Barriers to opioid use disorder treatment among people who use drugs in the rural United States: A qualitative, multi-site study

BACKGROUND

In 2020, 2.8 million people required substance use disorder (SUD) treatment in nonmetropolitan or 'rural' areas in the U.S. Among this population, only 10% received SUD treatment from a specialty facility, and 1 in 500 received medication for opioid use disorder (MOUD). We explored the context surrounding barriers to SUD treatment in the rural United States.

METHODS

We conducted semi-structured, in-depth interviews from 2018 to 2019 to assess barriers to SUD treatment among people who use drugs (PWUD) across seven rural U.S. study sites. Using the social-ecological model (SEM), we examined individual, interpersonal, organizational, community, and policy factors contributing to perceived barriers to SUD treatment. We employed deductive and inductive coding and analytical approaches to identify themes. We also calculated descriptive statistics for participant characteristics and salient themes.

RESULTS

Among 304 participants (55% male, mean age 36 years), we identified barriers to SUD treatment in rural areas across SEM levels. At the individual/interpersonal level, relevant themes included: fear of withdrawal, the need to "get things in order" before entering treatment, close-knit communities and limited confidentiality, networks and settings that perpetuated drug use, and stigma. Organizational-level barriers included: strict facility rules, treatment programs managed like corrections facilities, lack of gender-specific treatment programs, and concerns about jeopardizing employment. Community-level barriers included: limited availability of treatment in local rural communities, long distances and limited transportation, waitlists, and a lack of information about treatment options. Policy-level themes included insurance challenges and system-imposed barriers such as arrest and incarceration.

CONCLUSION

Our findings highlight multi-level barriers to SUD treatment in rural U.S. communities. Salient barriers included the need to travel long distances to treatment, challenges to confidentiality due to small, close-knit communities where people are highly familiar with one another, and high-threshold treatment program practices. Our findings point to the need to facilitate the elimination of treatment barriers at each level of the SEM in rural America.

Gas Chromatographic Determination of Mixtures of Captan, Folpet, and Captafol

A gas chromatographic procedure, using electron capture detection, has been studied and found to be applicable for determining 3 structurally similar fungicides, captan, folpet, and captafol, which are often found in combination in certain foods. Eight liquid stationary phases (AN-600, OV-25, OV-101, OV-210, OV-225, QF-1, SP-2401, and XE-60) were evaluated. A fluorosilicone stationary phase of moderate polarity, SP-2401, was best suited for column stability, response, resolution of captan and folpet, and freedom from on-column decomposition of the 3 fungicides.

Determination of Captan, Folpet, and Captafol in Fruits and Vegetables, Using Two Multiresidue Methods

Two multiresidue methods, the Mills method and the Luke et al. method, are widely used for the determination of pesticides in foods. These methods were evaluated for the determination of the fungicides captan, folpet, and captafol in selected fruits and vegetables. The analytical behavior of standards through these methods was investigated first. Recoveries from apples, strawberries, lettuce, and tomatoes fortified with these compounds at levels of 0.2-5.9 ppm were then obtained. The analytes were quantitated by gas chromatography with electron capture detection, using a column of 5% SP-2401 on 100-120 mesh Supelcoport. Recoveries of captan, folpet, and captafol from fortified crops ranged from 69 to 78, 90 to 93, and 67 to 83%, respectively, by the Mills procedure and from 87 to 102, 81 to 106, and 91 to 109%, respectively, by the Luke et al. method modified to include additional solvent elution of the optional Florisil column.

Gas Chromatographic Determination of Captan, Folpet, and Captafol Residues in Tomatoes, Cucumbers, and Apples Using a Wide-Bore Capillary Column: Interlaboratory Study

An interlaboratory study of the determination of captan, folpet, and captafol in tomatoes, cucumbers, and apples was conducted by 4 laboratories using wide-bore capillary column gas chromatography with electron capture detection. The 3 fungicides were determined using the Luke et al. multlresidue method modified to Include additional solvent elutlon in the optional Florisll column cleanup step used with this method. The crops were fortified with each fungicide at 3 levels per crop. Mean recoveries ranged from 86.2% for a 25.1 ppm level of captan in apples to 115.4% for a 0.288 ppm level of captafol In apples. Interlaboratory coefficients of variation ranged from 3.4% (24.7 ppm folpet) to 9.7% (0.243 ppm captafol) for tomatoes; from 2.8% (2.0 ppm captafol) to 8.2% (24.8 ppm captan) for cucumbers; and from 1.5% (0.234 ppm folpet) to 22.1% (0.266 ppm captafol) for apples.

Multicolumn Solid-Phase Extraction Cleanup of Organophosphorus and Organochlorine Pesticide Residues in Vegetable Oils and Butterfat

Diatomaceous earth columns used with reversed and normal solid phase extraction (SPE) cartridges were evaluated for the quantitative determination of a number of organophosphorus (OP) and organochlorine (OC) pesticide residues in edible vegetable oils and butterfat. An oil or fat sample (about 2 g) in hexane was passed through a diatomaceous earth (Extrelut QE) column and a Cis bonded silica (ODS) SPE cartridge, resulting in the separation of the pesticides from about 98% of the lipids. The eluate was split in half, with the first portion concentrated into acetone for the determination of OP pesticides by gas chromatography with flame photometric detection (GC–FPD). The other half was passed through an Alumina-N SPE cartridge for additional cleanup of lipid matrix to determine OC pesticides by GC with electron-capture detection (GC–ECD). Average recoveries from fortified samples were greater than 89% for the pesticides studied.

TCDD Residues in Fish and Shellfish from U.S. Waterways

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) in the edible portion of fish and shellfish from various U.S. waterways has been monitored since 1979. Analytical results for the period 1979-1994 are reported. Extracts obtained after column chromatographic and liquid chromatographic cleanup were examined by electron capture detection-gas chromatography (GC), and final quantitation and confirmation were performed by GC/mass spectrometry with multiple ion detection. Analyses of 1623 test samples indicated that TCDD residues in fish and shellfish were not widespread but rather were localized in areas near waste sites, chlorophenol manufacturers, and pulp and paper mills. Analytical results indicated that levels in aquatic species from these sites have been declining steadily. No TCDD (limit of detection and confirmation, 1 - 2 ppt) has been found in recent years in aquatic species from most Atlantic, Pacific, and Gulf of Mexico sites and Great Lakes other than Lake Ontario and Saginaw Bay (Lake Huron).

Determination of 2,3?7,8-Tetrachlorodibenzo-p-Dioxin in Fish, Using Electron Capture Gas Chromatography with Confirmation by Mass Spectrometry: Interlaboratory Study

An interlaboratory study of the determination of 2,3,7,8-tetrachlorodibenzo- p-dioxin (2,3,7,8-TCDD) in fish was conducted by 6 analysts in 4 laboratories using high resolution gas chromatography with electron capture detection (HRGC-EC) for quantitative screening analysis. Samples consisted of 3 Great Lakes channel catfish homogenates containing different levels of bioincurred 2,3,7,8-TCDD; 1 of these was prepared in duplicate and another was prepared both with and without standard 2,3,7,8-TCDD fortification for a total of 5 samples per set. All methods used included addition of 1,3,7,8-TCDD surrogate (to correct for procedural losses) followed by ethanolic KOH digestion and hexane extraction. Certain cleanup steps used, including sulfuric acid washing and multidimensional column liquid chromatographic procedures, varied among laboratories. Mean HRGC-EC results for the bioincurred residues were 56.6, 25.2, and 7.7 pg/g (ppt) with corresponding relative standard deviations (RSDs) of 9.1,18.6, and 53.2%. Average determination of standard 2,3,7,8- TCDD from the fortified sample (corrected for surrogate recoveries averaging 74.6%) was 106% of the added amount (30.9 pg/g) with 11.0% RSD. HRGC-multiple ion detection mass spectrometry (MS), monitoring 12 ions, was used for confirmation. With the exception of several results from 1 analyst, HRGC-MS and HRGC-EC quantitations were in good agreement. All but 1 result reported met all of the MS ide ntity criteria.

Ion-Pairing Liquid Chromatographic Determination of Benzimidazole Fungicides in Foods

A method Is described for determining residues in foods of thiabendazole, thlophanate methyl, the dl-oxygen analogue metabolite [dimethyl 4,4'-0-phenylene bis (allophanate)] that Is the metabolite name of the latter, and methyl-2- benzlmldazole carbamate, which Is the major metabolite and fungltoxlc principle common to both thlophanate methyl and benomyl. The residues are extracted from the product using methanol and are partitioned Into dlchloromethane after initial acidification and again after subsequent alkalinization of the extract. Residues are separated and quantified by reverse- phase liquid chromatography using an ion-pairing mobile phase with UV and fluorescence detectors In tandem. Recoveries from 7 different food crops fortified at 0.2-35 ppm levels ranged from 64 to 105%.

Liquid Chromatographic Determination of Paraquat and Diquat in Crops Using a Silica Column with Aqueous Ionic Mobile Phase

A method was developed for the determination of paraquat (PQ) and diquat (DQ) in high moisture food crops. Samples were digested with 6M HCI, and the herbicides were isolated from the digest using pH-controlled silica solid phase extraction. The analyte8 were then determined by ion-pairing liquid chromatography with a silica analytical column, sodium chloride as the ion-pairing reagent, and acetonitrile as the organic modifier. A diode array UV absorbance detector was used to simultaneously quantify PQ and DQ at their respective maximum absorbance wavelengths, 257 and 310 nm. Average recoveries of PQ and DQ standards from 4 different crops fortified at 0.01-0.50 ppm levels ranged from 79.3 to 104.8%.

Antibiotic-induced Porphyromonas gingivalis LPS release and inhibition of LPS-stimulated cytokines by antimicrobial peptides

Bacterial lipopolysaccharide (LPS) release during periodontal infection is a significant component of periodontal disease. We hypothesized that some bacterial LPS release results from bacterial exposure to antibiotics. Therefore, we examined the ability of various classes of antibiotics to induce LPS release from Porphyromonas gingivalis as well as the ability of antimicrobial peptides (AMPs) to inhibit purified LPS. All antibiotics tested against P. gingivalis were able to liberate 1.9-12.9 times more LPS as compared to untreated bacteria. Among the three AMPs tested, LL-37 was found to be the most potent inhibitor of cytokine (tumor necrosis factor-alpha, interleukin-1beta, interleukin-6) production and completely neutralized purified P. ginigivalis LPS activity in the chromogenic limulus amebocyte lysate (LAL) and whole blood cytokine stimulation assays. These observations suggest that therapeutic approaches utilizing AMPs as adjuncts to neutralize released LPS should be considered.

Synthesis and antimalarial activity of sixteen dispiro-1,2,4, 5-tetraoxanes: alkyl-substituted 7,8,15,16-tetraoxadispiro[5.2.5. 2]hexadecanes

Sixteen alkyl-substituted dispiro-1,2,4,5-tetraoxanes (7,8,15, 16-tetraoxadispiro[5.2.5.2]hexadecanes) were synthesized to explore dispiro-1,2,4,5-tetraoxane SAR and to identify tetraoxanes with better oral antimalarial activity than prototype tetraoxane 1 (WR 148999). The tetraoxanes were prepared either by peroxidation of the corresponding cyclohexanone derivatives in H(2)SO(4)/CH(3)CN or by ozonolysis of the corresponding cyclohexanone methyl oximes. Those tetraoxanes with alkyl substituents at the 1 and 10 positions were formed as single stereoisomers, whereas the five tetraoxanes formed without the stereochemical control provided by alkyl groups at the 1 and 10 positions were isolated as mixtures of diastereomers. Three of the sixteen tetraoxanes were inactive (IC(50)'s > 1000 nM), but five (2, 6, 10, 11, 12) had IC(50)'s between 10 and 30 nM against the chloroquine-sensitive D6 and chloroquine-resistant W2 clones of Plasmodium falciparum compared to corresponding IC(50)'s of 55 and 32 nM for 1 and 8.4 and 7.3 nM for artemisinin. We suggest that tetraoxanes 13, 16, and 17 were inactive and tetraoxanes 4 and 7 were weakly active due to steric effects preventing or hindering peroxide bond access to parasite heme. Tetraoxanes 1, 10, 11, and 14, along with artemisinin and arteether as controls, were administered po b.i.d. (128 mg/kg/day) to P. berghei-infected mice on days 3, 4, and 5 post-infection. At this dose, tetraoxanes 10, 11, and 14 cured between 40% and 60% of the infected animals. In comparison, artemisinin and tetraoxane 1 produced no cures, whereas arteether cured 100% of the infected animals. There was no apparent relationship between tetraoxane structure and in vitro neurotoxicity, nor was there any correlation between antimalarial activity and neurotoxicity for these seventeen tetraoxanes.

TCDD residues in fish and shellfish from U.S. waterways

TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) in the edible portion of fish and shellfish from various U.S. waterways has been monitored since 1979. Analytical results for the period 1979-1994 are reported. Extracts obtained after column chromatographic and liquid chromatographic cleanup were examined by electron capture detection-gas chromatography (GC), and final quantitation and confirmation were performed by GC/mass spectrometry with multiple ion detection. Analyses of 1623 test samples indicated that TCDD residues in fish and shellfish were not widespread but rather were localized in areas near waste sites, chlorophenol manufacturers, and pulp and paper mills. Analytical results indicated that levels in aquatic species from these sites have been declining steadily. No TCDD (limit of detection and confirmation, 1-2 ppt) has been found in recent years in aquatic species from most Atlantic, Pacific, and Gulf of Mexico sites and Great Lakes other than Lake Ontario and Saginaw Bay (Lake Huron).

Multicolumn solid-phase extraction cleanup of organophosphorus and organochlorine pesticide residues in vegetable oils and butterfat

Diatomaceous earth columns used with reversed and normal solid phase extraction (SPE) cartridges were evaluated for the quantitative determination of a number of organophosphorus (OP) and organochlorine (OC) pesticide residues in edible vegetable oils and butterfat. An oil or fat sample (about 2 g) in hexane was passed through a diatomaceous earth (Extrelut QE) column and a C18 bonded silica (ODS) SPE cartridge, resulting in the separation of the pesticides from about 98% of the lipids. The eluate was split in half, with the first portion concentrated into acetone for the determination of OP pesticides by gas chromatography with flame photometric detection (GC-FPD). The other half was passed through an Alumina-N SPE cartridge for additional cleanup of lipid matrix to determine OC pesticides by GC with electron-capture detection (GC-ECD). Average recoveries from fortified samples were greater than 89% for the pesticides studied.

Inhibition of insulin secretion by KN-62, a specific inhibitor of the multifunctional Ca2+/calmodulin-dependent protein kinase II

The effects of KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (CamPKII), on insulin secretion and protein phosphorylation were studied in rat pancreatic islets and RINm5F cells. KN-62 was found to dose-dependently inhibit autophosphorylation of CamPKII in subcellular preparations of RINm5F cells (K0.5 = 3.1 +/- 0.3 microM), but had no effect on protein kinase C or myosin light chain kinase activity. KN-62, but not the inactive analogue KN-04, dose-dependently inhibited glucose-induced insulin release (K0.5 = 1.5 +/- 0.5 microM) in a manner similar to the inhibition of CamPKII autophosphorylation. KN-62 (10 microM) inhibited carbachol (in the presence of 8 mM glucose) and potassium-stimulated insulin secretion from islets by 53% and 59%, respectively. These results support a role of CamPKII in glucose-sensitive insulin secretion.

Liquid chromatographic determination of paraquat and diquat in crops using a silica column with aqueous ionic mobile phase

A method was developed for the determination of paraquat (PQ) and diquat (DQ) in high moisture food crops. Samples were digested with 6M HCl, and the herbicides were isolated from the digest using pH-controlled silica solid phase extraction. The analytes were then determined by ion-pairing liquid chromatography with a silica analytical column, sodium chloride as the ion-pairing reagent, and acetonitrile as the organic modifier. A diode array UV absorbance detector was used to simultaneously quantify PQ and DQ at their respective maximum absorbance wavelengths, 257 and 310 nm. Average recoveries of PQ and DQ standards from 4 different crops fortified at 0.01-0.50 ppm levels ranged from 79.3 to 104.8%.

Gas chromatographic determination of captan, folpet, and captafol residues in tomatoes, cucumbers, and apples using a wide-bore capillary column: interlaboratory study

An interlaboratory study of the determination of captan, folpet, and captafol in tomatoes, cucumbers, and apples was conducted by 4 laboratories using wide-bore capillary column gas chromatography with electron capture detection. The 3 fungicides were determined using the Luke et al. multiresidue method modified to include additional solvent elution in the optional Florisil column cleanup step used with this method. The crops were fortified with each fungicide at 3 levels per crop. Mean recoveries ranged from 86.2% for a 25.1 ppm level of captan in apples to 115.4% for a 0.288 ppm level of captafol in apples. Interlaboratory coefficients of variation ranged from 3.4% (24.7 ppm folpet) to 9.7% (0.243 ppm captafol) for tomatoes; from 2.8% (2.0 ppm captafol) to 8.2% (24.8 ppm captan) for cucumbers; and from 1.5% (0.234 ppm folpet) to 22.1% (0.266 ppm captafol) for apples.

Determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in fish, using electron capture gas chromatography with confirmation by mass spectrometry: interlaboratory study

An interlaboratory study of the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in fish was conducted by 6 analysts in 4 laboratories using high resolution gas chromatography with electron capture detection (HRGC-EC) for quantitative screening analysis. Samples consisted of 3 Great Lakes channel catfish homogenates containing different levels of bioincurred 2,3,7,8-TCDD; 1 of these was prepared in duplicate and another was prepared both with and without standard 2,3,7,8-TCDD fortification for a total of 5 samples per set. All methods used included addition of 1,3,7,8-TCDD surrogate (to correct for procedural losses) followed by ethanolic KOH digestion and hexane extraction. Certain cleanup steps used, including sulfuric acid washing and multidimensional column liquid chromatographic procedures, varied among laboratories. Mean HRGC-EC results for the bioincurred residues were 56.6, 25.2, and 7.7 pg/g (ppt) with corresponding relative standard deviations (RSDs) of 9.1, 18.6, and 53.2%. Average determination of standard 2,3,7,8-TCDD from the fortified sample (corrected for surrogate recoveries averaging 74.6%) was 106% of the added amount (30.9 pg/g) with 11.0% RSD. HRGC-multiple ion detection mass spectrometry (MS), monitoring 12 ions, was used for confirmation. With the exception of several results from 1 analyst, HRGC-MS and HRGC-EC quantitations were in good agreement. All but 1 result reported met all of the MS identity criteria.

THE NAME OF THE ROSE: A REVIEW OF IDEAS ON THE EUROPEAN BIAS IN ANGIOSPERM CLASSIFICATION

This 'Tansley Review' paper takes as its starting point a paper of mine published in 1961, which explored the shape and size of modern Angiosperm families and genera as a product of taxonomic practice over centuries. It considers how far the conclusion - that our existing scientific classification, based on Linnaeus' masterly standardization in the eighteenth century, is very markedly 'Eurocentric'- has been criticized, accepted or modified by subsequent writers. In particular, it assesses the important contribution made in recent years by ethnobiologists using expert knowledge from social anthropology, linguistics and other disciplines. Finally, the paper considers briefly the broader aspects of current controversies about the nature and purpose of taxonomic activity, including the argument about its relevance to evolutionary knowledge and speculation. It concludes that, to a remarkable degree, practising taxonomists ignore conceptual or philosophical difficulties and are able to co-operate, although their leisurely and arcane procedures may not measure up to the'information explosion'. Contents Summary 527 I. Introduction 528 II. The age and size of Angiosperm families and genera 530 III. Recognition of the European bias in classification 539 IV. Conclusions 542 References 544.

Gas chromatographic method for ethylene dibromide in grains and grain-based products: collaborative study

Nine laboratories analyzed samples of whole grain, intermediate, and ready-to-eat products for ethylene dibromide (EDB) residues. Supplied samples of wheat, rice, and flour contained both fortified and incurred EDB; corn bread mix, baby cereal, and bread contained only fortified EDB. The whole grains and intermediates were analyzed by the same basic procedural steps as in the official method for multifumigants: They were extracted by soaking in acetone-water (5 + 1). The baby cereal and bread were analyzed by a modification of the Rains and Holder hexane co-distillation procedure. EDB was determined by electron capture gas chromatography operated with an SP-1000 column. All products contained 3 different levels of EDB and were analyzed as blind duplicates. Overall mean recoveries ranged from 85.2% for 69.6 ppb to 105.0% for 4.35 ppb, both in baby cereal. Interlaboratory relative standard deviations ranged from 5.7% for 869 ppb in wheat to 20.2% for 69.6 ppb in baby cereal, both fortified. Mean levels of incurred EDB in wheat, rice, and flour were 926.7, 982.0, and 49.9 ppb, respectively; corresponding relative standard deviations were 9.9, 7.7, and 13.1%. The method was adopted official first action.

Residues of Captan and Folpet in Strawberries and Grapes

Fresh strawberries and grapes grown in Michigan and Indiana were surveyed for residues of captan and folpet, 2 fungicides commonly used on these crops. The fungicides were reportedly applied to the crops by overhead irrigation, tractor sprayer, or aerial spraying, in amounts ranging from 0.5 to 6 lb formulation/acre for captan and from 1 to 4 lb formulation/acre for folpet. Reported dates of last application ranged from just 2 days to nearly 5 months before samples were collected. Twenty-eight strawberry samples and 24 grape samples were collected of crops field-treated with one or both of these fungicides. Samples were analyzed by previously described methodology. Captan residues were found in all strawberry samples, ranging from < 0.01 to 1.5 ppm. Folpet was found in only one strawberry sample at 0.041 ppm. Captan residues were found in only 6 grape samples, ranging from < 0.01 to 0.082 ppm. Folpet residues were found in 12 grape samples, ranging from < 0.01 to 0.50 ppm. All residues were well below the current tolerances of 25 ppm for both captan and folpet in strawberries and 50 ppm for captan and 25 ppm for folpet in grapes. Residue levels of these surface-applied, nonsystemic fungicides were inconsistent with amounts and dates of application, most likely because of variations in weather conditions, especially rainfall. Residues were quite stable in frozen sample homogenates, declining only 5-10% after 2 months.

Gas Chromatographic Method for Ethylene Dibromide in Grains and Grain-Based Products: Collaborative Study

Nine laboratories analyzed samples of whole grain, intermediate, and ready-to-eat products for ethylene dibromide (EDB) residues. Supplied samples of wheat, rice, and flour contained both fortified and incurred EDB; corn bread mix, baby cereal, and bread contained only fortified EDB. The whole grains and intermediates were analyzed by the same basic procedural steps as in the official method for multifumigants: They were extracted by soaking in acetone-water (5 + 1). The baby cereal and bread were analyzed by a modification of the Rains and Holder hexane co-distillation procedure. EDB was determined by electron capture gas chromatography operated with an SP-1000 column. All products contained 3 different levels of EDB and were analyzed as blind duplicates. Overall mean recoveries ranged from 85.2% for 69.6 ppb to 105.0% for 4.35 ppb, both in baby cereal. Interlaboratory relative standard deviations ranged from 5.7% for 869 ppb in wheat to 20.2% for 69.6 ppb in baby cereal, both fortified. Mean levels of incurred EDB in wheat, rice, and flour were 926.7, 982.0, and 49.9 ppb, respectively; corresponding relative standard deviations were 9.9, 7.7, and 13.1%. The method was adopted official first action.

Residues of captan and folpet in strawberries and grapes

Fresh strawberries and grapes grown in Michigan and Indiana were surveyed for residues of captan and folpet, 2 fungicides commonly used on these crops. The fungicides were reportedly applied to the crops by overhead irrigation, tractor sprayer, or aerial spraying, in amounts ranging from 0.5 to 6 lb formulation/acre for captan and from 1 to 4 lb formulation/acre for folpet. Reported dates of last application ranged from just 2 days to nearly 5 months before samples were collected. Twenty-eight strawberry samples and 24 grape samples were collected of crops field-treated with one or both of these fungicides. Samples were analyzed by previously described methodology. Captan residues were found in all strawberry samples, ranging from less than 0.01 to 1.5 ppm. Folpet was found in only one strawberry sample at 0.041 ppm. Captan residues were found in only 6 grape samples, ranging from less than 0.01 to 0.082 ppm. Folpet residues were found in 12 grape samples, ranging from less than 0.01 to 0.50 ppm. All residues were well below the current tolerances of 25 ppm for both captan and folpet in strawberries and 50 ppm for captan and 25 ppm for folpet in grapes. Residue levels of these surface-applied, nonsystemic fungicides were inconsistent with amounts and dates of application, most likely because of variations in weather conditions, especially rainfall. Residues were quite stable in frozen sample homogenates, declining only 5-10% after 2 months.

Evaluation of Capillary Gas Chromatography for Pesticide and Industrial Chemical Residue Analysis. II. Comparison of Quantitative Results Obtained on Capillary and Packed Columns

Results of pesticide and industrial chemical residue determinations, using both capillary and packed column gas chromatography (GC), in 3 Food and Drug Administration (FDA) laboratories have been compiled and compared. Samples consisted of food products collected for routine residue screening by the respective laboratories. Extracts were prepared by conventional multiresidue methodology. Capillary column systems and operating conditions were selected at the discretion of each laboratory and were therefore variable, although split/splitless injectors in the split mode were used with prescribed precautions in all cases. Packed column systems were operated as specified in the FDA Pesticide Analytical Manual (PAM). Overall correlation between the 2 systems, expressed as the average ratio of packed column result to capillary column result, was 0.99 for 120 determinations in 41 samples. The higher resolving power of the capillary systems allowed quantitation of several residues that were incompletely separated and therefore unquantifiable using the packed columns. Capillary column GC with the split injection technique, used with appropriate precautions, was found to be both reliable and advantageous for regulatory determination of pesticide and industrial chemical residues in foods and feeds.

Evaluation of capillary gas chromatography for pesticide and industrial chemical residue analysis. II. Comparison of quantitative results obtained on capillary and packed columns

Results of pesticide and industrial chemical residue determinations, using both capillary and packed column gas chromatography (GC), in 3 Food and Drug Administration (FDA) laboratories have been compiled and compared. Samples consisted of food products collected for routine residue screening by the respective laboratories. Extracts were prepared by conventional multiresidue methodology. Capillary column systems and operating conditions were selected at the discretion of each laboratory and were therefore variable, although split/splitless injectors in the split mode were used with prescribed precautions in all cases. Packed column systems were operated as specified in the FDA Pesticide Analytical Manual (PAM). Overall correlation between the 2 systems, expressed as the average ratio of packed column result to capillary column result, was 0.99 for 120 determinations in 41 samples. The higher resolving power of the capillary systems allowed quantitation of several residues that were incompletely separated and therefore unquantifiable using the packed columns. Capillary column GC with the split injection technique, used with appropriate precautions, was found to be both reliable and advantageous for regulatory determination of pesticide and industrial chemical residues in foods and feeds.

Determination of phenylurea pesticides by high-performance liquid chromatography with UV and photoconductivity detectors in series

High-performance liquid chromatographic (HPLC) separations of eighteen phenylurea pesticides were investigated using both reversed-phase and normal-phase systems. A photoconductivity detector, which responds selectively to ionic products formed via postcolumn UV irradiation of photolabile analytes, was connected in tandem with a UV detector permitting serial dual detection of these compounds. The photoconductivity detector responded selectively to the thirteen halogen and sulfur containing compounds whereas the UV detector responses were of the same order of magnitude for all eighteen compounds at 250 nm. The HPLC-UV-photoconductivity detection system was successfully applied to the determination of chloroxuron in strawberries at the official tolerance level of 0.5 ppm. The tandem detectors combined with a choice of columns and chromatographic modes offers enhanced selectivity for the HPLC analysis of these pesticides as trace contaminants in complex samples.

Determination of captan, folpet, and captafol in fruits and vegetables, using two multiresidue methods

Two multiresidue methods, the Mills method and the Luke et al. method, are widely used for the determination of pesticides in foods. These methods were evaluated for the determination of the fungicides captan, folpet, and captafol in selected fruits and vegetables. The analytical behavior of standards through these methods was investigated first. Recoveries from apples, strawberries, lettuce, and tomatoes fortified with these compounds at levels of 0.2-5.9 ppm were then obtained. The analytes were quantitated by gas chromatography with electron capture detection, using a column of 5% SP-2401 on 100-120 mesh Supelcoport. Recoveries of captan, folpet, and captafol from fortified crops ranged from 69 to 78, 90 to 93, and 67 to 83%, respectively, by the Mills procedure and from 87 to 102, 81 to 106, and 91 to 109%, respectively, by the Luke et al. method modified to include additional solvent elution of the optional Florisil column.

THE RELATION BETWEEN THE BRITISH AND THE EUROPEAN FLORAS

The paper presents a brief and personal history of the main developments in British vascular plant taxonomy and distribution studies in a European setting since the Second World War. It assesses the importance of the'European view', and considers recent and current work under two main heads: the factual information itself, and the presentation of the facts, especially in the form of dot distribution maps.

Alumina blending technique for separation of pesticides from lipids

An evaluation of an extraction technique for elimination of lipids during pesticide residue analysis was undertaken, which included a study of the parameters involved in an attempt to optimize the separation and recovery of selected pesticides from lipid samples. The choice of alumina, the degree of water deactivation of alumina, the amount of alumina relative to the weight of sample taken, the volume and composition of extraction solvent, the blending time, and the filtration procedure were all significant factors. Optimization of these factors resulted in greater than 90% recoveries of selected chlorinated pesticides from fortified fatty samples. In addition, the amount of co-extracted lipid material was about one-third of that obtained with the official method (AOAC 29.014), and less analytical time was required for the extraction by the proposed technique. The formation of troublesome emulsions sometimes encountered with the official method was also eliminated.

Alumina Blending Technique for Separation of Pesticides from Lipids

An evaluation of an extraction technique for elimination of lipids during pesticide residue analysis was undertaken, which included a study of the parameters involved in an attempt to optimize the separation and recovery of selected pesticides from lipid samples. The choice of alumina, the degree of water deactivation of alumina, the amount of alumina relative to the weight of sample taken, the volume and composition of extraction solvent, the blending time, and the filtration procedure were all significant factors. Optimization of these factors resulted in >90% recoveries of selected chlorinated pesticides from fortified fatty samples. In addition, the amount of co-extracted lipid material was about one-third of that obtained with the official method (AOAC 29.014), and less analytical time was required for the extraction by the proposed technique. The formation of troublesome emulsions sometimes encountered with the official method was also eliminated.

Evaluation of Capillary Gas Chromatography for Pesticide and Industrial Chemical Residue Analysis. I. Comparison of Retention Ratios Obtained on Methyl Silicone-Coated Capillary Columns with Published Values for Packed Columns

Many residue laboratories use the retention ratio data compiled by the Food and Drug Administration in its Pesticide Analytical Manual (PAM) for the tentative identification of pesticide and industrial chemical residues detected in food samples. These data were compiled using packed gas chromatographic columns. A study was undertaken to determine if these retention ratios could be used when applying capillary gas chromatography to residue analysis. Retention ratios of a selected group of 108 of the materials listed in the PAM tables were determined isothermally with split injection on 4 WCOT capillary columns obtained from 3 commercial suppliers and coated with 4 different methyl silicone coatings. Of the tested reference materials, 90 displayed retention ratios that matched the PAM values on all columns, 10 differed on at least one of the 4 columns, and only omethoate and monocrotophos gave retention ratios differing on all 4 columns.

Preliminary evaluation of high-performance liquid chromatography with photoconductivity detection for the determination of selected pesticides as potential food contaminants

The applicability of the Tracor Model 965 photoconductivity detector to the determination of a variety of pesticide chemicals, particularly polar and/or thermally labile compounds which are troublesome in gas chromatographic analysis, has been investigated. The effects of various operating parameters (e.g., mobile phase composition, flow-rate and irradiation wavelength) on signal-to-noise output for selected compounds have been evaluated. A comparison of photoconductivity responses with those obtained from a UV detector connected in tandem was made for selected reference standards and food sample extracts. The photoconductivity detector was found to be suitable for the determination of pesticide residues at sub-parts-per-million levels. The linearity and reproducibility of response are adequate for practical quantitative applications.

Determination of chlorthalidone and clonidine hydrochloride in tablets by HPLC

A rapid, reversed-phase high performance liquid chromatographic method is described for the determination of chlorthalidone and clonidine hydrochloride combinations in tablets. Individual tablets or composite samples were sonicated in water, diluted with methanol, and filtered prior to chromatographing. Chlorthalidone, formulated at 15 mg/tablet, was chromatographed on octadecylsilyl-bonded, 5 to 6-micrometers, spherical silica with 50% methanol in water mobile phase. Clonidine hydrochloride, formulated at 0.1 or 0.2 mg/tablet, was chromatographed on trimethylsilyl-bonded, 5 to 6-micrometers, spherical silica with 65% methanol in pH 7.9 phosphate buffer mobile phase. Both were determined with a spectrophotometric detector at 254 nm. Mean recoveries of the drugs from six synthetic tablet samples were 100.3% for chlorthalidone and 99.7% for clonidine hydrochloride (at 0.1 mg/tablet level) with coefficients of variation of 0.79 and 1.55%, respectively.

Influence of pH on hydrolytic decomposition of diethylpropion hydrochloride: stability studies on drug substance and tablets using high-performance liquid chromatography

The influence of pH on the hydrolysis of diethylpropion hydrochloride was investigated. Hydrolytic decomposition of the drug in solution at 45 degrees occurred at a very slow and constant rate at pH 3.5 and below but increased rapidly as the pH was raised above 3.5. Results of stability studies performed on six commercial tablet products from five manufacturers showed a similar relationship between the decomposition rate and the formulation pH. A reaction pathway based on the formation of an enamine structure is proposed for the pH-dependent hydrolysis. A high-performance liquid chromatographic assay for the drug is presented, which also separates and detects the hydrolysis product 1-phenyl-1,2-propanedione and the compound assumed to be the enol tautomer of this product.

Determination of diphenoxylate hydrochloride and atropine sulfate in solutions and tablets

Methods for the determination of diphenoxylate hydrochloride and atropine sulfate combinations in solutions and powdered tablet composites are presented. A semiautomated assay for diphenoxylate hydrochloride in individual tablets (content uniformity) also is presented. The USP XIX assays for these products are cumbersome and, in the case of solutions, inaccurate due to spectral interferences; the proposed methods offer substantial improvements in sensitivity, specificity, and speed. Results obtained by the USP and proposed methods are compared for several lots of commercial products. The accuracy and precision of the proposed methods are shown by standard recovery studies.

High-performance liquid chromatographic determination of diethylpropion hydrochloride in tablets: isolation and identification of two decomposition products

A rapid assay was developed for diethylpropion hydrochloride tablets using high-performance liquid chromatography (HPLC) with UV detection. This technique provided separation of the drug from other UV-absorbing components present as the result of decomposition. A major decomposition product detected by HPLC in extracts of tablets and of the cotton filler from a tablet bottle was collected from the column effluents. This product was subsequently identified as 1-phenyl-1,2-propanedione, a highly volatile compound. A second decomposition product, isolated from decomposed drug by distillation from alkaline solution, was identified as diethylamine, apparently present as the hydrochloride salt, GLC, UV, IR, NMR, and mass spectrometry were used to confirm the identity of the decomposition products. HPLC assay results compared favorably with results of the NF assay; the latter procedure separated the drug from 1-phenyl-1,2-propanedione via liquid-liquid extraction.

A Study of Testing Methods for the Detection of Defects in Disposable Latex and Plastic Glovse

Several testing methods for the detection of holes in disposable gloves intended for medical use were investigated. An air inflation method was developed which proved to be the most sensitive and reliable. A survey of the quality of commercially available disposable latex and plastic gloves was conducted in which the air inflation method was compared with the pinhole testing procedure prescribed in the Department of Defense specifications for disposable gloves. The air inflation method gave more reliable results.

Gas-Liquid Chromatographic Analysis of Piperazine as Diacetylpiperazine in Animal Feed

A gas-liquid chromatographic method is presented for the analysis of piperazine in feeds. The feed, containing levels of either 0.11 or 0.25% piperazine, is extracted with water, acetylated, and gas chromatographed, using phenothiazine as an internal standard. Recoveries of piperazine base added to a blank feed ranged from 97.6 to 100.2% with a mean of 99.1%. Results on two commercial feeds compared favorably with the quinone colorimetric method. The procedure is specific, accurate, and not subject to the interferences which cause difficulties in other methods.