Portable Capillary Electrophoresis Instrument Research Articles

Portable capillary electrophoresis coupled with swab-based extraction device for cleaning validation in pharmaceutical facilities

All pharmaceutical manufacturers are required to verify that their production equipment is free from contaminants. Here, we report the capability of a fully automated portable capillary electrophoresis instrument with an integrated sample swab extraction – the Grey Scan ETD-100 – for the detection of pharmaceutical residues on surfaces of manufacturing equipment. Lidocaine was used as a model compound and could be recovered from a surface by swabbing, extracted from the swab, and analysed within 1 min. The recovery of lidocaine from a stainless-steel coupon was 81.3 %, with a LOD of 0.13 µg/swab. This fast, sensitive, and simple method implemented on a user-friendly portable CE instrument without the need for manual sample pre-treatment provides the possibility for on-site rapid determination of equipment cleanliness in the pharmaceutical industry.

Portable fully automated oral fluid extraction device for illegal drugs

Currently used methods for in-field determination of illegal drugs involve various test kits based mainly on the immunoassay technique, where the presence of a compound of interest is assessed by antibody-antigen reaction and manifested by observable color change. Despite being accepted and widely used by police forces to test the presence of illegal drugs in a suspect person, these tests often suffer from unreliable results (high level of false-positive and/or false-negative) due to the cross-reactivity and difficulties with quantification. Therefore, we have developed a portable capillary electrophoresis instrument to determine illegal drugs in oral fluid collected from a suspected person. However, this drug analyzer has still required manual sample preparation. Therefore, this research aimed to develop, test, and validate a fully automated sample pretreatment (purification, extraction, pre-concentration) prototype compatible with the capillary electrophoresis drug of abuse analyzer and suitable for confirmatory analysis by mass spectrometry. The cotton swab from Salivette® oral fluid collector was examined and integrated into the fully automated extractor prototype. The recoveries for the automated extractor were between 18 and 20%, with repeatabilities within 5–11% for 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), cocaine (COC), and cocaethylene (COET). The developed extraction device was easy to use even for unskilled persons, required minimal liquid handling, and was applicable to use in field conditions.

Inexpensive portable capillary electrophoresis instrument for Monitoring Zinc(II) in remote areas

A compact, inexpensive capillary electrophoresis instrument was developed for monitoring metal ions and evaluated for Zn(II) in remote contaminated locations in western Tasmania, Australia. The portable instrument, measuring 21 cm x 10 cm x 7 cm, was powered from the USB port of a laptop computer and built from off-the-shelf components costing ∼$1200 USD. Electrophoretic separations were conducted using a fused silica capillary (10–50 µm I.D.), applying 8.5 kV over capillaries ranging from 25 cm to 40 cm in length. The capillary inlet was connected with an electrically grounded cross-piece as flow-through injection interface. Automated fluidic management was achieved by controlling four mini peristaltic pumps and a solenoid valve. Detection was realised using a purpose-built visible LED absorption detector, optimised for the detection of Co(II), Cu(II) and Zn(II) after complexation with 4-(2-Pyridylazo) resorcinol (PAR). Limits of detection of sub-µM were obtained. The instrument was tested for continuous operation in the laboratory for up to 3 months, and relative standard deviations of <5.4% were found over 945 consecutive injections. In the field, the system was able to measure 106 samples within 11 h, the time it can be powered from the laptop computer. As Field measurement of Zn(II) in western Tasmania was demonstrated to show capability for on-site metal testing.

Emerging techniques for the detection of pyrotechnic residues from seized postal packages containing fireworks

High volume screening of parcels with the aim to trace the illegal distribution and selling of fireworks using postal services is challenging. Inspection services have limited manpower and means to perform extensive visual inspection. In this study, the presence of solid pyrotechnic residues collected from cardboard shipping parcels containing fireworks was investigated for direct in-field chemical detection. Two emerging trace detection techniques, i.e., capillary electrophoresis (CE)-based inorganic oxidizer detector and infrared thermal desorption (IRTD) coupled with direct analysis in real time mass spectrometry (DART-MS), were investigated for their potential as screening tools. Detection of non-visible pyrotechnic trace residues from real-case seized parcels was demonstrated using both screening techniques. However, the high nitrate background in the commercial CE system complicated its screening for black powder traces. IRTD-DART-MS allowed differentiation between flash and black powder by identification of the molecular inorganic ions. Compared to the portable CE instrument, rapid screening using IRTD-DART-MS is currently limited to laboratory settings. The capabilities of these emerging techniques established solid particle and trace residue chemical detection as interesting options for parcel screening in a logistic setting.

Use of a newly-developed portable capillary electrophoresis analyser to detect drugs of abuse in oral fluid: A case study

The aim of the current study was to develop and validate an analytical method to determine whether drugs of abuse (DOA) were present in oral fluid (OF) using a newly-developed, portable capillary electrophoresis (CE) instrument coupled to a deep ultra-violet fluorescence detector (FD). The performance of this portable CE-FD DOA analyser was tested at the Weekend Festival Baltic (Pärnu, Estonia) between 2016 and 2018 as well as on the roadside OF samples collected by the police. The study reported 128 analysed cases in which persons were allegedly found to have been under the influence of DOA. The samples were analysed for amphetamine (AMP), methamphetamine (METH), 3,4-methylenedioxy-methamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxy-N-ethylamphetamine (MDEA), cocaine (COC) and cocaethylene (COET). Subsequent toxicological reports revealed that 26% cases were negative, and 74% were positive. The most frequently detected and quantified DOA was MDMA (68 cases, 62%). A comparative study was conducted to validate the accuracy of using the CE-FD DOA analyser versus classic high-performance liquid chromatography coupled to mass spectrometry (HPLC-ESI-MS). Diagnostic statistics for CE-FD DOA were also evaluated and were higher than 99.5%. In addition, all zeta-scores were lower than 2 when both methods were compared, showing that the CE-FD analyser can be implemented as a reliable, sensitive and convenient tool for roadside and workplace testing for DOA.

In Situ Determination of Illegal Drugs in Oral Fluid by Portable Capillary Electrophoresis with Deep UV Excited Fluorescence Detection.

The present study demonstrates the potential of a portable capillary electrophoresis (CE) instrument, coupled to deep UV fluorescence detector (FD) with a 230-255 nm excitation wavelength range, for the determination of the abuse of illegal drugs in oral fluids in situ. CE was introduced in this study due its exceptional power of separation and resolution, short analysis time, and ability for miniaturization for on-site assessment of different substances. The deep UV fluorescence detector was equipped with five interchangeable emission filters, in the emission wavelength range from 278 to 600 nm, and was successfully employed for determination of natively fluorescing illegal drugs, such as cocaine, cocaethylene, 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxeamphetamine (MDA), 3,4-methylenedioxy- N-ethylamphetamine (MDEA), para-methoxyamphetamine (PMA), para-methoxy- N-methylamphetamine (PMMA), amphetamine (AMP), methamphetamine (METH), tetrahydrocannabinol (THC) and cannabidiol (CBD). The developed FD showed impressive sensitivity. The instrumental detection limit was 0.5 μg/L for MDMA. It also showed broad linearity, up to 50 mg/L for MDMA. The noise CV% was 1.1% for an empty capillary and 0.6% for a capillary filled with acetonitrile. The portable CE-FD with developed electrophoretic methodologies was successfully utilized for the determination of illegal abuse of drugs during "Weekend" 2016 and 2017 Music Festivals (Estonia). Moreover, CE-FD can be employed for detection of other natively fluorescing compounds in the proposed range (e.g., for different phenolic compounds, BTEX, naphthalene derivatives, and others), significantly widening the applicability of developed CE-FD instrument.

Determination of Inorganic Ion Profiles of Illicit Drugs by Capillary Electrophoresis.

A portable capillary electrophoresis instrument with dual capacitively coupled contactless conductivity detection (C4 D) was used to determine the inorganic ionic profiles of three pharmaceutical samples and precursors of two illicit drugs (contemporary samples of methylone and para-methoxymethamphetamine). The LODs ranged from 0.10 μmol/L to 1.25 μmol/L for the 10 selected cations, and from 0.13 μmol/L to 1.03 μmol/L for the eight selected anions. All separations were performed in less than 6 min with migration times and peak area RSD values ranging from 2 to 7%. The results demonstrate the potential of the analysis of inorganic ionic species to aid in the identification and/or differentiation of unknown tablets, and real samples found in illicit drug manufacture scenarios. From the resulting ionic fingerprint, the unknown tablets and samples can be further classified.

Simultaneous determination of rare earth elements in ore and anti-corrosion coating samples using a portable capillary electrophoresis instrument with contactless conductivity detection

The employment of an in-house-made capillary electrophoresis (CE) instrument with capacitively coupled contactless conductivity detection (C4D) as a simple and inexpensive solution for simultaneous determination of many rare earth elements (REEs) in ore samples from Vietnam, as well as in anti-corrosion coating samples is reported. 14 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) were determined using an electrolyte composed of 20mM arginine and 10mM α-hydroxyisobutyric acid adjusted to pH 4.2 with acetic acid. The best detection limit achieved was 0.24mg/L using the developed CE-C4D method. Good agreement between results from CE-C4D and the confirmation method (ICP-MS) was achieved, with a coefficient of determination (r2) for the two pairs of data of 0.998.

Triple-channel portable capillary electrophoresis instrument with individual background electrolytes for the concurrent separations of anionic and cationic species

The portable capillary electrophoresis instrument is automated and features three independent channels with different background electrolytes to allow the concurrent optimized determination of three different categories of charged analytes. The fluidic system is based on a miniature manifold which is based on mechanically milled channels for injection of samples and buffers. The planar manifold pattern was designed to minimize the number of electronic valves required for each channel. The system utilizes pneumatic pressurization to transport solutions at the grounded as well as the high voltage side of the separation capillaries. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 (w) × 35 (d) × 15 cm (h) and a weight of about 15 kg. It can operate continuously for 8 h in the battery-powered mode if only one electrophoresis channel is in use, or for about 2.5 h in the case of simultaneous employment of all three channels. The different operations, i.e. capillary flushing, rinsing of the interfaces at both capillary ends, sample injection and electrophoretic separation, are activated automatically with a control program featuring a graphical user interface. For demonstration, the system was employed successfully for the concurrent separation of different inorganic cations and anions, organic preservatives, additives and artificial sweeteners in various beverage and food matrices.

A Novel Method to Quantify Bioavailable Elements and Mobile ATP on Rock Surfaces and Lichens

The quantification of mobile ions on rock surfaces is essential for the investigation of mineral weathering. A need for such measurements arises from the study of initial soil formation in pioneering environments, the biogeochemical weathering of monuments and buildings, and the chemical reactivity of minerals in general. In the case of mineral surfaces covered by lichens, the quantification of adenosine triphosphate (ATP) is a measure of the vitality of the organisms. To date, non-destructive investigations of rock surfaces and growth of biofilms have generally been limited to visual methods. We evaluated a new technique for the analysis of readily available ions and ATP. For this, a single drop of pure water is spread on bare mineral surfaces or rock-based crustose lichens. The solution is recollected and analyzed for dissolved ions and ATP using a portable capillary electrophoresis instrument and a luminometer, respectively. We illustrate the natural heterogeneity of available ions on freshly broken granite surfaces and the effects of subsequent wetting, freezing, and thawing. In addition, the influence of humidity and age of crustose lichens is demonstrated by ion and ATP analysis.

Portable capillary electrophoresis instrument with contactless conductivity detection for on-site analysis of small volumes of biological fluids

A novel, easy to use and portable capillary electrophoretic instrument for injection of small volumes of biological fluids equipped with contactless conductivity detection was constructed. The instrument is lightweight (<5 kg), all necessary parts including a tablet computer are accommodated in a plastic briefcase with dimensions 20cm×33cm×17cm (w×l×h), allows hydrodynamic injection of small sample volumes and can continuously operate for at least 10hours. The semi-automated hydrodynamic sample injection is accomplished via a specially designed PMMA interface that is able to repeatedly inject sample aliquots from a sample volume as low as 10μL, with repeatability of peak areas below 5%. The developed interface and the instrument were optimized for the injection of biological fluids. Practical utility was demonstrated on the determination of formate in blood serum samples from acute methanol intoxication patients and on the analysis of ionic profile (nitrosative stress markers, including nitrite and nitrate) in the exhaled breath condensate from one single exhalation.

Screening determination of four amphetamine-type drugs in street-grade illegal tablets and urine samples by portable capillary electrophoresis with contactless conductivity detection

A simple and inexpensive method for the identification of four substituted amphetamines, namely, 3,4-methylenedioxy methamphetamine (MDMA), methamphetamine (MA), 3,4-methylenedioxy amphetamine (MDA) and 3,4-methylenedioxy-N-ethylamphetamine (MDEA) was developed using an in-house constructed semi-automated portable capillary electrophoresis instrument (CE) with capacitively coupled contactless conductivity detection (C4D). Arginine 10mM adjusted to pH4.5 with acetic acid was found to be the optimal background electrolyte for the CE-C4D determination of these compounds. The best detection limits achieved with and without a sample preconcentration process were 10ppb and 500ppb, respectively. Substituted amphetamines were found in different seized illicit club drug tablets and urine samples collected from different suspected users. Good agreement between results from CE-C4D and those with the confirmation method (GC-MS) was achieved, with correlation coefficients for the two pairs of data of more than 0.99.

Simple semi-automated portable capillary electrophoresis instrument with contactless conductivity detection for the determination of β-agonists in pharmaceutical and pig-feed samples

An inexpensive, robust and easy to use portable capillary electrophoresis instrument with miniaturized high-voltage capacitively coupled contactless conductivity detection was developed. The system utilizes pneumatic operation to manipulate the solutions for all flushing steps. The different operations, i.e. capillary flushing, interface rinsing, and electrophoretic separation, are easily activated by turning an electronic switch. To allow the analysis of samples with limited available volume, and to render the construction less complicated compared to a computer-controlled counterpart, sample injection is carried out hydrodynamically directly from the sample vial into the capillary by manual syphoning. The system is a well performing solution where the financial means for the highly expensive commercial instruments are not available and where the in-house construction of a sophisticated automated instrument is not possible due to limited mechanical and electronic workshop facilities and software programming expertise. For demonstration, the system was employed successfully for the determination of some β-agonists, namely salbutamol, metoprolol and ractopamine down to 0.7ppm in pharmaceutical and pig-feed sample matrices in Vietnam.

Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia

Distinct layers of iron(III) and manganese(IV) (Fe/Mn) oxides are found buried within the reducing part of the sediments in Lake Baikal and cause considerable complexity and steep vertical gradients with respect to the redox sequence. For the on-site investigation of the responsible biogeochemical processes, we applied filter tube samplers for the extraction of sediment porewater combined with a portable capillary electrophoresis instrument for the analyses of inorganic cations and anions. On the basis of the new results, the sequence of diagenetic processes leading to the formation, transformation, and dissolution of the Fe/Mn layers was investigated. With two exemplary cores we demonstrate that the dissolution of particulate Fe and Mn is coupled to the anaerobic oxidation of CH₄ (AOM) either via the reduction of sulphate (SO₄(2-)) and the subsequent generation of Fe(II) by S(-II) oxidation, or directly coupled to Fe reduction. Dissolved Fe(II) diffuses upwards to reduce particulate Mn(IV) thus forming a sharp mineral boundary. An alternative dissolution pathway is indicated by the occurrence of anaerobic nitrification of NH₄(+) observed at locations with Mn(IV). Furthermore, the reasons and consequences of the non-steady-state sediment pattern and the resulting redox discontinuities are discussed and a suggestion for the burial of active Fe/Mn layers is presented.

Determination of nitrogen mustard degradation products in water samples using a portable capillary electrophoresis instrument

In this work, a new purpose-made portable CE instrument with a contactless conductivity detector was used for the determination of degradation products of nitrogen mustards in different water samples. The capillary was coated with poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) to avoid analyte-wall interactions. The coating procedure was studied to obtain the best repeatability of the migration time of the analytes. Four different coating procedures were compared; flushing the capillary with the copolymer at 100 psi for 2 min at 60°C provided the best RSD values (<4%). The analytical method was also optimized. The use of 20 mM of MES adjusted to pH 6.0 with His as running buffer allowed a good baseline separation of the three analytes in different water samples without matrix interferences. The method permitted the detection of the three degradation products down to 5 μM.

Portable Capillary Electrophoresis Instrument with Automated Injector and Contactless Conductivity Detection

A portable capillary electrophoresis instrument featuring an automated, robust, valve-based injection system was developed. This significantly facilitates operation in the field compared to previous injection approaches. These generally required delicate manual operations which are difficult to perform outside the laboratory environment. The novel system relies on pressurized air for solution delivery and a micromembrane pump for sample aspiration. Contactless conductivity detection was employed for its versatility and low power requirement. The instrument has a compact design, with all components arranged in a briefcase with dimensions of 45 × 35 × 15 cm (w × d × h) and a weight of about 8 kg. It can operate continuously for 9 h in the battery-powered mode. Depending on the task at hand, the injection system allows easy optimization for high separation efficiency, for fast separations, or for low limits of detection. To illustrate these features, the separation of four anions within 16 s is demonstrated as well as the determination of nitrite below 1 μM. The determination of phosphate at a sewage treatment plant was carried out to demonstrate a field application.

Sediment porewater extraction and analysis combining filter tube samplers and capillary electrophoresis

Careful extraction and analysis of porewater from sediment cores are critical for the investigation of small-scale biogeochemical processes. Firstly, small sample volumes and high spatial resolution are required. Secondly, several chemical species in the anaerobic porewater are sensitive to oxidation when brought in contact with ambient air. Here we present the combination of a special sampling technique and an analytical method for the porewater extraction of a varved sediment core from Lake Baldegg in central Switzerland, using MicroRhizon samplers and a portable capillary electrophoresis (CE) instrument. MicroRhizon filter tubes of 1 mm diameter and 20 mm length are suitable for fast retrieval of particle-free porewater samples directly from the sediment core. Since the time-span between sampling and analysis is less than 20 seconds, oxygen-sensitive Fe(ii) can be analyzed in one go together with Na(+), K(+), Ca(2+), Mg(2+), NH4(+), and Mn(ii) without splitting, acidification or dilution of the sample. The major inorganic cations and anions of the sediment porewater can be determined in less than 15 minutes. Detection limits are in the sub-micromolar concentration range. The capillary electrophoresis instrument used in this study requires sample volumes of only 20 μL. These remarkable small sample volumes allow the minimization of disturbance of the sediment cores and a high spatial resolution of the sediment profile, even in sediments with low water content. The equipment is inexpensive, easy to handle, fully portable and therefore suitable for environmental on-site applications.

Analysis of the degradation products of chemical warfare agents using a portable capillary electrophoresis instrument with various sample injection devices

In the present research, the performance of three sample injection devices in a portable capillary electrophoresis (CE) instrument was examined. These were the so-called cross-sampler, horizontal injection channel and vertical injection channel. All the three showed a good reproducibility of migration times (the relative standard deviation (RSD) was 4.3% in the case of the cross-sampler, 6.0% in the case of the horizontal injection channel and 1.7% in the case of the vertical channel). However, the reproducibility of peak areas was not sufficient. Hence, this study was mainly focused on qualitative analysis. The cross-sampler injection device was used in the portable CE instrument to analyse the composition of degradation products of chemical warfare agents (CWA). For the analysis of CWA degradation products simple procedures for the extraction of phosphonic acids from different surfaces, such as soil, concrete and granite blocks, tile floor, were developed.

New Fully Portable Instrument for the Versatile Determination of Cations and Anions by Capillary Electrophoresis with Contactless Conductivity Detection

AbstractA new portable capillary electrophoresis instrument with capacitively coupled contactless conductivity detection was developed and optimized for the sensitive field measurements of ionic compounds in environmental samples. It is powered by batteries and the high voltage modules are capable of delivering up to 15 kV at either polarity for more than one working day. Inorganic cations and anions, including ions of heavy metals and arsenate, could be determined with detection limits in the range from about 0.2 to 1 μM. The instrument was field tested in a remote region of Tasmania and nitrite and ammonium could be determined on‐site at concentrations as low as 10 ppb in presence of other common inorganic ions at concentrations which were 2 to 3 orders of magnitude higher.

Identification of Inorganic Improvised Explosive Devices by Analysis of Postblast Residues Using Portable Capillary Electrophoresis Instrumentation and Indirect Photometric Detection with a Light-Emitting Diode

A commercial portable capillary electrophoresis (CE) instrument has been used to separate inorganic anions and cations found in postblast residues from improvised explosive devices (IEDs) of the type used frequently in terrorism attacks. The purpose of this analysis was to identify the type of explosive used. The CE instrument was modified for use with an in-house miniaturized light-emitting diode (LED) detector to enable sensitive indirect photometric detection to be employed for the detection of 15 anions (acetate, benzoate, carbonate, chlorate, chloride, chlorite, cyanate, fluoride, nitrate, nitrite, perchlorate, phosphate, sulfate, thiocyanate, thiosulfate) and 12 cations (ammonium, monomethylammonium, ethylammonium, potassium, sodium, barium, strontium, magnesium, manganese, calcium, zinc, lead) as the target analytes. These ions are known to be present in postblast residues from inorganic IEDs constructed from ammonium nitrate/fuel oil mixtures, black powder, and chlorate/perchlorate/sugar mixtures. For the analysis of cations, a blue LED (470 nm) was used in conjunction with the highly absorbing cationic dye, chrysoidine (absorption maximum at 453 nm). A nonaqueous background electrolyte comprising 10 mM chrysoidine in methanol was found to give greatly improved baseline stability in comparison to aqueous electrolytes due to the increased solubility of chrysoidine and its decreased adsorption onto the capillary wall. Glacial acetic acid (0.7% v/v) was added to ensure chrysoidine was protonated and to enhance separation selectivity by means of complexation with transition metal ions. The 12 target cations were separated in less than 9.5 min with detection limits of 0.11-2.30 mg/L (calculated at a signal-to-noise ratio of 3). The anions separation system utilized a UV LED (370 nm) in conjunction with an aqueous chromate electrolyte (absorption maximum at 371 nm) consisting of 10 mM chromium(VI) oxide and 10 mM sodium chromate, buffered with 40 mM tris(hydroxymethyl)aminomethane at pH 8.05. All 15 target anions were baseline separated in less than 9 min with limits of detection ranging from 0.24 to 1.15 mg/L (calculated at a signal-to-noise ratio of 3). Use of the portable instrumentation in the field was demonstrated by analyzing postblast residues in a mobile laboratory immediately after detonation of the explosive devices. Profiling the ionic composition of the inorganic IEDs allowed identification of the chemicals used in their construction.