Real-time bioelectronic sensing of environmental contaminants.

Real-time chemical sensing is crucial for applications in environmental and health monitoring1. Biosensors can detect a variety of molecules through genetic circuits that use these chemicals to trigger the synthesis of a coloured protein, thereby producing an optical signal2-4. However, the process of protein expression limits the speed of this sensing to approximately half an hour, and optical signals are often difficult to detect in situ5-8. Here we combine synthetic biology and materials engineering to develop biosensors that produce electrical readouts and have detection times of minutes. We programmed Escherichia coli to produce an electrical current in response to specific chemicals using a modular, eight-component, synthetic electron transport chain. As designed, this strain produced current following exposure to thiosulfate, an anion that causes microbial blooms, within 2 min. This amperometric sensor was then modified to detect an endocrine disruptor. The incorporation of a protein switch into the synthetic pathway and encapsulation of the bacteria with conductive nanomaterials enabled the detection of the endocrine disruptor in urban waterway samples within 3 min. Our results provide design rules to sense various chemicals with mass-transport-limited detection times and a new platform for miniature, low-power bioelectronic sensors that safeguard ecological and human health.

Determinação do período de estabilidade de soluções volumétricas rotineiramente utilizadas em laboratórios de análises químicas / Determination of the stability period of volumetric solutions routinely used in chemical analysis laboratories / Determinación del período de estabilidad de las soluciones volumétricas utilizadas habitualmente en los laboratorios de análisis químicos

As soluções volumétricas são rotineiramente utilizadas nos laboratórios, principalmente nos processos de síntese de produtos e nas análises quantitativas de matéria-prima e/ou produto acabado, entretanto poucos são os estudos que abordam a estabilidade destas soluções. Considerando que a qualidade das soluções volumétricas pode afetar os procedimentos de análises químicas e consequentemente induzir a erros, e ainda que, a Farmacopeia Brasileira (2010) não cita tempo máximo de utilização dessas soluções padronizadas, a avaliação da estabilidade das mesmas é importante. Sendo assim, o objetivo do trabalho foi avaliar a estabilidadede 10 soluções volumétricas, empregadas rotineiramente em laboratórios de análises químicas, com o intuito de estabelecer o período que essas soluções permanecem estáveis, isto é, sem sofrer alteração na concentração. As metodologias de preparo e padronização das soluções volumétricas seguiram os métodos descritos na Farmacopeia Brasileira (2010), sendo as mesmas padronizadas no momento do preparo e a cada 20 dias, por um período de 180 dias. As soluções contendo ácidos e bases, bem como as soluções de iodato de potássio e nitrato de prata, permaneceram constantes durante o período de análises. As soluções de EDTA, iodo, nitrito de sódio, permanganato de potássio e tiossulfato de sódio apresentaram estabilidade inferior a 180 dias, tornando necessária a realização de padronização periódica. As soluções volumétricas utilizadas nos laboratórios apresentam diferentes estabilidades, o que ressalta a importância da determinação do período que as mesmas se mantêmcom as concentrações estáveis, evitando possíveis alterações de resultados nas análises químicas.

Volumetric solutions are routinely used in laboratories, mainly in product synthesis processes and in quantitative analyzes of raw materials and/or finished products, however there are few studies that address the stability of these solutions. Considering that the quality of volumetric solutions can affect chemical analysis procedures and consequently induce errors, and even though the Brazilian Pharmacopoeia (2010) does not mention the maximum time for using these standardized solutions, the evaluation of their stability is important. Therefore, the aim of this work was to evaluate the stability of 10 volumetric solutions, routinely used in chemical analysis laboratories, in order to establish the period that these solutions remain stable without changing their concentrations. The methodologies for preparing and standardizing the volumetric solutions followed the methods described in the Brazilian Pharmacopoeia (2010), being standardized at the time of preparation and every 20 days, for a period of 180 days. Solutions containing acids and bases, as well as potassium iodate and silver nitrate solutions, were stable during the analysis period. The solutions of EDTA, iodine, sodium nitrite, potassium permanganate and sodium thiosulfate showed stability less than 180 days, making it necessary to carry out periodic standardization of these solutions. The volumetric solutions used in the laboratories have different stabilities, which highlights the importance of determining the period in which they remain stable, avoiding possible changes in results in chemical analyzes.

Las soluciones volumétricas se utilizan de forma rutinaria en los laboratorios, principalmente en los procesos de síntesis de productos y en el análisis cuantitativo de materias primas y/o productos acabados. Sin embargo, existen pocos estudios que aborden la estabilidad de estas soluciones. Considerando que la calidad de las soluciones volumétricas puede afectar los procedimientos de análisis químico y consecuentemente inducir a errores, y también que, la Farmacopea Brasileña (2010) no menciona el tiempo máximo de uso de estas soluciones estandarizadas, la evaluación de su estabilidad es importante. Así, el objetivo del trabajo fue evaluar la estabilidad de 10 soluciones volumétricas, utilizadas rutinariamente en los laboratorios de análisis químico, con el fin de establecer el período en que estas soluciones permanecen estables, es decir, sin sufrir alteraciones en la concentración. Las metodologías de preparación y estandarización de las soluciones volumétricas siguieron los métodos descritos en la Farmacopea Brasileña (2010), siendo las mismas estandarizadas en el momento de la preparación y cada 20 días, por un período de 180 días. Las soluciones que contienen ácidos y bases, así como las soluciones de yodato de potasio y nitrato de plata, permanecieron constantes durante el periodo de análisis. Las soluciones de EDTA, yodo, nitrito de sodio, permanganato de potasio y tiosulfato de sodio fueron estables durante menos de 180 días, por lo que fue necesario realizar estandarizaciones periódicas. Las soluciones volumétricas utilizadas en los laboratorios presentan diferentes estabilidades, lo que pone de manifiesto la importancia de determinar el periodo que permanecen con concentraciones estables, evitando posibles cambios en los resultados en los análisis químicos.

Solid-state and solution characterizations of [(TMPA)Cu(II)(SO3)] and [(TMPA)Cu(II)(S2O3)] complexes: Application to sulfite and thiosulfate fast detection.

Sulfite (SO32-) and thiosulfate (S2O32-) ions are used as food preservative and antichlor agent respectively. To detect low levels of such anions we used Cu(II) complex of the Tris-Methyl Pyridine Amine (TMPA) ligand, denoted L. Formation of [LCu(SO3)] (1) and [LCu(S2O3)] (2) in solution were monitored using UV-Vis, EPR and cyclic voltammetry, while the solid-state X-ray structures of both complexes were solved. In addition, we also evaluated the pH range in which the complexes are stable, and the anions binding affinity values for the [LCu(solvent)]2+ (3) parent complex. As a matter of illustration, we determined the sulfite content in a commercial crystal sugar.

Fatal poisoning of four workers in a farm: Distribution of hydrogen sulfide and thiosulfate in 10 different biological matrices.

We evaluate the distribution of sulfide and thiosulfate (TS) in biological samples of four dairy farmers died inside a pit connected to a manure lagoon. Autopsies were performed 4 days later. Toxicological analyses of sulfide and TS were made using an extractive alkylation technique combined with gas chromatography/mass spectrometry (GC/MS). Autopsies revealed: multiorgan congestion; pulmonary edema; manure inside distal airways of three of the four victims. Sulfide concentrations were cardiac blood: 0.5-3.0 µg/mL, femoral blood: 0.5-1.2 µg/mL, bile: <0.1-2.2 µg/mL; liver 2.8-8.3 µg/g, lung: 5.0-9.4 µg/g, brain: 2.7-13.9 µg/g, spleen: 3.3-6.3 µg/g, fat: <0.1-1.5 µg/g, muscle: 2.6-3.5 µg/g. TS concentrations were cardiac blood: 2.1-4.9 µg/mL, femoral blood: 2.1-2.3 µg/mL, bile: 2.5-4.4 µg/mL, urine: <0.5-1.8 µg/mL; liver <0.5-2.6, lung: 2.8-5.4 µg/g, brain: <0.5-1.9 µg/g, spleen: 1.2-2.9 µg/g, muscle: <0.5-5.6 µg/g. The cause of death was assessed to be acute poisoning by hydrogen sulfide (H2S) for all the victims. Manure inhalation contributed to the death of three subjects. The measurement of sulfide and TS concentrations in biological samples contributed to better understand the sequence of the events. Subjects 3 provided the highest concentration of sulfide in brain, thus, supporting the hypothesis of a rapid loss of consciousness and respiratory depression. One by one, the other farmers entered the pit in attempts to rescue the coworkers but collapsed. Despite the rapid death, subject 3 was the only one with TS detectable in urine. This could be due to differences in metabolism of H2S.

Phosphatase activity tunes two-component system sensor detection threshold.

Two-component systems (TCSs) are the largest family of multi-step signal transduction pathways in biology, and a major source of sensors for biotechnology. However, the input concentrations to which biosensors respond are often mismatched with application requirements. Here, we utilize a mathematical model to show that TCS detection thresholds increase with the phosphatase activity of the sensor histidine kinase. We experimentally validate this result in engineered Bacillus subtilis nitrate and E. coli aspartate TCS sensors by tuning their detection threshold up to two orders of magnitude. We go on to apply our TCS tuning method to recently described tetrathionate and thiosulfate sensors by mutating a widely conserved residue previously shown to impact phosphatase activity. Finally, we apply TCS tuning to engineer B. subtilis to sense and report a wide range of fertilizer concentrations in soil. This work will enable the engineering of tailor-made biosensors for diverse synthetic biology applications.

Determination of Total Sulfur, Sulfate, Sulfite, Thiosulfate, and Sulfolipids in Plants.

In response to oxidative stress the biosynthesis of the ROS scavenger, glutathione is induced. This requires the induction of the sulfate reduction pathway for an adequate supply of cysteine, the precursor for glutathione. Cysteine also acts as the sulfur donor for the sulfuration of the molybdenum cofactor, crucial for the last step of ABA biosynthesis. Sulfate and sulfite are, respectively, the precursor and intermediate for cysteine biosynthesis and there is evidence for stress-induced sulfate uptake and further downstream, enhanced sulfite generation by 5'-phosphosulfate (APS) reductase (APR, EC 1.8.99.2) activity. Sulfite reductase (SiR, E.C.1.8.7.1) protects the chloroplast against toxic levels of sulfite by reducing it to sulfide. In case of sulfite accumulation as a result of air pollution or stress-induced premature senescence, such as in extended darkness, sulfite can be oxidized to sulfate by sulfite oxidase. Additionally sulfite can be catalyzed to thiosulfate by sulfurtransferases or to UDP-sulfoquinovose by SQD1, being the first step toward sulfolipid biosynthesis.Determination of total sulfur in plants can be accomplished using many techniques such as ICP-AES, high-frequency induction furnace, high performance ion chromatography, sulfur combustion analysis, and colorimetric titration. Here we describe a total sulfur detection method in plants by elemental analyzer (EA). The used EA method is simple, sensitive, and accurate, and can be applied for the determination of total S content in plants.Sulfate anions in the soil are the main source of sulfur, required for normal growth and development, of plants. Plants take up sulfate ions from the soil, which are then reduced and incorporated into organic matter. Plant sulfate content can be determined by ion chromatography with carbonate eluents.Sulfite is an intermediate in the reductive assimilation of sulfate to the essential amino acids cysteine and methionine, and is cytotoxic above a certain threshold if not rapidly metabolized and can wreak havoc at the cellular and whole plant levels. Plant sulfite content affects carbon and nitrogen homeostasis Therefore, methods capable of determining sulfite levels in plants are of major importance. Here we present two robust laboratory protocols which can be used for sulfite detection in plants.Thiosulfate is an essential sulfur intermediate less toxic than sulfite which is accumulating in plants in response to sulfite accumulation. The complexity of thiosulfate detection is linked to its chemical properties. Here we present a rapid, sensitive, and accurate colorimetric method based on the enzymatic conversion of thiosulfate to thiocyanate.The plant sulfolipid sulfoquinovosyldiacylglycerol (SQDG) accounts for a large fraction of organic sulfur in the biosphere. Aside from sulfur amino acids, SQDG represents a considerable sink for sulfate in plants and is the only sulfur-containing anionic glycerolipid that is found in the photosynthetic membranes of plastids. We present the separation of sulfolipids from other fatty acids in two simple ways: by one- and two-dimensional thin-layer chromatography.

Engineering bacterial thiosulfate and tetrathionate sensors for detecting gut inflammation.

There is a groundswell of interest in using genetically engineered sensor bacteria to study gut microbiota pathways, and diagnose or treat associated diseases. Here, we computationally identify the first biological thiosulfate sensor and an improved tetrathionate sensor, both two-component systems from marine Shewanella species, and validate them in laboratory Escherichia coli Then, we port these sensors into a gut-adapted probiotic E. coli strain, and develop a method based upon oral gavage and flow cytometry of colon and fecal samples to demonstrate that colon inflammation (colitis) activates the thiosulfate sensor in mice harboring native gut microbiota. Our thiosulfate sensor may have applications in bacterial diagnostics or therapeutics. Finally, our approach can be replicated for a wide range of bacterial sensors and should thus enable a new class of minimally invasive studies of gut microbiota pathways.

An optical material for the detection of trace S2O32- in milk based on a copper complex.

A novel S2O32- luminescent sensor (Cu2+-p-CPIP) was developed and the presence of S2O32- caused an obvious fluorescence enhancement at 420 nm upon excitation at 330 nm, which could be distinguished with the naked eye under a UV lamp. Remarkably, the compound exhibited excellent selective and sensitive response to S2O32- over other common anions with a micromolar limit of detection (0.442 µM) in DMSO/H2O (v/v, 1:1) buffer. The absorbance intensity and the color of Cu2+-p -CPIP solution changed gradually with the increase of S2O32- concentration. The proposed method was applied to the determination of S2O32- in milk samples and the recoveries were 97.5-105%. The preparation of Cu2+-p -CPIP exhibited the quick, simple and facile advantages. The results showed that Cu2+-p -CPIP can be a good candidate for simple, rapid and sensitive colorimetric detection of S2O32- in aqueous solution.

Mechanisms of hydrogen sulfide removal by ground granulated blast furnace slag amended soil.

Ground granulated blast furnace slag (GGBS) amended soil has been found able to remove gaseous hydrogen sulfide (H2S). However, how H2S is removed by GGBS amended soil and why GGBS amended soil can be regenerated to remove H2S are not fully understood. In this study, laboratory column tests together with chemical analysis were conducted to investigate and reveal the mechanisms of H2S removal process in GGBS amended soil. Sulfur products formed on the surface of soil particle and in pore water were quantified. The test results reveal that the reaction between H2S and GGBS amended soil was a combined process of oxidation and acid-base reaction. The principal mechanism to remove H2S in GGBS amended soil was through the formation of acid volatile sulfide (AVS), elemental sulfur and thiosulfate. Soil pH value decreased gradually during regeneration and reuse cycles. It is found that the AVS plays a significant role in H2S removal during regeneration and reuse cycles. Adding GGBS increased the production of AVS and at the same time suppressed the formation of elemental sulfur. This mechanism is found to be more prominent when the soil water content is higher, leading to increased removal capacity.

Testing the degradation effects of three reagents on various antineoplastic compounds.

OBJECTIVE: Studies for decontamination of antineoplastic compounds have been conducted for decades. Nevertheless, recent studies indicate the contamination of work place in hospitals, and the exposure of workers. In this study, to develop an effective cleaning method for contaminated environments, the degradation efficacies of antineoplastic compounds by reagents were evaluated. METHODS: The degradation efficacies of various combinations of three reagents (sodium hypochlorite, sodium thiosulfate, and sodium hydroxide) were evaluated with four antineoplastic compounds (cyclophosphamide, epirubicin, cisplatin, and carboplatin). The residues of antineoplastic compounds were measured with high-performance liquid chromatography. RESULTS: Of the three reagents, sodium hypochlorite was the most effective to all antineoplastic compounds used in this study. Although sodium hypochlorite degraded 86.6% of cyclophosphamide, it degraded other three antineoplastic compounds completely. The combination with sodium hypochlorite and sodium thiosulfate degraded only 3.3% of cyclophosphamide, since sodium thiosulfate inhibited the degradation ability of sodium hypochlorite. Similarly, the combinations used in all three reagents failed to degrade cyclophosphamide. CONCLUSION: Although three of four antineoplastic compounds were degraded successfully, any combinations of three reagents could not degrade cyclophosphamide completely. However, the addition of sodium thiosulfate which inhibits the corrosion of metal by sodium hypochlorite is essential for daily cleaning. Therefore, the evaluation of reaction time before the addition of sodium thiosulfate may be required. We will continue to investigate the reagents for degradation.

A fatal work-related poisoning by hydrogen sulfide: report on a case.

Hydrogen sulfide (H2S) is a colorless and potentially deadly gas that may cause rapid loss of consciousness and respiratory depression without warning. Although occupational exposure to H2S and the medical management of H2S-associated toxicity are widely established, it remains a problem in the sour gas industry and in other industrial settings, predominantly in new workers. In this article, the authors report a fatal case of a factory worker who died after breathing in H2S while undertaking a task that he was not trained to perform. Toxicological assessment supported by autopsy findings and circumstantial data was essential to clarify the cause of death, determined as H2S poisoning. This case emphasizes the need to develop work safety initiatives, improve on-the-job training, and introduce more consciousness to put on protective equipment for workers; indeed, correct training and education for workers regarding safety in the workplace may help to reduce worker fatalities.

Micro coulometric titration in a liquid drop.

Miniaturized coulometric titration in a liquid drop has been investigated. Assays of ascorbic acid and thiosulfate with iodine titration were chosen as models. Constant volumes of falling liquid drops containing sample or reagent are manipulated via gravimetrical force to move along a slope hydrophobic path and directed to stop or to move out from an electrode. Such manipulation is useful for delivery of sample and reagents, in a way of flow without tubing. Electrochemical generation of titrant, in this case, iodine, is started at the electrode and micro coulometric titration can be performed in a drop by applying constant current. Timing in the titration can be made via naked eye with a stopwatch or via recording with a webcam camera connecting to a computer to detect the change due to the blue color complex of the excess iodine and starch.

Effect of ethanol addition on the determination of thiosulfate based on reduction of Ce(IV) and fluorescence detection of Ce(III).

The effect of ethanol addition on the determination of thiosulfate based on the reduction of Ce(IV) and fluorescence detection of Ce(III) was investigated by flow-injection analysis. It was found that the sensitivity of thiosulfate detection was significantly increased by injecting thiosulfate into a mixed solution of Ce(IV) and ethanol, rather than a solution of Ce(IV) alone. This is probably due to trace amounts of thiosulfate accelerating the rate of reduction of Ce(IV) by ethanol: Ce(IV) is slowly reduced by ethanol in the absence of thiosulfate, and thiosulfate serves as a catalyst to the reduction. The detection limits as S/N = 3 for thiosulfate were very low (10(-9) M level).

Sulfidogenesis in hypersaline chloride-sulfate lakes of Kulunda Steppe (Altai, Russia).

The activity and culturable diversity of sulfidogens were investigated in anoxic sediments of four hypersaline lakes with pH 7.6-8.2 in the Kulunda Steppe (Altai, Russia). Sulfate reduction rates were low, varying from 0.1 to 6.0 nmol HS(-) /(cm(3) h) with a maximum in the top 10 cm layer. Potential sulfidogenic rates with thiosulfate and sulfur as the e-acceptors were higher than with sulfate and were stimulated by formate, lactate, and acetate. Sulfidogenesis was optimal at salt concentrations below 2 M NaCl. Cultivation at 2 M NaCl resulted in the isolation of several strains of moderately halophilic SRB, but no growth of SRB was observed at 4 M NaCl. At lithotrophic conditions (i.e., with formate or H(2) as e-donors), several closely related alkalitolerant strains belonging to the genus Desulfonatronovibrio were isolated. Enrichments at heterotrophic conditions with lactate, propionate, acetate, or butyrate using sulfate or thiosulfate as e-acceptors yielded isolates related to Desulfosalsimonas propionicica, Desulfohalobium utahense, and Desulfocella halophila. Sulfur-reducing enrichments at 2 M NaCl with ethanol produced a member of the genus Halanaerobium, while enrichments at 4 M NaCl with acetate were dominated by archaea, demonstrating for the first time such type of catabolism in haloarchaea.

Operational aspects of the desulfurization process of energy gases mimics in biotrickling filters.

Biological removal of reduced sulfur compounds in energy-rich gases is an increasingly adopted alternative to conventional physicochemical processes, because of economical and environmental benefits. A lab-scale biotrickling filter reactor for the treatment of high-H(2)S-loaded gases was developed and previously proven to effectively treat H(2)S concentrations up to 12,000 ppm(v) at gas contact times between 167 and 180 s. In the present work, a detailed study on selected operational aspects affecting this system was carried out with the objective to optimize performance. The start-up phase was studied at an inlet H(2)S concentration of 1000 ppm(v) (loading of 28 g H(2)S m(-3) h(-1)) and inoculation with sludge from a municipal wastewater treatment plant. After reactor startup, the inlet H(2)S concentration was doubled and the influence of different key process parameters was tested. Results showed that there was a significant reduction of the removal efficiency at gas contact times below 120 s. Also, mass transfer was found to be the main factor limiting H(2)S elimination, whereas performance was not influenced by the bacterial colonization of the packed column after the initial startup. The effect of gas supply shutdowns for up to 5 days was shown to be irrelevant on process performance if the trickling liquid recirculation was kept on. Also, the trickling liquid velocity was investigated and found to influence sulfate production through a better use of the supplied dissolved oxygen. Finally, short-term pH changes revealed that the system was quite insensitive to a pH drop, but was markedly affected by a pH increase, affecting both the biological activity and the removal of H(2)S. Altogether, the results presented and discussed herein provide new insight and operational data on H(2)S removal from energy gases in biotrickling filters.

Toxicological analysis of 17 autopsy cases of hydrogen sulfide poisoning resulting from the inhalation of intentionally generated hydrogen sulfide gas.

Although many cases of fatal hydrogen sulfide poisoning have been reported, in most of these cases, it resulted from the accidental inhalation of hydrogen sulfide gas. In recent years, we experienced 17 autopsy cases of fatal hydrogen sulfide poisoning due to the inhalation of intentionally generated hydrogen sulfide gas. In this study, the concentrations of sulfide and thiosulfate in blood, urine, cerebrospinal fluid and pleural effusion were examined using GC/MS. The sulfide concentrations were blood: 0.11-31.84, urine: 0.01-1.28, cerebrospinal fluid: 0.02-1.59 and pleural effusion: 2.00-8.59 (µg/ml), while the thiosulfate concentrations were blood: 0-0.648, urine: 0-2.669, cerebrospinal fluid: 0.004-0.314 and pleural effusion: 0.019-0.140 (µmol/ml). In previous reports, the blood concentration of thiosulfate was said to be higher than that of sulfide in hydrogen sulfide poisoning cases, although the latter was higher than the former in 8 of the 14 cases examined in this study. These results are believed to be strongly influenced by the atmospheric concentration of hydrogen sulfide the victims were exposed to and the time interval between exposure and death.

Occupational asphyxiation by unknown compound(s): environmental and toxicological approach.

During a routine truck-tank washing operation, five healthy workers were found motionless inside an empty tanker. Four of them died inside the tanker while the fifth died the following day in hospital. Since the true nature of the fatal compound(s) were not known, a rigorous environmental and toxicological approach supported by autopsy findings was essential to clarify the cause of death. Environmental results indicated that H(2)S fumes arising from the liquid sulfur previously shipped were responsible for the serial deaths, also confirmed by a simulation performed on two similar truck-tanks. These environmental findings were supported by toxicological analyses through the measurement of thiosulfate, one of the main H(2)S metabolites. Abnormal thiosulfate concentrations from 1.1 to 186.2 mg/kg were revealed in all post-mortem biological samples (blood, lung, liver, kidney, brain and fat). Finally, the cluster analysis performed on thiosulfate body distribution contributed to establishing the time of death according to the accident scene reconstruction. This report presents valuable findings in correctly identifying the cause of death in gas asphyxiation cases by unknown compound(s).

[HPLC tandem-mass spectrometric analysis of the chemical components and decomposition products of allicin extract of garlic].

To analyze the chemical components and decomposition products in allicin extract of garlic, the chemical components screening and identification were made with HPLC-MS/MS method by full scan TIC MS, HPLC retention time, product MS spectra and chemical reference standards. The stability of the extract in water and alcoholic solutions was also investigated. There were five major components in allicin extract which were all identified as thiosulfinates. The extract was stable for at least 3 months when stored at -20 degrees C as water solution, but obvious decomposition was observed with the increase of alcoholic concentration. The decomposition products were also identified by HPLC-MS/MS.

Surface analysis under ambient conditions using plasma-assisted desorption/ionization mass spectrometry.

A novel plasma-assisted desorption/ionization (PADI) method that can be coupled with atmospheric pressure sampling mass spectrometry to yield mass spectral information under ambient conditions of pressure and humidity from a range of surfaces without the requirement for sample preparation or additives is reported. PADI is carried out by generating a nonthermal plasma which interacts directly with the surface of the analyte. Desorption and ionization then occur at the surface, and ions are sampled by the mass spectrometer. The PADI technique is demonstrated and compared with desorption electrospray ionization (DESI) for the detection of active ingredients in a range of over-the-counter and prescription pharmaceutical formulations, including nonsterodial anti-inflammatory drugs (mefenamic acid, Ibugel, and ibuprofen), analgesics (paracetamol, Anadin Extra), and Beecham's "all in one" cold and flu remedy. PADI has also been successfully applied to the analysis of nicotine in tobacco and thiosulfates in garlic. PADI experiments have been performed using a prototype source interfaced with a Waters Platform LCZ single-quadrupole mass spectrometer with limited modifications and a Hiden Analytical HPR-60 molecular beam mass spectrometer (MBMS). The ability of PADI to rapidly detect active ingredients in pharmaceuticals without the need for prior sample preparation, solvents, or exposed high voltages demonstrates the potential of the technique for high-throughput screening in a pharmaceutical or forensic environment.