title: Microscale chemistry-based design of eco-friendly, reagent-saving and efficient pharmaceutical analysis: a miniaturized Volhard's titration for the assay of sodium chloride.
abstract: This work demonstrates the extended application of microscale chemistry which has been used in the educational discipline to the real analytical purposes. Using Volhard's titration for the determination of sodium chloride as a paradigm, the reaction was downscaled to less than 2 mL conducted in commercially available microcentrifuge tubes and using micropipettes for the measurement and transfer of reagents. The equivalence point was determined spectrophotometrically on the microplates which quickened the multi-sample measurements. After the validation and evaluation with bulk and dosage forms, the downsized method showed good accuracy comparable to the British Pharmacopeial macroscale method and gave satisfactory precision (intra-day, inter-day, inter-analyst and inter-equipment) with the relative standard deviation of less than 0.5%. Interestingly, the amount of nitric acid, silver nitrate, ferric alum and ammonium thiocyanate consumed in the miniaturized titration was reduced by the factors of 25, 50, 50 and 215 times, respectively. The use of environmentally dangerous dibutyl phthalate was absolutely eliminated in the proposed method. Furthermore, the release of solid waste silver chloride was drastically reduced by about 25 folds. Therefore, microscale chemistry is an attractive, facile and powerful green strategy for the development of eco-friendly, safe, and cost-effective analytical methods suitable for a sustainable environment.
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand. teerasak@su.ac.th
authors.forename: Theerasak
authors.initials: T
authors.lastname: Rojanarata
authors.forename: Krissadecha
authors.initials: K
authors.lastname: Sumran
authors.forename: Paksupang
authors.initials: P
authors.lastname: Nateetaweewat
authors.forename: Weerapath
authors.initials: W
authors.lastname: Winotapun
authors.forename: Sirarat
authors.initials: S
authors.lastname: Sukpisit
authors.forename: Praneet
authors.initials: P
authors.lastname: Opanasopit
authors.forename: Tanasait
authors.initials: T
authors.lastname: Ngawhirunpat
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry; D003362:Cost-Benefit Analysis; D017753:Ecosystem; D004784:Environmental Monitoring / Q000191:economics / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D008832:Microchemistry / Q000191:economics / Q000379:methods*; D008904:Miniaturization / Q000379:methods; D017942:Nitric Acid / Q000737:chemistry; D018030:Silver Compounds / Q000737:chemistry; D012835:Silver Nitrate / Q000737:chemistry; D012965:Sodium Chloride / Q000032:analysis* / Q000737:chemistry; D013678:Technology, Pharmaceutical / Q000191:economics / Q000379:methods*; D013861:Thiocyanates / Q000737:chemistry; D017186:Titrimetry / Q000379:methods
chemical_list: D017607:Aluminum Compounds; D005290:Ferric Compounds; D007202:Indicators and Reagents; D018030:Silver Compounds; D013861:Thiocyanates; D017942:Nitric Acid; D012965:Sodium Chloride; D012835:Silver Nitrate; C026976:thiocyanic acid; C037548:silver chloride