A new method based on high-resolution continuum source flame atomic absorption spectrometry (HR-CS-FAAS) was validated for the determination of selected toxic and potentially toxic metals in wastewater resulting from mining activity. The results were compared with inductively coupled plasma optical emission spectrometry (ICP-OES). The HR-CS-FAAS method was characterized by detection limits in the range (µg L-1) 0.9(Mn)-33.6(Pb), better than ICP-OES for Cu, Fe, Ni, Co, Pb and Mn, and poorer for Cd, Zn and Cr. The Dunnett's and Tukey's statistical test showed that both methods were not affected by significant bias against certified value and between them. The recovery in HR-CS-FAAS method was in the range of 98-103% with relative extended uncertainty of 9-25%, and precision of 1.5-14.1%. The results indicated that the HR-CS-FAAS method is suitable for the determination of toxic and potentially toxic elements directly in filtered water samples without any chemical treatment.

Pit latrines represent the predominant form of on-site sanitation in Botswana, posing unique challenges in faecal sludge (FS) management. The key concerns revolve around FS extraction, treatment, and safe disposal. Currently, co-treatment with wastewater is the primary approach, but it strains wastewater treatment plants (WWTPs) and compromises effluent quality. This study comprehensively assesses FS quality from pit latrines and evaluates the potential health risks when used in agriculture for soil improvement/amendment. Systematic sampling of soils at various depth intervals, approximately 30 cm apart, was conducted, followed by extensive laboratory analysis, including determination of heavy metals (copper, iron, lead, cadmium, zinc, manganese, and arsenic) using inductively coupled plasma atomic emission spectroscopy (ICP-OES) and nutrient analysis using ion chromatography (IC). The findings unequivocally demonstrate that FS from VIP (ventilated improved pit) latrines poses no significant health risks due to heavy metal content. Specifically, Geo-accumulation Index (Igeo) values for nickel (Ni), chromium (Cr), and arsenic (As) were consistently negative, indicating negligible risk of environmental contamination. Copper (Cu) concentrations averaged 40.36 mg/kg in samples collected from Mogoditshane and 591.61 mg/kg in those collected from Broadhurst (Gaborone, Botswana) with Igeo values indicating a moderate pollution risk. Nutrient analysis showed high levels of nitrogen (NO3−), with concentrations reaching 4.47 × 103 mg/kg in some samples, and phosphorus (PO43−) levels as high as 3.9 × 104 mg/kg. These findings highlight its agricultural potential for soil amendment, though prudent management is needed to mitigate eutrophication. The study advocates for separate FS treatment, resolving co-treatment operational challenges and enhancing sustainability. Implementing these recommendations promises to address FS management issues, bolster food security, and enhance Botswana’s ecological well-being.

Iron (Fe) is a micronutrient that can be toxic at elevated concentrations, prompting its significance in frequent environmental monitoring. Typically analyzed using methods such as FAAS, ICP-OES and ICP-MS, the challenge of expensive instrumentation operated only in the laboratory presents a barrier for rapid and frequent testing. This study aimed to develop a silica-based smartphone-assisted on-site method for rapid detection of Fe in water using ImageJ software. Suitable conditions, including reagents and a color intensity measurement tool, were optimized for this method. Figures of merit such as detection limit, accuracy and precision were determined. The results showed that adding polyacrylic acid to detection points for silica worsened the results, in contrast to results for paper devices. It was also found that, on ImageJ, it is best to use an integrated density tool to measure color intensity, contrary to the previously reported mean gray tool. Results showed a limit of detection of 0.2 ng, a limit of quantification of 0.6 ng, a linear range of 0.6 ng to 4.5 ng and RSD of <20%. This method is therefore an alternative in field pre-testing and screening. Future studies include application of this method in the field with real samples and in the analysis of other metals.

The world’s population is growing continually and is projected to reach nine billion by the year 2050. This growth rate requires increased and economically viable food production and an adequate supply of quality water to sustain life. Increased food production and supply of water require adding fertilizers and possible recycling of wastewater, to address the improvement of soils’ nutritional status and potable water shortages, respectively. The objectives of this work were to determine the nutrients in sewage-impacted wastewater, borehole water, agricultural waste, and commercial fertilizer (control) materials, and their heavy metal content was also carried out to determine their suitability for use. In addition, Moringa seed pods and Morula nutshells were investigated as a bioremedial approach for the removal of toxic metals from aqueous samples. An attempt to regenerate sorbent was made since the saturated sorbents that contain the metal ions are not safe for disposal as they can pollute the environment. Nutrients were analyzed by HPLC, while metals were analyzed using a Varian 220FS Atomic Absorption Spectrometer operated with air/acetylene. Nonedible agricultural materials were found to contain appreciable amounts of plant nutrients such as nitrates (NO3 -), nitrites (NO2 -), and phosphates (PO4 3-) as well as metal ions such as magnesium, copper, and zinc, which are beneficial for plant growth. Results obtained from analysis of sewage water effluent showed that heavy metal and nutrient concentrations decreased in the treatment stage. The utilization of Moringa oleifera seed pods for metal removal from wastewater is viable and would reduce costs for waste disposal and can offer alternatives to conventional methods for the removal of unwanted or toxic species from the environment. It showed potential for removing selected metal ions such as Pb, Cd, Cu, Fe, and Zn from polluted water. This organically treated wastewater is environmentally friendly and may be used for applications which do not require potable water, such as irrigating golf courses, lawns, and crops, or for industrial purposes, if proper measures are taken to ensure its quality.

An HPLC method using an UV detector was developed for the simultaneous determination of nitrites, nitrates and phosphates in environmental samples. Chromatographic separation was achieved isocratically on a Phenomenex Synergi Polar-RP LC column using acetonitrile and acidified water (pH 2.7) at 60:40 v/v as mobile phase. Baseline resolution of all the three analytes was achieved within 3 min. The developed method was applied to water samples obtained from the wastewater treatment plant in Gaborone, Botswana. The use of HPLC technique in this study demonstrated its ability to carry out a simultaneous determination of NO2-, NO3- and PO43- in water samples. The treatment plant was found to be functioning within expectations, removing 97.6 % 88.0 % NO3- and 90.9 % PO: from the received wastewater. Results of the developed method were comparable with those of the traditional ion chromatography method, showing accuracy values between 95.22 % and 98.04 %. The precision of the method for the determination of all analytes was determined by RSD values, all of which were lower than 5 %. The method is of low cost, fast, has an easy procedure and avoids the use of many reagents some of which may be hazardous.

This review article describes the structure of zeolites starting from atomic level to the complex networks of channels and voids that permeate the material. The chemistry within the material is outlined relating it to its crystal structure. The resulting properties are described relating them to the crystal structure and the chemistry. Finally, the applications of the material are summarised relating them to the material crystal structure, chemistry and properties.

Use of nonedible seed pods of Moringa oleifera (Moringa) tree and nutshells of Sclerocarya birrea (Morula) tree for removal of selected metal ions (lead, cadmium, copper, manganese, iron, zinc, and magnesium) from wastewater and borehole water samples was investigated. Removal parameters such as contact time, pH, temperature, particle size, sorbent dose, and initial metal concentration were optimized. Determination of residual metal ions after employing sorbent was done using flame atomic absorption spectroscopy (FAAS). Using 200 ng synthetic metal ion mixture in 50 mL of water sample, the optimized parameters for Moringa seed pods were 60 min contact time, 1.0 g of sorbent dose, pH 8, 100 μm sorbent particle size, and extraction temp 35°C. While using Morula nutshells, the optimized conditions were 120 min contact time, 2.0 g sorbent dose, pH 8, 100 μm sorbent particle size, and extraction temp of 35°C. The removal efficiency of acid treated sorbents was compared to that of untreated sorbents and it was found to be higher for acid treated sorbents. These nonedible plant parts for Morula and Moringa plants are proposed as a cheap, simple, and an effective alternative for purification of water contaminated with heavy metals.

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58±7.20 to 113±15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R2>0.9900) in the range of 2 to 100 ng g−1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48±0.16 to 1.50±0.50 ng g−1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

We have interrogated the characteristics of six pharmacologically active compounds in a hot gas chromatograph injector including some mass spectral characteristics in a quadrupole mass analyzer. The analytes are dimetridazole, metronidazole, chlorpromazine, trimethoprim, sulfamethazine, and dapsone. We have demonstrated the impact of the injector on the conversion efficiency of solvent to vapor in relation to analytes under investigation. The overall analytical performance of key parameters that were scrutinized and tested on a spiked raw sewer water sample using electron ionization (EI), positive chemical ionization (PCI), and negative chemical ionization (NCI) in the full and selected ion monitoring (SIM) scan modes are also presented. These parameters were the instrument detection limits (IDLs), method detection limits (MDLs), linearities, and percent recoveries. Correlation coefficients (R-2) were greater than 0.9950 using all ionization and scan modes. Better MDLs were obtained using the SIM mode in all instances. The SIM mode MDLs ranged as follows: EI 0.308-0.711 and PCI 0.656-1.14 mg/L. Extremely good signals were observed in the NCI mode with dimetridazole and metronidazole where MDLs in the SIM mode were estimated to be 0.057 and 0.062 mg/L. Percent relative standard deviations (n = 3) were all less than 5% using EI employing full and SIM scan modes. Recoveries ranged from 55% to 96% in the full scan mode and from 67% to 94% in the SIM mode. Signal losses and ion population ratios in relation to the number of samples, i.e., scan speed and the mass scan range, are also interrogated.

Microbiological indicators such as Escherichia coli (E. coli) have been extensively applied to monitor sewage contamination in waters and sediments. However, it has been accomplished by many researchers that microorganism indicators of faecal pollution in aquatic environments have limited applicability, owing to their lack of specificity and variable life span induced by environmental factors such as sunlight and chlorination. This review highlights the use of chemical indicators for faecal or sewage pollution monitoring. It highlights that the differences in bile acid distributions in animal faeces could be utilized to differentiate inputs in an environment. Furthermore, the high resistance to degradation by some of the bile acids would make them better suited for long standing pollution compared to coprostanol, as it is more readily degraded. Bile acid data could be used in conjunction with other available evidence, be it ethnographic or as part of a multi-biomarker approach, employing 5-stanols and bacterial indicators, such as C. perfringens, to distinguish amongst the different environmental inputs.

A study employing dispersive solid phase extraction in the form of the quick, easy, cheap, effective, rugged and safe (QuEChERS) method and solid phase microextraction (SPME) for the cleanup of pesticides in plant samples from the Okavango Delta (Botswana) is presented. Concentration levels of aldrin, 1,1-dichloro-2,4-bis(chlorophenyl)ethane (DDD), 1,1-dichloro- 2,2-bis(p-chlorophenyl)ethylene(DDE), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), dieldrin, endosulfan and endrin were investigated using gas chromatography with electron capture detection (GC-ECD) and confirmed with gas chromatography with high resolution time of flight mass spectrometry (GC-TOFMS). Parameters affecting the extraction efficiencies of both tech- niques were optimized. In the absence of CRMs for the plants under investigation, method validation and evaluation of the ex- traction efficiencies were achieved through spiking of Nymphaea nouchali (Tswii) leaves at two concentration levels with trichlorobenzene as an internal standard. Recoveries for both SPME and QuEChERS were in the range 61-95 %. The calibration plots were reproducible and linear (R 2 > 0.995) with limits of detection ranging from 0.102 to 1.693 µg L -1 for all the pesticides. The optimal conditions for QuEChERS and SPME were applied to the extraction of pesticides residues from the edible parts (leaves, roots and/ or stems) of Asparagus africanus, Cleome hirta and Nymphaea nouchali plants. No pesticides were detected in the leaves and stems of all the plants studied. Aldrin and endosulfan were detected in the Nymphaea nouchali roots at concentrations of 3-21 µg kg -1 and 5-3 µg kg -1 , respectively. Pentachlorobenzene (PCB) and hexachlorobenzene (HCB) were also detected but

This work was supported United Nations Development Program – Global Environmental Facility – Small Grants Programme Botswana (UNDP-GEF/SGF-Botswana), Department of Chemistry, University of Botswana main campus as well as the Okavango Research Centre Institute (ORI), Andrew Mellon Foundation and STINT (the Swedish Foundation for International Cooperation in Research and Higher Education, YR2009-7015).

As a result of the new economic order in Africa, scientists face enormous challenges due to an increase in socio and economic activities. Gas chromatography–mass spectrometry (GC–MS) will be expected to play a big role in providing some of the solutions to the challenges. Up to now, applications of GC–MS in Africa have focused on profiling natural products for their chemical composition as seen from the number of papers published between 2005 and 2011, i.e. at approximately 62 % of the total. In order to meet the new challenges, a paradigm shift is suggested in the design of research projects. Some economic activities envisaged to boom are food and beverage production for local consumption and for export to markets in the developed world. To meet the requirements of these markets, monitoring pesticides and metabolites of veterinary drugs and other toxins in food will become paramount. Africa also needs to put stringent environmental monitoring policies in place. This will aid remediation following accidental or intentional spillages of chemicals not benign to the environment.

Uptake for lead, copper, cadmium, nickel and manganese from aqueous solution using the Moringa oleifera seeds biomass (MOSB) and amine-based ligand (ABL) was investigated. Experiments on two synthetic multi-solute systems revealed that MOSB performed well in the biosorption and followed the decreasing orders Pb(II)>Cu(II)>Cd(II)>Ni(II)>Mn(II) and Zn(II)>Cu(II)>Ni(II). The general trend of the heavy metal ions uptake by the amine-based ligand followed decreased in the order Mn>Cd>Cu>Ni>Pb, which is the reverse trend for what was observed for MOSB. Comparing the single- and multi-metal solutions, there was no clear effect in the biosorption capacity of MOSB suggesting the presence of sufficient active binding sites for all metal ions studied. The MOSB performance is also not affected by pH in the range 3.5-8.

Deltamethrin concentrations were determined in 35 sediment samples collected from three different habitats: channel, lagoon and pool sites from Xakanaxa in the Okavango Delta, NW Botswana. The samples were Soxhlet-extracted in acetone to extract deltamethrin residues and subsequently cleaned-up with silica gel 60. The final determination was carried out with a gas chromatograph equipped with an electron capture detector (GC-ECD). The sample work-up and determination gave deltamethrin recoveries of 54 to 97%, and detection limits of 0.004 mg/kg dw. The concentration of deltamethrin residues in the sediment samples collected from the three sprayed areas in the Okavango delta ranged between 0.013 and 0.291 mg/kg dw, with the highest concentrations observed in samples obtained from the pool sites. Analysis of samples for organic matter content showed percentage total organic carbon (%TOC) ranging between 0.19% and 8.21%, with samples collected from the pool having the highest total organic carbon. The concentrations of deltamethrin residues and the %TOC in sediment samples showed a similar trend with the highest levels recorded in the pool samples. These data confirmed that a simple method based on GC-ECD, after Soxhlet extraction, was robust enough to enable quantification of deltamethrin in the sediments, because comparable results were obtained with a more sophisticated system consisting of a GC coupled to a mass spectrometer with a time of flight (TOF) analyser.

The studies of low-molecular-mass carboxylic acids in complex matrices as root exudates and soil liquids are important for the evaluation of their ecological significance and role in pedological processes and chemical reactions. A supported liquid membrane, impregnated with 10% tri-n-octylphosphine oxide in di-n-hexyl ether, was used for selective enrichment of the carboxylic acids in soil samples. The acids were determined by an anion-exchange chromatograph coupled to the enrichment system. A cation-exchange precolumn was found to improve the resolution of the peaks. Two short ion-exchange columns were incorporated into the automatic flow system to remove interfering inorganic ions. Extraction efficiencies in the range 14–75%, depending on the polarity and acidic strength of the analytes, were achieved. The system permits the determination of low-molecular-mass carboxylic acids at micromolar level in the presence of interfering ions such as nitrite, chloride, sulphate, iron and aluminium at the concentration found in authentic samples.