Scoring of Solvents Used in Analytical Laboratories by Their Toxicological and Exposure Hazards

Scoring of solvents used in analytical laboratories by their toxicological and exposure hazards

Introduction

Analytical chemistry laboratories consume high-purity sol-vents, which are widely applied in procedures as extraction agents, cleaning agents and mobile phases in liquid chromatography. Solvents mentioned above come from a variety of chemical groups, from polar alcohols to no polar aliphatic or aromatic hydrocarbons and halogenated solvents. Their physicochemical properties are relatively diverse, similarly to their in-halation and oral toxicities, influence on the environment (especially aquatic ecosystem) and the exposure parameters. Preparation of analytical sample solvents consumption, related to this analytical step, is concerned as the most polluting and hazardous of the whole analytical procedure.

Green analytical chemistry is the concept that recently finds more acceptances among the analysts. It assumes that the results of chemical measurements can be obtained with minimizing the consumption of chemicals, reduction of emission and exposure without sacrificing the quality of analytical parameters. Environmental impact is the factor that makes statistical difference between the analytical

Procedures, while parameters like limits of detection, recoveries and precisions are in most of the cases at comparable levels. Green analytical chemistry favors the procedures that minimize their impact by miniaturization, application of solvent less extraction techniques, greener reagents and alternative solvents.

Only few propositions of techniques are known for assessment of the environmental impact or “greenness” of analytical procedures and these include NEMI labeling, analytical Eco-scale, application of HPLC-EAT tool or multivariate statistics. The details of techniques mentioned are accessible in the references and have been discussed recently. All of them are characterized by severe drawbacks, like tedious assessment procedures, lack of data availability as well as lack of information about the structure or nature of the hazards carried by application of the procedure. Still, this field requires new solutions to give easy-to-use, based on easily available information and clear-to-read “greenness” assessment procedures.

The aim of the study is to perform scoring of the solvents commonly used in analytical laboratories with CHEMS-1 model. Such scores can be useful at initial stages of procedure development, when solvents are selected. The scores can be also successfully used as one of the factors when assessing greenness of analytical procedures.

 Method

The CHEMS-1 procedure was developed for relative scoring and ranking of chemicals with respect to their hazard. For the detailed discussion about CHEMS-1 the reader should kindly refer to the source article but brief introduction to the scoring procedure is presented below. Although the CHEMS-1 model was developed to score the risk of using chemicals in industry, we find such approach very attractive for scoring of sol-vents used in analytical laboratories. The procedure considers toxicity of chemicals to human and the environment as well as chemical exposure potential. The input data are toxicological and ecotoxicological endpoints collected from material safety data sheets (MSDS). Such data sources are easily available, which is very important to perform the chemical scoring by potential user. The assessment procedure involves transformation and scaling of the numerical values to give similar weights to each parameter. For non-toxic compounds the value for respective hazard values is set to 0, while for very toxic compounds the hazard value is set to maximum value of 5. Parameters included in the algorithm are hazards related to oral toxicity (HVORAL), inhalation toxicity (HVINH), carcinogenicity (HVCAR), other hazardous effects (HVHE), aquatic acute toxicity (HVFA), aquatic chronic toxicity (HVFC) and exposure-related parameters like biodegrability (HVBOD), hydrolysis (HVHYD) and bioconcentration (HVBCF).

The algorithm to assess the total hazard (tHV) by CHEMS-1 algorithm is multiplication of the sum of hazards related to toxicity by hazards related to exposure factors

tHV =(HVORAL + HVINH + HVCAR + HVHE + HVORAL + HVFA

+ HVFC)*(HVBOD + HVHYD + HVBCF)

The main exposure pathway when solvents are applied in analytical laboratories is inhalation. The original scoring algorithm does not have any term related to exposure via inhalation. The hazard value related to exposure via inhalation could be calculated based on boiling point (BP) or vapor pressure. Both parameters are easily accessible but the operation with boiling points seems to be more convenient. Very volatile solvents (BPo50 °C) are scored by 2.5 while semi-volatile solvents (BP4200 °C) are scored by 1 hazard value. The hazard value, related to the volatility (HVVOL), was calculated with the following formulas:

The algorithm of total analytical hazard value (taHV) calculation is like follows:

taHV =(HVORAL + HVINH + HVCAR + HVHE + HVORAL + HVFA

+ HVFC)*(HVBOD + HVHYD + HVBCF + HVVOL)

Original algorithm included the possibility of weighting hazard values. In this study, however, we apply no weights, as we assume each hazard is equally important. Weighting of hazard values can be applied if there is one dominating exposure pathway or some data are significantly more or less reliable than other.