Sample Flow Rate Research Articles

Microextraction on a screw

For the first time, a rapid, efficient, simple, and inexpensive approach for solid phase microextraction on a screw (MES) was developed. MES is a miniaturized form of solid-phase extraction without any backpressure. In this system, analytes were adsorbed on the surface of micro channels of a screw that was coated by polypyrrole (PPy). Based on this procedure, the analytes are adsorbed on the solid phase and then eluted by a desorption solvent. The MES method followed by gas chromatography–mass spectrometry (MES-GC-MS) was applied for the rapid extraction and determination of six polycyclic aromatic hydrocarbons (PAHs) (as model analytes) in well water samples. Several parameters affecting the extraction procedure, including the sampling flow rate, the number of the loading/desorption cycles of the sample, and the volume of the desorption solvent, were evaluated and optimized. Under optimum conditions, the detection limits for the PAHs varied between 0.5 and 1 μg L−1 and linear ranges varied between 2 and 600 μg L−1. The results showed good correlation coefficients (R > 0.99) for all of the analytes in the studied calibration range. The relative recovery (RR%) of the desired MES–GC–MS method for the studied PAHs was between 83.0 and 104.0% and the interday and intraday precision (n = 5 days), expressed as relative standard deviation (RSD %), were between 3.9-6.2% and 6.2–8.9%, respectively. To evaluate the matrix effect, the developed method was also applied for preconcentration and determination of the selected PAHs in real water samples, and good results were obtained.

Surfactant-modified Zn/Al-layered double hydroxides for efficient extraction of alkyl phenols from aqueous samples

Zn/Al-layered double hydroxides (LDHs) modified by sodium dodecylsulfate (SDS) were synthesized as a hydrophobic organic sorbent via urea hydrolysis. LDHs were applied as adsorbent for solid phase extraction (SPE) analysis to determine three alkylphenols (namely, p-tert-amylphenol (PTAP), p-cumylphenol (PCP), and p-n-octylphenol (POP)) in water samples using gas chromatography-mass spectrometry. The extraction efficiency was optimized by adjusting key variables of eluent volume, eluent type, sample flow rate, adsorbent amount, pH, and the effect of salt addition. Under the optimal conditions, APs showed excellent linearity (1–250 ng/mL: R2 > 0.99) and reproducibility (relative standard deviation: <5%). The detection limits for PTAP, PCP, and POP were 19, 16, and 33 pg/mL, respectively. LDHs based SPE method offered high recovery for aqueous samples (e.g., 83.2–99.46%) with enhanced reusability (e.g., up to 10 cycles). The feasibility of the developed method has thus been validated for quantitation of three alkyl phenols (i.e., PTAP, PCP, and POP) in aqueous environmental samples with high sensitivity and good stability.

Column and batch sorption investigations of nickel(II) on extractant-impregnated resin.

Macroporous resin-supported reagents have been identified as potential adsorbents for removal of toxic pollutants. This article presents an experimental designed to evaluate the sorption and desorption of nickel(II) with the help of column and batch procedure using simple extractant-impregnated resin (EIR). Isonitroso-4-methyl-2-pentanone (IMP) as an extractant was impregnated on a solid support like Amberlite XAD-4 to prepare the EIR sorbent. Column experimental conditions such as pH, sample flow rate and volume, eluting solution, and interfering ions were studied to optimize the nickel(II) sorption and recovery from aqueous media. The column results suggest that the quantitative nickel(II) sorption was observed at pH 5-6, and the quantitative recovery (≥ 95%) was achieved by using 1.0 M HNO3. The high concentrations of cations and anions (except EDTA) present in the spiked binary and multi-element mixture solution show no interferences in both quantitative sorption and recovery of nickel(II), whereas the batch experiments were performed to evaluate nickel(II) sorption behavior using the linearized and non-linearized kinetic and isotherm models. By error function analysis, the Freundlich isotherm and the pseudo-first-order kinetic model were found to describe best the experimental data obtained over the studied concentration range and sorption time, respectively. The maximum sorption capacity of nickel(II) onto the EIR sorbent was found to be ~ 81 mg/g. The mean free energy (E = 10.1 kJ/mol) determined using Dubinin-Radushkevich isotherm suggests chemical nature of nickel(II) sorption on EIR. The novelty of the EIR adsorbent lies in its potential for separation and recovery of nickel(II) at trace level in water samples of different origin.

A Miniature Gas Sampling Interface with Open Microfluidic Channels: Characterization of Gas-to-Liquid Extraction Efficiency of Volatile Organic Compounds.

Chemosensory protein based olfactory biosensors are expected to play a significant role in next-generation volatile organic compound (VOC) detection systems due to their ultra-high sensitivity and selectivity. As these biosensors can perform most efficiently in aqueous environments, the detection systems need to incorporate a gas sampling interface for gas-to-liquid extraction. This interface should extract the VOCs from the gas phase with high efficiency and transfer them into the liquid containing biosensors to enable subsequent detection. To design such a transfer interface, an understanding of the key parameters influencing the gas-to-liquid extraction efficiency of target VOCs is crucial. This paper reports a gas sampling interface system based on a microfluidic open-channel device for gas-to-liquid extraction. By using this device as a model platform, the key parameters dictating the VOC extraction efficiency were identified. When loaded with 30 μL of capture liquid, the microfluidic device generates a gas-liquid interface area of 3 cm2 without using an interfacial membrane. The pumpless operation based on capillary flow was demonstrated for capture liquid loading and collection. Gas samples spiked with lipophilic model volatiles (hexanal and allyl methyl sulfide) were used for characterization of the VOC extraction efficiency. Decreasing the sampling temperature to 15 °C had a significant impact on increasing capture efficiency, while variation in the gas sampling flow rate had no significant impact in the range between 40–120 mL min−1. This study found more than a 10-fold increase in capture efficiency by chemical modification of the capture liquid with alpha-cyclodextrin. The highest capture efficiency of 30% was demonstrated with gas samples spiked with hexanal to a concentration of 16 ppm (molar proportion). The approach in this study should be useful for further optimisation of miniaturised gas-to-liquid extraction systems and contribute to the design of chemosensory protein-based VOC detection systems.

Development of Membrane Hollow Fiber for Determination of Maleic Anhydride in Ambient Air as a Field Sampler.

This research develops a rapid method for sampling and analysis of maleic anhydride (MA) in air using a one-step hollow fiber (HF) membrane in the liquid phase followed by high-performance liquid chromatography. A sampling chamber was prepared for sampling of MA with HF-supported de-ionized water absorbency. Several important parameters, such as sampling flow rate, sampling time, and breakthrough volume (BTV), were optimized at different concentrations using a central composite design. The results showed that sampling could be performed at the maximum period of 4 h with a flow rate of 1 mL min-1 for different concentrations (in the range of 0.05-2 mg m-3). The BTV was 240 mL. The relative standard deviations for the repeatability of interday and intraday were 7-10%, 10%, respectively, and the pooled standard deviation was 0.088. The limit of detection and limit of quantitation values were 0.033 and 0.060 mg m-3, respectively. Moreover, our findings revealed that the samples could be stored in sealed HF flexible plastic tubes in a cover at refrigerator temperature (4°C) for up to 7 days. The HF method was compared with method number 3512 National Institute Occupational Safety and Health for determination of MA. There was a good correlation (R2 = 0.99) between the two methods at a concentration of 0.05 to 2 mg m-3 in the laboratory and the average concentration of MA for both methods was 0.11 mg m-3 in the ambient air at an adhesive manufacturer. Our findings indicated that the proposed HF can act as a reliable, rapid, and effective approach for sampling of MA in workplaces.

Modified 3D-printed device for mercury determination in waters

3D printing technology is increasingly used in flow analysis, to develop low cost and tailor-made devices. The possibility of grafting specific molecules onto 3D printed parts offers new perspectives for the development of flow systems. In this study, a MPFS system including a dicarboxylate 1,5-diphenyl-3-thiocarbazone grafted 3D-printed device has been developed for mercury determination. For this purpose, the surface of 3D-printed cuboids was first modified with amine functional groups and then grafted with dicarboxylate 1,5-diphenyl-3-thiocarbazone. This new grafted device resulted in selective mercury preconcentration with extraction and elution yields higher than 90% even at high sampling flow rates. The detection can then be carried out in two ways: a direct detection of mercury extracted onto 3D-printed grafted cuboids by atomic absorption spectrophotometry after amalgam on gold or a detection of mercury in solution after elution with l-cysteine by spectrophotometry or cold vapour atomic absorption spectrometry.

Ozone removal efficiency of the KI-denuder in the carbonyl sampling

In the carbonyl sampling of 2, 4- dinitrophenylhydrazine (DNPH) impregnated cartridge, the ozone removal was necessary because ozone reacted with the DNPH derivatives. A commercial ozone scrubber was usually used to remove O3. However, high humidity leaded to carbonyl compounds being trapped on the ozone scrubber before passing through the DNPH cartridge. The purpose of this study was to assess the ozone removal by KI-denuder under the climatic conditions of Ho Chi Minh City. Several parameters including air sampling flow rate and denuder length were optimized to achieve the highest removal efficiency. The optimum parameters of the KI denuder were the sampling flow rate of less than 1 L/min, and the denuder length of 20 cm. The effect of the initial O3 concentration on the removal efficiency was also investigated. Finally, the ozone removal efficiency of KI-denuder was compared to that of ozone scrubber when two devices were applied for the carbonyl sampling during field measurement. The results show that KI-denuder could be used to replace the ozone scrubber with high removal efficiency, particularly in high humidity condition. In conclusion, KI-denuder was effective, simple, easy to use and cheap. Therefore, it was encouraged to use in carbonyl sampling.

Solid phase extraction and preconcentration of some metal ions using Schiff base immobilised silica gel followed by ICP-OES

ABSTRACTIn this study, a simple and efficient solid phase extraction procedure was developed for simultaneous separation and preconcentration of Ba, Cd, Co, Cu, Mn and Ni. The methodology was based on preconcentration of the target analytes on N,N’-bis(4-methoxysalicylidene)-1,3-propanediamine modified silica gel prior to inductively coupled plasma optic emission spectrometry detection. The experimental conditions were as follows: pH of sample 5.00; sample and eluent flow rates 3 mL min−1; sample volume 25 mL; eluent 0.5 mol L−1 HNO3; eluent volume 3.0 mL. Preconcentration factor was achieved as 33.3 for Ba, Co, Mn; 83.3 for Cd, Ni; 166.7 for Cu. Limits of detection were found as 0.33, 0.26, 0.27, 0.36, 0.27 and 0.19 µg L−1 for Ba, Cd, Co, Cu, Mn and Ni, respectively. The relative standard deviations of 2.6–3.8% were obtained via nine parallel analyses. The suggested procedure was successfully validated by the analysis of TMDA-53.3 Lake Ontario water and ERM-CA022a soft drinking water certified reference materials and applied to various natural water samples.

Исследование &lt;i&gt;in vitro&lt;/i&gt; влияния скорости потока на аэродинамические показатели дозированного аэрозольного ингалятора «Кромоспир»

Изучено влияние изменения скорости потока на аэродинамическое распределение частиц дозированного аэрозольного ингалятора (ДАИ) «Кромоспир» с использованием каскадного импактора Андерсена (КИА) в стандартной конфигурации, предназначенной для анализа при скорости потока 28,3 л/мин, и в модифицированной конфигурации, предназначенной для анализа при скорости потока 60 л/мин. Показано, что изменение скорости потока воздуха, проходящего через импактор, приводит к изменению профиля аэродинамического распределения частиц и значений респирабельной фракции аэрозоля. Рекомендовано при разработке методик оценки качества аэрозолей, а также in vitro сравнении эффективности ДАИ, проведение исследований аэродинамических свойств аэрозолей с моделированием вдоха пациента при различных скоростях потока воздуха.

A new hybrid sorbent 2,2’-pyridil functionalized SBA-15 (Pyl-SBA-15) synthesis and its applications in solid phase extraction of Cu(II) from water samples

A mesoporous hybrid material, 2,2’-Pyridil-SBA-15 (Pyl-SBA-15) was synthesized by anchoring 2,2’-Pyridil onto the surface of SBA-15. The application of Pyl-SBA-15 as a sorbent in separation and preconcentration of Cu(II) ions in water samples was studied. Effect of different parameters like pH, volume of eluent, sample flow rate and interfering ions was investigated. The preconcentration capacity value of the prepared material under optimized conditions for Cu(II) was 0.88 ± 0.01 mmol g−1. The Cu(II) ions collected onto the sorbent were eluted out with 6 mL of 1 M HNO3 and determined by atomic absorption spectroscopy (AAS). The enrichment factor and detection limit of Cu(II) were found to be 66.6 and 0.38 μg L-1 respectively.

A novel method for the simultaneous determination of Pb (II), Cd (II) and Zn (II) in environmental water samples

ABSTRACTA novel UV-VIS spectrophotometric method was developed in this study by using solid phase extraction procedure for the simultaneous preconcentration, separation and determination of trace levels of Pb (II), Cd (II) and Zn (II) ions in various water samples by using Amberlite N,N-bis(salicylidene)cyclohexanediamine (SCHD) resin. This study presents the results of experimental procedures carried out like the adsorption of analytes to the resin, influences of some analytical parameters that effect the recovery such as pH, sample volume, sample flow rate, eluent type and concentration, eluent volume, eluent flow rate and the effects of alkaline metals, earth alkaline metals and some other transition metals. The analytes in the samples with the adjusted pH range of 4–7 were adsorbed on XAD-4-SCHD resin and eluted by using 1.0 mol L−1 nitric acid. The amounts of ions were determined by using UV-VIS spectrometer. The limits of detection were 0.03, 0.07 and 0.05 µg mL−1 for Pb (II), Cd (II) and Zn (II), respectively. The accuracy of the method was assured by the analysis of the certified standard water sample NW-TMDA-70.2 and the observed recoveries were above 93%. Different environmental water samples that contain trace amounts of Pb (II), Cd (II) and Zn (II) were analysed by using the method developed in this study. Same samples were also analysed by ICP-MS for comparison and almost the similar results were observed. The method developed in this study was successfully applied to the various environmental water samples to determine the trace levels of Pb (II), Cd (II) and Zn (II) ions.

Experimental and numerical study of elasto-inertial focusing in straight channels.

Elasto-inertial microfluidics has drawn significant attention in recent years due to its enhanced capabilities compared to pure inertial systems in control of small microparticles. Previous investigations have focused mainly on the applications of elasto-inertial sorting, rather than studying its fundamentals. This is because of the complexity of simulation and analysis, due to the presence of viscoelastic force. There have been some investigative efforts on the mechanisms of elasto-inertial focusing in straight channels; however, these studies were limited to simple rectangular channels and neglected the effects of geometry and flow rates on focusing positions. Herein, for the first time, we experimentally and numerically explore the effects of elasticity accompanying channel cross-sectional geometry and sample flow rates on the focusing phenomenon in elasto-inertial systems. The results reveal that increasing the aspect ratio weakens the elastic force more than inertial force, causing a transition from one focusing position to two. In addition, they show that increasing the angle of a channel corner causes the elastic force to push the particles more efficiently toward the center over a larger area of the channel cross section. Following on from this, we proposed a new complex straight channel which demonstrates a tighter focusing band compared to other channel geometries. Finally, we focused Saccharomyces cerevisiae cells (3-5 μm) in the complex channel to showcase its capability in focusing small-size particles. We believe that this research work improves the understanding of focusing mechanisms in viscoelastic solutions and provides useful insights into the design of elasto-inertial microfluidic devices.

MEASUREMENT OF AMBIENT CARBON-14 BY USING THE GEL SUSPENSION COUNTING METHOD.

For monitoring the ambient 14C, the CaCO3 suspension counting method was established in this work. In the preparation of CaCO3 powder, a two-stage sampler with 3 mol L-1 NaOH absorbent was designed to collect the ambient CO2 at a sampling flow rate of 1 L min-1, and then the CaCO3 was precipitated by adding saturated CaCl2 solution. By using 2 g of CaCO3 powder, 4 mL double-distilled water and 14 mL scintillation cocktail, the lower limit detection could reach 20.0 mBq m-3 by using a commercially available low background liquid scintillation counter. Co-comparison experiments showed that the activity concentration of 14C measured by the gel suspension counting method consisted well with the results of other three methods. It indicates that the CaCO3 suspension counting method is also a practical method for routine monitoring of ambient 14C.

Graphene oxide as an efficient adsorbent of solid-phase extraction for online preconcentration of inorganic and organic mercurials in freshwater followed by HPLC-ICP-MS determination

For the past several decades, lots of adsorbent nanomaterials have been adopted for the enrichment of mercuric compounds. In this paper, graphene oxide bounded silica particles were employed as the absorbent for online preconcentration of Hg(II), methylmercury (MeHg) and ethylmercury (EtHg) by solid phase extraction. The adsorbent offered satisfactory adsorption capacities of 40.7 for Hg(II), 91.4 for MeHg and 103.8 mg g−1 for EtHg. Enrichment conditions such as type, concentration and volume of conditioning and eluting reagents were optimized. The pH, volume and flow rate of sample were also optimized. High enrichment factors (1963, 1881 and 1794 for Hg(II), MeHg and EtHg, respectively) were obtained with 10 mL sample (adjusted to pH 4–7) at 10 mL min−1 flow rate, 5 μL of 10 mM benzoic acid for elution and 4 mL of 1 mM 4-phenyl-3-aminothiourea for preconditioning. The detection limits obtained were downscaled to be 0.005 for Hg(II), 0.006 for MeHg and 0.009 ng L−1 for EtHg with relative standard deviations of all the analytes below 5%. Standard reference material and spiked water samples were analyzed for validating the method with satisfactory recoveries of 89–106%. The present method was successfully applied to determine mercury compounds in drinking water, and river and tap water, in which Hg(II), MeHg and EtHg were presented below the China's drinking standard limit of 1 μg L−1.

Application of a low-cost water level circuit for an accurate pulse detection of a tipping-bucket rain gauge as an alternative method for reed switch sensors.

This paper introduces a data acquisition mechanism working on similar functionality to that of conventional tipping-bucket rain gauge (TBRG) but unaffected from magnetic and electromagnetic interferences. Unlike the common reed switch application, the mechanism of this study only uses a two-wire water level sensor for tip detection. Specifically, a different method of detecting the tipping count of the rain gauge through a switching type scheme is introduced without using the conventional magnetic detection concept. The designed electronic two-wire TBRG has so many features, with its low-cost and its resistance to metallic or electromagnetic interference the most important. The sensor design makes the circuit assembly applicable to any cylindrical or cube-type rain gauge sizes. The only important thing to properly mount is the placement of the wire contacts. A bottom-feed design was implemented in this study. The RI approximation resulted in relative errors - 5%, - 3.27%, and - 4.73 from the sample flow rates 11mL/min, 32mL/min, and 57mL/min respectively. Underestimations of 0.09mL (approximately 0-mm water depth), 2.48mL (0.45mm), and 5.65mL (1.03mm) were recorded from calculating the tips made without the calibrating algorithms from the 10-mL, 40-mL, and 70-mL samples respectively. Although it proves its measuring ability through its slight underestimation results, the hardware and its corresponding mechanism have proven reliable in accordance with its functionality. The measuring performance of the device proved that it has the capability to work in similar to the conventional TBRG.

Time-integrated thermal desorption for quantitative SIFT-MS analyses of atmospheric monoterpenes.

A new time-integrated thermal desorption technique has been developed that can be used with selected ion flow tube mass spectrometry, TI-TD/SIFT-MS, for off-line quantitative analyses of VOCs accumulated onto sorbents. Using a slow desorption temperature ramp, the absolute amounts of desorbed compounds can be quantified in real time by SIFT-MS and constitutional isomers can be separated. To facilitate application of this technique to environmental atmospheric monitoring, method parameters were optimised for quantification of the three common atmospheric monoterpenes: β-pinene, R-limonene and 3-carene. Three sorbent types, Tenax TA, Tenax GR and Porapak Q, were tested under 26 different desorption conditions determined by the "design of experiment", DOE, systematic approach. The optimal combination of type of sorbent, bed length, sampling flow rate, sample volume and the initial desorption temperature was determined from the experimental results by ANOVA. It was found that Porapak Q exhibited better efficiency of sample collection and further extraction for total monoterpene concentration measurements. On the other hand, Tenax GR or TA enabled separation of all three monoterpenes. The results of this laboratory study were tested with the sample accumulated from a branch of a Pinus nigra tree. Graphical abstract.

A novel aptamer-based online magnetic solid phase extraction method for simultaneous determination of urinary 8-hydroxy-2′-deoxyguanosine and monohydroxylated polycyclic aromatic hydrocarbons

In this work, an innovative aptamer-based magnetic adsorbent (Fe3O4@PDA-aptamer MNPs) was prepared by hydrothermal synthesis method followed by the surface functionalization of nanoparticles. After fixing in a steel stainless tube as sorbent of magnetic solid phase extraction (MSPE), an online magnetic solid phase extraction-high performance liquid chromatography-mass spectrometry (online-MSPE-HPLC-MS) method was developed and applied for the determination of 8-hydroxy-2′-deoxyguanosine (8-OHdG) and monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) simultaneously in urine. The synthesized sorbent presented outstanding features, including large specific surface area, high enrichment capacity and excellent stability. High throughput analysis can be achieved by affinity-specific adsorption of 8-OHdG and non-specific adsorption of OH-PAHs at the same time. In addition, online MSPE can greatly simplify the analysis process, reduce human errors and enhance the sensitivity. When compared with offline MSPE, a sensitivity enhancement of 30–400 times was obtained for the online method. Some experimental parameters such as the amount of the sorbent, sampling flow rate and sample volume, were optimized systematically. Under the optimal conditions, the limits of detection (LOD) were in the range of 0.028–0.114 ng mL−1, and the correlation coefficients (R2) were higher than 0.9962. The relative standard deviations (RSDs) were less than 16.1% (n = 5) and the recoveries ranged from 71% to 116%. The above results show that the rapid, sensitive and automated online-MSPE-HPLC-MS method has potential application in the simultaneous determination of 8-OHdG and PAHs in complex sample matrix to assess the environmental exposure level.

Effect of baking soda solution on saliva properties in a group of children: A Randomized control trial

Aim: To measure the effect of baking soda oral rinse on saliva properties of active caries and caries free childrenMethods: This is a randomized controlled clinical study with a sample of 96 children with mean age 10.4 years old selected and divided into two main groups; group (1) include 48 children with active caries and group (2) include 48 caries free children. Saliva samples were taken at baseline and after drinking sugary juice then all children were further divided randomly from each group into two subgroups. Group A: (test) include 24 children rinsed using Baking Soda 2% and Group B: (control) include 24 children rinsed using distilled water. Flow rate, pH and buffer capacity of saliva samples were measured after rinsing with distilled water or BS. The group comparison was done using Student’s t-test. A value of PResults: After rinsing with BS the pH, flow rate and buffer capacity of saliva were increased than rinsing with distilled water in both caries free and caries active children.Conclusion: BS 2% solution enhances the pH, flow rate and buffer capacity of saliva compared to distilled water if rinsed directly after a significant drop in saliva properties followed by sugar consumption.

A microchip device to enhance free flow electrophoresis using controllable pinched sample injections

Micro free flow electrophoresis (µFFE) is a valuable technique capable of high throughput rapid microscale electrophoretic separation along with mild operating conditions. However, the stream flow separation nature of free flow electrophoresis affects its separation performance with additional stream broadening due to sample stream deflection. To reduce stream broadening and enhance separation performance of µFFE, we presented a simple microfluidic device that enables injection bandwidth control. A pinched injection was formed in the reported µFFE system using operating buffer at sample flow rate ratio (r) setting. Initial bandwidth at the entrance of separation chamber can be shrunk from 800 to 30µm when r increased from 1 to 256. Stream broadening at the exit of separation chamber can be reduced by about 96% when r increased from 4 to 128, according to both theoretical and experimental results. Moreover, the separation resolution for a dye mixture was enhanced by a factor of 4 when r increased from 16 to 128, which corresponded to an 80% reduction in sample initial bandwidth. Furthermore, a similar enhancement on amino acids separation was obtained by using injection control in the reported µFFE device and readily integrated into online/offline sample preparation and/or downstream analysis procedures.

Investigation of the conditions for selenium determination by photochemical vapor generation coupled to graphite furnace atomic absorption spectrometry

In this study instrumental parameters and sample preparation methods for Se determination using photochemical vapor generation (PVG) coupled to graphite furnace atomic absorption spectrometry (GF AAS) were investigated. Coconut water was selected as sample due to its nutritional importance and matrix complexity. The PVG was performed in a flow injection mode. The Se volatile species, generated in the UV reactor, were separated from the condensed phase in a gas-liquid separator and introduced automatically in the graphite furnace. These species were trapped on the integrated graphite platform surface coated with Ir as permanent modifier. The PVG conditions such as concentration of low molecular weight organic compound (LMWC), sample and carrier gas flow rate, effect of reagents frequently used in sample preparation (HNO3 and H2O2) were investigated. Formic acid 0.44 mol L−1 was selected as LMWC. The addition of HNO3 (14 mmol L−1) and H2O2 (145 mmol L−1) increased the sensitivity. Pre-reduction of Se (VI) to Se (IV) was performed on-line in a quartz spiral tube coated with a thin film of TiO2. The insertion of Ar flow rate (115 mL min−1) before the reactor inlet has improved the sensitivity, comparing with the introduction of Ar after the reactor. UV-assisted photo-oxidation of coconut water samples was employed as an alternative sample preparation to avoid the NO3−/NO2−, and H2O2 interference. The figures of merit were: sensitivity 0.0680 s ng−1, limits of detection and quantification 0.65 μg L−1 and 2.2 μg L−1, respectively, and characteristic mass of 62 pg. The PVG efficiency was estimated as 79% when comparing with conventional hydride generation. Furthermore, a mass balance study was accomplished in order to identify possible analyte losses in the PVG system, which the overall recovery was up to 85%. The results of recovery tests accomplished with real samples of coconut waters varied between 80 and 103% for Se (IV), Se (VI), and selenomethionine.