A simple paper-based biosensor for on-site visual detection of organophosphate residues

2021 ◽  
Vol 25 (12) ◽  
pp. 82-87
Author(s):  
C. Phromchaloem ◽  
L. Muensritharam
Keyword(s):  
Colorimetric Assay ◽  
Laboratory Method ◽  
Testing Time ◽  
Organophosphate Pesticides ◽  
Test Results ◽  
Farmers Market ◽  
Nitrobenzoic Acid ◽  
Ache Inhibitors ◽  
Test Kit ◽  
Colorimetric Reagent

In general, the laboratory method of analyzing pesticides in vegetables is complicated due to the high cost of equipment and chemicals. The process of analyzing pesticide residues generally requires expertise as well as a significant period of time. In this study, a paper-based biosensor was developed for the detection of acetylcholinesterase (AChE) inhibitors, particularly organophosphate pesticides. The paperbased biosensor was constructed based on the Ellman colorimetric assay by immobilizing AChE on cellulose paper with 2% alginate gel, 0.25% glutaraldehyde and the colorimetric reagent 5,5-dithio-bis-(2-nitrobenzoic acid) (DTNB) in phosphate buffer (pH 8.0). As a substrate, acetylthiocholine chloride (ATChCl) was used. The results showed that the developed paperbased biosensor has been stable for 2 weeks with a detection limit of 0.03 mM of chlorpyrifos. The paper-based biosensor was applied to detect organophosphate pesticides in vegetables from the farmers’ market, Ratchaburi Province. It was found that the test results of the paper-based biosensor were similar to the commercial GT-test kit. The paper-based biosensor was 10 times faster than the GT-test kit in terms of testing time and the results were easy to identify due to the color-based indicator. As a result, a paper-based biosensor is rapid, portable and easy to use by the general population.

Colorimetric solid-phase minisequencing assay illustrated by detection of alpha 1-antitrypsin Z mutation

1993 ◽  
Vol 39 (11) ◽  
pp. 2282-2287 ◽  
Author(s):  
L Harju ◽  
T Weber ◽  
L Alexandrova ◽  
M Lukin ◽  
M Ranki ◽  
...  
Keyword(s):  
Solid Phase ◽  
Colorimetric Assay ◽  
Point Mutations ◽  
High Specificity ◽  
Microtiter Plate ◽  
Test Results ◽  
Single Nucleotide ◽  
Nitrophenyl Phosphate ◽  
Simple Alternative ◽  
Alpha 1 Antitrypsin

Abstract In solid-phase minisequencing, a defined point mutation is detected in microtiter plate-immobilized DNA by a single nucleotide primer extension reaction. We have here developed the method into a colorimetric assay and applied it to the detection of the Z mutation of the alpha 1-antitrypsin gene. We used novel nucleoside triphosphates modified with dinitrophenyl (DNP) hapten, permitting detection by anti-DNP-alkaline phosphatase conjugate, with p-nitrophenyl phosphate as substrate. The Z mutation is detected in two reactions: DNP-labeled dCTP is incorporated when the template is normal, DNP-dUTP when the Z mutation is present. Both modified nucleotides were incorporated with high specificity and with an efficiency similar to that of unmodified nucleotides. The test results are measured by spectrophotometry, yielding quantitative absorbance values. Calculation of the ratio of C to U signal permitted unambiguous distinction of normal homozygous, ZZ homozygous, and ZM heterozygous genotypes. The colorimetric minisequencing assay is rapid, standardized, and automatable, and thus provides an accurate and simple alternative for the analysis of known point mutations.

DETECTION EFFICIENCY OF MASTITIS SCREENING TESTS

1965 ◽  
Vol 28 (1) ◽  
pp. 5-8 ◽  
Author(s):  
E. J. Cole ◽  
E. V. Painter ◽  
G. H. Schnepper
Keyword(s):  
Detection Efficiency ◽  
Leukocyte Count ◽  
False Positives ◽  
Laboratory Method ◽  
Screening Tests ◽  
Test Results ◽  
California Mastitis Test ◽  
Strip Plate ◽  
Disk Test ◽  
Cent Detection

Summary A comparison of the detection efficiency of five screening tests for mastitis was made by correlating test results with results of a specific laboratory standard based on a direct leukocyte count and/or the culturing of infectious organisms on the same samples of milk. Since the screening tests are “indirect” or non-specific in nature, the measure of effectiveness took into consideration not only the per cent detected as compared to that detected by the laboratory method, but also the per cent of readings which were false positives. Both per cent detection and per cent false positives increased with increasing test sensitivity. The level of detection at which the per cent of false positives began to increase rapidly was chosen as the optimum efficiency for each type of test. This optimum efficiency correlated with the presence of mastitis as follows: California Mastitis Test 69.5%; Whiteside Test 65.5%; Filter Disk Test 45.0%; Catalase Test 43.8%; Strip Plate Test 4.7%.

Obtaining HIV Test Results With a Home Collection Test Kit in a Community Telephone Sample

2000 ◽  
Vol 24 (4) ◽  
pp. 363-368 ◽  
Author(s):  
Dennis H. Osmond ◽  
Joseph Catania ◽  
Lance Pollack ◽  
Jesse Canchola ◽  
Deborah Jaffe ◽  
...  
Keyword(s):  
Test Results ◽  
Hiv Test ◽  
Test Kit

scholarly journals Diagnostic Reliability of Architect Anti-HCV Tests and Diagnostic Cost of False Positivity; A Single Center Study in Turkey.

2021 ◽  
Author(s):  
Sinem Akkaya Isik ◽  
Ersin Tural ◽  
ERCAN YENİLMEZ ◽  
RIZA AYTAÇ ÇETİNKAYA ◽  
Orhan Baylan ◽  
...  
Keyword(s):  
Working Hours ◽  
Hcv Infection ◽  
Hcv Rna ◽  
Test Results ◽  
Potential Cost ◽  
Diagnostic Reliability ◽  
False Positivity ◽  
Test Kit ◽  
The Hours ◽  
Pcr Test

Background:Although the sensitivity of third generation anti-HCV CIA tests is high, false positivity rates, especially in populations with low HCV infection endemicity, are still high. Objectives:We aimed to determine the S/Co cut-off value of anti-HCV in the diagnosis of real positive patients based on the CIA test kit absorbance routinely used in our laboratory and to reveal the potential cost effectiveness of confirmatory tests for false positive samples. Methods:All anti-HCV CIA test results which were performed in the microbiology laboratory of our hospital between 2016-2019 were retrospectively screened and S/Co values of the patients were recorded. Among these, the results that were confirmed with HCV-RNA real-time PCR test were included. Patients who were previously diagnosed and treated were excluded. Results:A total of 257 patients, who were tested for HCV-RNA after reactive anti-HCV test results, were included in the study. Of the cases, 84(32.68%) had positive HCV-RNA. According to the ROC analysis, the optimal S/Co value was 8.58 with the sensitivity and specificity values 95.24% and 85.55%, respectively. According to this 8.58S/Co value, anti-HCV test was reactive in 105 cases and 80(76.2%) of these cases had active HCV infection. In order to prevent the false-negativity, the additional cost of using 1.0S/Co value to our institution was 4114.64USD, meaning that we spent 1028.66USD to diagnose per true-case of active HCV infection when using 1.0S/Co value. In our institution, approximately 6.25 working hours are spent to finalize the HCV-RNA PCR test. The hours spent for S/Co of 1.0 and 8.58 were 1606.25 and 658.25, respectively. Conclusions:False positive anti-HCV results are an economic burden on health economics of countries. At least, different S/Co values might be used in accordance with the purpose of the screening (like blood donors or pre-operative screening) and prevalence of HCV infection in different laboratories and different populations.

scholarly journals Verification of reference intervals in routine clinical laboratories: practical challenges and recommendations

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Yesim Ozarda ◽  
Victoria Higgins ◽  
Khosrow Adeli
Keyword(s):  
Clinical Laboratory ◽  
Local Population ◽  
Age Groups ◽  
External Source ◽  
Reference Intervals ◽  
Laboratory Method ◽  
Test Results ◽  
Multicenter Studies ◽  
Clinical Laboratories ◽  
Laboratory Test Results

Abstract Reference intervals (RIs) are fundamental tools used by healthcare and laboratory professionals to interpret patient laboratory test results, ideally enabling differentiation of healthy and unhealthy individuals. Under optimal conditions, a laboratory should perform its own RI study to establish RIs specific for its method and local population. However, the process of developing RIs is often beyond the capabilities of an individual laboratory due to the complex, expensive and time-consuming process to develop them. Therefore, a laboratory can alternatively verify RIs established by an external source. Common RIs can be established by large, multicenter studies and can subsequently be received by local laboratories using various verification procedures. The standard approach to verify RIs recommended by the Clinical Laboratory Standards Institute (CLSI) EP28-A3c guideline for routine clinical laboratories is to collect and analyze a minimum of 20 samples from healthy subjects from the local population. Alternatively, “data mining” techniques using large amounts of patient test results can be used to verify RIs, considering both the laboratory method and local population. Although procedures for verifying RIs in the literature and guidelines are clear in theory, gaps remain for the implementation of these procedures in routine clinical laboratories. Pediatric and geriatric age-groups also continue to pose additional challenges in respect of acquiring and verifying RIs. In this article, we review the current guidelines/approaches and challenges to RI verification and provide a practical guide for routine implementation in clinical laboratories.

scholarly journals Kontaminasi Residu Pestisida Organoposfat: Klorpirifos, Fenitrotion dan Profenofos dalam Bivalvia yang Ditangkap di Pesisir Utara Pulau Jawa

2019 ◽  
Vol 22 (2) ◽  
pp. 103
Author(s):  
Chrisna Adhi Suryono ◽  
Agus Sabdono ◽  
Subagiyo Subagiyo
Keyword(s):  
Pesticide Residues ◽  
Aquatic Environment ◽  
North Coast ◽  
Organophosphate Pesticides ◽  
Test Results ◽  
Organophosphate Pesticide ◽  
Anova Test ◽  
Significant Difference ◽  
Seawater Samples

Organophosphate pesticides were widely used in agriculture and OPP which was less accumulative and degradable but It has been found in an aquatic environment. The purpose of this study was to determine the level of organophosphate pesticide residues in bivalve which was fishing in North Coast of Java specifically the Demak and Surabaya.  Bivalvia, sediment and seawater samples were analysed using GC-MS. The results showed that the bivalves of A inaequivalvis, P viridis, A pectinata captured in Demak and Surabaya were contaminated with organophosphate pesticide of chlorpyrifos, fenitrothion and profenofos. The chlorpyrifos was found in all species of bivalves, but the highest concentrations of OPP were profenophos> chlorpyrifos > fenitrothion respectively. ANOVA test results show that there was a very significant difference in OPP residues in bivalves p = 0.009, but there was no difference in OPP residues between locations.Organoposfat pestisida (OPP) banyak digunakan secara meluas dalam pertanian dan OPP tersebut kurang akumulatif dan mudah terurai namun keberdaanya telah di temukan dala lingkungan perairan. Tujuan dari penelitian adalah untuk mengetahui tingkat akumulasi residu pestisida organoposfat yang terdapat di bivalvia yang ditangkap di pesisir Utara Jawa khususnya wilayah Demak dan Surabaya.  Sampel bivalvia, sedimen dan air laut dianalisa menggunakan GC-MS. Hasil penelitian menunjukan bahwa bivalvia A inaequivalvis, P viridis, A pectinata yang ditangkap di Demak dan Surabaya terkontaminasi pestisida organoposfat jenis Klorpirifos, Fenitrotion dan Profenofos. Klorpirifos ditemukan pada semua bivalvia, namun konsentrasi tertinggi OPP secara berurutan profenofos > klorpirifos > fenitrotion.  Hasil uji ANOVA  menunjukan adanya perbedaan yang sangat nyata residu OPP dalam bivalvia p= 0.009,  namun tidak ada berbedaan residu OPP antar wilayah lokasi.

Validation of Antibiotic Residue Tests for Dairy Goats

1998 ◽  
Vol 61 (3) ◽  
pp. 344-349 ◽  
Author(s):  
S. S. ZENG ◽  
S. HART ◽  
E. N. ESCOBAR ◽  
K. TESFAI
Keyword(s):  
High Performance ◽  
Goat Milk ◽  
High Sensitivity ◽  
Penicillin G ◽  
Antibiotic Residues ◽  
Test Results ◽  
Beta Lactam ◽  
Dairy Goats ◽  
Test Kit ◽  
Antibiotic Residue

The SNAP test, LacTek test (B-L and CEF), Charm Bacillus sterothermophilus var. calidolactis disk assay (BsDA), and Charm II Tablet Beta-lactam sequential test were validated using antibiotic-fortified and -incurred goat milk following the protocol for test kit validations of the U.S. Food and Drug Administration Center for Veterinary Medicine. SNAP, Charm BsDA, and Charm II Tablet Sequential tests were sensitive and reliable in detecting antibiotic residues in goat milk. All three assays showed greater than 90% sensitivity and specificity at tolerance and detection levels. However, caution should be taken in interpreting test results at detection levels. Because of the high sensitivity of these three tests, false-violative results could be obtained in goat milk containing antibiotic residues below the tolerance level. Goat milk testing positive by these tests must be confirmed using a more sophisticated methodology, such as high-performance liquid chromatography, before the milk is condemned. LacTek B-L test did not detect several antibiotics, including penicillin G, in goat milk at tolerance levels. However, LacTek CEF was excellent in detecting ceftiofur residue in goat milk.

Analysis for glutathione in blood by high-performance liquid chromatography.

1978 ◽  
Vol 24 (7) ◽  
pp. 1140-1143 ◽  
Author(s):  
D L Rabenstein ◽  
R Saetre
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Colorimetric Assay ◽  
High Performance Liquid Chromatographic ◽  
Electrochemical Detector ◽  
Nitrobenzoic Acid ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic Analysis ◽  
Liquid Chromatographic

Abstract A high-performance liquid chromatographic method is presented for determination of glutathione in whole blood. Sample preparation involves hemolysis, protein precipitation, centrifugation, and filtration. The glutathione in the filtrate is then separated from other sulfhydryl-containing molecules by liquid chromatography with Zipax SCX cation-exchanger followed by detection with a mercury-based electrochemical detector. The liquid-chromatographic analysis time is approximately 5 min. Because of the chromatographic separation and the selectivity of the detector, the detection step is free from interferences from other components of blood. The method has been checked by comparison with the colorimetric assay based on reaction with 5,5'-dithiobis(2-nitrobenzoic acid). The chromatographic results are consistently slightly lower, presumably because of the greater selectivity of this method.

Viral Load Test Reports

2001 ◽  
Vol 125 (12) ◽  
pp. 1546-1554
Author(s):  
Diane P. Francis ◽  
K. Michael Peddecord ◽  
Louise K. Hofherr ◽  
J. Rex Astles ◽  
William O. Schalla
Keyword(s):  
Viral Load ◽  
Telephone Survey ◽  
Health Department ◽  
Load Test ◽  
Load Testing ◽  
Test Results ◽  
Viral Load Testing ◽  
Viral Load Test ◽  
Test Kit ◽  
Hiv 1

Abstract Context.— Human immunodeficiency virus (HIV) RNA testing (viral load testing) is increasingly important in the care of patients infected with HIV-1 to determine when to initiate, monitor, and change antiretroviral therapy. Patient viral load testing information is communicated to the clinician through the laboratory test report. Objectives.—To examine the format and information used in reporting viral load testing results and determine the clarity of the information provided in these reports. Design.—Patient test reports with all personal identifiers removed were requested of viral load testing laboratories participating in a telephone survey of laboratory practices. Hospital, independent, health department, and “other type” laboratories identified as university-associated laboratories participated in the telephone survey. Results.—Thirty-seven unique test reports were collected. All laboratories reported results in copies/mL, while 14% also reported results as “log10 copies/mL.” The test kit was identified by only 24% of the laboratories. Reportable ranges were specified by 70% of the laboratories, but there was considerable variation in terminology. One laboratory reported a viral load copy number below the manufacturer's test kit lower limit of sensitivity. The layout and format differed among reports. Some results were expressed in log10, others contained nonsignificant integers, while others contained exponential numbers. Supplemental information in some reports included previous patient test results and significance of changes from baseline. The format of some reports made it difficult to read the report information and interpret the testing results. Conclusion.—This study emphasizes the importance of standardizing the reporting of HIV-1 viral load test results to minimize result misinterpretation and incorrect treatment.

Evaluation of a Human On-site Urine Multidrug Test for Emergency Use With Dogs

2009 ◽  
Vol 45 (2) ◽  
pp. 59-66 ◽  
Author(s):  
Joan B. Teitler
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Illicit Drugs ◽  
Gas Chromatography Mass Spectrometry ◽  
Professional Judgment ◽  
Test Results ◽  
Clinical Consideration ◽  
Drug Classes ◽  
Test Kit ◽  
Site Test

A rapid, human on-site urine multidrug test was used to screen canine urine samples for the presence of five illegal drugs and drugs from three commonly abused drug classes. Each sample was sent to a toxicology laboratory for gas chromatography/mass spectrometry (GC/MS) validation. On-site test results and GC/MS assays confirmed that the human on-site test kit did identify barbiturates, opiates, benzodiazepines, and amphetamines/methamphetamines in urine from dogs that had received these common illicit drugs/drug classes either intravenously and/or orally. However, neither the on-site test kit nor the GC/MS individual assays for marijuana or methadone, a synthetic opiate, were effective in identifying marijuana and methadone in urine from dogs with suspected or known exposure. No index of suspicion was seen for exposure to phencyclidines or cocaine during the study period, and no exposures were indicated by the on-site test results. Overall, the test is a rapid, readily available, affordable, and useful complement to the veterinarian’s clinical consideration and professional judgment.

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