•Sample preparation techniques coupled with high-performance liquid chromatography and a suitable detector.•Combining sample preparation techniques to achieve satisfactory extraction efficiency, ...cleanup as well as excellent preconcentration capacity.•Validating an analytical method to ensure the quality and reliability of any data produced is a fundamental step in any measurement's life-cycle.•Sample preparation techniques future.
This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001–2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.
The monitoring of metals in commercial products is essential for protecting public health against the hazards of metal toxicity. This article presents a guided inquiry (GI) experimental lab approach ...in a quantitative analysis lab class that enabled students’ to determine the levels of aluminum in deodorant brands. The utility of a GI experimental lab introduced in the quantitative analysis lab class as part of an active learning hands-on-experience approach enhances student learning, improves students’ critical thinking and problem solving skills, and motivates underrepresented students to work independently in solving a real-world scenario-type problem. Students were required to develop certain lab skills at the start of the semester and apply these skills toward the end of the semester to investigate the GI project. The GI project that analyzes for aluminum improves the overall student engagement, enthusiasm for the quantitative analysis laboratory course, and even the overall success rate in scientific report writing.
A new approach to reduce the false-positive responses commonly encountered in the field when drugs and explosives are detected is reported for an electrospray ionization high-performance ion mobility ...spectrometry (ESI-HPIMS). In this article, we report on the combination of reduced mobility and the width-at-half-height of a peak to give a new parameter called conditional reduced mobility (CRM). It was found that the CRM was capable of differentiating between real drugs peaks from that of a false-positive peak and may help to reduce false-positive rates. This effect was demonstrated using 11 drugs (amphetamine, cannabidiol, cocaine, codeine, heroine, methamphetamine, morphine, phentermine, l-phenylepherine, proglitazone, and rosiglitazone) and seven interferences chosen from off-the-shelf products. This report determined and compared CRM, resolving power (R m), and diffusion-limited conditional theoretical reduced mobility (DLCTRM) for ESI-HPIMS. The most important parameters for determining CRM are reduced mobility and width-at-half-height of a peak. There is a specific optimum voltage, gate pulse width, resolving power, and now CRM for each ion. DLCTRM indicate the optimum reduced mobility that is not normally possible under field conditions. CRM predicts the condition at which a target compound can be differentiated from a false-positive response. This was possible because different ions exhibits different drifting patterns and hence a different peak broadening phenomenon inside an ion mobility tube. Reduced mobility for target compounds reported were reproducible to within 2% for ESI-HPIMS. The estimated resolving power for the ESI-HPIMS used in this study was 61 ± 0.22. Conditional reduced mobility introduced in this paper show differences between target compounds and false-positive peaks as high as 74%, as was the case for cannabidiol and interference #1 at 70 μs gate pulse width.
The ability to use positive ion monitoring mode with an atmospheric pressure ion mobility time-of-flight mass spectrometer (APIM(tof)MS) to detect psychoactive cathinones and tryptamines from aqueous ...phase samples was evaluated. The study used a traditional electrospray ionization (ESI) source for sample introduction and ionization. A total of four cathinones (mephedrone, butylone, 4-Me-PPP, and 4-MEC) and five tryptamines (5-EtO-DPT, 5-EtO-DALT, 5-EtO-MIPT, 5-EtO-ALCHT, and 5-EtO-2MALET) were investigated, and we report on parent ions, collision induced dissociation (CID) fragment ions, reduced mobility (K o), mass flight times, and detection limits obtained from a single instrument run for the psychoactive substances. Detection limits reported ranged from 3 to 11 μM concentration for the compounds studied. This detection limit range corresponded to 1–5 ng of material needed for improved detection on the instrument. This article demonstrates that it was possible to use a single instrument platform for the separation, detection, and identification of cathinones and tryptamines in less than 1 min. The application holds great promise for detecting and identifying a new class of drugs often referred to as “bath salts” or “legal highs” distributed over the Internet.
A fast, straightforward, efficient, and high throughput reverse-phase high-performance liquid chromatography and electrospray ionization mass spectrometry method has been developed to analyze tea ...extracts containing polyphenols. The polyphenols detected in green tea (GT), black tea (BT), and paradise tropical tea (PTT) were separated in 18 min at wavelengths 254 nm, 260 nm, and 280 nm with a gradient elution on the RP-HPLC system. Our approach detected, identified, and quantified three catechins in the tea extracts analyzed, and the response at 280 nm wavelength was the best. The ESI-MS data confirmed the fragmentation patterns of the catechins detected in the tea extract. The validation data showed that the limit of detection (LOD) and limit of quantitation (LOQ) of catechins ranged from 5.26 ± 0.02 to 36.44 ± 0.02 ppb, and 17.52 ± 0.03 to 121.45 ± 0.16 ppb, respectively, for six catechins studied. The standard addition calibration approach used to quantify the catechin content in the tea extract simultaneously showed that PTT has a higher catechin content than GT and BT. The content of polyphenols in GT, BT, and PTT are summarized. This approach holds great promise for quality control studies to quantify polyphenols in nutritional products.
An approach using method validation (MV) parameters, otherwise known as analytical figures of merit was combined with electrospray ionization high performance ion mobility spectrometry (ESI-HPIMS) to ...describe an approach for evaluating drugs and explosives analysis in the field. MV parameters such as reduced mobility (
K
o
), conditional reduced mobility (
K
c
), resolving power (
R
p
), theoretical plates (
N
), linearity, accuracy, precision, limit of detection (LOD), limit of quantitation (LOQ), repeatability, range, and reporting limit were investigated and developed for eleven drugs and six explosives. Our investigation estimated resolving power at 66 ± 0.64 for the ESI-HPIMS used. The LOD’s calculated ranged from 0.45–2.97 ng of material electrosprayed into the ESI-HPIMS. The LOQ’s calculated falls in the range 4.11–8.63 ng of material electrosprayed into the ESI-HPIMS. The key findings from this investigation were the following:
K
c
proves to be a measure of the identity of an explosive or drug ion; a parameter that may be applied to help aid IMS devices when detecting drugs and explosives. MV parameters, especially,
K
c
, introduced in this study is an effective parameter for establishing a unique identity of a drug or explosive. A control chart is an effective way to monitor the performance of an instrument and may be a useful tool for establishing reliability of confirmatory data in forensic investigations. MV parameters may be a reliable, accurate and unique identification marker for target drugs and explosives capable of differentiating these substances from false positive responses.
In today’s complex world, there is a continued demand for recently graduated forensic chemists (criminalists) who have some background in forensic experimental techniques. This article describes ...modern forensic experimental approaches designed and implemented from a unique instructional perspective to present certain facets of crime scene investigation. Physical evidence collection, handling, and evaluation are reviewed, as are challenges associated with carrying out these tasks. The interrelation of the responsibilities of the crime scene investigator and criminalist also is addressed, as this can be highlighted in an instructional setting. If the investigator does not collect sufficient evidence or collects the evidence improperly, the criminalist will be unable to effectively interpret the data. In this report, the authors describe their experiences at a mock crime scene designed for investigation by undergraduate forensic science students. Key points that must be considered include evidence collection, analysis of the evidence, interpretation of the results, and drawing conclusions from those interpretations. We have presented the information in a way that may be beneficial to instructors looking to create or update existing forensic science courses, or scholars interested in the drawbacks of certain aspects of evidence collection.
Volatile Organic Compounds (VOCs) mixtures in aqueous solutions have been investigated using a simple and efficient all-in-one on-line sampling, isolation, enrichment and pre-concentration internally ...heated membrane connected to a gas chromatography flame ionization detector (GC-FID). In our previous study with the internally heated membrane, no GC column was used in the instrument. In this new study, we introduce a GC column in the instrument design and this makes it possible for mixtures to be investigated. This new experimental design enabled high resolution separation of analyte mixtures capable of being adsorbed, diffused, and desorbed from the device for detection with an FID. With the new design we present data from investigation of competitive adsorption effects on the membrane. The data showed that analyte adsorption and diffusion onto the membrane can be affected when mixtures of analytes are introduced. The application of multiple linear regressions approach to the data enabled us to correct for the problem of competitive adsorption. Analyte adsorption and diffusion was affected by the diffusion coefficients of the analytes; the higher the diffusion coefficient the better the extraction from the membrane. Increasing the sampling time from 1 to 4min increases the response by 77%. The sampling time responses were linear up to 4min sampling time. Above 4min sampling time, the data deviate from linearity. The effect of adding salt to standards has no effect on analyte absorption onto the membrane. The detection limits for key VOCs studied with an internal standard calibration ranged from 0.2 to 194ngcm−3.
► Sample introduction unit designed with a membrane. ► A membrane sample introduction unit that can perform temperature programming. ► Correcting competitive adsorption effects. ► Good sensitivity and selectivity for volatiles and semi-volatiles. ► Detailed statistical analysis of an analytical data.
Marburg virus (MARV) causes sporadic outbreaks of severe Marburg virus disease (MVD). Most MVD outbreaks originated in East Africa and field studies in East Africa, South Africa, Zambia, and Gabon ...identified the Egyptian rousette bat (ERB; Rousettus aegyptiacus) as a natural reservoir. However, the largest recorded MVD outbreak with the highest case-fatality ratio happened in 2005 in Angola, where direct spillover from bats was not shown. Here, collaborative studies by the Centers for Disease Control and Prevention, Njala University, University of California, Davis USAID-PREDICT, and the University of Makeni identify MARV circulating in ERBs in Sierra Leone. PCR, antibody and virus isolation data from 1755 bats of 42 species shows active MARV infection in approximately 2.5% of ERBs. Phylogenetic analysis identifies MARVs that are similar to the Angola strain. These results provide evidence of MARV circulation in West Africa and demonstrate the value of pathogen surveillance to identify previously undetected threats.
Over the years to date, there had been many emerging issues in the world. These issues include human right violations, discrimination against women, child abuse, climate change, HIV/ AIDS and bad ...governance. These issues are very prominent in developing countries in which Sierra Leone coming from a brutal civil conflict which lasted a little over a decade is not exclusion. The war was formally declared ended in the year, 2002. However, the prevailing conditions of the country send a very worrisome signal. This research entitled “The Role of Teachers, Facilitators, Teacher-Trainees and other Education Stakeholders in the Participatory and Behaviour Change programme in Sierra Leone. A case study of the Introduction of Emerging Issues Course in the Teachers Certificate Programme in post War Sierra Leone” has been undertaken to investigate the roles of the following factors: - teachers, facilitators, teacher-trainees and other education stakeholders in the reform of the curriculum and the introduction of the new course of study knownas Emerging Issues. The study adopted a descriptive Research Survey design with a focus on two research questions such as “In what extent to which teachers, facilitators, teacher-trainees and other education stakeholders understood their roles in fostering positive constructive behaviour change in students? And what challenges associated with the implementation of the introduction of participatory and behavioural change in the Teacher Certificate Programme?” The study reveals that among the teacher trainees, 60% of them stated they should serve as role models whilst 21.6% of the respondents disclose that they should use participatory teaching techniques in school. Other responses recorded 17 respondents (11%) reveals that teacher trainees should avoid negative practices. The study also shows that; 45% of the respondents said facilitators too must serve as role models, 40.0% opined that the facilitators should use participatory techniques in their lessons so that teachers will be familiar with such techniques. 10% pointed out those facilitators should avoid negative practices and 5.0% stated that they should do the correct things at all times respectively.
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