TB and interstitial lung disease: a systematic review and meta-analysis.

To determine the frequency of TB among patients with interstitial lung diseases (ILDs).We performed a comprehensive search in the PubMed/Medline, EMBASE and Scopus databases up to 1 August 2023 of studies reporting on the prevalence of TB among patients with ILDs.Twelve studies comprising 3,817 patients with ILD were found: the pooled prevalence of TB among ILD patients was 11.0% (95% CI 5.4-21.0). In the subgroup analysis, the TB rate among patients with silicosis and idiopathic pulmonary fibrosis (IPF) was respectively 35.6% (95% CI 32.6-38.8) and 4.4% (95% CI 3.6-5.3) (P = 0.00). The frequency of TB among ILD patients was higher in high TB burden countries than in low/intermediate-burden countries: 26.3%, 95% CI 17.7-37.3 vs. 4.9%, 95% CI 3.3-7.2; P = 0.00.This study shows the frequency of TB among ILD patients. The meta-analysis reveals a significantly increased prevalence of TB among ILD patients with silicosis compared to IPF, and among individuals in high TB burden countries than in those with low/intermediate burden. The study results can help physicians and policymakers make efficient decisions for prompt screening and anti-TB treatment initiation in ILD patients..

The Effects of Melatonin Alone or in Combination with Zinc on Gonadotropin and Thyroid Hormones in Female Rats.

Thyroid and gonadotropin hormones play an essential role in the regulation of regulating various physiological functions. The effects of melatonin and zinc (Zn) on these hormones have already been investigated. The aim of the present study was to investigate the effect of melatonin with and without zinc on the levels of gonadotropin hormones and thyroid hormones (triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH)) in female rats. In general, 35 sexually mature female rats were randomly divided into five treatment groups, with each group comprising 7 rats, in a completely randomized design (CRD) during the research. The rats were treated daily with Zn and melatonin via gavage as follows T1 (control 1, basal diet), T2 (control 2, treatment with normal saline) and the other experimental groups, including T3, T4 and T5, were treated with Zn (40 ppm), melatonin (5 mg/kg) or a combination of Zn and melatonin at the same dose. The administration of the drugs was continued for 20 days (daily) . Plasma samples were then taken for the determination of LH, FFH, LH/FSH, estrogen, progesterone, T3, T4 and TSH levels. The results showed no significant differences in FSH and LH levels between treatments. Estrogen, progesterone and TSH levels were higher in the rats receiving 5 mg melatonin per day than in the other groups, but not statistically significant (P>0.05). However, T3 levels decreased significantly in the group receiving 40 mg/kg Zn compared to the other experiments. (P<0.05). The results showed no significant difference between the treatments in terms of T4 levels (P>0.05). In conclusion, no remarkable changes in other variables were observed in female rats receiving melatonin, Zn or a combination of melatonin and Zn, with the exception of T3.

Different strategies for the lipase immobilization on the chitosan based supports and their applications.

Immobilized enzymes have received incredible interests in industry, pharmaceuticals, chemistry and biochemistry sectors due to their various advantages such as ease of separation, multiple reusability, non-toxicity, biocompatibility, high activity and resistant to environmental changes. This review in between various immobilized enzymes focuses on lipase as one of the most practical enzyme and chitosan as a preferred biosupport for lipase immobilization and provides a broad range of studies of recent decade. We highlight several aspects of lipase immobilization on the surface of chitosan support containing various types of lipase and immobilization techniques from physical adsorption to covalent bonding and cross-linking with their benefits and drawbacks. The recent advances and future perspectives that can improve the present problems with lipase and chitosan such as high-price of lipase and low mechanical resistance of chitosan are also discussed. According to the literature, optimization of immobilization methods, combination of these methods with other techniques, physical and chemical modifications of chitosan, co-immobilization and protein engineering can be useful as a solution to overcome the mentioned limitations.

Urothelial cell carcinoma of the bladder in pediatric patients: a systematic review and data analysis of the world literature.

BACKGROUND: Urothelial cell carcinoma (UCC) of the bladder is exceedingly rare in pediatric patients. Limited data are available to guide management in this population. METHODS: The authors systematically searched MEDLINE, Cochrane Library, and Google Scholar (through February 2019) for case reports and series to summarize data regarding presentation, evaluation, management, and follow-up for patients ≤ 18 years diagnosed with UCC of the bladder. Patient-level data were abstracted, and adjusted logistic regression was used to identify factors associated with a combined outcome of recurrence or death. RESULTS: One hundred two articles describing 243 patients from 26 countries met criteria. Average age was 12.5 years, 32.6% were female, 15.3% had medical comorbidities, and 13.2% had known risk factors for bladder cancer. Initial management was transurethral resection in 95.5% of patients, whereas 6.2% required secondary intervention. Tumor stage was TaN0M0 in 86.4% and low grade in 93.4%. Recurrence and death occurred in 8.6% and 3.7%, respectively. Mean time to recurrence or death was 8.6 months (standard deviation [SD] 7.6) for 10.7%. Mean disease free follow-up without recurrence or death was 56.9 months (SD 54.2) for 89.3%. Patients with comorbidities, risk factors, or family history (odds ratio [OR]: 2.4, 95% confidence interval [CI]: 1.02-5.6); ≥TaN0M0 disease (OR: 6.2, 95% CI: 2.5-15.6); and larger tumors at diagnosis (OR: 1.7, 95% CI: 1.2-2.4) had significantly greater adjusted odds of recurrence or death after initial treatment. CONCLUSION: Based on pooled results, disease recurrence or death occurred in 10.7% of pediatric patients and within 9 months for most and within 32 months for all patients. This may suggest that low-grade and stage UCC of the bladder in pediatric patients can be systematically monitored for at least 3 years. However, prospective evaluation of this clinical strategy is warranted.

Mood disorders and circulating levels of inflammatory markers in a longitudinal population-based study.

BACKGROUND: There has been increasing evidence that chronic low-grade inflammation is associated with mood disorders. However, the findings have been inconsistent because of heterogeneity across studies and methodological limitations. Our aim is to prospectively evaluate the bi-directional associations between inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α and high sensitivity C-reactive protein (hsCRP) with mood disorders. METHODS: The sample consisted of 3118 participants (53.7% women; mean age: 51.0, s.d. 8.8 years), randomly selected from the general population, who underwent comprehensive somatic and psychiatric evaluations at baseline and follow-up (mean follow-up duration = 5.5 years, s.d. 0.6). Current and remitted mood disorders including bipolar and major depressive disorders (MDD) and its subtypes (atypical, melancholic, combined atypical and melancholic, and unspecified) were based on semi-structured diagnostic interviews. Inflammatory biomarkers were analyzed in fasting blood samples. Associations were tested by multiple linear and logistic regression models. RESULTS: Current combined MDD [ß = 0.29, 95% confidence interval (CI) 0.03-0.55] and current atypical MDD (ß = 0.32, 95% CI 0.10-0.55) at baseline were associated with increased levels of hsCRP at follow-up. There was little evidence for inflammation markers at baseline predicting mood disorders at follow-up. CONCLUSIONS: The prospective unidirectional association between current MDD subtype with atypical features and hsCRP levels at follow-up suggests that inflammation may be a consequence of this condition. The role of inflammation, particularly hsCRP that is critically involved in cardiovascular diseases, warrants further study. Future research that examines potential influences of medications on inflammatory processes is indicated.

Campylobacter jejuni and Campylobacter coli in cecum contents of chickens of slaughter age: A microbiological surveillance.

The presence of foodborne pathogens is a major concern for the food industry and increase in antibiotic resistance adds to the seriousness of this issue. Epidemiological studies have shown that there is little or no information from Iran on the prevalence of Campylobacter spp. in chickens of slaughter age. The aim of this study was to determine the prevalence, antibacterial susceptibility and type of Campylobacter species isolated from the cecum of chickens bred in Saqqez city, Kurdistan, western Iran. Campylobacter was isolated and identified by culture and molecular methods. Antibiotic susceptibility of Campylobacter species was performed by disk agar diffusion test and agar dilution methods. The bacterial isolates were typed by repetitive element sequence based polymerase chain reaction (rep-PCR) method. Fifty-five percent of the farms were found to be contaminated with Campylobacter spp. Gene amplification assay confirmed 67 isolates with Campylobacter spp., of which 57 (85.1%) were identified as C. jejuni and 10 (14.9%) as C. coli. Resistance to tetracycline was the most common finding (70.6%), followed by ciprofloxacin (63.7%) and amoxicillin (27.5%). All isolates retained their susceptibility towards gentamicin and meropenem. Results of MIC50 and MIC90 confirmed high resistance towards tetracycline and ciprofloxacin. Repetitive element sequence based-polymerase chain reaction (rep-PCR) placed C. jejuni in six profiles, while C. coli could not be separated as diverse clones. The present study focused on obtaining data regarding prevalence, antibiotic susceptibilities, genetic diversity at regular intervals and maintain and improve hygiene. The results of this study showed substantial genetic diversity of C. jejuni in chickens from western Iran.

Virulence genes in biofilm producer Enterococcus faecalis isolates from root canal infections.

Enterococcus faecalis is occurring in opportunistic infections involving the oral cavity. This study aimed to evaluate the presence of E. faecalis virulence genes in dental root canal isolates recovered from advanced chronic periodontitis patients. One hundred E. faecalis isolated from dental root canal during July 2015 to Oct 2016. After analysis of biofilm formation by the semi-quantitative determination in 96-well flat bottom polystyrene plates, the presence of asa, esp, efaA, ace, ebpR, gel and hyl gene were studied by PCR. Gelatinase and hemolytic activity were detected by phenotypic methods. Ninety-one percent of isolates had ebpR gene, 85% ace, 82% efaA, 81% gel, 56% esp, 33% asa1, 2% hyl and 0% cyl gene. Evaluation of biofilm formation by microtiter plate method presented 49% of the isolates as strong biofilm producer, 42% displayed moderate biofilm formation, and 10 % weak or no biofilm was observed. asa1, efaA, esp, and ebpR positive isolates had significantly higher biofilm formation than negative isolates, while no significant differences were found when comparing ace-positive and - negative isolates. Present study showed that the ace genes do not seem to be necessary nor sufficient for the production of biofilm in Enterococcus faecalis but the presence of asa1, efaA, esp, and ebpR correlates with increased biofilm formation of dental root canal isolates.

Prospective associations of depression subtypes with cardio-metabolic risk factors in the general population.

The mechanisms and temporal sequence underlying the association between major depressive disorder (MDD) and cardio-metabolic diseases are still poorly understood. Recent research suggests subtyping depression to study the mechanisms underlying its association with biological correlates. Accordingly, our aims were to (1) assess the prospective associations of the atypical, melancholic and unspecified subtypes of MDD with changes of fasting glucose, high-density lipoprotein-cholesterol, triglycerides, systolic blood pressure and the incidence of the metabolic syndrome, (2) determine the potential mediating role of inflammatory marker or adipokine concentrations, eating behaviors and changes in waist circumference during follow-up. Data stemmed from CoLaus|PsyCoLaus, a prospective cohort study including 35-66-year-old randomly selected residents of an urban area. Among the Caucasian participants who underwent the physical and psychiatric baseline evaluations, 2813 (87% participation rate) also accepted the physical follow-up exam (mean follow-up duration=5.5 years). Symptoms of mental disorders were elicited using a semi-structured interview. The atypical MDD subtype, and only this subtype, was prospectively associated with a higher incidence of the metabolic syndrome (OR=2.49; 95% CI 1.30-4.77), a steeper increase of waist circumference (ß=2.41; 95% CI 1.19-3.63) and independently of this, with a steeper increase of the fasting glucose level (ß=131; 95% CI 38-225) during follow-up. These associations were not attributable to or mediated by inflammatory marker or adipokine concentrations, eating behaviors, comorbid psychiatric disorders or lifestyle factors. Accordingly, our results further support the subtyping of MDD and highlight the particular need for prevention and treatment of metabolic consequences in patients with atypical MDD.

On the removal of hexavalent chromium from a Class F fly ash.

Coarse and fine samples of a Class F fly ash obtained from commercial combustion of Illinois bituminous coal have been exposed to two long-term leaching tests designed to simulate conditions in waste impoundments. ICP-AES analysis indicated that the coarse and fine fly ash samples contained 135 and 171mg/kg Cr, respectively. Measurements by XAFS spectroscopy showed that the ash samples originally contained 5 and 8% of the chromium, respectively, in the hexavalent oxidation state, Cr(VI). After exposure to water for more than four months, the percentage of chromium as Cr(VI) in the fly-ash decreased significantly for the coarse and fine fly-ash in both tests. Combining the XAFS data with ICP-AES data on the concentration of chromium in the leachates indicated that, after the nineteen-week-long, more aggressive, kinetic test on the coarse fly ash, approximately 60% of the Cr(VI) had been leached, 20% had been reduced to Cr(III) and retained in the ash, and 20% remained as Cr(VI) in the ash. In contrast, during the six-month-long baseline test, very little Cr was actually leached from either the coarse or the fine fly-ash (<0.1mg/kg); rather, about 66% and 20%, respectively, of the original Cr(VI) in the coarse and fine fly-ash was retained in the ash in that form, while the remainder, 34% and 80%, respectively, was reduced and retained in the ash as Cr(III). The results are interpreted as indicating that Cr(VI) present in Class F fly-ash can be reduced to Cr(III) when in contact with water and that such chemical reduction can compete with physical removal of Cr(VI) from the ash by aqueous leaching.

Childhood sexual and physical abuse: age at exposure modulates impact on functional outcome in early psychosis patients.

BACKGROUND: Evidence suggests a relationship between exposure to trauma during childhood and functional impairments in psychotic patients. However, the impact of age at the time of exposure has been understudied in early psychosis (EP) patients. METHOD: Two hundred and twenty-five patients aged 18-35 years were assessed at baseline and after 2, 6, 18, 24, 30 and 36 months of treatment. Patients exposed to sexual and/or physical abuse (SPA) were classified according to age at the time of first exposure (Early SPA: before age 11 years; Late SPA: between ages 12 and 15 years) and then compared to patients who were not exposed to such trauma (Non-SPA). The functional level in the premorbid phase was measured with the Premorbid Adjustment Scale (PAS) and with the Global Assessment of Functioning (GAF) scale and the Social and Occupational Functioning Assessment Scale (SOFAS) during follow-up. RESULTS: There were 24.8% of patients with a documented history of SPA. Late SPA patients were more likely to be female (p = 0.010). Comparison with non-SPA patients revealed that: (1) both Early and Late SPA groups showed poorer premorbid social functioning during early adolescence, and (2) while patients with Early SPA had poorer functional level at follow-up with lower GAF (p = 0.025) and lower SOFAS (p = 0.048) scores, Late SPA patients did not. CONCLUSION: Our results suggest a link between exposure to SPA and the later impairment of social functioning before the onset of the disease. EP patients exposed to SPA before age 12 may present long-lasting functional impairment, while patients exposed at a later age may improve in this regard and have a better functional outcome.

Non-DSB clustered DNA lesions induced by ionizing radiation are largely responsible for the loss of plasmid DNA functionality in the presence of cisplatin.

The combination of cisplatin and ionizing radiation (IR) increases cell toxicity by both enhancing DNA damage and inhibiting repair mechanisms. Although the formation of cluster DNA lesions, particularly double-strand breaks (DSB) at the site of cisplatin-DNA-adducts has been reported to induce cell death, the contribution of DSB and non-DSB cluster lesions to the cellular toxicity is still unknown. Although both lesions are toxic, it is not always possible to measure their frequency and cell survival in the same model system. To overcome this problem, here, we investigate the effect of cisplatin-adducts on the induction of DSB and non-DSB cluster DNA lesions by IR and determine the impact of such lesions on plasmid functionality. Cluster lesions are two or more lesions on opposite DNA strands with a short distance such that error free repair is difficult or impossible. At a ratio of two cisplatin per plasmid, irradiation of platinated DNA in solution with (137)Cs γ-rays shows enhancements in the formation of DNA DSB and non-DSB cluster lesions by factors of 2.6 and 2.1, respectively, compared to unmodified DNA. However, in absolute terms, the yield for non-DSB cluster lesions is far larger than that for DSB, by a factor of 26. Unmodified and cisplatin-modified DNA were irradiated and subsequently transformed into Escherichia coli to give survival curves representing the functionality of the plasmid DNA as a function of radiation dose. Our results demonstrate that non-DSB cluster lesions are the only toxic lesions present at a sufficient frequency to account for the loss of DNA functionality. Our data also show that Frank-DSB lesions are simply too infrequent to account for the loss of DNA functionality. In conclusion, non-DSB cluster DNA damage is known to be difficult to repair and is probably the lesion responsible for the loss of functionality of DNA modified by cisplatin.

Atypical depression and alcohol misuse are related to the cardiovascular risk in the general population.

OBJECTIVE: The aims of the present study were to assess the associations between mood, anxiety and substance use disorders, including their subtypes, and the prevalence of cardiovascular risk factors (CVRFs). METHOD: Thorough physical investigations, biological measures and standardized interview techniques were used to assess 3716 subjects of an urban area, aged 35-66 years. RESULTS: Atypical depression was associated with increased prevalence of overweight, diabetes and the metabolic syndrome (OR = 1.5, 95% C.I. 1.1-2.0; OR = 2.0, 95% C.I. 1.1-3.5, OR = 1.6, 95% C.I. 1.0-2.4 respectively), whereas decreased prevalence of overweight was found in melancholic (OR = 0.7, 95% C.I. 0.6-0.9) and unspecified depression (OR = 0.8, 95% C.I. 0.7-1.0). Alcohol abuse was associated with diabetes (OR = 1.8, 95% C.I. 1.1-2.9) and dyslipidemia (OR = 1.3, 95% C.I. 1.0-1.8), alcohol dependence with dyslipidemia only (OR = 1.4, 95% C.I. 1.0-2.0). Almost all mental disorders were associated with a lifetime history of regular cigarette smoking, and atypical depression, alcohol misuse and drug dependence were associated with inactivity. CONCLUSION: To conclude results emphasize the need to subtype depression and to pay particular attention to the atypical subtype. Comorbid alcohol misuse may further increase the cardiovascular risk. Efforts to diminish smoking in subjects with mental disorders could be crucial measures to reduce their high incidence of cardiovascular disease.

Rietveld analysis of the effect of annealing atmosphere on phase evolution of nanocrystalline TiO2 powders.

The structural evolution of nanocrystalline TiO2 was studied by X-ray diffraction (XRD) and the Rietveld refinement method (RRM). TiO2 powders were prepared by the sol-gel technique. Post annealing of as-synthesized powders in the temperature range from 500 degrees C to 800 degrees C under air and argon atmospheres led to the formation of TiO2 nanoparticles with mean crystallite size in the range of 37-165 nm, based on the Rietveld refinement results. It was found that the phase structure, composition, and crystallite size of the resulting particles were dependent on not only the annealing temperature, but also the annealing atmosphere. Rietveld refinement of the XRD data showed that annealing the powders under argon atmosphere promoted the polymorphic phase transformation from anatase to rutile. Field emission scanning electron microscopy (FESEM) was employed to investigate the morphology and size of the annealed powders.

Serum level of matrix metalloproteinase-3 in patients with oral lichen planus.

BACKGROUND: Oral Lichen planus (OLP) is a chronic lesion of the oral mucosa with unknown origin. Basement membrane changes are common in OLP and may be mediated by proteases such as matrix metalloproteinase (MMPs) and mast cell chymase. The aim of our study was to evaluate the level of serum MMP-3 in OLP com-pared to normal individuals and assess its clinical significance. METHODS: Thirty four serum samples from patients diagnosed with OLP (12 males, 22 females, age: 42.2±10.8 years) and 34 serum samples from healthy control subjects (11 males, 23 females, age: 42.5±13.3 years) were collected and MMP-3 concentration was measured by ELISA. RESULTS: The serum MMP-3 level in OLP patients was higher (21.64±24.31 ng/ml) compared with healthy con-trols (16.52±23.63 ng/ml), but showed no statistically significant difference. A statistically significant difference was demonstrated between the two types of OLP, being more pronounced in the erosive/atrophic form 6). CONCLUSION: The different clinical appearances of OLP are associated with significant differences in MMP-3 serum level.

Synthesis of wide band gap nanocrystalline NiO powder via a sonochemical method.

A sonochemistry-based synthesis method was used to produce nanocrystalline nickel oxide powder with ≈ 20 nm average crystallite diameter from Ni(OH)(2) precursor. Ultrasound waves were applied to the primary solution to intensify the Ni(OH)(2) precipitation. Dried precipitates were calcined at 320°C to form nanocrystalline NiO particles. The morphology of the produced powder was characterized by transmission electron microscopy. Using sonochemical waves resulted in lowering of the size of the nickel oxide crystallites. FT-IR spectroscopy and X-ray diffraction revealed high purity well-crystallized structure of the synthesized powder. Photoluminescence spectroscopy confirmed production of a wide band-gap structure.

The Wound Healing Effects of Iloprost in Patients with Buerger's Disease: Claudication and Prevention of Major Amputations.

BACKGROUND: This study analyzes the therapeutic effects of intravenous infusion of iloprost in wound healing, healing of the amputation stump wound, improvement in intermittent claudication and prevention of major amputation in patients with Buerger's disease. METHODS: In a prospective study, 19 patients with known Buerger's disease, received intravenous iloprost infusion, 6 hours per day for 10 days. Iloprost with a dose of 0.5-2 ng/kg/min according to the patients' tolerance and using cardiac monitoring during the whole infusion period was administered for 6 hours/day using saline solution. Patients with larger wounds underwent simultaneous transmetatarsal or Ray amputation of the involved toe(s). All patients were discharged after 10 days. Patients were followed to detect their healing changes. RESULTS: Nineteen patients, 19-55 years old received 0.5-2 ng/kg/min iloprost intravenously for 6 hours/day for 10 days. During this period, there was relative improvement in resting pain, but no significant amelioration was noticed in wound healing. In a 2 years follow-up, 14 patients showed a complete healing of the amputation stump and increased distance of walking without any pain. Some previous candidates of major amputation did not need amputation anymore. Five patients (26%) did not respond to therapy. CONCLUSION: Although Buerger's disease patients who were under iloprost therapy, may not show significant changes in wound healing during treatment and at discharge, late results have proved that iloprost infusion is promising in improving wound healing and claudication and preventing major amputations.

The effect of inhaling peppermint odor and ethanol in women athletes.

The purpose of this study was to determine whether inhaling peppermint odor has effects on time of running, maximum heart rate (MHR), maximum oxygen consumption (VO2max), oxygen consumption (VO2), minute ventilation (VE) and respiratory exchange ratio (RER) during acute intensive exercise or not. 36 women soccer player were chosen for participating in this research. They were randomly divided in 3 groups (control, inhaling peppermint, inhaling mixture of peppermint and ethanol). In order to be aware of similarity of groups, the subjects' BMI was determined and ANOVA did not show any significant differences (p < 0.05). The subjects of three groups ran on treadmill according to Bruce test. Heart rate, time of running, VO2max, VO2, VE and RER were measured by Gas Analyzer. After collecting the data, ANOVA was done (p < 0.05) and the results showed that in this study the inhaling of fragrant odors did not have any significant effect on the time of running, MHR, VO2max, VO2, VE and RER, which we think is due to the intensity and duration of training. Referring to our results of the present study; we suggest that inhaling peppermint odor during acute intensive exercise has no significant effect on pulmonary indexes and physical performance (Tab. 4, Fig. 1, Ref. 21).

Latex gloves allergy in dental workers, Iran.

Dermal-respiratory reactions to latex glove is a common problem and sometimes life threatening. Some of the health related past histories such as hand dermatitis, atopy and food allergy increase the probability of these reaction. The purpose of this study was to evaluate reactions to latex gloves amongst dental workers in military dental health centers. In this cross-sectional descriptive survey, dental workers with minimum three months length of employment and most often use of latex gloves were asked to fill standard questionnaire regarding latex related clinical manifestation and personal medical history and predisposing factors. Those with clinical problems did Skin Prick Test (SPT). In this study 330 personnel were assessed. The mean age and length of employment was 31.6 and 8 years, respectively. The most occupation was dentistry. A total of 232 subjects (70.3%) reported latex gloves-allergic symptoms. 72 (21.8%) of persons have history of atopy and food allergy was seen in 114 (34.5%). 63 (19.1%) of subjects reported history of hand dermatitis. All of these had positive regression with allergic responses. Among 73 (34%) symptom positives, 28 (38%) had positive result of SPT. In this survey, the prevalence of allergic reactions is higher than similar studies, which may be due to type of gloves, lack of preemployment assessments and other factors. Because of relationship between allergic reactions to latex gloves and some medical histories, it seems to be necessary for preemployment evaluation and periodic health surveillance of dental workers.

Determination of organophosphorus pesticides in water samples by single drop microextraction and gas chromatography-flame photometric detector.

In this paper we have developed single drop microextraction (SDME) with modified 1.00 microl microsyringe, followed by gas chromatography with flame photometric detector (GC-FPD) for determination of 13 organophosphorus pesticides (OPPs) in water samples. By using a 1.00 microl microsyringe the repeatability of drop volume and injection were improved, because of using maximum volume of microsyringe and no dead volume. On the other hand, the modification of needle tip caused increasing cross section of needle tip and increasing adhesion force between needle tip and drop, thereby increasing drop stability and achieving a higher stirrer speed (up to 1700 rpm). The method used 0.9 microl of carbon tetrachloride as extractant solvent, 40 min extraction time, stirring at 1300 rpm and no salt addition. The enrichment factor of this method ranged from 540 to 830. The linear ranges were 0.01-100 microg/l (four orders of magnitude) and limits of detection were 0.001-0.005 microg/l for most of analyte. The relative standard deviation (RSD%) for 2 microg/l of OPPs in water by using internal standard was in the range 1.1-8.6% (n = 5). The recoveries of OPPs from farm water at spiking level of 1.0 microg/l were 91-104%.