanism of HUFA degradation and to develop prevention protocols. Methods: Free fatty acid (FFA) standards and whole blood reference material from a single participant were used to examine sample storage at 220C for up to 90 d in triplicate. Iron chelation with deferoxamine (0‐5000 mg), antioxidant protection with butylated hydroxytoluene (50 mg), cryopreservation with glycerol, and blood drying were examined using whole blood on chromatography strips. Biological replicate blood samples from additional participants (n = 6) with a range of v-3 (n‐3) HUFA concentrations were similarly assessed. Results: FFAs were relatively stable when stored on chromatography strips at 220C. Glycerol treatment prevented HUFA degradation in whole blood reference material for 30 d (45 6 0.4 to 46.8 6 0.1, means 6 SDs) compared to untreated saline controls (45.9 6 1.0 to 6.8 6 0.2). Pretreatment of paper for blood spots with deferoxamine and drying blood before storage slowed, but not entirely prevented, HUFA degradation over 30 d to 22% and 19% below baseline, respectively, compared to 86‐92% in the controls. Protection against HUFA degradation with blood drying and glycerol treatment was confirmed in the biological replicate study and confirmed by prevention of cell lysis. Conclusions: HUFA degradation during storage at 220C appears to be due to hemolysis and subsequent iron-initiated peroxidation. This degradation may be prevented by glycerol, iron chelation, and/or dried blood spotting. A more thorough understanding of methods to prevent degradation during storage is critical with increasing use of FA profiling in large clinical studies. J Nutr doi: 10.3945/jn.114.203679.

Two series of “papers” that were made from natural fibers and synthetic fibers, respectively, were examined for use in paper-spray mass spectrometry and the results were compared to chromatography paper that is currently being used. In the former case, four types of papers were used, including gampi paper, tengujou paper, glassine paper and cicada paper, and the findings show that the limit of detection can be improved when gampi paper was used. This is because gampi paper is very tough and extremely thin (thickness, l -lactic acid (PLLA), respectively, by means of a co-axial electrospinning technique. The findings show that the limit of detection also can be improved, when a PLLA nanofiber was used. This is because this type of paper-like nanofiber is also very thin, tough and hydrophobic, which permits to ionization to occur within a very short period. Detailed information on methods for synthesizing these fibers and their use in the analysis of a real sample are also reported.

Reactions and purifications, including carbon-carbon bond forming reactions, can be carried out on a cellulose support on which the substrates are non-covalently absorbed.

Telomerase is extensively expressed in various cancer cells and recognized as a target for cancer drug discovery. In the present study, a simple and amplification-free fluorescence assay based on polyamidoamine starburst dendrimer (PAMAM dendrimer)-activated paper device is proposed for sensitive detection of telomerase activity through hybridization of Cy5 modified single strand DNA probes with telomerase extension products. The paper substrate is fabricated by hand drawing according to a template, which is low cost, instrument free and easy operation. PAMAM is rich in amino groups on its surface and employed to immobilize the telomerase substrate (TS) primer. Highly sensitive detection of telomerase activity in HeLa cell lysate of 10 cells is achieved since the PAMAM dendrimer-activated paper surface can provide high density of binding sites for immobilization of TS primer. The experimental results also demonstrate that the assay can be employed to evaluate telomerase activity levels of various cell lines and screen telomerase inhibitors.

This paper presents an alternative analytical method employing energy dispersive X-ray fluorescence (EDXRF) to determine copper, iron, nickel and zinc ions in ethanol fuel samples after a pre-concentration procedure. Our pre-concentration strategy utilizes analyte retention on cation exchange chromatography paper, a convenient substrate for direct EDXRF measurements. The repeatability, expressed in terms of RSD of standard solutions containing 0.25 μg mL −1 of Cu, Fe, Ni and Zn, and calculated from fifteen consecutive measurements, was 2.5, 2.8, 3.0, and 2.7%, respectively. The limits of detection (LOD), defined as the analyte concentration that gives a response equivalent to three times the standard deviation of the blank ( n = 10), were found to be 13, 15, 15 and 12 μg L −1 for Cu, Fe, Ni and Zn, respectively. The proposed method was applied to Cu, Fe, Ni and Zn determination in hydrated ethanol fuel samples collected from different gas stations.

Background: To evaluate a simple and safe method to estimate the salivary flow using chromatography paper. Materials and Methods: A total of 30 volunteers participated in the study. The salivary flow rate was estimated using chromatography filter paper and compared with the salivary flow rate per minute. The assay consisted of 3 spots containing starch and potassium iodide per spot on filter paper. Based on the color reaction on the chromatography filter paper the salivary flow rate was estimated. Results: Pearson’s correlation test showed highly significant negative correlation when the salivary flow rate and the number of colored dots were compared. Conclusion: This method can be used as a chair side diagnostic aid in the estimation of salivary flow.

In order to investigate the adduct-forming properties of sterols with very small quantities of these compounds a method has been developed which uses acetylated chromatography paper as the medium in which the adduct can be formed. For the adduct formation of· cholesterol the results appear to be in agreement with those obtained on a larger scale by refluxing a solution of the sterol in the presence of the other component. The method is also suitable for the investigation of the adduct formation of sterols other than cholesterol. The relative humidity of the atmosphere in which the reaction takes place has an important influence on the adduct formation. Two colour reagents for detecting steroids on acetylated paper are described: a solution of benzenesulphonic acid in ether-methanol, and a solution of antimony trichloride in tetrahydrofurane.

To achieve the goal of poliovirus eradication, surveillance of endemic areas is a crucial step in the poliovirus eradication program. Currently, six countries still have endemic poliovirus. We have tested a novel method which uses SDS/EDTA-treated chromatography paper strips to collect and transport poliovirus-containing stool samples. The SDS/EDTA-treated paper strips were soaked with different dilutions of poliovirus-containing feces and stored at different temperatures. After storing the SDS/EDTA paper strips for 5 months at 37 degrees C, poliovirus RNA could be successfully amplified using RT-PCR. Infectivity of wild-type poliovirus type 1, 2, and 3 was lost upon contact with the SDS/EDTA-treated strips. This easy, inexpensive, and biosafe chromatography paper strip method for the collection and transportation of poliovirus samples can be of use in poliovirus surveillance and polio vaccination programs.

Noroviruses are the most common cause of nonbacterial gastroenteritis outbreaks. A novel method was tested that utilizes sodium dodecyl sulfate (SDS)/EDTA-pretreated chromatography paper strips to collect and transport norovirus-containing fresh stool samples. As confirmation, the strips were infected with different dilutions of human norovirus-containing faeces and stored at different temperatures ( −80, −20, 4 ◦ C, room temperature and 37 ◦ C). Reverse transcription (RT)-PCR analysis was carried out after storage of the strips for 1, 7, 14, 60, and 120 days. The presence of amplifiable norovirus RNA on the strips was inversely correlated with the duration of storage and the storage temperature. Norovirus RNA remained detectable for a sufficient amount of time at room temperature or even in warmer climatic conditions to allow transportation of the samples from a field site to a reference laboratory using regular postal mail. To prove that viral infectivity was lost upon contact with the SDS/EDTA-treated strips, feline calicivirus F9 (10 7 TCID50/ml) was loaded onto the strips. After elution and dialysis, no cytopatic effect could be observed upon incubation on Crandell–Reese feline kidney cells. The SDS/EDTA-pretreated chromatography filter paper strips are an inexpensive, biosafe and adequate method to collect, transport and store norovirus samples. © 2004 Elsevier B.V. All rights reserved.

Cellulose chromatography paper provides a novel non-covalent support for synthesis and in-situ purification of multi-dimensional arrays.

Enzymatic sensors on complementary metal–oxide–semiconductor (CMOS) chips are realized using carbon ink and chromatography paper (ChrPr). Electrodes are fabricated from carbon ink on CMOS chips. The carbon ink electrodes work as well-behaving electrochemical electrodes. Enzyme electrodes are realized by covering the carbon ink electrodes on the CMOS chip with ChrPr supporting enzymes and electron mediators. Such enzyme electrodes successfully give anodic current proportional to the glucose concentration. Good linearity is observed up to 10 mM glucose concentration, which is sufficient for blood glucose testing applications.

Construction and use of a simple scanning device are described for locating small amounts of radioactivity on large uncut filter papers used for chromatography and electrophoresis. With this device the use of autoradiographs in eliminated from the original method for determining urinary hydroxyproline on the principle of isotope dilution. The modified method is described, and eight results are reported for the recovery of added nonradioactive dipeptide. Percentage of recovery varied from 84.5 to 111% with an average of 98.4%.

The efficiency of several chromatography papers and thin-layer cellulose powders for the separation of amino acids is investigated, using the minimum elution time for a given resolution as the criterion.

From a mixture of labelled proteins specific proteins can be isolated by immunological precipitation on chromatography paper disks and their radioactivity can be determined in liquid scintillation counting systems. Precipitation is completed within 2 hours. Analysis of double labelled proteins can also be performed on disks of chromatography paper. The counting efficiency for [14C]protein disks is 60%, for [3H]protein disks 8%. The statistical variation of the method (m.e.m. for n=10) is lower than 5%. Quenching, unspecific adsorption of aromatic ammoacids and immunological cross reactions are discussed. The method is especially useful when many samples are to be processed simultaneously.

Summary The properties of a commercial chromatography paper (Whatman No. 4) were studied with water and nine organic fluids. Imbibition was greater with the more polar fluids and ranged from 22.0 mm3/cm2 for water to 11.9 mm3/cm2 for benzene. Measurements of flow rates under the influence of gravity showed that, the more polar the fluid, the smaller the resistance to flow offered by the paper. The rate of water was 0.23 ml per hour per cm width at 20°.

A device for scanning electrophoresis and chromatography paper strips is described. A pen recorder traces the curves of the optical density, integral of the optical density, radioactivity intensity and integral of the radioactivity intensity as a function of position of the paper strip. The scanning is carried out automatically.

After concentration of the organic substances from water samples of 700 to 20,000 l by adsorption on active carbon and desorption with chloroform in a large Soxhlet apparatus, tlie organic compounds were separated by extraction into 5 different groups: acids, phenols, bases, neutral and amphoteric substances. The phenol group was investigated by gas and paper chromatography, ultraviolet difference spectrophotometry and infrared spectroscopy. Phenol, 2,4,6-trichlorophcnol, 2- and 3-cresol, 2,4-xylenol and 2,4-dichlorophenol were identified in samples of raw and treated water. Quantitative measurements proved to be possible with gas chromatography. The conditions for quantitative desorption and separation were studied.

The adulteration of herbal medicines by dexamethasone or prednisolone is regarded as a serious problem in many communities. Herein, a novel platform for the separation and quantification of both target steroids in herbal medicines based on electrochemical paper-based analytical devices (ePADs) has been created. The ePAD was composed of Whatman SG81 chromatography paper, 3D-printed devices and a commercial screen-printed electrode. Whatman SG81 silica-coated paper was used for the separation of dexamethasone and prednisolone based on the difference in their partition coefficients during the flow of the mobile phase. The optimal mobile phase was composed of 60% ethyl acetate in cyclohexane and required 7 min for separation. The separated steroids on the paper were then quantified by electrochemical detection using differential pulse voltammetry, in which the 3D-printed devices facilitated the measurement. Analytical detection ranges of 10–500 μg mL−1 were obtained for both dexamethasone and prednisolone (r2 = 0.988 and 0.994, respectively). The limits of detection for dexamethasone and prednisolone were 3.59 and 11.98 μg mL−1, respectively, whereas the limits of quantification were 6.00 and 20.02 μg mL−1, respectively. The amounts of both target steroids derived from real herbal medicine samples determined by the proposed method were comparable to those obtained with assays using standard high-performance liquid chromatography. In addition, a simple evaporation step can be used to increase the concentration of the samples before analysis. These ePADs are simple, low-cost, rapid, and very promising for on-site quantitative detection.

In this study, we developed a point-of-care assay platform with simultaneous detection and self-calibration capabilities for multiple targets based on a microfluidic paper-based analytical device (μPAD). This system is easily manufactured using a wax printing method on chromatographic paper. The design pattern consists of a zone of detection and a calibrant zone for controlled loading using wax barriers with different thicknesses. We showed the utility and applicability of this approach by a proof-of-concept study for two clinically important markers: glucose and lactate. With the naked eye, the results could be fully distinguished and recorded to evaluate the analytical performance with a flatbed scanner. The detection limits of glucose and lactate were 0.3125 mM and 0.2975 mM, respectively, and simultaneous detection was possible from a small sample (0.4 μL) with high sensitivity. Furthermore, this device has a self-calibration function, which minimizes the influence of environmental conditions (i.e., ambient light intensity, temperature, humidity, and pressure). Therefore, the developed multiplex paper-based device is promising for clinical multianalyte point-of-care testing since it is easy to manufacture, cost-effective, user-friendly, and highly sensitive.

In the last decades, there is a growing search for analytical strategies to ensure clinical analysis without the need of laboratory set-up and skilled personnel. Indeed, user-friendly and low-cost devices are highly valued in the era of sustainability for their capability to be applied in low-resource contexts, such as developing countries. To address this issue, herein we report a 96-well paper-based and laboratory setup-free optical platform for the detection of butyrylcholinesterase enzyme (BChE) activity in human serum. We used chromatographic paper to realize a novel analytical tool exploiting its porous structure for reagentless synthesize Prussian Blue Nanoparticles (the sensing element), as well to load all the reagents required for the measurement. The principle of BChE activity detection relies on the reaction between the enzymatic product thiocholine and Prussian Blue, giving the Prussian White with subsequently Prussian Blue's fading, detected by a common office scanner supported by ImageJ software. Using this novel paper-based optical platform, BChE activity was linearly detected in the 2–15 U/mL range with a detection limit down to 0.8 U/mL. The accuracy was successfully demonstrated by recovery study with spiked serum and by comparing the data with the gold standard method.

This paper describes a paper-based biochemical sensor that realizes redox cycling with close interelectrode distance. Two electrodes, the generator and collector electrodes, can detect steady-state oxidation and reduction currents when suitable potential is held at each electrode. The sensor has two gold plates on both sides of a piece of chromatography paper and defines the interelectrode distance by the thickness of the paper (180 μm) without any micro-fabrication processes. Our proposed sensor geometry has successfully exhibited signatures of redox cycling. As a result, the concentration of ferrocyanide as reversible redox molecules was successfully quantified under the interference by ascorbic acid as a strong irreversible reducing agent. This was possible because the ascorbic acids are completely consumed by the irreversible reaction, while maintaining redox cycling of reversible ferrocyanide. This suggests that a sensor based on the redox cycling method will be suitable for detecting target molecules at low concentration.

The analytical performance and a suggested mechanism for zero volt paper spray using chromatography paper are presented. A spray is generated by the action of the pneumatic force of the mass spectrometer (MS) vacuum at the inlet. Positive and negative ion signals are observed, and comparisons are made with standard kV paper spray (PS) ionization and nanoelectrospray ionization (nESI). While the range of analytes to which zero volt PS is applicable is very similar to kV PS and nESI, differences in the mass spectra of mixtures are interpreted in terms of the more significant effects of analyte surface activity in the gentler zero volt experiment than in the other methods due to the significantly lower charge. The signal intensity of zero volt PS is also lower than in the other methods. A Monte Carlo simulation based on statistical fluctuation of positive and negative ions in solution has been implemented to explain the production of ions from initially uncharged droplets. Uncharged droplets first break up due to aerodynamics forces until they are in the 2-4 ?m size range and then undergo Coulombic fission. A model involving statistical charge fluctuations in both phases predicts detection limits similar to those observed experimentally and explains the effects of binary mixture components on relative ionization efficiencies. The proposed mechanism may also play a role in ionization by other voltage-free methods. (Figure Presented). � 2015 American Chemical Society.

High-performance affinity chromatography is limited by its high cost and high pressure. Paper is made up of porous fiber networks and has the properties of low cost, ease of fabrication, and biodegradable. Due to these advantages, herein, we immobilized beta2-adrenoceptor (β2-AR) onto the surface of the polytetrafluoroethylene membrane, a paper-based material, and constructed a G protein-coupled receptor (GPCR)-in-paper chromatographic platform. This platform was characterized by Fourier transform infrared spectroscopy, fluorescence analysis, X-ray photoelectron spectroscopy, and chromatographic studies. These morphological and elemental analysis showed that β2-AR was successfully immobilized on the paper surface. The specific drugs have good retentions on the GPCR-in-paper chromatographic platform. The association constants of salbutamol, terbutaline and bambuterol to β2-AR were calculated to be 2.02 × 104 M−1, 1.15 × 104 M−1, 1.75 × 104 M−1 by adsorption energy distribution, which were in good line with the values from frontal analysis, zonal elution and previous literatures. We demonstrated that the GPCR-in-paper platform was cost-effective, easy to be modified for protein immobilization, and applicable in the receptor-drug interaction analysis. We believe such a platform sheds new light on paper chromatography for receptor-drug interaction analysis and other applications.

Herein, we report three-dimensional paper chromatography (3D-PC) as a micro-chromatographic platform. The method was based on applying the origami microfluidic device for separation, coupled by colorimetric methods for simultaneous determination. The microfluidic device fabrication was a facile printing approach. Two azo food dyes, Tartrazine (E102) and Indigo carmine (E132), were selected as a model analyte, while carbonate-bicarbonate buffer was used as the mobile phase. Our micro-chromatographic device is associated with two big advantages including needing very small volume of mobile phase ( ~12 µL) and ultrafast separation time (~35 s). Under the optimal conditions, the method provided acceptable linear ranges of 0. 0 g L 1–18.0 g L 1 (R2 = 0.997) for E102 and 0.070 g L 1–10.0 g L 1 for E132 and the limits of detection (3σ/slope) were evaluated as 0.620 and 0.060 g L 1, respectively. The proposed method was successfully applied in the separation and quantification of these dyes in commercial food products such as jelly, candy, and four kinds of drink samples without any sample preparation prior to analysis. The mean recovery values for the real sample analysis were in the range of 100.14%–102.38% for E132 and E102 respectively. The inter-device relative standard deviations were in the ranges of 1.5%–11.8%. In total, our chromatographic μPAD is small (1.0 cm × 1.0 cm × 0.5 cm), portable, inexpensive, no need of specialized user, requires low volumes of sample (0.5 μL), and can perform separation using 12 μL of aqueous mobile phase in very short time.