Determination of formic acid in urine by automatic headspace-gas chromatography-mass spectrometry / 中国职业医学

OBJECTIVE: To establish a method for the determination of formic acid in urine by automatic headspace-gas chromatography-mass spectrometry. METHODS: The urine sample was added with 3 mL 15.00%(V/V) sulfuric acid ethanol and heated in an automatic headspace sampler. The formic acid and ethanol underwent an esterification reaction to produce ethyl formate which was separated by gas chromatographic column and detected by mass spectrometer. The quantification was based on external standard method. RESULTS: The linear range of the method was 2.93-97.60 mg/L, with the regression equation correlation coefficient of 0.999 5. The detection limit was 0.65 mg/L and the minimum quantitative limit was 2.17 mg/L, with the recoveries of 95.61%-106.47%. The within-run relative standard deviation(RSD) ranged from 2.52% to 8.05% and the between-run RSD ranged from 6.58% to 8.42%. CONCLUSION: The method has simple pretreatment, good specificity, high precision and has little interference. It is suitable for large scale rapid determination of formic acid in urine in occupational contact population, patients with acute methanol poisoning and general population.

Systemic Effects and Medicolegal Aspects of Formic Acid Poisoning - An Autopsy Study.

Formic acid is easily available in open market, because of its wide use in the rubber industry for processing of latex. Because of the easy availability, case of accidental and suicidal poisoning by formic acid are on the rise and most of them end fatally. On reviewing the literature, only a few were found to be reported and studied in detail. MethodsThis study was carried out on seventy-five medicolegal cases, brought with history of formic acid poisoning which were brought for autopsy during the period February 2012 - July 2013. Bits of tissues from upper part of oesophagus, lesser curvature of stomach, lungs, liver, kidney and pancreas were collected. The tissues were processed, and slides were prepared. Microscopic study of each slide was done. ResultsMales (57.3%) outnumbered females and maximum number of cases was of age group 41-70 yrs. (72%). Most of the victims were taken to hospital for treatment and died after admission (85.3%). Laboratory investigations revealed that most of the cases (85.3%) showed impairment in renal function tests, evidence of haemolysis, and metabolic acidosis, corrosion of the upper part of alimentary tract, glottic oedema and brownish fluid in peritoneal cavity. ConclusionsIn Kerala the incidence of formic acid poisoning is on the rise, probably because of the easy availability of the acid to people engaged in rubber industry which is widely prevalent in this state. Ingestion of formic acid leads to a serious systemic and metabolic damage

Progress in biological utilization of formic acid / 生物工程学报

The use of microbial cell factories to achieve efficient conversion of raw materials and synthesis of target substances is one of the important research directions of synthetic biology. Traditional industrial microorganisms have mainly used sugar-based raw materials as fermentation substrates. How to adopt cheaper carbon resources and realize their efficient use has been widely concerned. Formic acid is an important organic one-carbon source and widely used in industrial manufacturing of pesticides, leather, dyes, medicine and rubber. In recent years, due to the demand fluctuation in downstream industries, formic acid production is facing the dilemma of overcapacity, and therefore, requiring new conversion paths for expansion and extension of the related industrial chain. Biological route is one of the important options. However, natural formate-utilizing microorganisms generally grow slowly when metabolizing formic acid, and moreover, are difficult to be artificially modified by the absence of effective genetic tools. Construction of non-natural formate-utilizing microorganisms is another alternative strategy, but still in its infancy and has a huge space for further improvements. Here, we briefly summarize the recent research progress of biological utilization of formic acid, and also propose the future research focus and direction.

A case of formic acid poisoning: prompting for a different line of management

Formic acid is an easily available substance and can thus be consumed voluntarily or accidentally. Here is a case who presented to our center 5 days post accidental ingestion of formic acid. He had developed acute renal failure requiring hemodialysis. Post admission he had altered sensorium probably alcohol withdrawal and later aspiration pneumonia and ARDS. He developed a late onset GI bleed on day 8 of ingestion with significant hemoglobin drop. An emergency endoscopy was done which showed a normal esophagus but extensive corrosive damage and active bleeding from gastric area. He continued to have drop in hemoglobin in-spite of aggressive volume and blood product transfusions. He was taken up for an emergency subtotal gastrectomy and viable tissue was demarcated with intraoperative endoscopy and a subtotal gastrectomy was performed. He stabilized initially but worsened again 2 days later with worsening lactic acidosis and succumbed to his illness. The fact that esophagus was completely spared with extensive involvement of stomach could possibly indicate a need for review of initial management of corrosive/organic acid poisoning.

Comparison of the Bruker Biotyper and VITEK MS Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Systems Using a Formic Acid Extraction Method to Identify Common and Uncommon Yeast Isolates

BACKGROUND: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) allows rapid and accurate identification of clinical yeast isolates. In-tube formic acid/acetonitrile (FA/ACN) extraction is recommended prior to the analysis with MALDI Biotyper, but the direct on-plate FA extraction is simpler. We compared the Biotyper with the VITEK MS for the identification of various clinically relevant yeast species, focusing on the use of the FA extraction method. METHODS: We analyzed 309 clinical isolates of 42 yeast species (four common Candida species, Cryptococcus neoformans, and 37 uncommon yeast species) using the Biotyper and VITEK MS systems. FA extraction was used initially for all isolates. If ‘no identification' result was obtained following the initial FA extraction, these samples were then retested by using FA (both systems, additive FA) or FA/ACN (Biotyper only, additive FA/ACN) extraction. These results were compared with those obtained by sequence-based identification. RESULTS: Both systems correctly identified all 158 isolates of the four common Candida species after the initial FA extraction. The Biotyper correctly identified 8.7%, 30.4%, and 100% of 23 C. neoformans isolates after performing initial FA, additive FA, and FA/ACN extractions, respectively, while VITEK MS identified all C. neoformans isolates after the initial FA extraction. Both systems had comparable identification rates of 37 uncommon yeast species (128 isolates), following the initial FA (Biotyper, 74.2%; VITEK MS, 73.4%) or additive FA (Biotyper, 82.0%; VITEK MS, 73.4%). CONCLUSIONS: The identification rate of most common and uncommon yeast isolates is comparable between simple FA extraction/Biotyper method and VITEK MS methods, but FA/ACN extraction is necessary for C. neoformans identification by Biotyper.

Use of acids as additives in sugarcane silage / Uso de ácidos como aditivos en el ensilaje de caña de azúcar / Uso de ácidos como aditivos na silagem de cana de açúcar

Background: sugarcane silage often becomes a problem for the producers due to its high population of yeast and its high content of soluble carbohydrates. Objective: to evaluate the effect of formic and phosphoric acid on the chemical composition, fermentation characteristics, and digestibility of sugarcane silages. Methods: sugarcane was ensiled in experimental mini-silos. Five treatments were evaluated in the ensilage process (sugarcane added with 0.5 or 1% formic acid and 0.5 or 1% phosphoric acid, and a control treatment without additives). A completely randomized design was used. Results: the dry matter content of silages containing phosphoric acid was lower. Lower values of NDF, ADF, and hemicellulose were observed in the control and formic acid treatments. Conclusions: formic and phosphoric acids promote beneficial changes in the chemical composition of sugar cane silage.

Antecedentes: debido a la elevada presencia de levaduras y a la alta proporción de carbohidratos, el ensilaje de caña de azúcar presenta problemas de manejo para los productores. Objetivo: evaluar el efecto de la adición de ácidos fórmico y fosfórico sobre la composición química, características fermentativas y digestibilidad del ensilaje de caña de azúcar. Métodos: la caña de azúcar se ensiló en mini silos. Fueron evaluados cinco tratamientos en el proceso de ensilaje de caña de azúcar (caña de azúcar adicionada con 0,5 o 1% de ácido fórmico, o con 0,5 o 1% de ácido fosfórico, y un tratamiento control sin aditivos). Se utilizó un diseño completamente aleatorizado. Resultados: la proporción de materia seca de los ensilajes con ácido fosfórico fue menor. Se observaron menores proporciones de NDF, ADF y hemicelulosa en los ensilajes sin adición de ácido y en los adicionados con ácido fórmico. Conclusiones: el uso de ácidos fórmico y fosfórico en el ensilaje de caña de azúcar promueve modificaciones benéficas en su composición química.

Antecedentes: devido à elevada presença de leveduras como também excessiva proporção de carboidratos, a silagem de cana apresenta problemas de manejo para os produtores. Objetivo: avaliar o efeito da adição do ácido fórmico e ácido fosfórico sobre composição química, características fermentativas e digestibilidade de silagens de cana-de-açúcar. Métodos: a cana-de-açúcar foi ensilada em mini silos. Foram avaliados cinco tratamentos no processo de ensilagem de cana de açúcar (cana-de-açúcar adicionada com 0,5 ou 1% de ácido fórmico ou com 0,5 ou 1% de ácido fosfórico, e um tratamento controle sem aditivos), utilizando um delineamento inteiramente casualizado. Resultados: os teores de matéria seca das silagens contendo ácido fosfórico foram menores. Menores valores de NDF, ADF e hemicelulose foram observados para as silagens de cana-de-açúcar in natura e adicionadas de ácido fórmico. Conclusões: o uso de ácido fórmico e fosfórico promove mudanças benéficas na composição química da silagem de cana de açúcar.

A comparative study of various decalcification techniques.

Background : Study of fibrilar, cellular and sub cellular structures of mineralized tissues is only possible after the removal of the calcium apatite of these tissues by the process of demineralization. Aims: The present study aims to evaluate six commonly used demineralizing agents to identify the best decalcifying agent. Materials and Methods: The present study included six different decalcifying solutions: 10% formal nitric acid, 8% formal nitric acid, 10% formic acid, 8% formic acid, Perenyi's fluid and Ethylene Di-Amine Tetra Acetic Acid. eight samples of posterior mandible of rat were decalcified in each of the decalcifying solutions and subjected to chemical end-point test. Ehrlich's Hematoxylin stain was used. Statistical Analysis Used: One way ANOVA was used for multiple group comparisons and Chi-square test was used for analyzing categorical data. P value of 0.05/less was set for statistical significance. Results: Samples treated with EDTA showed the best overall histological impression and the tissue integrity were well preserved. Formal nitric of both the percentages 10 and 8% gave fairly good cellular detail and were rapid in their action. Conclusion: The final impression led to the proposition that EDTA was indeed the best decalcifying agent available. However, with time constraint, the use of formal nitric acid is advocated.

Anatomopatologia de amostras de bovinos alimentados com glicerol / Anatomic-pathological samples of cattle fed with glycerol

O aumento na produção de biodiesel vem acompanhado do incremento na geração de subprodutos, dentre os quais a glicerina bruta e o glicerol, que vem sendo objeto de inúmeros trabalhos em que se destaca seu uso como fonte energética para alimentação de animais de produção. Entretanto, sua utilização tem sido observada com atenção devido à presença de contaminantes como o metanol, utilizado no processo de separação dos ácidos graxos do glicerol. O metanol é um álcool e tem sido responsável por intoxicações, principalmente em seres humanos e primatas, caracterizadas por acidose metabólica e problemas oculares, apresentando menor toxidade a outras espécies animais. Os efeitos tóxicos da intoxicação por metanol são atribuídos principalmente ao ácido fórmico, um metabólito do processo de degradação do metanol no fígado. Objetivou-se com esse estudo verificar a possível ação tóxica da glicerina bruta e do metanol por análises histopatológicas do sistema nervoso central (SNC), fígado, rúmen, intestino delgado e rim de 24 bovinos confinados por 84 dias, consumindo rações contendo até 24% de glicerina bruta na matéria seca (MS),a qual apresentava 80,35% de glicerol, e <0,01% de metanol. À análise histopatológica, não foram observadas alterações patológicas em amostras provenientes de vacas e novilhos de raças de aptidão leiteira com até 24% de inclusão de glicerol com base na MS, da dieta. O ganho de peso total e a conversão alimentar não foram afetados pela inclusão da glicerol. Conclui-se que a glicerina bruta pode ser incluída até 24% da MS total nas dietas de novilhos e vacas de aptidão leiteira sem comprometer o desempenho dos animais e apresentar toxicidade.

The increase in biodiesel production has led to higher production of crude glycerin, thus, numerous studies have highlighted the use of crude glycerin and glycerol as energy source to be used for animal feed production. However, its use has been closely watched because of the presence of contaminants such as methanol used in the process of separating fatty acids from glycerol. Methanol is an alcohol and has been responsible for intoxication in humans and primates, characterized by metabolic acidosis and eye problems, with less toxicity to other species. The toxic effects of methanol poisoning are attributed mainly to formic acid, a metabolite of the degradation process of methanol in the liver. The objective of this study was to verify the possible toxic action of crude glycerin and methanol by pathological examinations of the central nervous system (CNS), liver, rumen, small intestine and kidney from 24 feedlot cattle for 84 days, feed containing up to 24% of crude glycerin in dry matter (DM) presenting in its composition 80.35% glycerol, and <0.01% methanol. There were no pathological changes observed in dairy cows and steers up to 24% of glycerol inclusion based on the diet DM. The total weight gain and feed conversion were not affected by inclusion of glycerol. We conclude that crude glycerin can be included up to 24% of total DM in the diets of steers and dairy cows without compromising animal performance or display toxicity.

Proteomic Evaluation of Cellular Responses of Saccharomyces cerevisiae to Formic Acid Stress

Formic acid is a representative carboxylic acid that inhibits bacterial cell growth, and thus it is generally considered to constitute an obstacle to the reuse of renewable biomass. In this study, Saccharomyces cerevisiae was used to elucidate changes in protein levels in response to formic acid. Fifty-seven differentially expressed proteins in response to formic acid toxicity in S. cerevisiae were identified by 1D-PAGE and nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS) analyses. Among the 28 proteins increased in expression, four were involved in the MAP kinase signal transduction pathway and one in the oxidative stress-induced pathway. A dramatic increase was observed in the number of ion transporters related to maintenance of acid-base balance. Regarding the 29 proteins decreased in expression, they were found to participate in transcription during cell division. Heat shock protein 70, glutathione reductase, and cytochrome c oxidase were measured by LC-MS/MS analysis. Taken together, the inhibitory action of formic acid on S. cerevisiae cells might disrupt the acid-base balance across the cell membrane and generate oxidative stress, leading to repressed cell division and death. S. cerevisiae also induced expression of ion transporters, which may be required to maintain the acid-base balance when yeast cells are exposed to high concentrations of formic acid in growth medium.

Esophageal Stricture and Acute Renal Failure after Formic Acid Poisoning: A Case Report

Formic acid or formate is a common industrial compound used in the production of ensilage, disinfectants, decalcifying agents and mainly as a precursor in industrial chemical synthesis. It is also a well-known toxic metabolite produced in methanol poisoning. Thus, formate is a potential source of both accidental and deliberate poisoning. Very few reports have been published thus far, on the toxicology of direct formic acid poisoning. Here, we report a case of a 74-year-old man without a history of depression, who ingested about 30 gm of formic acid. The patient presented with profound high anion gap metabolic acidosis, acute renal failure and esophageal stricture. The patient was successfully treated with hemodialysis and supportive measures. But permanent esophageal stricture was complicated by formic acid burns in the gastrointestinal tract. We discuss the pathophysiology and treatment of this case.

Comparision of Effectiveness of Formic Acid and Liquid Nitrogen in the Treatment of Recalcitrant Warts / 대한피부과학회지

BACKGROUND: Liquid nitrogen (LN2) has been widely used in the treatment of warts. However, formic acid (FA), the keratolytic agent, has recently been introduced for the treatment of recalcitrant warts, such as palmoplantar or periungual warts. The efficacy of treatment varies depending on the location, size, number and type of wart, as well as the age and co-operation of the patient. OBJECTIVE: The aim of this study was to evaluate the efficacy and safety of FA and LN2 therapy for the treatment of warts. METHODS: Twenty-four patients with a total of 101 warts were treated with FA, and fifty-three patients with 248 warts were treated with LN2. In the FA-treated group, 85% FA was applied to the warts 2 to 7 times using a stick, according to the degree of response. In the LN2-treated group, LN2 was applied with the sustained 10-s freeze technique using a cotton tip. Treatment with FA was administered weekly, whereas treatment with LN2 (with 2 freeze thaw cycles) was administered in 2 week intervals. Treatment effectiveness was assessed when the complete clearance of warts had occurred or after 12 weeks of treatment. RESULTS: Complete clearance of warts occurred in 30.7% (31/101warts) of the FA-treated group, and 47.2% (119/248warts) of the LN2 treated group. Cryotherapy with LN2 was more effective than FA in the cure rate (p=0.001). In the FA-treated group, 11 patients reported adverse effects such as pain, stinging and erythema, however it was generally found to be tolerable and transient. In addition, 10 patients reported hyperpigmentation. In the LN2 group, 38 patients experienced mild- to-moderate vesicle formation and 9 patients reported hypopigmentation. CONCLUSION: This study shows that cryotherapy with LN2 is more effective than FA in the treatment of recalcitrant warts. However, LN2 causes a significantly greater morbidity in terms of pain and blistering. FA is an effective and safe alternative treatment, so can be considered for patients who are intolerable to pain.

Treatment of Wart by Formic acid / 대한피부과학회지

BACKGROUND: Various modalities are available to treat warts, but surgical or destructive treatments are problematic in children and intolerable patients because these modalities are painful and frightening. For these reasons, some treatment strategies, such as keratolytic, caustic, and immunomodulatory agents, to reduce pain and discomfort are under investigation. OBJECTIVE: This study is to evaluate the efficacy and safety of 85% formic acid for the treatment of warts. METHODS: Twenty patients with 52 lesions of warts were included. Formic acid was applied to the warts using stick 1 to 5 times according to the degree of response. This procedure was repeated at 2-6 day-intervals until the lesions disappeared. Assessment for response and the occurrence of side-effects was performed every visit until clinical cure or up to a maximum of 10 weeks RESULTS: Twenty-six of 52 (50%) lesions showed complete clearance. Fifteen (29%) showed partial clearance-good, which is a >50% reduction in wart size, and 10 (19%) showed partial clearance-poor, which is a <50% reduction. Only one(2%) showed no response. The number of treatments required for the warts to disappear was 1-9 (mean 5). Seven patients reported adverse effects, such as pain, stinging, nail discoloration, and erythema, but were generally mild and transient. CONCLUSION: 85% formic acid is a relatively safe and effective alternative in the treatment of warts with few side-effects and good compliance.

Study on Optimization of Nano-silver Prepared by Method of Liquid Reduction / 环境与健康杂志

Objective The various influencing factors in the process of nano-silver preparation were studied in order to prepare nano-silver that has uniformity particle size distribution and good crystallinity. Methods Through the method of liquid reduction at room temperature,the nano-silver powders were prepared directly using silver nitrate as raw material,water as the reactive medium,polyvinylpyrrolidone(PVP) as protecting agent and ammonium formate as reducing agent. By means of EDS and TEM(transmission electron microscopy),the prepared silver particles were characterized. The various influencing factors in the process of preparation were also discussed. Results With the increasing concentration of AgNO3,the particle diameter of nano-silver changed obviously. When the concentration of silver nitrate was 0.25-0.30 mol/L,the size of product is the smallest. With the increasing concentration of reductant,the diameter of nano-silver decreased gradually. While at the concentration of 0.70 mol/L HCOOH,the average diameter of nano-silver is not more than 10 nm. Smaller and more well-distributed silver powder could be prepared at ratio of concentration of PVP to AgNO3 with the value of 1.5-1.0,at which PVP presented effective protection. Conclusions This method can prepare particle of nano-silver which revealed well dispersed and uniform size. The process is stable and reliable,easy to operate,high yields and suitable for industrial production.

Corrosive oesophagitis after formic acid ingestion.

The occurrence of corrosive oesophagitis following ingestion of formic acid has been studied. Twelve patients with this condition were seen by the authors in Songklanagarind Hospital during the three years period, January 1983 to December 1985. The sex ratio, male: female was 1 : 5. The ingestion of formic acid was due to attempted suicide in 83.3% of patients, and accidental in 16.7% of patients. Oesophagoscopy was done in all patients in every case. Pathological changes were seen in the oesophagus, in seven cases also in the stomach, and in one case even in the duodenum. The treatment varied from simple oesophageal dilatation in mild cases to surgical intervention in the more severe cases. The mean length of stay in hospital was 36.5 days (3-60 days). Postoperative complications occurred in 3 patients in 3 patients and 2 patients died.